CELLAR Group S. Lhomme Internet-Draft Intended status: Standards Track M. Bunkus Expires: 13 February 2024 D. Rice 12 August 2023 Matroska Media Container Format Specifications draft-ietf-cellar-matroska-19 Abstract This document defines the Matroska audiovisual data container structure, including definitions of its structural elements, as well as its terminology, vocabulary, and application. This document updates [RFC8794] to permit the use of a previously reserved EBML Element ID. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 13 February 2024. Copyright Notice Copyright (c) 2023 IETF Trust and the persons identified as the document authors. All rights reserved. Lhomme, et al. Expires 13 February 2024 [Page 1] Internet-Draft Matroska Format August 2023 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 6 2. Status of this document . . . . . . . . . . . . . . . . . . . 7 3. Notation and Conventions . . . . . . . . . . . . . . . . . . 7 4. Matroska Overview . . . . . . . . . . . . . . . . . . . . . . 7 4.1. Principles . . . . . . . . . . . . . . . . . . . . . . . 7 4.2. Updates to RFC 8794 . . . . . . . . . . . . . . . . . . . 7 4.3. Added EBML Constraints . . . . . . . . . . . . . . . . . 8 4.4. Design Rules . . . . . . . . . . . . . . . . . . . . . . 9 4.5. Data Layout . . . . . . . . . . . . . . . . . . . . . . . 9 5. Matroska Schema . . . . . . . . . . . . . . . . . . . . . . . 18 5.1. Segment Element . . . . . . . . . . . . . . . . . . . . . 18 5.1.1. SeekHead Element . . . . . . . . . . . . . . . . . . 19 5.1.1.1. Seek Element . . . . . . . . . . . . . . . . . . 19 5.1.2. Info Element . . . . . . . . . . . . . . . . . . . . 19 5.1.2.1. SegmentUUID Element . . . . . . . . . . . . . . . 19 5.1.2.2. SegmentFilename Element . . . . . . . . . . . . . 20 5.1.2.3. PrevUUID Element . . . . . . . . . . . . . . . . 20 5.1.2.4. PrevFilename Element . . . . . . . . . . . . . . 20 5.1.2.5. NextUUID Element . . . . . . . . . . . . . . . . 20 5.1.2.6. NextFilename Element . . . . . . . . . . . . . . 21 5.1.2.7. SegmentFamily Element . . . . . . . . . . . . . . 21 5.1.2.8. ChapterTranslate Element . . . . . . . . . . . . 21 5.1.2.9. TimestampScale Element . . . . . . . . . . . . . 22 5.1.2.10. Duration Element . . . . . . . . . . . . . . . . 23 5.1.2.11. DateUTC Element . . . . . . . . . . . . . . . . . 23 5.1.2.12. Title Element . . . . . . . . . . . . . . . . . . 23 5.1.2.13. MuxingApp Element . . . . . . . . . . . . . . . . 23 5.1.2.14. WritingApp Element . . . . . . . . . . . . . . . 23 5.1.3. Cluster Element . . . . . . . . . . . . . . . . . . . 24 5.1.3.1. Timestamp Element . . . . . . . . . . . . . . . . 24 5.1.3.2. Position Element . . . . . . . . . . . . . . . . 24 5.1.3.3. PrevSize Element . . . . . . . . . . . . . . . . 24 5.1.3.4. SimpleBlock Element . . . . . . . . . . . . . . . 24 5.1.3.5. BlockGroup Element . . . . . . . . . . . . . . . 25 5.1.4. Tracks Element . . . . . . . . . . . . . . . . . . . 28 5.1.4.1. TrackEntry Element . . . . . . . . . . . . . . . 28 5.1.5. Cues Element . . . . . . . . . . . . . . . . . . . . 67 Lhomme, et al. Expires 13 February 2024 [Page 2] Internet-Draft Matroska Format August 2023 5.1.5.1. CuePoint Element . . . . . . . . . . . . . . . . 67 5.1.6. Attachments Element . . . . . . . . . . . . . . . . . 69 5.1.6.1. AttachedFile Element . . . . . . . . . . . . . . 69 5.1.7. Chapters Element . . . . . . . . . . . . . . . . . . 70 5.1.7.1. EditionEntry Element . . . . . . . . . . . . . . 71 5.1.8. Tags Element . . . . . . . . . . . . . . . . . . . . 76 5.1.8.1. Tag Element . . . . . . . . . . . . . . . . . . . 76 6. Matroska Element Ordering . . . . . . . . . . . . . . . . . . 82 6.1. Top-Level Elements . . . . . . . . . . . . . . . . . . . 82 6.2. CRC-32 . . . . . . . . . . . . . . . . . . . . . . . . . 83 6.3. SeekHead . . . . . . . . . . . . . . . . . . . . . . . . 83 6.4. Cues (index) . . . . . . . . . . . . . . . . . . . . . . 83 6.5. Info . . . . . . . . . . . . . . . . . . . . . . . . . . 83 6.6. Chapters Element . . . . . . . . . . . . . . . . . . . . 84 6.7. Attachments . . . . . . . . . . . . . . . . . . . . . . . 84 6.8. Tags . . . . . . . . . . . . . . . . . . . . . . . . . . 84 7. Matroska versioning . . . . . . . . . . . . . . . . . . . . . 84 8. Stream Copy . . . . . . . . . . . . . . . . . . . . . . . . . 85 9. DefaultDecodedFieldDuration . . . . . . . . . . . . . . . . . 86 10. Cluster Blocks . . . . . . . . . . . . . . . . . . . . . . . 86 10.1. Block Structure . . . . . . . . . . . . . . . . . . . . 87 10.2. SimpleBlock Structure . . . . . . . . . . . . . . . . . 88 10.3. Block Lacing . . . . . . . . . . . . . . . . . . . . . . 90 10.3.1. No lacing . . . . . . . . . . . . . . . . . . . . . 90 10.3.2. Xiph lacing . . . . . . . . . . . . . . . . . . . . 91 10.3.3. EBML lacing . . . . . . . . . . . . . . . . . . . . 92 10.3.4. Fixed-size lacing . . . . . . . . . . . . . . . . . 94 10.3.5. Laced Frames Timestamp . . . . . . . . . . . . . . . 94 10.4. Random Access Points . . . . . . . . . . . . . . . . . . 95 11. Timestamps . . . . . . . . . . . . . . . . . . . . . . . . . 98 11.1. Timestamp Ticks . . . . . . . . . . . . . . . . . . . . 99 11.1.1. Matroska Ticks . . . . . . . . . . . . . . . . . . . 99 11.1.2. Segment Ticks . . . . . . . . . . . . . . . . . . . 99 11.1.3. Track Ticks . . . . . . . . . . . . . . . . . . . . 100 11.2. Block Timestamps . . . . . . . . . . . . . . . . . . . . 100 11.3. TimestampScale Rounding . . . . . . . . . . . . . . . . 101 12. Language Codes . . . . . . . . . . . . . . . . . . . . . . . 101 13. Country Codes . . . . . . . . . . . . . . . . . . . . . . . . 102 14. Encryption . . . . . . . . . . . . . . . . . . . . . . . . . 102 15. Image Presentation . . . . . . . . . . . . . . . . . . . . . 103 15.1. Cropping . . . . . . . . . . . . . . . . . . . . . . . . 103 15.2. Rotation . . . . . . . . . . . . . . . . . . . . . . . . 104 16. Segment Position . . . . . . . . . . . . . . . . . . . . . . 104 16.1. Segment Position Exception . . . . . . . . . . . . . . . 104 16.2. Example of Segment Position . . . . . . . . . . . . . . 104 17. Linked Segments . . . . . . . . . . . . . . . . . . . . . . . 105 17.1. Hard Linking . . . . . . . . . . . . . . . . . . . . . . 106 17.2. Medium Linking . . . . . . . . . . . . . . . . . . . . . 108 Lhomme, et al. Expires 13 February 2024 [Page 3] Internet-Draft Matroska Format August 2023 17.2.1. Linked-Duration . . . . . . . . . . . . . . . . . . 109 17.2.2. Linked-Edition . . . . . . . . . . . . . . . . . . . 109 18. Track Flags . . . . . . . . . . . . . . . . . . . . . . . . . 109 18.1. Default flag . . . . . . . . . . . . . . . . . . . . . . 109 18.2. Forced flag . . . . . . . . . . . . . . . . . . . . . . 110 18.3. Hearing-impaired flag . . . . . . . . . . . . . . . . . 110 18.4. Visual-impaired flag . . . . . . . . . . . . . . . . . . 110 18.5. Descriptions flag . . . . . . . . . . . . . . . . . . . 110 18.6. Original flag . . . . . . . . . . . . . . . . . . . . . 110 18.7. Commentary flag . . . . . . . . . . . . . . . . . . . . 110 18.8. Track Operation . . . . . . . . . . . . . . . . . . . . 110 18.9. Overlay Track . . . . . . . . . . . . . . . . . . . . . 111 18.10. Multi-planar and 3D videos . . . . . . . . . . . . . . . 111 19. Default track selection . . . . . . . . . . . . . . . . . . . 112 19.1. Audio Selection . . . . . . . . . . . . . . . . . . . . 112 19.2. Subtitle selection . . . . . . . . . . . . . . . . . . . 114 20. Chapters . . . . . . . . . . . . . . . . . . . . . . . . . . 116 20.1. EditionEntry . . . . . . . . . . . . . . . . . . . . . . 116 20.1.1. EditionFlagDefault . . . . . . . . . . . . . . . . . 116 20.1.2. Default Edition . . . . . . . . . . . . . . . . . . 116 20.1.3. EditionFlagOrdered . . . . . . . . . . . . . . . . . 117 20.1.3.1. Ordered-Edition and Matroska Segment-Linking . . 118 20.2. ChapterAtom . . . . . . . . . . . . . . . . . . . . . . 119 20.2.1. ChapterTimeStart . . . . . . . . . . . . . . . . . . 119 20.2.2. ChapterTimeEnd . . . . . . . . . . . . . . . . . . . 119 20.2.3. Nested Chapters . . . . . . . . . . . . . . . . . . 119 20.2.4. Nested Chapters in Ordered Chapters . . . . . . . . 120 20.2.5. ChapterFlagHidden . . . . . . . . . . . . . . . . . 120 20.3. Menu features . . . . . . . . . . . . . . . . . . . . . 121 20.4. Physical Types . . . . . . . . . . . . . . . . . . . . . 121 20.5. Chapter Examples . . . . . . . . . . . . . . . . . . . . 122 20.5.1. Example 1 : basic chaptering . . . . . . . . . . . . 122 20.5.2. Example 2 : nested chapters . . . . . . . . . . . . 124 20.5.2.1. The Micronauts "Bleep To Bleep" . . . . . . . . 124 21. Attachments . . . . . . . . . . . . . . . . . . . . . . . . . 126 21.1. Cover Art . . . . . . . . . . . . . . . . . . . . . . . 126 21.2. Font files . . . . . . . . . . . . . . . . . . . . . . . 128 22. Cues . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 22.1. Recommendations . . . . . . . . . . . . . . . . . . . . 130 23. Matroska Streaming . . . . . . . . . . . . . . . . . . . . . 130 23.1. File Access . . . . . . . . . . . . . . . . . . . . . . 130 23.2. Livestreaming . . . . . . . . . . . . . . . . . . . . . 131 24. Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 24.1. Tags Precedence . . . . . . . . . . . . . . . . . . . . 132 24.2. Tag Levels . . . . . . . . . . . . . . . . . . . . . . . 133 25. Implementation Recommendations . . . . . . . . . . . . . . . 133 25.1. Cluster . . . . . . . . . . . . . . . . . . . . . . . . 133 25.2. SeekHead . . . . . . . . . . . . . . . . . . . . . . . . 133 Lhomme, et al. Expires 13 February 2024 [Page 4] Internet-Draft Matroska Format August 2023 25.3. Optimum Layouts . . . . . . . . . . . . . . . . . . . . 133 25.3.1. Optimum layout for a muxer . . . . . . . . . . . . . 133 25.3.2. Optimum layout after editing tags . . . . . . . . . 134 25.3.3. Optimum layout with Cues at the front . . . . . . . 134 25.3.4. Optimum layout for livestreaming . . . . . . . . . . 134 26. Security Considerations . . . . . . . . . . . . . . . . . . . 135 27. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 135 27.1. Matroska Element IDs Registry . . . . . . . . . . . . . 136 27.2. Chapter Codec IDs Registry . . . . . . . . . . . . . . . 152 27.3. Media Types . . . . . . . . . . . . . . . . . . . . . . 153 27.3.1. For files containing video tracks . . . . . . . . . 153 27.3.2. For files containing audio tracks with no video tracks . . . . . . . . . . . . . . . . . . . . . . . 154 27.3.3. For files containing a stereoscopic video track . . 154 28. Annex A: Historic Deprecated Elements . . . . . . . . . . . . 155 28.1. SilentTracks Element . . . . . . . . . . . . . . . . . . 155 28.2. SilentTrackNumber Element . . . . . . . . . . . . . . . 156 28.3. BlockVirtual Element . . . . . . . . . . . . . . . . . . 156 28.4. ReferenceVirtual Element . . . . . . . . . . . . . . . . 156 28.5. Slices Element . . . . . . . . . . . . . . . . . . . . . 156 28.6. TimeSlice Element . . . . . . . . . . . . . . . . . . . 156 28.7. LaceNumber Element . . . . . . . . . . . . . . . . . . . 156 28.8. FrameNumber Element . . . . . . . . . . . . . . . . . . 157 28.9. BlockAdditionID Element . . . . . . . . . . . . . . . . 157 28.10. Delay Element . . . . . . . . . . . . . . . . . . . . . 157 28.11. SliceDuration Element . . . . . . . . . . . . . . . . . 157 28.12. ReferenceFrame Element . . . . . . . . . . . . . . . . . 157 28.13. ReferenceOffset Element . . . . . . . . . . . . . . . . 157 28.14. ReferenceTimestamp Element . . . . . . . . . . . . . . . 157 28.15. EncryptedBlock Element . . . . . . . . . . . . . . . . . 158 28.16. MinCache Element . . . . . . . . . . . . . . . . . . . . 158 28.17. MaxCache Element . . . . . . . . . . . . . . . . . . . . 158 28.18. TrackOffset Element . . . . . . . . . . . . . . . . . . 158 28.19. CodecSettings Element . . . . . . . . . . . . . . . . . 158 28.20. CodecInfoURL Element . . . . . . . . . . . . . . . . . . 158 28.21. CodecDownloadURL Element . . . . . . . . . . . . . . . . 159 28.22. CodecDecodeAll Element . . . . . . . . . . . . . . . . . 159 28.23. TrackOverlay Element . . . . . . . . . . . . . . . . . . 159 28.24. AspectRatioType Element . . . . . . . . . . . . . . . . 159 28.25. GammaValue Element . . . . . . . . . . . . . . . . . . . 159 28.26. FrameRate Element . . . . . . . . . . . . . . . . . . . 159 28.27. ChannelPositions Element . . . . . . . . . . . . . . . . 160 28.28. TrickTrackUID Element . . . . . . . . . . . . . . . . . 160 28.29. TrickTrackSegmentUID Element . . . . . . . . . . . . . . 160 28.30. TrickTrackFlag Element . . . . . . . . . . . . . . . . . 160 28.31. TrickMasterTrackUID Element . . . . . . . . . . . . . . 160 28.32. TrickMasterTrackSegmentUID Element . . . . . . . . . . . 160 28.33. ContentSignature Element . . . . . . . . . . . . . . . . 161 Lhomme, et al. Expires 13 February 2024 [Page 5] Internet-Draft Matroska Format August 2023 28.34. ContentSigKeyID Element . . . . . . . . . . . . . . . . 161 28.35. ContentSigAlgo Element . . . . . . . . . . . . . . . . . 161 28.36. ContentSigHashAlgo Element . . . . . . . . . . . . . . . 161 28.37. CueRefCluster Element . . . . . . . . . . . . . . . . . 161 28.38. CueRefNumber Element . . . . . . . . . . . . . . . . . . 161 28.39. CueRefCodecState Element . . . . . . . . . . . . . . . . 161 28.40. FileReferral Element . . . . . . . . . . . . . . . . . . 162 28.41. FileUsedStartTime Element . . . . . . . . . . . . . . . 162 28.42. FileUsedEndTime Element . . . . . . . . . . . . . . . . 162 28.43. TagDefaultBogus Element . . . . . . . . . . . . . . . . 162 29. Normative References . . . . . . . . . . . . . . . . . . . . 162 30. Informative References . . . . . . . . . . . . . . . . . . . 164 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 166 1. Introduction Matroska is an audiovisual data container format. It was derived from a project called [MCF], but diverges from it significantly because it is based on EBML (Extensible Binary Meta Language) [RFC8794], a binary derivative of XML. EBML provides significant advantages in terms of future format extensibility, without breaking file support in old parsers. First, it is essential to clarify exactly "What an Audio/Video container is", to avoid any misunderstandings: * It is NOT a video or audio compression format (codec) * It is an envelope in which there can be many audio, video, and subtitles streams, allowing the user to store a complete movie or CD in a single file. Matroska is designed with the future in mind. It incorporates features such as: * Fast seeking in the file * Chapter entries * Full metadata (tags) support * Selectable subtitle/audio/video streams * Modularly expandable * Error resilience (can recover playback even when the stream is damaged) * Streamable over the internet and local networks (HTTP [RFC9110], FTP [RFC0959], SMB [SMB-CIFS], etc.) * Menus (like DVDs have [DVD-Video]) Lhomme, et al. Expires 13 February 2024 [Page 6] Internet-Draft Matroska Format August 2023 2. Status of this document This document covers Matroska versions 1, 2, 3 and 4. Matroska v4 is the current version. Matroska 1 to 3 are no longer maintained. No new elements are expected in files with version numbers 1, 2, or 3. 3. Notation and Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. This document defines specific terms in order to define the format and application of Matroska. Specific terms are defined below: Matroska: A multimedia container format based on EBML (Extensible Binary Meta Language). Matroska Reader: A data parser that interprets the semantics of a Matroska document and creates a way for programs to use Matroska. Matroska Player: A Matroska Reader with a primary purpose of playing audiovisual files, including Matroska documents. Matroska Writer: A data writer that creates Matroska documents. 4. Matroska Overview 4.1. Principles Matroska is a Document Type of EBML (Extensible Binary Meta Language). This specification is dependent on the EBML Specification [RFC8794]. For an understanding of Matroska's EBML Schema, see in particular the sections of the EBML Specification covering EBML Element Types (Section 7), EBML Schema (Section 11.1), and EBML Structure (Section 3). 4.2. Updates to RFC 8794 Because of an oversight, [RFC8794] reserved EBML ID 0x80, which is used by deployed Matroska implementations. For this reason, this specification updates [RFC8794] to make 0x80 a legal EBML ID. Specifically, the following are changed in [RFC8794]: * From Errata 7189 OLD: Lhomme, et al. Expires 13 February 2024 [Page 7] Internet-Draft Matroska Format August 2023 One-octet Element IDs MUST be between 0x81 and 0xFE. These items are valuable because they are short, and they need to be used for commonly repeated elements. Element IDs are to be allocated within this range according to the "RFC Required" policy [RFC8126]. The following one-octet Element IDs are RESERVED: 0xFF and 0x80. NEW: One-octet Element IDs MUST be between 0x80 and 0xFE. These items are valuable because they are short, and they need to be used for commonly repeated elements. Element IDs are to be allocated within this range according to the "RFC Required" policy [RFC8126]. The following one-octet Element ID is RESERVED: 0xFF. * From Errata 7191 OLD: +=========================+================+=================+ | Element ID Octet Length | Range of Valid | Number of Valid | | | Element IDs | Element IDs | +=========================+================+=================+ | 1 | 0x81 - 0xFE | 126 | +-------------------------+----------------+-----------------+ NEW: +=========================+================+=================+ | Element ID Octet Length | Range of Valid | Number of Valid | | | Element IDs | Element IDs | +=========================+================+=================+ | 1 | 0x80 - 0xFE | 127 | +-------------------------+----------------+-----------------+ 4.3. Added EBML Constraints As an EBML Document Type, Matroska adds the following constraints to the EBML specification. * The docType of the EBML Header MUST be "matroska". * The EBMLMaxIDLength of the EBML Header MUST be 4. * The EBMLMaxSizeLength of the EBML Header MUST be between 1 and 8 inclusive. Lhomme, et al. Expires 13 February 2024 [Page 8] Internet-Draft Matroska Format August 2023 4.4. Design Rules The Root Element and all Top-Levels Elements MUST use 4 octets for their EBML Element ID -- i.e. Segment and direct children of Segment. Legacy EBML/Matroska parsers did not handle Empty Elements properly, elements present in the file but with a length of zero. They always assumed the value was 0 for integers/dates or 0x0p+0, the textual expression of floats using the [ISO9899] format, no matter the default value of the element which should have been used instead. Therefore, Matroska writers MUST NOT use EBML Empty Elements, if the element has a default value that is not 0 for integers/dates and 0x0p+0 for floats. When adding new elements to Matroska, these rules apply: * A non-mandatory integer/date Element MUST NOT have a default value other than 0. * A non-mandatory float Element MUST NOT have a default value other than 0x0p+0. * A non-mandatory string Element MUST NOT have a default value, as empty string cannot be defined in the XML Schema. 4.5. Data Layout A Matroska file MUST be composed of at least one EBML Document using the Matroska Document Type. Each EBML Document MUST start with an EBML Header and MUST be followed by the EBML Root Element, defined as Segment in Matroska. Matroska defines several Top-Level Elements which may occur within the Segment. As an example, a simple Matroska file consisting of a single EBML Document could be represented like this: * EBML Header * Segment A more complex Matroska file consisting of an EBML Stream (consisting of two EBML Documents) could be represented like this: * EBML Header * Segment * EBML Header * Segment The following diagram represents a simple Matroska file, comprised of an EBML Document with an EBML Header, a Segment Element (the Root Element), and all eight Matroska Top-Level Elements. In the Lhomme, et al. Expires 13 February 2024 [Page 9] Internet-Draft Matroska Format August 2023 following diagrams of this section, horizontal spacing expresses a parent-child relationship between Matroska Elements (e.g., the Info Element is contained within the Segment Element) whereas vertical alignment represents the storage order within the file. +-------------+ | EBML Header | +---------------------------+ | Segment | SeekHead | | |-------------| | | Info | | |-------------| | | Tracks | | |-------------| | | Chapters | | |-------------| | | Cluster | | |-------------| | | Cues | | |-------------| | | Attachments | | |-------------| | | Tags | +---------------------------+ Figure 1: Basic layout of a Matroska file. The Matroska EBML Schema defines eight Top-Level Elements: * SeekHead (Section 6.3), * Info (Section 6.5), * Tracks (Section 18), * Chapters (Section 20), * Cluster (Section 10), * Cues (Section 22), * Attachments (Section 21), * and Tags (Section 6.8). The SeekHead Element (also known as MetaSeek) contains an index of Top-Level Elements locations within the Segment. Use of the SeekHead Element is RECOMMENDED. Without a SeekHead Element, a Matroska parser would have to search the entire file to find all of the other Top-Level Elements. This is due to Matroska's flexible ordering requirements; for instance, it is acceptable for the Chapters Element to be stored after the Cluster Elements. Lhomme, et al. Expires 13 February 2024 [Page 10] Internet-Draft Matroska Format August 2023 +--------------------------------+ | SeekHead | Seek | SeekID | | | |--------------| | | | SeekPosition | +--------------------------------+ Figure 2: Representation of a SeekHead Element. The Info Element contains vital information for identifying the whole Segment. This includes the title for the Segment, a randomly generated unique identifier, and the unique identifier(s) of any linked Segment Elements. +-------------------------+ | Info | SegmentUUID | | |------------------| | | SegmentFilename | | |------------------| | | PrevUUID | | |------------------| | | PrevFilename | | |------------------| | | NextUUID | | |------------------| | | NextFilename | | |------------------| | | SegmentFamily | | |------------------| | | ChapterTranslate | | |------------------| | | TimestampScale | | |------------------| | | Duration | | |------------------| | | DateUTC | | |------------------| | | Title | | |------------------| | | MuxingApp | | |------------------| | | WritingApp | |-------------------------| Figure 3: Representation of an Info Element and its Child Elements. Lhomme, et al. Expires 13 February 2024 [Page 11] Internet-Draft Matroska Format August 2023 The Tracks Element defines the technical details for each track and can store the name, number, unique identifier, language, and type (audio, video, subtitles, etc.) of each track. For example, the Tracks Element MAY store information about the resolution of a video track or sample rate of an audio track. The Tracks Element MUST identify all the data needed by the codec to decode the data of the specified track. However, the data required is contingent on the codec used for the track. For example, a Track Element for uncompressed audio only requires the audio bit rate to be present. A codec such as AC-3 would require that the CodecID Element be present for all tracks, as it is the primary way to identify which codec to use to decode the track. Lhomme, et al. Expires 13 February 2024 [Page 12] Internet-Draft Matroska Format August 2023 +------------------------------------+ | Tracks | TrackEntry | TrackNumber | | | |--------------| | | | TrackUID | | | |--------------| | | | TrackType | | | |--------------| | | | Name | | | |--------------| | | | Language | | | |--------------| | | | CodecID | | | |--------------| | | | CodecPrivate | | | |--------------| | | | CodecName | | | |----------------------------------+ | | | Video | FlagInterlaced | | | | |-------------------| | | | | FieldOrder | | | | |-------------------| | | | | StereoMode | | | | |-------------------| | | | | AlphaMode | | | | |-------------------| | | | | PixelWidth | | | | |-------------------| | | | | PixelHeight | | | | |-------------------| | | | | DisplayWidth | | | | |-------------------| | | | | DisplayHeight | | | | |-------------------| | | | | AspectRatioType | | | | |-------------------| | | | | Color | | | |----------------------------------| | | | Audio | SamplingFrequency | | | | |-------------------| | | | | Channels | | | | |-------------------| | | | | BitDepth | |--------------------------------------------------------| Figure 4: Representation of the Tracks Element and a selection of its Descendant Elements. Lhomme, et al. Expires 13 February 2024 [Page 13] Internet-Draft Matroska Format August 2023 The Chapters Element lists all of the chapters. Chapters are a way to set predefined points to jump to in video or audio. +-----------------------------------------+ | Chapters | Edition | EditionUID | | | Entry |--------------------| | | | EditionFlagDefault | | | |--------------------| | | | EditionFlagOrdered | | | |---------------------------------+ | | | ChapterAtom | ChapterUID | | | | |-------------------| | | | | ChapterStringUID | | | | |-------------------| | | | | ChapterTimeStart | | | | |-------------------| | | | | ChapterTimeEnd | | | | |-------------------| | | | | ChapterFlagHidden | | | | |-------------------------------+ | | | | ChapterDisplay | ChapString | | | | | |--------------| | | | | | ChapLanguage | +------------------------------------------------------------------+ Figure 5: Representation of the Chapters Element and a selection of its Descendant Elements. Cluster Elements contain the content for each track, e.g., video frames. A Matroska file SHOULD contain at least one Cluster Element. In the rare case it doesn't, there should be a form of Segment linking with other Segments, possibly using Chapters, see Section 17. The Cluster Element helps to break up SimpleBlock or BlockGroup Elements and helps with seeking and error protection. Every Cluster Element MUST contain a Timestamp Element. This SHOULD be the Timestamp Element used to play the first Block in the Cluster Element, unless a different value is needed to accommodate for more Blocks, see Section 11.2. Cluster Elements contain one or more block element, such as BlockGroup or SimpleBlock elements. In some situations, a Cluster Element MAY contain no block element, for example in a live recording when no data has been collected. A BlockGroup Element MAY contain a Block of data and any information relating directly to that Block. Lhomme, et al. Expires 13 February 2024 [Page 14] Internet-Draft Matroska Format August 2023 +--------------------------+ | Cluster | Timestamp | | |----------------| | | Position | | |----------------| | | PrevSize | | |----------------| | | SimpleBlock | | |----------------| | | BlockGroup | +--------------------------+ Figure 6: Representation of a Cluster Element and its immediate Child Elements. +----------------------------------+ | Block | Portion of | Data Type | | | a Block | - Bit Flag | | |--------------------------+ | | Header | TrackNumber | | | |-------------| | | | Timestamp | | | |-------------| | | | Flags | | | | - Gap | | | | - Lacing | | | | - Reserved | | |--------------------------| | | Optional | FrameSize | | |--------------------------| | | Data | Frame | +----------------------------------+ Figure 7: Representation of the Block Element structure. Each Cluster MUST contain exactly one Timestamp Element. The Timestamp Element value MUST be stored once per Cluster. The Timestamp Element in the Cluster is relative to the entire Segment. The Timestamp Element SHOULD be the first Element in the Cluster it belongs to, or the second Element if that Cluster contains a CRC-32 element (Section 6.2) Lhomme, et al. Expires 13 February 2024 [Page 15] Internet-Draft Matroska Format August 2023 Additionally, the Block contains an offset that, when added to the Cluster's Timestamp Element value, yields the Block's effective timestamp. Therefore, timestamp in the Block itself is relative to the Timestamp Element in the Cluster. For example, if the Timestamp Element in the Cluster is set to 10 seconds and a Block in that Cluster is supposed to be played 12 seconds into the clip, the timestamp in the Block would be set to 2 seconds. The ReferenceBlock in the BlockGroup is used instead of the basic "P-frame"/"B-frame" description. Instead of simply saying that this Block depends on the Block directly before, or directly afterwards, the Timestamp of the necessary Block is used. Because there can be as many ReferenceBlock Elements as necessary for a Block, it allows for some extremely complex referencing. The Cues Element is used to seek when playing back a file by providing a temporal index for some of the Tracks. It is similar to the SeekHead Element, but used for seeking to a specific time when playing back the file. It is possible to seek without this element, but it is much more difficult because a Matroska Reader would have to 'hunt and peck' through the file looking for the correct timestamp. The Cues Element SHOULD contain at least one CuePoint Element. Each CuePoint Element stores the position of the Cluster that contains the BlockGroup or SimpleBlock Element. The timestamp is stored in the CueTime Element and location is stored in the CueTrackPositions Element. The Cues Element is flexible. For instance, Cues Element can be used to index every single timestamp of every Block or they can be indexed selectively. +-------------------------------------+ | Cues | CuePoint | CueTime | | | |-------------------| | | | CueTrackPositions | | |------------------------------| | | CuePoint | CueTime | | | |-------------------| | | | CueTrackPositions | +-------------------------------------+ Figure 8: Representation of a Cues Element and two levels of its Descendant Elements. The Attachments Element is for attaching files to a Matroska file such as pictures, fonts, webpages, etc. Lhomme, et al. Expires 13 February 2024 [Page 16] Internet-Draft Matroska Format August 2023 +------------------------------------------------+ | Attachments | AttachedFile | FileDescription | | | |-------------------| | | | FileName | | | |-------------------| | | | FileMediaType | | | |-------------------| | | | FileData | | | |-------------------| | | | FileUID | | | |-------------------| | | | FileName | | | |-------------------| | | | FileReferral | | | |-------------------| | | | FileUsedStartTime | | | |-------------------| | | | FileUsedEndTime | +------------------------------------------------+ Figure 9: Representation of an Attachments Element. The Tags Element contains metadata that describes the Segment and potentially its Tracks, Chapters, and Attachments. Each Track or Chapter that those tags applies to has its UID listed in the Tags. The Tags contain all extra information about the file: scriptwriter, singer, actors, directors, titles, edition, price, dates, genre, comments, etc. Tags can contain their values in multiple languages. For example, a movie's "title" Tag might contain both the original English title as well as the title it was released as in Germany. Lhomme, et al. Expires 13 February 2024 [Page 17] Internet-Draft Matroska Format August 2023 +-------------------------------------------+ | Tags | Tag | Targets | TargetTypeValue | | | | |------------------| | | | | TargetType | | | | |------------------| | | | | TagTrackUID | | | | |------------------| | | | | TagEditionUID | | | | |------------------| | | | | TagChapterUID | | | | |------------------| | | | | TagAttachmentUID | | | |------------------------------| | | | SimpleTag | TagName | | | | |------------------| | | | | TagLanguage | | | | |------------------| | | | | TagDefault | | | | |------------------| | | | | TagString | | | | |------------------| | | | | TagBinary | | | | |------------------| | | | | SimpleTag | +-------------------------------------------+ Figure 10: Representation of a Tags Element and three levels of its Children Elements. 5. Matroska Schema This specification includes an EBML Schema, which defines the Elements and structure of Matroska using the EBML Schema elements and attributes defined in Section 11.1 of [RFC8794]. The EBML Schema defines every valid Matroska element in a manner defined by the EBML specification. Here the definition of each Matroska Element is provided. 5.1. Segment Element id / type: 0x18538067 / master unknownsizeallowed: True path: \Segment minOccurs / maxOccurs: 1 / 1 definition: The Root Element that contains all other Top-Level Lhomme, et al. Expires 13 February 2024 [Page 18] Internet-Draft Matroska Format August 2023 Elements; see Section 4.5. 5.1.1. SeekHead Element id / type: 0x114D9B74 / master path: \Segment\SeekHead maxOccurs: 2 definition: Contains seeking information of Top-Level Elements; see Section 4.5. 5.1.1.1. Seek Element id / type: 0x4DBB / master path: \Segment\SeekHead\Seek minOccurs: 1 definition: Contains a single seek entry to an EBML Element. 5.1.1.1.1. SeekID Element id / type: 0x53AB / binary length: 4 path: \Segment\SeekHead\Seek\SeekID minOccurs / maxOccurs: 1 / 1 definition: The binary EBML ID of a Top-Level Element. 5.1.1.1.2. SeekPosition Element id / type: 0x53AC / uinteger path: \Segment\SeekHead\Seek\SeekPosition minOccurs / maxOccurs: 1 / 1 definition: The Segment Position (Section 16) of a Top-Level Element. 5.1.2. Info Element id / type: 0x1549A966 / master path: \Segment\Info minOccurs / maxOccurs: 1 / 1 recurring: True definition: Contains general information about the Segment. 5.1.2.1. SegmentUUID Element id / type: 0x73A4 / binary length: 16 path: \Segment\Info\SegmentUUID Lhomme, et al. Expires 13 February 2024 [Page 19] Internet-Draft Matroska Format August 2023 maxOccurs: 1 definition: A randomly generated unique ID to identify the Segment amongst many others (128 bits). It is equivalent to a UUID v4 [RFC4122] with all bits randomly (or pseudo-randomly) chosen. An actual UUID v4 value, where some bits are not random, MAY also be used. usage notes: If the Segment is a part of a Linked Segment, then this Element is REQUIRED. The value of the unique ID MUST contain at least one bit set to 1. 5.1.2.2. SegmentFilename Element id / type: 0x7384 / utf-8 path: \Segment\Info\SegmentFilename maxOccurs: 1 definition: A filename corresponding to this Segment. 5.1.2.3. PrevUUID Element id / type: 0x3CB923 / binary length: 16 path: \Segment\Info\PrevUUID maxOccurs: 1 definition: An ID to identify the previous Segment of a Linked Segment. usage notes: If the Segment is a part of a Linked Segment that uses Hard Linking (Section 17.1), then either the PrevUUID or the NextUUID Element is REQUIRED. If a Segment contains a PrevUUID but not a NextUUID, then it MAY be considered as the last Segment of the Linked Segment. The PrevUUID MUST NOT be equal to the SegmentUUID. 5.1.2.4. PrevFilename Element id / type: 0x3C83AB / utf-8 path: \Segment\Info\PrevFilename maxOccurs: 1 definition: A filename corresponding to the file of the previous Linked Segment. usage notes: Provision of the previous filename is for display convenience, but PrevUUID SHOULD be considered authoritative for identifying the previous Segment in a Linked Segment. 5.1.2.5. NextUUID Element id / type: 0x3EB923 / binary length: 16 path: \Segment\Info\NextUUID Lhomme, et al. Expires 13 February 2024 [Page 20] Internet-Draft Matroska Format August 2023 maxOccurs: 1 definition: An ID to identify the next Segment of a Linked Segment. usage notes: If the Segment is a part of a Linked Segment that uses Hard Linking (Section 17.1), then either the PrevUUID or the NextUUID Element is REQUIRED. If a Segment contains a NextUUID but not a PrevUUID, then it MAY be considered as the first Segment of the Linked Segment. The NextUUID MUST NOT be equal to the SegmentUUID. 5.1.2.6. NextFilename Element id / type: 0x3E83BB / utf-8 path: \Segment\Info\NextFilename maxOccurs: 1 definition: A filename corresponding to the file of the next Linked Segment. usage notes: Provision of the next filename is for display convenience, but NextUUID SHOULD be considered authoritative for identifying the Next Segment. 5.1.2.7. SegmentFamily Element id / type: 0x4444 / binary length: 16 path: \Segment\Info\SegmentFamily definition: A unique ID that all Segments of a Linked Segment MUST share (128 bits). It is equivalent to a UUID v4 [RFC4122] with all bits randomly (or pseudo-randomly) chosen. An actual UUID v4 value, where some bits are not random, MAY also be used. usage notes: If the Segment Info contains a ChapterTranslate element, this Element is REQUIRED. 5.1.2.8. ChapterTranslate Element id / type: 0x6924 / master path: \Segment\Info\ChapterTranslate definition: The mapping between this Segment and a segment value in the given Chapter Codec. rationale: Chapter Codec may need to address different segments, but they may not know of the way to identify such segment when stored in Matroska. This element and its child elements add a way to map the internal segments known to the Chapter Codec to the Segment IDs in Matroska. This allows remuxing a file with Chapter Codec without changing the content of the codec data, just the Segment mapping. Lhomme, et al. Expires 13 February 2024 [Page 21] Internet-Draft Matroska Format August 2023 5.1.2.8.1. ChapterTranslateID Element id / type: 0x69A5 / binary path: \Segment\Info\ChapterTranslate\ChapterTranslateID minOccurs / maxOccurs: 1 / 1 definition: The binary value used to represent this Segment in the chapter codec data. The format depends on the ChapProcessCodecID used; see Section 5.1.7.1.4.15. 5.1.2.8.2. ChapterTranslateCodec Element id / type: 0x69BF / uinteger path: \Segment\Info\ChapterTranslate\ChapterTranslateCodec minOccurs / maxOccurs: 1 / 1 definition: This ChapterTranslate applies to this chapter codec of the given chapter edition(s); see Section 5.1.7.1.4.15. defined values: +=======+=================+============================+ | value | label | definition | +=======+=================+============================+ | 0 | Matroska Script | Chapter commands using the | | | | Matroska Script codec. | +-------+-----------------+----------------------------+ | 1 | DVD-menu | Chapter commands using the | | | | DVD-like codec. | +-------+-----------------+----------------------------+ Table 1: ChapterTranslateCodec values 5.1.2.8.3. ChapterTranslateEditionUID Element id / type: 0x69FC / uinteger path: \Segment\Info\ChapterTranslate\ChapterTranslateEditionUID definition: Specify a chapter edition UID on which this ChapterTranslate applies. usage notes: When no ChapterTranslateEditionUID is specified in the ChapterTranslate, the ChapterTranslate applies to all chapter editions found in the Segment using the given ChapterTranslateCodec. 5.1.2.9. TimestampScale Element id / type / default: 0x2AD7B1 / uinteger / 1000000 range: not 0 path: \Segment\Info\TimestampScale minOccurs / maxOccurs: 1 / 1 Lhomme, et al. Expires 13 February 2024 [Page 22] Internet-Draft Matroska Format August 2023 definition: Base unit for Segment Ticks and Track Ticks, in nanoseconds. A TimestampScale value of 1000000 means scaled timestamps in the Segment are expressed in milliseconds; see Section 11 on how to interpret timestamps. 5.1.2.10. Duration Element id / type: 0x4489 / float range: > 0x0p+0 path: \Segment\Info\Duration maxOccurs: 1 definition: Duration of the Segment, expressed in Segment Ticks which is based on TimestampScale; see Section 11.1. 5.1.2.11. DateUTC Element id / type: 0x4461 / date path: \Segment\Info\DateUTC maxOccurs: 1 definition: The date and time that the Segment was created by the muxing application or library. 5.1.2.12. Title Element id / type: 0x7BA9 / utf-8 path: \Segment\Info\Title maxOccurs: 1 definition: General name of the Segment. 5.1.2.13. MuxingApp Element id / type: 0x4D80 / utf-8 path: \Segment\Info\MuxingApp minOccurs / maxOccurs: 1 / 1 definition: Muxing application or library (example: "libmatroska- 0.4.3"). usage notes: Include the full name of the application or library followed by the version number. 5.1.2.14. WritingApp Element id / type: 0x5741 / utf-8 path: \Segment\Info\WritingApp minOccurs / maxOccurs: 1 / 1 definition: Writing application (example: "mkvmerge-0.3.3"). usage notes: Include the full name of the application followed by the version number. Lhomme, et al. Expires 13 February 2024 [Page 23] Internet-Draft Matroska Format August 2023 5.1.3. Cluster Element id / type: 0x1F43B675 / master unknownsizeallowed: True path: \Segment\Cluster definition: The Top-Level Element containing the (monolithic) Block structure. 5.1.3.1. Timestamp Element id / type: 0xE7 / uinteger path: \Segment\Cluster\Timestamp minOccurs / maxOccurs: 1 / 1 definition: Absolute timestamp of the cluster, expressed in Segment Ticks which is based on TimestampScale; see Section 11.1. usage notes: This element SHOULD be the first child element of the Cluster it belongs to, or the second if that Cluster contains a CRC-32 element (Section 6.2). 5.1.3.2. Position Element id / type: 0xA7 / uinteger path: \Segment\Cluster\Position maxOccurs: 1 maxver: 4 definition: The Segment Position of the Cluster in the Segment (0 in live streams). It might help to resynchronise offset on damaged streams. 5.1.3.3. PrevSize Element id / type: 0xAB / uinteger path: \Segment\Cluster\PrevSize maxOccurs: 1 definition: Size of the previous Cluster, in octets. Can be useful for backward playing. 5.1.3.4. SimpleBlock Element id / type: 0xA3 / binary path: \Segment\Cluster\SimpleBlock minver: 2 definition: Similar to Block, see Section 10.1, but without all the extra information, mostly used to reduced overhead when no extra feature is needed; see Section 10.2 on SimpleBlock Structure. Lhomme, et al. Expires 13 February 2024 [Page 24] Internet-Draft Matroska Format August 2023 5.1.3.5. BlockGroup Element id / type: 0xA0 / master path: \Segment\Cluster\BlockGroup definition: Basic container of information containing a single Block and information specific to that Block. 5.1.3.5.1. Block Element id / type: 0xA1 / binary path: \Segment\Cluster\BlockGroup\Block minOccurs / maxOccurs: 1 / 1 definition: Block containing the actual data to be rendered and a timestamp relative to the Cluster Timestamp; see Section 10.1 on Block Structure. 5.1.3.5.2. BlockAdditions Element id / type: 0x75A1 / master path: \Segment\Cluster\BlockGroup\BlockAdditions maxOccurs: 1 definition: Contain additional binary data to complete the main one; see Codec BlockAdditions section of [MatroskaCodec] for more information. An EBML parser that has no knowledge of the Block structure could still see and use/skip these data. 5.1.3.5.2.1. BlockMore Element id / type: 0xA6 / master path: \Segment\Cluster\BlockGroup\BlockAdditions\BlockMore minOccurs: 1 definition: Contain the BlockAdditional and some parameters. 5.1.3.5.2.2. BlockAdditional Element id / type: 0xA5 / binary path: \Segment\Cluster\BlockGroup\BlockAdditions\BlockMore\BlockAddi tional minOccurs / maxOccurs: 1 / 1 definition: Interpreted by the codec as it wishes (using the BlockAddID). 5.1.3.5.2.3. BlockAddID Element id / type / default: 0xEE / uinteger / 1 range: not 0 path: \Segment\Cluster\BlockGroup\BlockAdditions\BlockMore\BlockAddI D Lhomme, et al. Expires 13 February 2024 [Page 25] Internet-Draft Matroska Format August 2023 minOccurs / maxOccurs: 1 / 1 definition: An ID to identify how to interpret the BlockAdditional data; see Codec BlockAdditions section of [MatroskaCodec] for more information. A value of 1 indicates that the meaning of the BlockAdditional data is defined by the codec. Any other value indicates the meaning of the BlockAdditional data is found in the BlockAddIDType found in the TrackEntry. usage notes: Each BlockAddID value MUST be unique between all BlockMore elements found in a BlockAdditions. usage notes: To keep MaxBlockAdditionID as low as possible, small values SHOULD be used. 5.1.3.5.3. BlockDuration Element id / type: 0x9B / uinteger path: \Segment\Cluster\BlockGroup\BlockDuration minOccurs / maxOccurs: see implementation notes / 1 definition: The duration of the Block, expressed in Track Ticks; see Section 11.1. The BlockDuration Element can be useful at the end of a Track to define the duration of the last frame (as there is no subsequent Block available), or when there is a break in a track like for subtitle tracks. notes: +===========+===================================================+ | attribute | note | +===========+===================================================+ | minOccurs | BlockDuration MUST be set (minOccurs=1) if the | | | associated TrackEntry stores a DefaultDuration | | | value. | +-----------+---------------------------------------------------+ | default | When not written and with no DefaultDuration, the | | | value is assumed to be the difference between the | | | timestamp of this Block and the timestamp of the | | | next Block in "display" order (not coding order). | +-----------+---------------------------------------------------+ Table 2: BlockDuration implementation notes 5.1.3.5.4. ReferencePriority Element id / type / default: 0xFA / uinteger / 0 path: \Segment\Cluster\BlockGroup\ReferencePriority minOccurs / maxOccurs: 1 / 1 definition: This frame is referenced and has the specified cache Lhomme, et al. Expires 13 February 2024 [Page 26] Internet-Draft Matroska Format August 2023 priority. In cache only a frame of the same or higher priority can replace this frame. A value of 0 means the frame is not referenced. 5.1.3.5.5. ReferenceBlock Element id / type: 0xFB / integer path: \Segment\Cluster\BlockGroup\ReferenceBlock definition: A timestamp value, relative to the timestamp of the Block in this BlockGroup, expressed in Track Ticks; see Section 11.1. This is used to reference other frames necessary to decode this frame. The relative value SHOULD correspond to a valid Block this Block depends on. Historically Matroska Writer didn't write the actual Block(s) this Block depends on, but _some_ Block in the past. The value "0" MAY also be used to signify this Block cannot be decoded on its own, but without knownledge of which Block is necessary. In this case, other ReferenceBlock MUST NOT be found in the same BlockGroup. If the BlockGroup doesn't have any ReferenceBlock element, then the Block it contains can be decoded without using any other Block data. 5.1.3.5.6. CodecState Element id / type: 0xA4 / binary path: \Segment\Cluster\BlockGroup\CodecState maxOccurs: 1 minver: 2 definition: The new codec state to use. Data interpretation is private to the codec. This information SHOULD always be referenced by a seek entry. 5.1.3.5.7. DiscardPadding Element id / type: 0x75A2 / integer path: \Segment\Cluster\BlockGroup\DiscardPadding maxOccurs: 1 minver: 4 definition: Duration of the silent data added to the Block, expressed in Matroska Ticks -- i.e., in nanoseconds; see Section 11.1 (padding at the end of the Block for positive value, at the beginning of the Block for negative value). The duration of DiscardPadding is not calculated in the duration of the TrackEntry and SHOULD be discarded during playback. Lhomme, et al. Expires 13 February 2024 [Page 27] Internet-Draft Matroska Format August 2023 5.1.4. Tracks Element id / type: 0x1654AE6B / master path: \Segment\Tracks maxOccurs: 1 recurring: True definition: A Top-Level Element of information with many tracks described. 5.1.4.1. TrackEntry Element id / type: 0xAE / master path: \Segment\Tracks\TrackEntry minOccurs: 1 definition: Describes a track with all Elements. 5.1.4.1.1. TrackNumber Element id / type: 0xD7 / uinteger range: not 0 path: \Segment\Tracks\TrackEntry\TrackNumber minOccurs / maxOccurs: 1 / 1 definition: The track number as used in the Block Header. 5.1.4.1.2. TrackUID Element id / type: 0x73C5 / uinteger range: not 0 path: \Segment\Tracks\TrackEntry\TrackUID minOccurs / maxOccurs: 1 / 1 definition: A unique ID to identify the Track. stream copy: True (Section 8) 5.1.4.1.3. TrackType Element id / type: 0x83 / uinteger path: \Segment\Tracks\TrackEntry\TrackType minOccurs / maxOccurs: 1 / 1 definition: The TrackType defines the type of each frame found in the Track. The value SHOULD be stored on 1 octet. defined values: Lhomme, et al. Expires 13 February 2024 [Page 28] Internet-Draft Matroska Format August 2023 +=======+==========+==========================================+ | value | label | each frame contains | +=======+==========+==========================================+ | 1 | video | An image. | +-------+----------+------------------------------------------+ | 2 | audio | Audio samples. | +-------+----------+------------------------------------------+ | 3 | complex | A mix of different other TrackType. The | | | | codec needs to define how the Matroska | | | | Player should interpret such data. | +-------+----------+------------------------------------------+ | 16 | logo | An image to be rendered over the video | | | | track(s). | +-------+----------+------------------------------------------+ | 17 | subtitle | Subtitle or closed caption data to be | | | | rendered over the video track(s). | +-------+----------+------------------------------------------+ | 18 | buttons | Interactive button(s) to be rendered | | | | over the video track(s). | +-------+----------+------------------------------------------+ | 32 | control | Metadata used to control the player of | | | | the Matroska Player. | +-------+----------+------------------------------------------+ | 33 | metadata | Timed metadata that can be passed on to | | | | the Matroska Player. | +-------+----------+------------------------------------------+ Table 3: TrackType values stream copy: True (Section 8) 5.1.4.1.4. FlagEnabled Element id / type / default: 0xB9 / uinteger / 1 range: 0-1 path: \Segment\Tracks\TrackEntry\FlagEnabled minOccurs / maxOccurs: 1 / 1 minver: 2 definition: Set to 1 if the track is usable. It is possible to turn a not usable track into a usable track using chapter codecs or control tracks. 5.1.4.1.5. FlagDefault Element id / type / default: 0x88 / uinteger / 1 range: 0-1 path: \Segment\Tracks\TrackEntry\FlagDefault minOccurs / maxOccurs: 1 / 1 Lhomme, et al. Expires 13 February 2024 [Page 29] Internet-Draft Matroska Format August 2023 definition: Set if that track (audio, video or subs) is eligible for automatic selection by the player; see Section 19 for more details. 5.1.4.1.6. FlagForced Element id / type / default: 0x55AA / uinteger / 0 range: 0-1 path: \Segment\Tracks\TrackEntry\FlagForced minOccurs / maxOccurs: 1 / 1 definition: Applies only to subtitles. Set if that track is eligible for automatic selection by the player if it matches the user's language preference, even if the user's preferences would normally not enable subtitles with the selected audio track; this can be used for tracks containing only translations of foreign- language audio or onscreen text. See Section 19 for more details. 5.1.4.1.7. FlagHearingImpaired Element id / type: 0x55AB / uinteger range: 0-1 path: \Segment\Tracks\TrackEntry\FlagHearingImpaired maxOccurs: 1 minver: 4 definition: Set to 1 if and only if that track is suitable for users with hearing impairments. 5.1.4.1.8. FlagVisualImpaired Element id / type: 0x55AC / uinteger range: 0-1 path: \Segment\Tracks\TrackEntry\FlagVisualImpaired maxOccurs: 1 minver: 4 definition: Set to 1 if and only if that track is suitable for users with visual impairments. 5.1.4.1.9. FlagTextDescriptions Element id / type: 0x55AD / uinteger range: 0-1 path: \Segment\Tracks\TrackEntry\FlagTextDescriptions maxOccurs: 1 minver: 4 definition: Set to 1 if and only if that track contains textual descriptions of video content. Lhomme, et al. Expires 13 February 2024 [Page 30] Internet-Draft Matroska Format August 2023 5.1.4.1.10. FlagOriginal Element id / type: 0x55AE / uinteger range: 0-1 path: \Segment\Tracks\TrackEntry\FlagOriginal maxOccurs: 1 minver: 4 definition: Set to 1 if and only if that track is in the content's original language. 5.1.4.1.11. FlagCommentary Element id / type: 0x55AF / uinteger range: 0-1 path: \Segment\Tracks\TrackEntry\FlagCommentary maxOccurs: 1 minver: 4 definition: Set to 1 if and only if that track contains commentary. 5.1.4.1.12. FlagLacing Element id / type / default: 0x9C / uinteger / 1 range: 0-1 path: \Segment\Tracks\TrackEntry\FlagLacing minOccurs / maxOccurs: 1 / 1 definition: Set to 1 if the track MAY contain blocks using lacing. When set to 0 all blocks MUST have their lacing flags set to No lacing; see Section 10.3 on Block Lacing. 5.1.4.1.13. DefaultDuration Element id / type: 0x23E383 / uinteger range: not 0 path: \Segment\Tracks\TrackEntry\DefaultDuration maxOccurs: 1 definition: Number of nanoseconds per frame, expressed in Matroska Ticks -- i.e., in nanoseconds; see Section 11.1 (frame in the Matroska sense -- one Element put into a (Simple)Block). stream copy: True (Section 8) 5.1.4.1.14. DefaultDecodedFieldDuration Element id / type: 0x234E7A / uinteger range: not 0 path: \Segment\Tracks\TrackEntry\DefaultDecodedFieldDuration maxOccurs: 1 minver: 4 Lhomme, et al. Expires 13 February 2024 [Page 31] Internet-Draft Matroska Format August 2023 definition: The period between two successive fields at the output of the decoding process, expressed in Matroska Ticks -- i.e., in nanoseconds; see Section 11.1. see Section 9 for more information stream copy: True (Section 8) 5.1.4.1.15. TrackTimestampScale Element id / type / default: 0x23314F / float / 0x1p+0 range: > 0x0p+0 path: \Segment\Tracks\TrackEntry\TrackTimestampScale minOccurs / maxOccurs: 1 / 1 maxver: 3 definition: The scale to apply on this track to work at normal speed in relation with other tracks (mostly used to adjust video speed when the audio length differs). stream copy: True (Section 8) 5.1.4.1.16. MaxBlockAdditionID Element id / type / default: 0x55EE / uinteger / 0 path: \Segment\Tracks\TrackEntry\MaxBlockAdditionID minOccurs / maxOccurs: 1 / 1 definition: The maximum value of BlockAddID (Section 5.1.3.5.2.3). A value 0 means there is no BlockAdditions (Section 5.1.3.5.2) for this track. 5.1.4.1.17. BlockAdditionMapping Element id / type: 0x41E4 / master path: \Segment\Tracks\TrackEntry\BlockAdditionMapping minver: 4 definition: Contains elements that extend the track format, by adding content either to each frame, with BlockAddID (Section 5.1.3.5.2.3), or to the track as a whole with BlockAddIDExtraData. 5.1.4.1.17.1. BlockAddIDValue Element id / type: 0x41F0 / uinteger range: >=2 path: \Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDValu e maxOccurs: 1 minver: 4 definition: If the track format extension needs content beside Lhomme, et al. Expires 13 February 2024 [Page 32] Internet-Draft Matroska Format August 2023 frames, the value refers to the BlockAddID (Section 5.1.3.5.2.3), value being described. usage notes: To keep MaxBlockAdditionID as low as possible, small values SHOULD be used. 5.1.4.1.17.2. BlockAddIDName Element id / type: 0x41A4 / string path: \Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDName maxOccurs: 1 minver: 4 definition: A human-friendly name describing the type of BlockAdditional data, as defined by the associated Block Additional Mapping. 5.1.4.1.17.3. BlockAddIDType Element id / type / default: 0x41E7 / uinteger / 0 path: \Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDType minOccurs / maxOccurs: 1 / 1 minver: 4 definition: Stores the registered identifier of the Block Additional Mapping to define how the BlockAdditional data should be handled. usage notes: If BlockAddIDType is 0, the BlockAddIDValue and corresponding BlockAddID values MUST be 1. 5.1.4.1.17.4. BlockAddIDExtraData Element id / type: 0x41ED / binary path: \Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDExtr aData maxOccurs: 1 minver: 4 definition: Extra binary data that the BlockAddIDType can use to interpret the BlockAdditional data. The interpretation of the binary data depends on the BlockAddIDType value and the corresponding Block Additional Mapping. 5.1.4.1.18. Name Element id / type: 0x536E / utf-8 path: \Segment\Tracks\TrackEntry\Name maxOccurs: 1 definition: A human-readable track name. 5.1.4.1.19. Language Element id / type / default: 0x22B59C / string / eng Lhomme, et al. Expires 13 February 2024 [Page 33] Internet-Draft Matroska Format August 2023 path: \Segment\Tracks\TrackEntry\Language minOccurs / maxOccurs: 1 / 1 definition: The language of the track, in the Matroska languages form; see Section 12 on language codes. This Element MUST be ignored if the LanguageBCP47 Element is used in the same TrackEntry. 5.1.4.1.20. LanguageBCP47 Element id / type: 0x22B59D / string path: \Segment\Tracks\TrackEntry\LanguageBCP47 maxOccurs: 1 minver: 4 definition: The language of the track, in the [BCP47] form; see Section 12 on language codes. If this Element is used, then any Language Elements used in the same TrackEntry MUST be ignored. 5.1.4.1.21. CodecID Element id / type: 0x86 / string path: \Segment\Tracks\TrackEntry\CodecID minOccurs / maxOccurs: 1 / 1 definition: An ID corresponding to the codec, see [MatroskaCodec] for more info. stream copy: True (Section 8) 5.1.4.1.22. CodecPrivate Element id / type: 0x63A2 / binary path: \Segment\Tracks\TrackEntry\CodecPrivate maxOccurs: 1 definition: Private data only known to the codec. stream copy: True (Section 8) 5.1.4.1.23. CodecName Element id / type: 0x258688 / utf-8 path: \Segment\Tracks\TrackEntry\CodecName maxOccurs: 1 definition: A human-readable string specifying the codec. 5.1.4.1.24. AttachmentLink Element id / type: 0x7446 / uinteger range: not 0 path: \Segment\Tracks\TrackEntry\AttachmentLink Lhomme, et al. Expires 13 February 2024 [Page 34] Internet-Draft Matroska Format August 2023 maxOccurs: 1 maxver: 3 definition: The UID of an attachment that is used by this codec. usage notes: The value MUST match the FileUID value of an attachment found in this Segment. 5.1.4.1.25. CodecDelay Element id / type / default: 0x56AA / uinteger / 0 path: \Segment\Tracks\TrackEntry\CodecDelay minOccurs / maxOccurs: 1 / 1 minver: 4 definition: CodecDelay is The codec-built-in delay, expressed in Matroska Ticks -- i.e., in nanoseconds; see Section 11.1. It represents the amount of codec samples that will be discarded by the decoder during playback. This timestamp value MUST be subtracted from each frame timestamp in order to get the timestamp that will be actually played. The value SHOULD be small so the muxing of tracks with the same actual timestamp are in the same Cluster. stream copy: True (Section 8) 5.1.4.1.26. SeekPreRoll Element id / type / default: 0x56BB / uinteger / 0 path: \Segment\Tracks\TrackEntry\SeekPreRoll minOccurs / maxOccurs: 1 / 1 minver: 4 definition: After a discontinuity, SeekPreRoll is the duration of the data the decoder MUST decode before the decoded data is valid, expressed in Matroska Ticks -- i.e., in nanoseconds; see Section 11.1. stream copy: True (Section 8) 5.1.4.1.27. TrackTranslate Element id / type: 0x6624 / master path: \Segment\Tracks\TrackEntry\TrackTranslate definition: The mapping between this TrackEntry and a track value in the given Chapter Codec. rationale: Chapter Codec may need to address content in specific track, but they may not know of the way to identify tracks in Matroska. This element and its child elements add a way to map the internal tracks known to the Chapter Codec to the track IDs in Matroska. This allows remuxing a file with Chapter Codec without changing the content of the codec data, just the track mapping. Lhomme, et al. Expires 13 February 2024 [Page 35] Internet-Draft Matroska Format August 2023 5.1.4.1.27.1. TrackTranslateTrackID Element id / type: 0x66A5 / binary path: \Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateTrackI D minOccurs / maxOccurs: 1 / 1 definition: The binary value used to represent this TrackEntry in the chapter codec data. The format depends on the ChapProcessCodecID used; see Section 5.1.7.1.4.15. 5.1.4.1.27.2. TrackTranslateCodec Element id / type: 0x66BF / uinteger path: \Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateCodec minOccurs / maxOccurs: 1 / 1 definition: This TrackTranslate applies to this chapter codec of the given chapter edition(s); see Section 5.1.7.1.4.15. defined values: +=======+=================+============================+ | value | label | definition | +=======+=================+============================+ | 0 | Matroska Script | Chapter commands using the | | | | Matroska Script codec. | +-------+-----------------+----------------------------+ | 1 | DVD-menu | Chapter commands using the | | | | DVD-like codec. | +-------+-----------------+----------------------------+ Table 4: TrackTranslateCodec values 5.1.4.1.27.3. TrackTranslateEditionUID Element id / type: 0x66FC / uinteger path: \Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateEditio nUID definition: Specify a chapter edition UID on which this TrackTranslate applies. usage notes: When no TrackTranslateEditionUID is specified in the TrackTranslate, the TrackTranslate applies to all chapter editions found in the Segment using the given TrackTranslateCodec. 5.1.4.1.28. Video Element id / type: 0xE0 / master path: \Segment\Tracks\TrackEntry\Video maxOccurs: 1 Lhomme, et al. Expires 13 February 2024 [Page 36] Internet-Draft Matroska Format August 2023 definition: Video settings. 5.1.4.1.28.1. FlagInterlaced Element id / type / default: 0x9A / uinteger / 0 path: \Segment\Tracks\TrackEntry\Video\FlagInterlaced minOccurs / maxOccurs: 1 / 1 minver: 2 definition: Specify whether the video frames in this track are interlaced. defined values: +=======+==============+==========================+ | value | label | definition | +=======+==============+==========================+ | 0 | undetermined | Unknown status.This | | | | value SHOULD be avoided. | +-------+--------------+--------------------------+ | 1 | interlaced | Interlaced frames. | +-------+--------------+--------------------------+ | 2 | progressive | No interlacing. | +-------+--------------+--------------------------+ Table 5: FlagInterlaced values stream copy: True (Section 8) 5.1.4.1.28.2. FieldOrder Element id / type / default: 0x9D / uinteger / 2 path: \Segment\Tracks\TrackEntry\Video\FieldOrder minOccurs / maxOccurs: 1 / 1 minver: 4 definition: Specify the field ordering of video frames in this track. defined values: Lhomme, et al. Expires 13 February 2024 [Page 37] Internet-Draft Matroska Format August 2023 +=======+==============+=========================================+ | value | label | definition | +=======+==============+=========================================+ | 0 | progressive | Interlaced frames.This value SHOULD be | | | | avoided, setting FlagInterlaced to 2 is | | | | sufficient. | +-------+--------------+-----------------------------------------+ | 1 | tff | Top field displayed first. Top field | | | | stored first. | +-------+--------------+-----------------------------------------+ | 2 | undetermined | Unknown field order.This value SHOULD | | | | be avoided. | +-------+--------------+-----------------------------------------+ | 6 | bff | Bottom field displayed first. Bottom | | | | field stored first. | +-------+--------------+-----------------------------------------+ | 9 | bff(swapped) | Top field displayed first. Fields are | | | | interleaved in storage with the top | | | | line of the top field stored first. | +-------+--------------+-----------------------------------------+ | 14 | tff(swapped) | Bottom field displayed first. Fields | | | | are interleaved in storage with the top | | | | line of the top field stored first. | +-------+--------------+-----------------------------------------+ Table 6: FieldOrder values usage notes: If FlagInterlaced is not set to 1, this Element MUST be ignored. stream copy: True (Section 8) 5.1.4.1.28.3. StereoMode Element id / type / default: 0x53B8 / uinteger / 0 path: \Segment\Tracks\TrackEntry\Video\StereoMode minOccurs / maxOccurs: 1 / 1 minver: 3 definition: Stereo-3D video mode. There are some more details in Section 18.10. restrictions: Lhomme, et al. Expires 13 February 2024 [Page 38] Internet-Draft Matroska Format August 2023 +=======+===================================================+ | value | label | +=======+===================================================+ | 0 | mono | +-------+---------------------------------------------------+ | 1 | side by side (left eye first) | +-------+---------------------------------------------------+ | 2 | top - bottom (right eye is first) | +-------+---------------------------------------------------+ | 3 | top - bottom (left eye is first) | +-------+---------------------------------------------------+ | 4 | checkboard (right eye is first) | +-------+---------------------------------------------------+ | 5 | checkboard (left eye is first) | +-------+---------------------------------------------------+ | 6 | row interleaved (right eye is first) | +-------+---------------------------------------------------+ | 7 | row interleaved (left eye is first) | +-------+---------------------------------------------------+ | 8 | column interleaved (right eye is first) | +-------+---------------------------------------------------+ | 9 | column interleaved (left eye is first) | +-------+---------------------------------------------------+ | 10 | anaglyph (cyan/red) | +-------+---------------------------------------------------+ | 11 | side by side (right eye first) | +-------+---------------------------------------------------+ | 12 | anaglyph (green/magenta) | +-------+---------------------------------------------------+ | 13 | both eyes laced in one Block (left eye is first) | +-------+---------------------------------------------------+ | 14 | both eyes laced in one Block (right eye is first) | +-------+---------------------------------------------------+ Table 7: StereoMode values stream copy: True (Section 8) 5.1.4.1.28.4. AlphaMode Element id / type / default: 0x53C0 / uinteger / 0 path: \Segment\Tracks\TrackEntry\Video\AlphaMode minOccurs / maxOccurs: 1 / 1 minver: 3 definition: Indicate whether the BlockAdditional Element with Lhomme, et al. Expires 13 February 2024 [Page 39] Internet-Draft Matroska Format August 2023 BlockAddID of "1" contains Alpha data, as defined by to the Codec Mapping for the CodecID. Undefined values SHOULD NOT be used as the behavior of known implementations is different (considered either as 0 or 1). defined values: +=======+=========+============================================+ | value | label | definition | +=======+=========+============================================+ | 0 | none | The BlockAdditional Element with | | | | BlockAddID of "1" does not exist or SHOULD | | | | NOT be considered as containing such data. | +-------+---------+--------------------------------------------+ | 1 | present | The BlockAdditional Element with | | | | BlockAddID of "1" contains alpha channel | | | | data. | +-------+---------+--------------------------------------------+ Table 8: AlphaMode values stream copy: True (Section 8) 5.1.4.1.28.5. OldStereoMode Element id / type: 0x53B9 / uinteger path: \Segment\Tracks\TrackEntry\Video\OldStereoMode maxOccurs: 1 maxver: 2 definition: Bogus StereoMode value used in old versions of libmatroska. restrictions: +=======+===========+ | value | label | +=======+===========+ | 0 | mono | +-------+-----------+ | 1 | right eye | +-------+-----------+ | 2 | left eye | +-------+-----------+ | 3 | both eyes | +-------+-----------+ Table 9: OldStereoMode values Lhomme, et al. Expires 13 February 2024 [Page 40] Internet-Draft Matroska Format August 2023 usage notes: This Element MUST NOT be used. It was an incorrect value used in libmatroska up to 0.9.0. 5.1.4.1.28.6. PixelWidth Element id / type: 0xB0 / uinteger range: not 0 path: \Segment\Tracks\TrackEntry\Video\PixelWidth minOccurs / maxOccurs: 1 / 1 definition: Width of the encoded video frames in pixels. stream copy: True (Section 8) 5.1.4.1.28.7. PixelHeight Element id / type: 0xBA / uinteger range: not 0 path: \Segment\Tracks\TrackEntry\Video\PixelHeight minOccurs / maxOccurs: 1 / 1 definition: Height of the encoded video frames in pixels. stream copy: True (Section 8) 5.1.4.1.28.8. PixelCropBottom Element id / type / default: 0x54AA / uinteger / 0 path: \Segment\Tracks\TrackEntry\Video\PixelCropBottom minOccurs / maxOccurs: 1 / 1 definition: The number of video pixels to remove at the bottom of the image. stream copy: True (Section 8) 5.1.4.1.28.9. PixelCropTop Element id / type / default: 0x54BB / uinteger / 0 path: \Segment\Tracks\TrackEntry\Video\PixelCropTop minOccurs / maxOccurs: 1 / 1 definition: The number of video pixels to remove at the top of the image. stream copy: True (Section 8) 5.1.4.1.28.10. PixelCropLeft Element id / type / default: 0x54CC / uinteger / 0 path: \Segment\Tracks\TrackEntry\Video\PixelCropLeft minOccurs / maxOccurs: 1 / 1 Lhomme, et al. Expires 13 February 2024 [Page 41] Internet-Draft Matroska Format August 2023 definition: The number of video pixels to remove on the left of the image. stream copy: True (Section 8) 5.1.4.1.28.11. PixelCropRight Element id / type / default: 0x54DD / uinteger / 0 path: \Segment\Tracks\TrackEntry\Video\PixelCropRight minOccurs / maxOccurs: 1 / 1 definition: The number of video pixels to remove on the right of the image. stream copy: True (Section 8) 5.1.4.1.28.12. DisplayWidth Element id / type: 0x54B0 / uinteger range: not 0 path: \Segment\Tracks\TrackEntry\Video\DisplayWidth maxOccurs: 1 definition: Width of the video frames to display. Applies to the video frame after cropping (PixelCrop* Elements). notes: +===========+=================================================+ | attribute | note | +===========+=================================================+ | default | If the DisplayUnit of the same TrackEntry is 0, | | | then the default value for DisplayWidth is | | | equal toPixelWidth - PixelCropLeft - | | | PixelCropRight, else there is no default value. | +-----------+-------------------------------------------------+ Table 10: DisplayWidth implementation notes stream copy: True (Section 8) 5.1.4.1.28.13. DisplayHeight Element id / type: 0x54BA / uinteger range: not 0 path: \Segment\Tracks\TrackEntry\Video\DisplayHeight maxOccurs: 1 definition: Height of the video frames to display. Applies to the video frame after cropping (PixelCrop* Elements). Lhomme, et al. Expires 13 February 2024 [Page 42] Internet-Draft Matroska Format August 2023 notes: +===========+==================================================+ | attribute | note | +===========+==================================================+ | default | If the DisplayUnit of the same TrackEntry is 0, | | | then the default value for DisplayHeight is | | | equal toPixelHeight - PixelCropTop - | | | PixelCropBottom, else there is no default value. | +-----------+--------------------------------------------------+ Table 11: DisplayHeight implementation notes stream copy: True (Section 8) 5.1.4.1.28.14. DisplayUnit Element id / type / default: 0x54B2 / uinteger / 0 path: \Segment\Tracks\TrackEntry\Video\DisplayUnit minOccurs / maxOccurs: 1 / 1 definition: How DisplayWidth & DisplayHeight are interpreted. restrictions: +=======+======================+ | value | label | +=======+======================+ | 0 | pixels | +-------+----------------------+ | 1 | centimeters | +-------+----------------------+ | 2 | inches | +-------+----------------------+ | 3 | display aspect ratio | +-------+----------------------+ | 4 | unknown | +-------+----------------------+ Table 12: DisplayUnit values 5.1.4.1.28.15. UncompressedFourCC Element id / type: 0x2EB524 / binary length: 4 path: \Segment\Tracks\TrackEntry\Video\UncompressedFourCC minOccurs / maxOccurs: see implementation notes / 1 definition: Specify the uncompressed pixel format used for the Lhomme, et al. Expires 13 February 2024 [Page 43] Internet-Draft Matroska Format August 2023 Track's data as a FourCC. This value is similar in scope to the biCompression value of AVI's BITMAPINFO [AVIFormat]. There is no definitive list of FourCC values, nor an official registry. Some common values for YUV pixel formats can be found at [MSYUV8], [MSYUV16] and [FourCC-YUV]. Some common values for uncompressed RGB pixel formats can be found at [MSRGB] and [FourCC-RGB]. notes: +===========+==============================================+ | attribute | note | +===========+==============================================+ | minOccurs | UncompressedFourCC MUST be set (minOccurs=1) | | | in TrackEntry, when the CodecID Element of | | | the TrackEntry is set to "V_UNCOMPRESSED". | +-----------+----------------------------------------------+ Table 13: UncompressedFourCC implementation notes stream copy: True (Section 8) 5.1.4.1.28.16. Colour Element id / type: 0x55B0 / master path: \Segment\Tracks\TrackEntry\Video\Colour maxOccurs: 1 minver: 4 definition: Settings describing the colour format. stream copy: True (Section 8) 5.1.4.1.28.17. MatrixCoefficients Element id / type / default: 0x55B1 / uinteger / 2 path: \Segment\Tracks\TrackEntry\Video\Colour\MatrixCoefficients minOccurs / maxOccurs: 1 / 1 minver: 4 definition: The Matrix Coefficients of the video used to derive luma and chroma values from red, green, and blue color primaries. For clarity, the value and meanings for MatrixCoefficients are adopted from Table 4 of [ITU-H.273]. restrictions: Lhomme, et al. Expires 13 February 2024 [Page 44] Internet-Draft Matroska Format August 2023 +=======+=======================================+ | value | label | +=======+=======================================+ | 0 | Identity | +-------+---------------------------------------+ | 1 | ITU-R BT.709 | +-------+---------------------------------------+ | 2 | unspecified | +-------+---------------------------------------+ | 3 | reserved | +-------+---------------------------------------+ | 4 | US FCC 73.682 | +-------+---------------------------------------+ | 5 | ITU-R BT.470BG | +-------+---------------------------------------+ | 6 | SMPTE 170M | +-------+---------------------------------------+ | 7 | SMPTE 240M | +-------+---------------------------------------+ | 8 | YCoCg | +-------+---------------------------------------+ | 9 | BT2020 Non-constant Luminance | +-------+---------------------------------------+ | 10 | BT2020 Constant Luminance | +-------+---------------------------------------+ | 11 | SMPTE ST 2085 | +-------+---------------------------------------+ | 12 | Chroma-derived Non-constant Luminance | +-------+---------------------------------------+ | 13 | Chroma-derived Constant Luminance | +-------+---------------------------------------+ | 14 | ITU-R BT.2100-0 | +-------+---------------------------------------+ Table 14: MatrixCoefficients values stream copy: True (Section 8) 5.1.4.1.28.18. BitsPerChannel Element id / type / default: 0x55B2 / uinteger / 0 path: \Segment\Tracks\TrackEntry\Video\Colour\BitsPerChannel minOccurs / maxOccurs: 1 / 1 minver: 4 definition: Number of decoded bits per channel. A value of 0 indicates that the BitsPerChannel is unspecified. stream copy: True (Section 8) Lhomme, et al. Expires 13 February 2024 [Page 45] Internet-Draft Matroska Format August 2023 5.1.4.1.28.19. ChromaSubsamplingHorz Element id / type: 0x55B3 / uinteger path: \Segment\Tracks\TrackEntry\Video\Colour\ChromaSubsamplingHorz maxOccurs: 1 minver: 4 definition: The amount of pixels to remove in the Cr and Cb channels for every pixel not removed horizontally. Example: For video with 4:2:0 chroma subsampling, the ChromaSubsamplingHorz SHOULD be set to 1. stream copy: True (Section 8) 5.1.4.1.28.20. ChromaSubsamplingVert Element id / type: 0x55B4 / uinteger path: \Segment\Tracks\TrackEntry\Video\Colour\ChromaSubsamplingVert maxOccurs: 1 minver: 4 definition: The amount of pixels to remove in the Cr and Cb channels for every pixel not removed vertically. Example: For video with 4:2:0 chroma subsampling, the ChromaSubsamplingVert SHOULD be set to 1. stream copy: True (Section 8) 5.1.4.1.28.21. CbSubsamplingHorz Element id / type: 0x55B5 / uinteger path: \Segment\Tracks\TrackEntry\Video\Colour\CbSubsamplingHorz maxOccurs: 1 minver: 4 definition: The amount of pixels to remove in the Cb channel for every pixel not removed horizontally. This is additive with ChromaSubsamplingHorz. Example: For video with 4:2:1 chroma subsampling, the ChromaSubsamplingHorz SHOULD be set to 1 and CbSubsamplingHorz SHOULD be set to 1. stream copy: True (Section 8) 5.1.4.1.28.22. CbSubsamplingVert Element id / type: 0x55B6 / uinteger path: \Segment\Tracks\TrackEntry\Video\Colour\CbSubsamplingVert maxOccurs: 1 minver: 4 definition: The amount of pixels to remove in the Cb channel for Lhomme, et al. Expires 13 February 2024 [Page 46] Internet-Draft Matroska Format August 2023 every pixel not removed vertically. This is additive with ChromaSubsamplingVert. stream copy: True (Section 8) 5.1.4.1.28.23. ChromaSitingHorz Element id / type / default: 0x55B7 / uinteger / 0 path: \Segment\Tracks\TrackEntry\Video\Colour\ChromaSitingHorz minOccurs / maxOccurs: 1 / 1 minver: 4 definition: How chroma is subsampled horizontally. restrictions: +=======+=================+ | value | label | +=======+=================+ | 0 | unspecified | +-------+-----------------+ | 1 | left collocated | +-------+-----------------+ | 2 | half | +-------+-----------------+ Table 15: ChromaSitingHorz values stream copy: True (Section 8) 5.1.4.1.28.24. ChromaSitingVert Element id / type / default: 0x55B8 / uinteger / 0 path: \Segment\Tracks\TrackEntry\Video\Colour\ChromaSitingVert minOccurs / maxOccurs: 1 / 1 minver: 4 definition: How chroma is subsampled vertically. restrictions: Lhomme, et al. Expires 13 February 2024 [Page 47] Internet-Draft Matroska Format August 2023 +=======+================+ | value | label | +=======+================+ | 0 | unspecified | +-------+----------------+ | 1 | top collocated | +-------+----------------+ | 2 | half | +-------+----------------+ Table 16: ChromaSitingVert values stream copy: True (Section 8) 5.1.4.1.28.25. Range Element id / type / default: 0x55B9 / uinteger / 0 path: \Segment\Tracks\TrackEntry\Video\Colour\Range minOccurs / maxOccurs: 1 / 1 minver: 4 definition: Clipping of the color ranges. restrictions: +=======+=========================================================+ | value | label | +=======+=========================================================+ | 0 | unspecified | +-------+---------------------------------------------------------+ | 1 | broadcast range | +-------+---------------------------------------------------------+ | 2 | full range (no clipping) | +-------+---------------------------------------------------------+ | 3 | defined by MatrixCoefficients / TransferCharacteristics | +-------+---------------------------------------------------------+ Table 17: Range values stream copy: True (Section 8) 5.1.4.1.28.26. TransferCharacteristics Element id / type / default: 0x55BA / uinteger / 2 path: \Segment\Tracks\TrackEntry\Video\Colour\TransferCharacteristic s minOccurs / maxOccurs: 1 / 1 Lhomme, et al. Expires 13 February 2024 [Page 48] Internet-Draft Matroska Format August 2023 minver: 4 definition: The transfer characteristics of the video. For clarity, the value and meanings for TransferCharacteristics are adopted from Table 3 of [ITU-H.273]. restrictions: Lhomme, et al. Expires 13 February 2024 [Page 49] Internet-Draft Matroska Format August 2023 +=======+=======================================+ | value | label | +=======+=======================================+ | 0 | reserved | +-------+---------------------------------------+ | 1 | ITU-R BT.709 | +-------+---------------------------------------+ | 2 | unspecified | +-------+---------------------------------------+ | 3 | reserved2 | +-------+---------------------------------------+ | 4 | Gamma 2.2 curve - BT.470M | +-------+---------------------------------------+ | 5 | Gamma 2.8 curve - BT.470BG | +-------+---------------------------------------+ | 6 | SMPTE 170M | +-------+---------------------------------------+ | 7 | SMPTE 240M | +-------+---------------------------------------+ | 8 | Linear | +-------+---------------------------------------+ | 9 | Log | +-------+---------------------------------------+ | 10 | Log Sqrt | +-------+---------------------------------------+ | 11 | IEC 61966-2-4 | +-------+---------------------------------------+ | 12 | ITU-R BT.1361 Extended Colour Gamut | +-------+---------------------------------------+ | 13 | IEC 61966-2-1 | +-------+---------------------------------------+ | 14 | ITU-R BT.2020 10 bit | +-------+---------------------------------------+ | 15 | ITU-R BT.2020 12 bit | +-------+---------------------------------------+ | 16 | ITU-R BT.2100 Perceptual Quantization | +-------+---------------------------------------+ | 17 | SMPTE ST 428-1 | +-------+---------------------------------------+ | 18 | ARIB STD-B67 (HLG) | +-------+---------------------------------------+ Table 18: TransferCharacteristics values stream copy: True (Section 8) Lhomme, et al. Expires 13 February 2024 [Page 50] Internet-Draft Matroska Format August 2023 5.1.4.1.28.27. Primaries Element id / type / default: 0x55BB / uinteger / 2 path: \Segment\Tracks\TrackEntry\Video\Colour\Primaries minOccurs / maxOccurs: 1 / 1 minver: 4 definition: The colour primaries of the video. For clarity, the value and meanings for Primaries are adopted from Table 2 of [ITU-H.273]. restrictions: +=======+========================================+ | value | label | +=======+========================================+ | 0 | reserved | +-------+----------------------------------------+ | 1 | ITU-R BT.709 | +-------+----------------------------------------+ | 2 | unspecified | +-------+----------------------------------------+ | 3 | reserved2 | +-------+----------------------------------------+ | 4 | ITU-R BT.470M | +-------+----------------------------------------+ | 5 | ITU-R BT.470BG - BT.601 625 | +-------+----------------------------------------+ | 6 | ITU-R BT.601 525 - SMPTE 170M | +-------+----------------------------------------+ | 7 | SMPTE 240M | +-------+----------------------------------------+ | 8 | FILM | +-------+----------------------------------------+ | 9 | ITU-R BT.2020 | +-------+----------------------------------------+ | 10 | SMPTE ST 428-1 | +-------+----------------------------------------+ | 11 | SMPTE RP 432-2 | +-------+----------------------------------------+ | 12 | SMPTE EG 432-2 | +-------+----------------------------------------+ | 22 | EBU Tech. 3213-E - JEDEC P22 phosphors | +-------+----------------------------------------+ Table 19: Primaries values stream copy: True (Section 8) Lhomme, et al. Expires 13 February 2024 [Page 51] Internet-Draft Matroska Format August 2023 5.1.4.1.28.28. MaxCLL Element id / type: 0x55BC / uinteger path: \Segment\Tracks\TrackEntry\Video\Colour\MaxCLL maxOccurs: 1 minver: 4 definition: Maximum brightness of a single pixel (Maximum Content Light Level) in candelas per square meter (cd/m^2). stream copy: True (Section 8) 5.1.4.1.28.29. MaxFALL Element id / type: 0x55BD / uinteger path: \Segment\Tracks\TrackEntry\Video\Colour\MaxFALL maxOccurs: 1 minver: 4 definition: Maximum brightness of a single full frame (Maximum Frame-Average Light Level) in candelas per square meter (cd/m^2). stream copy: True (Section 8) 5.1.4.1.28.30. MasteringMetadata Element id / type: 0x55D0 / master path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata maxOccurs: 1 minver: 4 definition: SMPTE 2086 mastering data. stream copy: True (Section 8) 5.1.4.1.28.31. PrimaryRChromaticityX Element id / type: 0x55D1 / float range: 0x0p+0-0x1p+0 path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Prim aryRChromaticityX maxOccurs: 1 minver: 4 definition: Red X chromaticity coordinate, as defined by [CIE-1931]. stream copy: True (Section 8) 5.1.4.1.28.32. PrimaryRChromaticityY Element id / type: 0x55D2 / float range: 0x0p+0-0x1p+0 Lhomme, et al. Expires 13 February 2024 [Page 52] Internet-Draft Matroska Format August 2023 path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Prim aryRChromaticityY maxOccurs: 1 minver: 4 definition: Red Y chromaticity coordinate, as defined by [CIE-1931]. stream copy: True (Section 8) 5.1.4.1.28.33. PrimaryGChromaticityX Element id / type: 0x55D3 / float range: 0x0p+0-0x1p+0 path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Prim aryGChromaticityX maxOccurs: 1 minver: 4 definition: Green X chromaticity coordinate, as defined by [CIE-1931]. stream copy: True (Section 8) 5.1.4.1.28.34. PrimaryGChromaticityY Element id / type: 0x55D4 / float range: 0x0p+0-0x1p+0 path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Prim aryGChromaticityY maxOccurs: 1 minver: 4 definition: Green Y chromaticity coordinate, as defined by [CIE-1931]. stream copy: True (Section 8) 5.1.4.1.28.35. PrimaryBChromaticityX Element id / type: 0x55D5 / float range: 0x0p+0-0x1p+0 path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Prim aryBChromaticityX maxOccurs: 1 minver: 4 definition: Blue X chromaticity coordinate, as defined by [CIE-1931]. stream copy: True (Section 8) Lhomme, et al. Expires 13 February 2024 [Page 53] Internet-Draft Matroska Format August 2023 5.1.4.1.28.36. PrimaryBChromaticityY Element id / type: 0x55D6 / float range: 0x0p+0-0x1p+0 path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Prim aryBChromaticityY maxOccurs: 1 minver: 4 definition: Blue Y chromaticity coordinate, as defined by [CIE-1931]. stream copy: True (Section 8) 5.1.4.1.28.37. WhitePointChromaticityX Element id / type: 0x55D7 / float range: 0x0p+0-0x1p+0 path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Whit ePointChromaticityX maxOccurs: 1 minver: 4 definition: White X chromaticity coordinate, as defined by [CIE-1931]. stream copy: True (Section 8) 5.1.4.1.28.38. WhitePointChromaticityY Element id / type: 0x55D8 / float range: 0x0p+0-0x1p+0 path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Whit ePointChromaticityY maxOccurs: 1 minver: 4 definition: White Y chromaticity coordinate, as defined by [CIE-1931]. stream copy: True (Section 8) 5.1.4.1.28.39. LuminanceMax Element id / type: 0x55D9 / float range: >= 0x0p+0 path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Lumi nanceMax maxOccurs: 1 minver: 4 definition: Maximum luminance. Represented in candelas per square Lhomme, et al. Expires 13 February 2024 [Page 54] Internet-Draft Matroska Format August 2023 meter (cd/m^2). stream copy: True (Section 8) 5.1.4.1.28.40. LuminanceMin Element id / type: 0x55DA / float range: >= 0x0p+0 path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Lumi nanceMin maxOccurs: 1 minver: 4 definition: Minimum luminance. Represented in candelas per square meter (cd/m^2). stream copy: True (Section 8) 5.1.4.1.28.41. Projection Element id / type: 0x7670 / master path: \Segment\Tracks\TrackEntry\Video\Projection maxOccurs: 1 minver: 4 definition: Describes the video projection details. Used to render spherical, VR videos or flipping videos horizontally/vertically. stream copy: True (Section 8) 5.1.4.1.28.42. ProjectionType Element id / type / default: 0x7671 / uinteger / 0 path: \Segment\Tracks\TrackEntry\Video\Projection\ProjectionType minOccurs / maxOccurs: 1 / 1 minver: 4 definition: Describes the projection used for this video track. restrictions: Lhomme, et al. Expires 13 February 2024 [Page 55] Internet-Draft Matroska Format August 2023 +=======+=================+ | value | label | +=======+=================+ | 0 | rectangular | +-------+-----------------+ | 1 | equirectangular | +-------+-----------------+ | 2 | cubemap | +-------+-----------------+ | 3 | mesh | +-------+-----------------+ Table 20: ProjectionType values stream copy: True (Section 8) 5.1.4.1.28.43. ProjectionPrivate Element id / type: 0x7672 / binary path: \Segment\Tracks\TrackEntry\Video\Projection\ProjectionPrivate maxOccurs: 1 minver: 4 definition: Private data that only applies to a specific projection. * If ProjectionType equals 0 (Rectangular), then this element MUST NOT be present. * If ProjectionType equals 1 (Equirectangular), then this element MUST be present and contain the same binary data that would be stored inside an ISOBMFF Equirectangular Projection Box ('equi'). * If ProjectionType equals 2 (Cubemap), then this element MUST be present and contain the same binary data that would be stored inside an ISOBMFF Cubemap Projection Box ('cbmp'). * If ProjectionType equals 3 (Mesh), then this element MUST be present and contain the same binary data that would be stored inside an ISOBMFF Mesh Projection Box ('mshp'). usage notes: ISOBMFF box size and fourcc fields are not included in the binary data, but the FullBox version and flag fields are. This is to avoid redundant framing information while preserving versioning and semantics between the two container formats. stream copy: True (Section 8) 5.1.4.1.28.44. ProjectionPoseYaw Element id / type / default: 0x7673 / float / 0x0p+0 range: >= -0xB4p+0, <= 0xB4p+0 Lhomme, et al. Expires 13 February 2024 [Page 56] Internet-Draft Matroska Format August 2023 path: \Segment\Tracks\TrackEntry\Video\Projection\ProjectionPoseYaw minOccurs / maxOccurs: 1 / 1 minver: 4 definition: Specifies a yaw rotation to the projection. Value represents a clockwise rotation, in degrees, around the up vector. This rotation must be applied before any ProjectionPosePitch or ProjectionPoseRoll rotations. The value of this element MUST be in the -180 to 180 degree range, both included. Setting ProjectionPoseYaw to 180 or -180 degrees, with the ProjectionPoseRoll and ProjectionPosePitch set to 0 degrees flips the image horizontally. stream copy: True (Section 8) 5.1.4.1.28.45. ProjectionPosePitch Element id / type / default: 0x7674 / float / 0x0p+0 range: >= -0x5Ap+0, <= 0x5Ap+0 path: \Segment\Tracks\TrackEntry\Video\Projection\ProjectionPosePitc h minOccurs / maxOccurs: 1 / 1 minver: 4 definition: Specifies a pitch rotation to the projection. Value represents a counter-clockwise rotation, in degrees, around the right vector. This rotation must be applied after the ProjectionPoseYaw rotation and before the ProjectionPoseRoll rotation. The value of this element MUST be in the -90 to 90 degree range, both included. stream copy: True (Section 8) 5.1.4.1.28.46. ProjectionPoseRoll Element id / type / default: 0x7675 / float / 0x0p+0 range: >= -0xB4p+0, <= 0xB4p+0 path: \Segment\Tracks\TrackEntry\Video\Projection\ProjectionPoseRoll minOccurs / maxOccurs: 1 / 1 minver: 4 definition: Specifies a roll rotation to the projection. Value represents a counter-clockwise rotation, in degrees, around the forward vector. This rotation must be applied after the ProjectionPoseYaw and ProjectionPosePitch rotations. The value of this element MUST be in the -180 to 180 degree range, both included. Lhomme, et al. Expires 13 February 2024 [Page 57] Internet-Draft Matroska Format August 2023 Setting ProjectionPoseRoll to 180 or -180 degrees, the ProjectionPoseYaw to 180 or -180 degrees with ProjectionPosePitch set to 0 degrees flips the image vertically. Setting ProjectionPoseRoll to 180 or -180 degrees, with the ProjectionPoseYaw and ProjectionPosePitch set to 0 degrees flips the image horizontally and vertically. stream copy: True (Section 8) 5.1.4.1.29. Audio Element id / type: 0xE1 / master path: \Segment\Tracks\TrackEntry\Audio maxOccurs: 1 definition: Audio settings. 5.1.4.1.29.1. SamplingFrequency Element id / type / default: 0xB5 / float / 0x1.f4p+12 range: > 0x0p+0 path: \Segment\Tracks\TrackEntry\Audio\SamplingFrequency minOccurs / maxOccurs: 1 / 1 definition: Sampling frequency in Hz. stream copy: True (Section 8) 5.1.4.1.29.2. OutputSamplingFrequency Element id / type: 0x78B5 / float range: > 0x0p+0 path: \Segment\Tracks\TrackEntry\Audio\OutputSamplingFrequency maxOccurs: 1 definition: Real output sampling frequency in Hz (used for SBR techniques). notes: +===========+======================================================+ | attribute | note | +===========+======================================================+ | default | The default value for OutputSamplingFrequency of the | | | same TrackEntry is equal to the SamplingFrequency. | +-----------+------------------------------------------------------+ Table 21: OutputSamplingFrequency implementation notes Lhomme, et al. Expires 13 February 2024 [Page 58] Internet-Draft Matroska Format August 2023 5.1.4.1.29.3. Channels Element id / type / default: 0x9F / uinteger / 1 range: not 0 path: \Segment\Tracks\TrackEntry\Audio\Channels minOccurs / maxOccurs: 1 / 1 definition: Numbers of channels in the track. stream copy: True (Section 8) 5.1.4.1.29.4. BitDepth Element id / type: 0x6264 / uinteger range: not 0 path: \Segment\Tracks\TrackEntry\Audio\BitDepth maxOccurs: 1 definition: Bits per sample, mostly used for PCM. stream copy: True (Section 8) 5.1.4.1.30. TrackOperation Element id / type: 0xE2 / master path: \Segment\Tracks\TrackEntry\TrackOperation maxOccurs: 1 minver: 3 definition: Operation that needs to be applied on tracks to create this virtual track. For more details look at Section 18.8. stream copy: True (Section 8) 5.1.4.1.30.1. TrackCombinePlanes Element id / type: 0xE3 / master path: \Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes maxOccurs: 1 minver: 3 definition: Contains the list of all video plane tracks that need to be combined to create this 3D track stream copy: True (Section 8) 5.1.4.1.30.2. TrackPlane Element id / type: 0xE4 / master path: \Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes\T rackPlane minOccurs: 1 Lhomme, et al. Expires 13 February 2024 [Page 59] Internet-Draft Matroska Format August 2023 minver: 3 definition: Contains a video plane track that need to be combined to create this 3D track stream copy: True (Section 8) 5.1.4.1.30.3. TrackPlaneUID Element id / type: 0xE5 / uinteger range: not 0 path: \Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes\T rackPlane\TrackPlaneUID minOccurs / maxOccurs: 1 / 1 minver: 3 definition: The trackUID number of the track representing the plane. stream copy: True (Section 8) 5.1.4.1.30.4. TrackPlaneType Element id / type: 0xE6 / uinteger path: \Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes\T rackPlane\TrackPlaneType minOccurs / maxOccurs: 1 / 1 minver: 3 definition: The kind of plane this track corresponds to. restrictions: +=======+============+ | value | label | +=======+============+ | 0 | left eye | +-------+------------+ | 1 | right eye | +-------+------------+ | 2 | background | +-------+------------+ Table 22: TrackPlaneType values stream copy: True (Section 8) 5.1.4.1.30.5. TrackJoinBlocks Element id / type: 0xE9 / master path: \Segment\Tracks\TrackEntry\TrackOperation\TrackJoinBlocks Lhomme, et al. Expires 13 February 2024 [Page 60] Internet-Draft Matroska Format August 2023 maxOccurs: 1 minver: 3 definition: Contains the list of all tracks whose Blocks need to be combined to create this virtual track stream copy: True (Section 8) 5.1.4.1.30.6. TrackJoinUID Element id / type: 0xED / uinteger range: not 0 path: \Segment\Tracks\TrackEntry\TrackOperation\TrackJoinBlocks\Trac kJoinUID minOccurs: 1 minver: 3 definition: The trackUID number of a track whose blocks are used to create this virtual track. stream copy: True (Section 8) 5.1.4.1.31. ContentEncodings Element id / type: 0x6D80 / master path: \Segment\Tracks\TrackEntry\ContentEncodings maxOccurs: 1 definition: Settings for several content encoding mechanisms like compression or encryption. stream copy: True (Section 8) 5.1.4.1.31.1. ContentEncoding Element id / type: 0x6240 / master path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding minOccurs: 1 definition: Settings for one content encoding like compression or encryption. stream copy: True (Section 8) 5.1.4.1.31.2. ContentEncodingOrder Element id / type / default: 0x5031 / uinteger / 0 path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co ntentEncodingOrder minOccurs / maxOccurs: 1 / 1 definition: Tell in which order to apply each ContentEncoding of the Lhomme, et al. Expires 13 February 2024 [Page 61] Internet-Draft Matroska Format August 2023 ContentEncodings. The decoder/demuxer MUST start with the ContentEncoding with the highest ContentEncodingOrder and work its way down to the ContentEncoding with the lowest ContentEncodingOrder. This value MUST be unique over for each ContentEncoding found in the ContentEncodings of this TrackEntry. stream copy: True (Section 8) 5.1.4.1.31.3. ContentEncodingScope Element id / type / default: 0x5032 / uinteger / 1 path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co ntentEncodingScope minOccurs / maxOccurs: 1 / 1 definition: A bit field that describes which Elements have been modified in this way. Values (big-endian) can be OR'ed. defined values: +=======+=========+===========================================+ | value | label | definition | +=======+=========+===========================================+ | 1 | Block | All frame contents, excluding lacing | | | | data. | +-------+---------+-------------------------------------------+ | 2 | Private | The track's CodecPrivate data. | +-------+---------+-------------------------------------------+ | 4 | Next | The next ContentEncoding (next | | | | ContentEncodingOrder. Either the data | | | | inside ContentCompression and/or | | | | ContentEncryption).This value SHOULD NOT | | | | be used as it's not supported by players. | +-------+---------+-------------------------------------------+ Table 23: ContentEncodingScope values stream copy: True (Section 8) 5.1.4.1.31.4. ContentEncodingType Element id / type / default: 0x5033 / uinteger / 0 path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co ntentEncodingType minOccurs / maxOccurs: 1 / 1 definition: A value describing what kind of transformation is applied. restrictions: Lhomme, et al. Expires 13 February 2024 [Page 62] Internet-Draft Matroska Format August 2023 +=======+=============+ | value | label | +=======+=============+ | 0 | Compression | +-------+-------------+ | 1 | Encryption | +-------+-------------+ Table 24: ContentEncodingType values stream copy: True (Section 8) 5.1.4.1.31.5. ContentCompression Element id / type: 0x5034 / master path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co ntentCompression maxOccurs: 1 definition: Settings describing the compression used. This Element MUST be present if the value of ContentEncodingType is 0 and absent otherwise. Each block MUST be decompressable even if no previous block is available in order not to prevent seeking. stream copy: True (Section 8) 5.1.4.1.31.6. ContentCompAlgo Element id / type / default: 0x4254 / uinteger / 0 path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co ntentCompression\ContentCompAlgo minOccurs / maxOccurs: 1 / 1 definition: The compression algorithm used. defined values: Lhomme, et al. Expires 13 February 2024 [Page 63] Internet-Draft Matroska Format August 2023 +=======+===========+=========================================+ | value | label | definition | +=======+===========+=========================================+ | 0 | zlib | zlib compression [RFC1950]. | +-------+-----------+-----------------------------------------+ | 1 | bzlib | bzip2 compression [BZIP2], SHOULD NOT | | | | be used; see usage notes. | +-------+-----------+-----------------------------------------+ | 2 | lzo1x | Lempel-Ziv-Oberhumer compression [LZO], | | | | SHOULD NOT be used; see usage notes. | +-------+-----------+-----------------------------------------+ | 3 | Header | Octets in ContentCompSettings | | | Stripping | (Section 5.1.4.1.31.7) have been | | | | stripped from each frame. | +-------+-----------+-----------------------------------------+ Table 25: ContentCompAlgo values usage notes: Compression method "1" (bzlib) and "2" (lzo1x) are lacking proper documentation on the format which limits implementation possibilities. Due to licensing conflicts on commonly available libraries compression methods "2" (lzo1x) does not offer widespread interoperability. A Matroska Writer SHOULD NOT use these compression methods by default. A Matroska Reader MAY support methods "1" and "2" as possible, and SHOULD support other methods. stream copy: True (Section 8) 5.1.4.1.31.7. ContentCompSettings Element id / type: 0x4255 / binary path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co ntentCompression\ContentCompSettings maxOccurs: 1 definition: Settings that might be needed by the decompressor. For Header Stripping (ContentCompAlgo=3), the bytes that were removed from the beginning of each frames of the track. stream copy: True (Section 8) 5.1.4.1.31.8. ContentEncryption Element id / type: 0x5035 / master path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co ntentEncryption maxOccurs: 1 definition: Settings describing the encryption used. This Element Lhomme, et al. Expires 13 February 2024 [Page 64] Internet-Draft Matroska Format August 2023 MUST be present if the value of ContentEncodingType is 1 (encryption) and MUST be ignored otherwise. A Matroska Player MAY support encryption. stream copy: True (Section 8) 5.1.4.1.31.9. ContentEncAlgo Element id / type / default: 0x47E1 / uinteger / 0 path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co ntentEncryption\ContentEncAlgo minOccurs / maxOccurs: 1 / 1 definition: The encryption algorithm used. defined values: +=======+===============+===========================================+ | value | label | definition | +=======+===============+===========================================+ | 0 | Not | The data are not encrypted. | | | encrypted | | +-------+---------------+-------------------------------------------+ | 1 | DES | Data Encryption Standard (DES) | | | | [FIPS.46-3].This value SHOULD be avoided. | +-------+---------------+-------------------------------------------+ | 2 | 3DES | Triple Data Encryption Algorithm | | | | [SP.800-67].This value SHOULD be avoided. | +-------+---------------+-------------------------------------------+ | 3 | Twofish | Twofish Encryption Algorithm [Twofish]. | +-------+---------------+-------------------------------------------+ | 4 | Blowfish | Blowfish Encryption Algorithm | | | | [Blowfish].This value SHOULD be avoided. | +-------+---------------+-------------------------------------------+ | 5 | AES | Advanced Encryption Standard (AES) | | | | [FIPS.197]. | +-------+---------------+-------------------------------------------+ Table 26: ContentEncAlgo values stream copy: True (Section 8) 5.1.4.1.31.10. ContentEncKeyID Element id / type: 0x47E2 / binary path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co ntentEncryption\ContentEncKeyID maxOccurs: 1 definition: For public key algorithms this is the ID of the public Lhomme, et al. Expires 13 February 2024 [Page 65] Internet-Draft Matroska Format August 2023 key the data was encrypted with. stream copy: True (Section 8) 5.1.4.1.31.11. ContentEncAESSettings Element id / type: 0x47E7 / master path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co ntentEncryption\ContentEncAESSettings maxOccurs: 1 minver: 4 definition: Settings describing the encryption algorithm used. notes: +===========+=================================================+ | attribute | note | +===========+=================================================+ | maxOccurs | ContentEncAESSettings MUST NOT be set | | | (maxOccurs=0) if ContentEncAlgo is not AES (5). | +-----------+-------------------------------------------------+ Table 27: ContentEncAESSettings implementation notes stream copy: True (Section 8) 5.1.4.1.31.12. AESSettingsCipherMode Element id / type: 0x47E8 / uinteger path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co ntentEncryption\ContentEncAESSettings\AESSettingsCipherMode minOccurs / maxOccurs: 1 / 1 minver: 4 definition: The AES cipher mode used in the encryption. defined values: +=======+=========+=====================================+ | value | label | definition | +=======+=========+=====================================+ | 1 | AES-CTR | Counter [SP.800-38A]. | +-------+---------+-------------------------------------+ | 2 | AES-CBC | Cipher Block Chaining [SP.800-38A]. | +-------+---------+-------------------------------------+ Table 28: AESSettingsCipherMode values notes: Lhomme, et al. Expires 13 February 2024 [Page 66] Internet-Draft Matroska Format August 2023 +===========+=================================================+ | attribute | note | +===========+=================================================+ | maxOccurs | AESSettingsCipherMode MUST NOT be set | | | (maxOccurs=0) if ContentEncAlgo is not AES (5). | +-----------+-------------------------------------------------+ Table 29: AESSettingsCipherMode implementation notes stream copy: True (Section 8) 5.1.5. Cues Element id / type: 0x1C53BB6B / master path: \Segment\Cues minOccurs / maxOccurs: see implementation notes / 1 definition: A Top-Level Element to speed seeking access. All entries are local to the Segment. notes: +===========+====================================================+ | attribute | note | +===========+====================================================+ | minOccurs | This Element SHOULD be set when the Segment is not | | | transmitted as a live stream; see Section 23.2. | +-----------+----------------------------------------------------+ Table 30: Cues implementation notes 5.1.5.1. CuePoint Element id / type: 0xBB / master path: \Segment\Cues\CuePoint minOccurs: 1 definition: Contains all information relative to a seek point in the Segment. 5.1.5.1.1. CueTime Element id / type: 0xB3 / uinteger path: \Segment\Cues\CuePoint\CueTime minOccurs / maxOccurs: 1 / 1 definition: Absolute timestamp of the seek point, expressed in Matroska Ticks -- i.e., in nanoseconds; see Section 11.1. Lhomme, et al. Expires 13 February 2024 [Page 67] Internet-Draft Matroska Format August 2023 5.1.5.1.2. CueTrackPositions Element id / type: 0xB7 / master path: \Segment\Cues\CuePoint\CueTrackPositions minOccurs: 1 definition: Contain positions for different tracks corresponding to the timestamp. 5.1.5.1.2.1. CueTrack Element id / type: 0xF7 / uinteger range: not 0 path: \Segment\Cues\CuePoint\CueTrackPositions\CueTrack minOccurs / maxOccurs: 1 / 1 definition: The track for which a position is given. 5.1.5.1.2.2. CueClusterPosition Element id / type: 0xF1 / uinteger path: \Segment\Cues\CuePoint\CueTrackPositions\CueClusterPosition minOccurs / maxOccurs: 1 / 1 definition: The Segment Position (Section 16) of the Cluster containing the associated Block. 5.1.5.1.2.3. CueRelativePosition Element id / type: 0xF0 / uinteger path: \Segment\Cues\CuePoint\CueTrackPositions\CueRelativePosition maxOccurs: 1 minver: 4 definition: The relative position inside the Cluster of the referenced SimpleBlock or BlockGroup with 0 being the first possible position for an Element inside that Cluster. 5.1.5.1.2.4. CueDuration Element id / type: 0xB2 / uinteger path: \Segment\Cues\CuePoint\CueTrackPositions\CueDuration maxOccurs: 1 minver: 4 definition: The duration of the block, expressed in Segment Ticks which is based on TimestampScale; see Section 11.1. If missing, the track's DefaultDuration does not apply and no duration information is available in terms of the cues. 5.1.5.1.2.5. CueBlockNumber Element id / type: 0x5378 / uinteger Lhomme, et al. Expires 13 February 2024 [Page 68] Internet-Draft Matroska Format August 2023 range: not 0 path: \Segment\Cues\CuePoint\CueTrackPositions\CueBlockNumber maxOccurs: 1 definition: Number of the Block in the specified Cluster. 5.1.5.1.2.6. CueCodecState Element id / type / default: 0xEA / uinteger / 0 path: \Segment\Cues\CuePoint\CueTrackPositions\CueCodecState minOccurs / maxOccurs: 1 / 1 minver: 2 definition: The Segment Position (Section 16) of the Codec State corresponding to this Cue Element. 0 means that the data is taken from the initial Track Entry. 5.1.5.1.2.7. CueReference Element id / type: 0xDB / master path: \Segment\Cues\CuePoint\CueTrackPositions\CueReference minver: 2 definition: The Clusters containing the referenced Blocks. 5.1.5.1.2.8. CueRefTime Element id / type: 0x96 / uinteger path: \Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefTi me minOccurs / maxOccurs: 1 / 1 minver: 2 definition: Timestamp of the referenced Block, expressed in Matroska Ticks -- i.e., in nanoseconds; see Section 11.1. 5.1.6. Attachments Element id / type: 0x1941A469 / master path: \Segment\Attachments maxOccurs: 1 definition: Contain attached files. 5.1.6.1. AttachedFile Element id / type: 0x61A7 / master path: \Segment\Attachments\AttachedFile minOccurs: 1 definition: An attached file. Lhomme, et al. Expires 13 February 2024 [Page 69] Internet-Draft Matroska Format August 2023 5.1.6.1.1. FileDescription Element id / type: 0x467E / utf-8 path: \Segment\Attachments\AttachedFile\FileDescription maxOccurs: 1 definition: A human-friendly name for the attached file. 5.1.6.1.2. FileName Element id / type: 0x466E / utf-8 path: \Segment\Attachments\AttachedFile\FileName minOccurs / maxOccurs: 1 / 1 definition: Filename of the attached file. 5.1.6.1.3. FileMediaType Element id / type: 0x4660 / string path: \Segment\Attachments\AttachedFile\FileMediaType minOccurs / maxOccurs: 1 / 1 definition: Media type of the file following the [RFC6838] format. stream copy: True (Section 8) 5.1.6.1.4. FileData Element id / type: 0x465C / binary path: \Segment\Attachments\AttachedFile\FileData minOccurs / maxOccurs: 1 / 1 definition: The data of the file. stream copy: True (Section 8) 5.1.6.1.5. FileUID Element id / type: 0x46AE / uinteger range: not 0 path: \Segment\Attachments\AttachedFile\FileUID minOccurs / maxOccurs: 1 / 1 definition: Unique ID representing the file, as random as possible. stream copy: True (Section 8) 5.1.7. Chapters Element id / type: 0x1043A770 / master path: \Segment\Chapters maxOccurs: 1 Lhomme, et al. Expires 13 February 2024 [Page 70] Internet-Draft Matroska Format August 2023 recurring: True definition: A system to define basic menus and partition data. For more detailed information, look at the Chapters explanation in Section 20. 5.1.7.1. EditionEntry Element id / type: 0x45B9 / master path: \Segment\Chapters\EditionEntry minOccurs: 1 definition: Contains all information about a Segment edition. 5.1.7.1.1. EditionUID Element id / type: 0x45BC / uinteger range: not 0 path: \Segment\Chapters\EditionEntry\EditionUID maxOccurs: 1 definition: A unique ID to identify the edition. It's useful for tagging an edition. stream copy: True (Section 8) 5.1.7.1.2. EditionFlagDefault Element id / type / default: 0x45DB / uinteger / 0 range: 0-1 path: \Segment\Chapters\EditionEntry\EditionFlagDefault minOccurs / maxOccurs: 1 / 1 definition: Set to 1 if the edition SHOULD be used as the default one. 5.1.7.1.3. EditionFlagOrdered Element id / type / default: 0x45DD / uinteger / 0 range: 0-1 path: \Segment\Chapters\EditionEntry\EditionFlagOrdered minOccurs / maxOccurs: 1 / 1 definition: Set to 1 if the chapters can be defined multiple times and the order to play them is enforced; see Section 20.1.3. 5.1.7.1.4. ChapterAtom Element id / type: 0xB6 / master path: \Segment\Chapters\EditionEntry\+ChapterAtom minOccurs: 1 Lhomme, et al. Expires 13 February 2024 [Page 71] Internet-Draft Matroska Format August 2023 recursive: True definition: Contains the atom information to use as the chapter atom (apply to all tracks). 5.1.7.1.4.1. ChapterUID Element id / type: 0x73C4 / uinteger range: not 0 path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterUID minOccurs / maxOccurs: 1 / 1 definition: A unique ID to identify the Chapter. stream copy: True (Section 8) 5.1.7.1.4.2. ChapterStringUID Element id / type: 0x5654 / utf-8 path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterStringUID maxOccurs: 1 minver: 3 definition: A unique string ID to identify the Chapter. For example it is used as the storage for [WebVTT] cue identifier values. 5.1.7.1.4.3. ChapterTimeStart Element id / type: 0x91 / uinteger path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterTimeStart minOccurs / maxOccurs: 1 / 1 definition: Timestamp of the start of Chapter, expressed in Matroska Ticks -- i.e., in nanoseconds; see Section 11.1. 5.1.7.1.4.4. ChapterTimeEnd Element id / type: 0x92 / uinteger path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterTimeEnd minOccurs / maxOccurs: see implementation notes / 1 definition: Timestamp of the end of Chapter timestamp excluded, expressed in Matroska Ticks -- i.e., in nanoseconds; see Section 11.1. The value MUST be greater than or equal to the ChapterTimeStart of the same ChapterAtom. usage notes: The ChapterTimeEnd timestamp value being excluded, it MUST take in account the duration of the last frame it includes, especially for the ChapterAtom using the last frames of the Segment. notes: Lhomme, et al. Expires 13 February 2024 [Page 72] Internet-Draft Matroska Format August 2023 +===========+====================================================+ | attribute | note | +===========+====================================================+ | minOccurs | ChapterTimeEnd MUST be set (minOccurs=1) if the | | | Edition is an ordered edition; see Section 20.1.3, | | | unless it's a Parent Chapter; see Section 20.2.3 | +-----------+----------------------------------------------------+ Table 31: ChapterTimeEnd implementation notes 5.1.7.1.4.5. ChapterFlagHidden Element id / type / default: 0x98 / uinteger / 0 range: 0-1 path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterFlagHidden minOccurs / maxOccurs: 1 / 1 definition: Set to 1 if a chapter is hidden. Hidden chapters SHOULD NOT be available to the user interface (but still to Control Tracks; see Section 20.2.5 on Chapter flags). 5.1.7.1.4.6. ChapterSegmentUUID Element id / type: 0x6E67 / binary length: 16 path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterSegmentUUID minOccurs / maxOccurs: see implementation notes / 1 definition: The SegmentUUID of another Segment to play during this chapter. usage notes: The value MUST NOT be the SegmentUUID value of the Segment it belongs to. notes: +===========+==============================================+ | attribute | note | +===========+==============================================+ | minOccurs | ChapterSegmentUUID MUST be set (minOccurs=1) | | | if ChapterSegmentEditionUID is used; see | | | Section 17.2 on medium-linking Segments. | +-----------+----------------------------------------------+ Table 32: ChapterSegmentUUID implementation notes 5.1.7.1.4.7. ChapterSegmentEditionUID Element id / type: 0x6EBC / uinteger range: not 0 path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterSegmentEdit Lhomme, et al. Expires 13 February 2024 [Page 73] Internet-Draft Matroska Format August 2023 ionUID maxOccurs: 1 definition: The EditionUID to play from the Segment linked in ChapterSegmentUUID. If ChapterSegmentEditionUID is undeclared, then no Edition of the linked Segment is used; see Section 17.2 on medium-linking Segments. 5.1.7.1.4.8. ChapterPhysicalEquiv Element id / type: 0x63C3 / uinteger path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterPhysicalEqu iv maxOccurs: 1 definition: Specify the physical equivalent of this ChapterAtom like "DVD" (60) or "SIDE" (50); see Section 20.4 for a complete list of values. 5.1.7.1.4.9. ChapterDisplay Element id / type: 0x80 / master path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay definition: Contains all possible strings to use for the chapter display. 5.1.7.1.4.10. ChapString Element id / type: 0x85 / utf-8 path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay\Cha pString minOccurs / maxOccurs: 1 / 1 definition: Contains the string to use as the chapter atom. 5.1.7.1.4.11. ChapLanguage Element id / type / default: 0x437C / string / eng path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay\Cha pLanguage minOccurs: 1 definition: A language corresponding to the string, in the Matroska languages form; see Section 12 on language codes. This Element MUST be ignored if a ChapLanguageBCP47 Element is used within the same ChapterDisplay Element. 5.1.7.1.4.12. ChapLanguageBCP47 Element id / type: 0x437D / string path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay\Cha pLanguageBCP47 Lhomme, et al. Expires 13 February 2024 [Page 74] Internet-Draft Matroska Format August 2023 minver: 4 definition: A language corresponding to the ChapString, in the [BCP47] form; see Section 12 on language codes. If a ChapLanguageBCP47 Element is used, then any ChapLanguage and ChapCountry Elements used in the same ChapterDisplay MUST be ignored. 5.1.7.1.4.13. ChapCountry Element id / type: 0x437E / string path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay\Cha pCountry definition: A country corresponding to the string, in the Matroska countries form; see Section 13 on country codes. This Element MUST be ignored if a ChapLanguageBCP47 Element is used within the same ChapterDisplay Element. 5.1.7.1.4.14. ChapProcess Element id / type: 0x6944 / master path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess definition: Contains all the commands associated to the Atom. 5.1.7.1.4.15. ChapProcessCodecID Element id / type / default: 0x6955 / uinteger / 0 path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapPr ocessCodecID minOccurs / maxOccurs: 1 / 1 definition: Contains the type of the codec used for the processing. A value of 0 means built-in Matroska processing (to be defined), a value of 1 means the DVD command set is used; see Section 20.3 on DVD menus. More codec IDs can be added later. 5.1.7.1.4.16. ChapProcessPrivate Element id / type: 0x450D / binary path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapPr ocessPrivate maxOccurs: 1 definition: Some optional data attached to the ChapProcessCodecID information. For ChapProcessCodecID = 1, it is the "DVD level" equivalent; see Section 20.3 on DVD menus. 5.1.7.1.4.17. ChapProcessCommand Element id / type: 0x6911 / master path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapPr Lhomme, et al. Expires 13 February 2024 [Page 75] Internet-Draft Matroska Format August 2023 ocessCommand definition: Contains all the commands associated to the Atom. 5.1.7.1.4.18. ChapProcessTime Element id / type: 0x6922 / uinteger path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapPr ocessCommand\ChapProcessTime minOccurs / maxOccurs: 1 / 1 definition: Defines when the process command SHOULD be handled restrictions: +=======+===============================+ | value | label | +=======+===============================+ | 0 | during the whole chapter | +-------+-------------------------------+ | 1 | before starting playback | +-------+-------------------------------+ | 2 | after playback of the chapter | +-------+-------------------------------+ Table 33: ChapProcessTime values 5.1.7.1.4.19. ChapProcessData Element id / type: 0x6933 / binary path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapPr ocessCommand\ChapProcessData minOccurs / maxOccurs: 1 / 1 definition: Contains the command information. The data SHOULD be interpreted depending on the ChapProcessCodecID value. For ChapProcessCodecID = 1, the data correspond to the binary DVD cell pre/post commands; see Section 20.3 on DVD menus. 5.1.8. Tags Element id / type: 0x1254C367 / master path: \Segment\Tags definition: Element containing metadata describing Tracks, Editions, Chapters, Attachments, or the Segment as a whole. A list of valid tags can be found in [MatroskaTags]. 5.1.8.1. Tag Element id / type: 0x7373 / master path: \Segment\Tags\Tag Lhomme, et al. Expires 13 February 2024 [Page 76] Internet-Draft Matroska Format August 2023 minOccurs: 1 definition: A single metadata descriptor. 5.1.8.1.1. Targets Element id / type: 0x63C0 / master path: \Segment\Tags\Tag\Targets minOccurs / maxOccurs: 1 / 1 definition: Specifies which other elements the metadata represented by the Tag applies to. If empty or omitted, then the Tag describes everything in the Segment. 5.1.8.1.1.1. TargetTypeValue Element id / type / default: 0x68CA / uinteger / 50 path: \Segment\Tags\Tag\Targets\TargetTypeValue minOccurs / maxOccurs: 1 / 1 definition: A number to indicate the logical level of the target. defined values: Lhomme, et al. Expires 13 February 2024 [Page 77] Internet-Draft Matroska Format August 2023 +=======+===================+=================================+ | value | label | definition | +=======+===================+=================================+ | 70 | COLLECTION | The highest hierarchical level | | | | that tags can describe. | +-------+-------------------+---------------------------------+ | 60 | EDITION / ISSUE / | A list of lower levels grouped | | | VOLUME / OPUS / | together. | | | SEASON / SEQUEL | | +-------+-------------------+---------------------------------+ | 50 | ALBUM / OPERA / | The most common grouping level | | | CONCERT / MOVIE / | of music and video (equals to | | | EPISODE | an episode for TV series). | +-------+-------------------+---------------------------------+ | 40 | PART / SESSION | When an album or episode has | | | | different logical parts. | +-------+-------------------+---------------------------------+ | 30 | TRACK / SONG / | The common parts of an album or | | | CHAPTER | movie. | +-------+-------------------+---------------------------------+ | 20 | SUBTRACK / | Corresponds to parts of a track | | | MOVEMENT / SCENE | for audio like a movement, or a | | | | scene in a movie. | +-------+-------------------+---------------------------------+ | 10 | SHOT | The lowest hierarchy found in | | | | music or movies. | +-------+-------------------+---------------------------------+ Table 34: TargetTypeValue values 5.1.8.1.1.2. TargetType Element id / type: 0x63CA / string path: \Segment\Tags\Tag\Targets\TargetType maxOccurs: 1 definition: An informational string that can be used to display the logical level of the target like "ALBUM", "TRACK", "MOVIE", "CHAPTER", etc. restrictions: Lhomme, et al. Expires 13 February 2024 [Page 78] Internet-Draft Matroska Format August 2023 +============+====================+ | value | label | +============+====================+ | COLLECTION | TargetTypeValue 70 | +------------+--------------------+ | EDITION | TargetTypeValue 60 | +------------+--------------------+ | ISSUE | TargetTypeValue 60 | +------------+--------------------+ | VOLUME | TargetTypeValue 60 | +------------+--------------------+ | OPUS | TargetTypeValue 60 | +------------+--------------------+ | SEASON | TargetTypeValue 60 | +------------+--------------------+ | SEQUEL | TargetTypeValue 60 | +------------+--------------------+ | ALBUM | TargetTypeValue 50 | +------------+--------------------+ | OPERA | TargetTypeValue 50 | +------------+--------------------+ | CONCERT | TargetTypeValue 50 | +------------+--------------------+ | MOVIE | TargetTypeValue 50 | +------------+--------------------+ | EPISODE | TargetTypeValue 50 | +------------+--------------------+ | PART | TargetTypeValue 40 | +------------+--------------------+ | SESSION | TargetTypeValue 40 | +------------+--------------------+ | TRACK | TargetTypeValue 30 | +------------+--------------------+ | SONG | TargetTypeValue 30 | +------------+--------------------+ | CHAPTER | TargetTypeValue 30 | +------------+--------------------+ | SUBTRACK | TargetTypeValue 20 | +------------+--------------------+ | MOVEMENT | TargetTypeValue 20 | +------------+--------------------+ | SCENE | TargetTypeValue 20 | +------------+--------------------+ | SHOT | TargetTypeValue 10 | +------------+--------------------+ Table 35: TargetType values Lhomme, et al. Expires 13 February 2024 [Page 79] Internet-Draft Matroska Format August 2023 5.1.8.1.1.3. TagTrackUID Element id / type / default: 0x63C5 / uinteger / 0 path: \Segment\Tags\Tag\Targets\TagTrackUID definition: A unique ID to identify the Track(s) the tags belong to. usage notes: If the value is 0 at this level, the tags apply to all tracks in the Segment. If set to any other value, it MUST match the TrackUID value of a track found in this Segment. 5.1.8.1.1.4. TagEditionUID Element id / type / default: 0x63C9 / uinteger / 0 path: \Segment\Tags\Tag\Targets\TagEditionUID definition: A unique ID to identify the EditionEntry(s) the tags belong to. usage notes: If the value is 0 at this level, the tags apply to all editions in the Segment. If set to any other value, it MUST match the EditionUID value of an edition found in this Segment. 5.1.8.1.1.5. TagChapterUID Element id / type / default: 0x63C4 / uinteger / 0 path: \Segment\Tags\Tag\Targets\TagChapterUID definition: A unique ID to identify the Chapter(s) the tags belong to. usage notes: If the value is 0 at this level, the tags apply to all chapters in the Segment. If set to any other value, it MUST match the ChapterUID value of a chapter found in this Segment. 5.1.8.1.1.6. TagAttachmentUID Element id / type / default: 0x63C6 / uinteger / 0 path: \Segment\Tags\Tag\Targets\TagAttachmentUID definition: A unique ID to identify the Attachment(s) the tags belong to. usage notes: If the value is 0 at this level, the tags apply to all the attachments in the Segment. If set to any other value, it MUST match the FileUID value of an attachment found in this Segment. 5.1.8.1.2. SimpleTag Element id / type: 0x67C8 / master path: \Segment\Tags\Tag\+SimpleTag minOccurs: 1 recursive: True Lhomme, et al. Expires 13 February 2024 [Page 80] Internet-Draft Matroska Format August 2023 definition: Contains general information about the target. 5.1.8.1.2.1. TagName Element id / type: 0x45A3 / utf-8 path: \Segment\Tags\Tag\+SimpleTag\TagName minOccurs / maxOccurs: 1 / 1 definition: The name of the Tag that is going to be stored. 5.1.8.1.2.2. TagLanguage Element id / type / default: 0x447A / string / und path: \Segment\Tags\Tag\+SimpleTag\TagLanguage minOccurs / maxOccurs: 1 / 1 definition: Specifies the language of the tag specified, in the Matroska languages form; see Section 12 on language codes. This Element MUST be ignored if the TagLanguageBCP47 Element is used within the same SimpleTag Element. 5.1.8.1.2.3. TagLanguageBCP47 Element id / type: 0x447B / string path: \Segment\Tags\Tag\+SimpleTag\TagLanguageBCP47 maxOccurs: 1 minver: 4 definition: The language used in the TagString, in the [BCP47] form; see Section 12 on language codes. If this Element is used, then any TagLanguage Elements used in the same SimpleTag MUST be ignored. 5.1.8.1.2.4. TagDefault Element id / type / default: 0x4484 / uinteger / 1 range: 0-1 path: \Segment\Tags\Tag\+SimpleTag\TagDefault minOccurs / maxOccurs: 1 / 1 definition: A boolean value to indicate if this is the default/ original language to use for the given tag. 5.1.8.1.2.5. TagString Element id / type: 0x4487 / utf-8 path: \Segment\Tags\Tag\+SimpleTag\TagString maxOccurs: 1 definition: The value of the Tag. Lhomme, et al. Expires 13 February 2024 [Page 81] Internet-Draft Matroska Format August 2023 5.1.8.1.2.6. TagBinary Element id / type: 0x4485 / binary path: \Segment\Tags\Tag\+SimpleTag\TagBinary maxOccurs: 1 definition: The values of the Tag, if it is binary. Note that this cannot be used in the same SimpleTag as TagString. 6. Matroska Element Ordering Except for the EBML Header and the CRC-32 Element, the EBML specification does not require any particular storage order for Elements. This specification however defines mandates and recommendations for ordering certain Elements in order to facilitate better playback, seeking, and editing efficiency. This section describes and offers rationale for ordering requirements and recommendations for Matroska. 6.1. Top-Level Elements The Info Element is the only REQUIRED Top-Level Element in a Matroska file. To be playable, Matroska MUST also contain at least one Tracks Element and Cluster Element. The first Info Element and the first Tracks Element MUST either be stored before the first Cluster Element or both SHALL be referenced by a SeekHead Element occurring before the first Cluster Element. All Top-Level Elements MUST use a 4-octet long EBML Element ID. When using Medium Linking, chapters are used to reference other Segments to play in a given order Section 17.2. A Segment containing these linked Chapters does not require a Track Element or a Cluster Element. It is possible to edit a Matroska file after it has been created. For example, chapters, tags, or attachments can be added. When new Top-Level Elements are added to a Matroska file, the SeekHead Element(s) MUST be updated so that the SeekHead Element(s) itemize the identity and position of all Top-Level Elements. Editing, removing, or adding Elements to a Matroska file often requires that some existing Elements be voided or extended. Transforming the existing Elements into Void Elements as padding can be used as a method to avoid moving large amounts of data around. Lhomme, et al. Expires 13 February 2024 [Page 82] Internet-Draft Matroska Format August 2023 6.2. CRC-32 As noted by the EBML specification, if a CRC-32 Element is used, then the CRC-32 Element MUST be the first ordered Element within its Parent Element. In Matroska all Top-Level Elements of an EBML Document SHOULD include a CRC-32 Element as their first Child Element. The Segment Element, which is the Root Element, SHOULD NOT have a CRC-32 Element. 6.3. SeekHead If used, the first SeekHead Element MUST be the first non-CRC-32 Child Element of the Segment Element. If a second SeekHead Element is used, then the first SeekHead Element MUST reference the identity and position of the second SeekHead. Additionally, the second SeekHead Element MUST only reference Cluster Elements and not any other Top-Level Element already contained within the first SeekHead Element. The second SeekHead Element MAY be stored in any order relative to the other Top-Level Elements. Whether one or two SeekHead Element(s) are used, the SeekHead Element(s) MUST collectively reference the identity and position of all Top-Level Elements except for the first SeekHead Element. 6.4. Cues (index) The Cues Element is RECOMMENDED to optimize seeking access in Matroska. It is programmatically simpler to add the Cues Element after all Cluster Elements have been written because this does not require a prediction of how much space to reserve before writing the Cluster Elements. However, storing the Cues Element before the Cluster Elements can provide some seeking advantages. If the Cues Element is present, then it SHOULD either be stored before the first Cluster Element or be referenced by a SeekHead Element. 6.5. Info The first Info Element SHOULD occur before the first Tracks Element and first Cluster Element except when referenced by a SeekHead Element. Lhomme, et al. Expires 13 February 2024 [Page 83] Internet-Draft Matroska Format August 2023 6.6. Chapters Element The Chapters Element SHOULD be placed before the Cluster Element(s). The Chapters Element can be used during playback even if the user does not need to seek. It immediately gives the user information about what section is being read and what other sections are available. In the case of Ordered Chapters it is RECOMMENDED to evaluate the logical linking even before playing. The Chapters Element SHOULD be placed before the first Tracks Element and after the first Info Element. 6.7. Attachments The Attachments Element is not intended to be used by default when playing the file, but could contain information relevant to the content, such as cover art or fonts. Cover art is useful even before the file is played and fonts could be needed before playback starts for initialization of subtitles. The Attachments Element MAY be placed before the first Cluster Element; however, if the Attachments Element is likely to be edited, then it SHOULD be placed after the last Cluster Element. 6.8. Tags The Tags Element is most subject to changes after the file was originally created. For easier editing, the Tags Element can be placed at the end of the Segment Element, even after the Attachments Element. On the other hand, it is inconvenient to have to seek in the Segment for tags, especially for network streams. So it's better if the Tags Element is found early in the stream. When editing the Tags Element, the original Tags Element at the beginning can be overwritten with a Void Element and a new Tags Element written at the end of the Segment Element. The file and Segment sizes will only marginally change. 7. Matroska versioning Matroska is based upon the principle that a reading application does not have to support 100% of the specifications in order to be able to play the file. A Matroska file therefore contains version indicators that tell a reading application what to expect. It is possible and valid to have the version fields indicate that the file contains Matroska Elements from a higher specification version number while signaling that a reading application MUST only support a lower version number properly in order to play it back (possibly with a reduced feature set). Lhomme, et al. Expires 13 February 2024 [Page 84] Internet-Draft Matroska Format August 2023 The EBML Header of each Matroska document informs the reading application on what version of Matroska to expect. The Elements within EBML Header with jurisdiction over this information are DocTypeVersion and DocTypeReadVersion. DocTypeVersion MUST be equal to or greater than the highest Matroska version number of any Element present in the Matroska file. For example, a file using the SimpleBlock Element (Section 5.1.3.4) MUST have a DocTypeVersion equal to or greater than 2. A file containing CueRelativePosition Elements (Section 5.1.5.1.2.3) MUST have a DocTypeVersion equal to or greater than 4. The DocTypeReadVersion MUST contain the minimum version number that a reading application can minimally support in order to play the file back -- optionally with a reduced feature set. For example, if a file contains only Elements of version 2 or lower except for CueRelativePosition (which is a version 4 Matroska Element), then DocTypeReadVersion SHOULD still be set to 2 and not 4 because evaluating CueRelativePosition is not necessary for standard playback -- it makes seeking more precise if used. A reading application supporting Matroska version V MUST NOT refuse to read a file with DocReadTypeVersion equal to or lower than V even if DocTypeVersion is greater than V. A reading application supporting at least Matroska version V reading a file whose DocTypeReadVersion field is equal to or lower than V MUST skip Matroska/EBML Elements it encounters but does not know about if that unknown element fits into the size constraints set by the current Parent Element. 8. Stream Copy It is sometimes necessary to create a Matroska file from another Matroska file, for example to add subtitles in a language or to edit out a portion of the content. Some values from the original Matroska file need to be kept the same in the destination file. For example, the SamplingFrequency of an audio track wouldn't change between the two files. Some other values may change between the two files, for example the TrackNumber of an audio track when another track has been added. An Element is marked with a property: stream copy: True when the values of that Element need to be kept identical between the source and destination file. If that property is not set, elements may or may not keep the same value between the source and destination. Lhomme, et al. Expires 13 February 2024 [Page 85] Internet-Draft Matroska Format August 2023 9. DefaultDecodedFieldDuration The DefaultDecodedFieldDuration Element can signal to the displaying application how often fields of a video sequence will be available for displaying. It can be used for both interlaced and progressive content. If the video sequence is signaled as interlaced Section 5.1.4.1.28.1, then DefaultDecodedFieldDuration equals the period between two successive fields at the output of the decoding process. For video sequences signaled as progressive, DefaultDecodedFieldDuration is half of the period between two successive frames at the output of the decoding process. These values are valid at the end of the decoding process before post-processing (such as deinterlacing or inverse telecine) is applied. Examples: * Blu-ray movie: 1000000000 ns/(48/1.001) = 20854167 ns * PAL broadcast/DVD: 1000000000 ns/(50/1.000) = 20000000 ns * N/ATSC broadcast: 1000000000 ns/(60/1.001) = 16683333 ns * hard-telecined DVD: 1000000000 ns/(60/1.001) = 16683333 ns (60 encoded interlaced fields per second) * soft-telecined DVD: 1000000000 ns/(60/1.001) = 16683333 ns (48 encoded interlaced fields per second, with "repeat_first_field = 1") 10. Cluster Blocks Frames using references SHOULD be stored in "coding order". That means the references first, and then the frames referencing them. A consequence is that timestamps might not be consecutive. But a frame with a past timestamp MUST reference a frame already known, otherwise it's considered bad/void. Matroska has two similar ways to store frames in a block: * in a Block which is contained inside a BlockGroup, * or in a SimpleBlock which is directly in the Cluster. The SimpleBlock is usually preferred unless some extra elements of the BlockGroup need to be used. A Matroska Reader MUST support both types of blocks. Each block contains the same parts in the following order: Lhomme, et al. Expires 13 February 2024 [Page 86] Internet-Draft Matroska Format August 2023 * a variable length header, * optionally the lacing information, * the consecutive frame(s) The block header starts with the number of the Track it corresponds to. The value MUST corresponding to the TrackNumber (Section 5.1.4.1.1) of a TrackEntry of the Segment. The TrackNumber is coded using the VINT mechanism described in Section 4 of [RFC8794]. To save space, the shortest VINT form SHOULD be used. The value can be coded on up to 8 octets. This is the only element with a variable size in the block header. The timestamp is expressed in Track Ticks; see Section 11.1. The value is stored as a signed value on 16 bits. 10.1. Block Structure This section describes the binary data contained in the Block Element Section 5.1.3.5.1. Bit 0 is the most significant bit. As the TrackNumber size can vary between 1 and 8 octets, there are 8 different sizes for the Block header. We only provide the definitions for TrackNumber sizes of 1 and 2. The other variants can be deduced by extending the size of the TrackNumber by multiples of 8 bits. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | |I|LAC|U| | Track Number | Timestamp | Rsvrd |N|ING|N| | | | |V| |U| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 11: Block Header with 1 octet TrackNumber 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Track Number | Timestamp | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |I|LAC|U| | Rsvrd |N|ING|N| ... | |V| |U| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 12: Block Header with 2 octets TrackNumber Lhomme, et al. Expires 13 February 2024 [Page 87] Internet-Draft Matroska Format August 2023 where: Track Number: 8, 16, 24, 32, 40, 48 or 64 bits an EBML VINT coded track number Timestamp: 16 bits signed timestamp in Track Ticks Rsvrd: 4 bits Reserved bits MUST be set to 0 INV: 1 bit Invisible, the codec SHOULD decode this frame but not display it LACING: 2 bits using lacing mode * 00b : no lacing (Section 10.3.1) * 01b : Xiph lacing (Section 10.3.2) * 11b : EBML lacing (Section 10.3.3) * 10b : fixed-size lacing (Section 10.3.4) UNU: 1 bit unused bit The following data in the Block correspond to the lacing data and frames usage as described in each respective lacing mode. 10.2. SimpleBlock Structure This section describes the binary data contained in the SimpleBlock Element Section 5.1.3.4. Bit 0 is the most significant bit. The SimpleBlock is inspired by the Block structure; see Section 10.1. The main differences are the added Keyframe flag and Discardable flag. Otherwise, everything is the same. As the TrackNumber size can vary between 1 and 8 octets, there are 8 different sizes for the SimpleBlock header. We only provide the definitions for TrackNumber sizes of 1 and 2. The other variants can be deduced by extending the size of the TrackNumber by multiples of 8 bits. Lhomme, et al. Expires 13 February 2024 [Page 88] Internet-Draft Matroska Format August 2023 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | |K| |I|LAC|D| | Track Number | Timestamp |E|Rsvrd|N|ING|I| | | |Y| |V| |S| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 13: SimpleBlock Header with 1 octet TrackNumber 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Track Number | Timestamp | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |K| |I|LAC|D| |E|Rsvrd|N|ING|I| ... |Y| |V| |S| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 14: SimpleBlock Header with 2 octets TrackNumber where: Track Number: 8, 16, 24, 32, 40, 48 or 64 bits an EBML VINT coded track number Timestamp: 16 bits signed timestamp in Track Ticks KEY: 1 bit Keyframe, set when the Block contains only keyframes Rsvrd: 3 bits Reserved bits MUST be set to 0 INV: 1 bit Invisible, the codec SHOULD decode this frame but not display it LACING: 2 bits using lacing mode * 00b : no lacing (Section 10.3.1) * 01b : Xiph lacing (Section 10.3.2) * 11b : EBML lacing (Section 10.3.3) * 10b : fixed-size lacing (Section 10.3.4) Lhomme, et al. Expires 13 February 2024 [Page 89] Internet-Draft Matroska Format August 2023 DIS: 1 bit Discardable, the frames of the Block can be discarded during playing if needed The following data in the SimpleBlock correspond to the lacing data and frames usage as described in each respective lacing mode. 10.3. Block Lacing Lacing is a mechanism to save space when storing data. It is typically used for small blocks of data (referred to as frames in Matroska). It packs multiple frames into a single Block or SimpleBlock. Lacing MUST NOT be used to store a single frame in a Block or SimpleBlock. There are 3 types of lacing: 1. Xiph, inspired by what is found in the Ogg container [RFC3533] 2. EBML, which is the same with sizes coded differently 3. fixed-size, where the size is not coded When lacing is not used, i.e. to store a single frame, the lacing bits 5 and 6 of the Block or SimpleBlock MUST be set to zero. For example, a user wants to store 3 frames of the same track. The first frame is 800 octets long, the second is 500 octets long and the third is 1000 octets long. As these data are small, they can be stored in a lace to save space. It is possible not to use lacing at all and just store a single frame without any extra data. When the FlagLacing -- Section 5.1.4.1.12 -- is set to "0" all blocks of that track MUST NOT use lacing. 10.3.1. No lacing When no lacing is used, the number of frames in the lace is ommitted and only one frame can be stored in the Block. The bits 5-6 of the Block Header flags are set to 00. The Block for an 800 octets frame is as follows: Lhomme, et al. Expires 13 February 2024 [Page 90] Internet-Draft Matroska Format August 2023 +==============+=========+===================+ | Block Octets | Value | Description | +==============+=========+===================+ | 4-803 | | Single frame data | +--------------+---------+-------------------+ Table 36: No lacing When a Block contains a single frame, it MUST use this No lacing mode. 10.3.2. Xiph lacing The Xiph lacing uses the same coding of size as found in the Ogg container [RFC3533]. The bits 5-6 of the Block Header flags are set to 01. The Block data with laced frames is stored as follows: * Lacing Head on 1 Octet: Number of frames in the lace minus 1. * Lacing size of each frame except the last one. * Binary data of each frame consecutively. The lacing size is split into 255 values, stored as unsigned octets -- for example, 500 is coded 255;245 or [0xFF 0xF5]. A frame with a size multiple of 255 is coded with a 0 at the end of the size -- for example, 765 is coded 255;255;255;0 or [0xFF 0xFF 0xFF 0x00]. The size of the last frame is deduced from the size remaining in the Block after the other frames. Because large sizes result in large coding of the sizes, it is RECOMMENDED to use Xiph lacing only with small frames. In our example, the 800, 500 and 1000 frames are stored with Xiph lacing in a Block as follows: Lhomme, et al. Expires 13 February 2024 [Page 91] Internet-Draft Matroska Format August 2023 +=============+=====================+==========================+ | Block Octet | Value | Description | +=============+=====================+==========================+ | 4 | 0x02 | Number of frames minus 1 | +-------------+---------------------+--------------------------+ | 5-8 | 0xFF 0xFF 0xFF 0x23 | Size of the first frame | | | | (255;255;255;35) | +-------------+---------------------+--------------------------+ | 9-10 | 0xFF 0xF5 | Size of the second frame | | | | (255;245) | +-------------+---------------------+--------------------------+ | 11-810 | | First frame data | +-------------+---------------------+--------------------------+ | 811-1310 | | Second frame data | +-------------+---------------------+--------------------------+ | 1311-2310 | | Third frame data | +-------------+---------------------+--------------------------+ Table 37: Xiph lacing example The Block is 2311 octets large and the last frame starts at 1311, so we can deduce the size of the last frame is 2311 - 1311 = 1000. 10.3.3. EBML lacing The EBML lacing encodes the frame size with an EBML-like encoding [RFC8794]. The bits 5-6 of the Block Header flags are set to 11. The Block data with laced frames is stored as follows: * Lacing Head on 1 Octet: Number of frames in the lace minus 1. * Lacing size of each frame except the last one. * Binary data of each frame consecutively. The first frame size is encoded as an EBML Variable-Size Integer value, also known as VINT in [RFC8794]. The remaining frame sizes are encoded as signed values using the difference between the frame size and the previous frame size. These signed values are encoded as VINT, with a mapping from signed to unsigned numbers. Decoding the unsigned number stored in the VINT to a signed number is done by subtracting 2^((7*n)-1)-1, where n is the octet size of the VINT. Lhomme, et al. Expires 13 February 2024 [Page 92] Internet-Draft Matroska Format August 2023 +===================================+======================+ | Bit Representation of signed VINT | Possible Value Range | +===================================+======================+ | 1xxx xxxx | 2^7 values from | | | -(2^6-1) to 2^6 | +-----------------------------------+----------------------+ | 01xx xxxx xxxx xxxx | 2^14 values from | | | -(2^13-1) to 2^13 | +-----------------------------------+----------------------+ | 001x xxxx xxxx xxxx xxxx xxxx | 2^21 values from | | | -(2^20-1) to 2^20 | +-----------------------------------+----------------------+ | 0001 xxxx xxxx xxxx xxxx xxxx | 2^28 values from | | xxxx xxxx | -(2^27-1) to 2^27 | +-----------------------------------+----------------------+ | 0000 1xxx xxxx xxxx xxxx xxxx | 2^35 values from | | xxxx xxxx xxxx xxxx | -(2^34-1) to 2^34 | +-----------------------------------+----------------------+ Table 38: EBML Lacing signed VINT bits usage In our example, the 800, 500 and 1000 frames are stored with EBML lacing in a Block as follows: +==============+===========+=====================================+ | Block Octets | Value | Description | +==============+===========+=====================================+ | 4 | 0x02 | Number of frames minus 1 | +--------------+-----------+-------------------------------------+ | 5-6 | 0x43 0x20 | Size of the first frame (800 = | | | | 0x320 + 0x4000) | +--------------+-----------+-------------------------------------+ | 7-8 | 0x5E 0xD3 | Size of the second frame (500 - 800 | | | | = -300 = - 0x12C + 0x1FFF + 0x4000) | +--------------+-----------+-------------------------------------+ | 8-807 | | First frame data | +--------------+-----------+-------------------------------------+ | 808-1307 | | Second frame data | +--------------+-----------+-------------------------------------+ | 1308-2307 | | Third frame data | +--------------+-----------+-------------------------------------+ Table 39: EBML lacing example The Block is 2308 octets large and the last frame starts at 1308, so we can deduce the size of the last frame is 2308 - 1308 = 1000. Lhomme, et al. Expires 13 February 2024 [Page 93] Internet-Draft Matroska Format August 2023 10.3.4. Fixed-size lacing The Fixed-size lacing doesn't store the frame size, only the number of frames in the lace. Each frame MUST have the same size. The frame size of each frame is deduced from the total size of the Block. The bits 5-6 of the Block Header flags are set to 10. The Block data with laced frames is stored as follows: * Lacing Head on 1 Octet: Number of frames in the lace minus 1. * Binary data of each frame consecutively. For example, for 3 frames of 800 octets each: +==============+==========+==========================+ | Block Octets | Value | Description | +==============+==========+==========================+ | 4 | 0x02 | Number of frames minus 1 | +--------------+----------+--------------------------+ | 5-804 | | First frame data | +--------------+----------+--------------------------+ | 805-1604 | | Second frame data | +--------------+----------+--------------------------+ | 1605-2404 | | Third frame data | +--------------+----------+--------------------------+ Table 40: Fixed-size lacing example This gives a Block of 2405 octets. When reading the Block we find that there are 3 frames (Octet 4). The data start at Octet 5, so the size of each frame is (2405 - 5) / 3 = 800. 10.3.5. Laced Frames Timestamp A Block only contains a single timestamp value. But when lacing is used, it contains more than one frame. Each frame originally has its own timestamp, or Presentation Timestamp (PTS). That timestamp applies to the first frame in the lace. In the lace, each frame after the first one has an underdetermined timestamp. But each of these frames MUST be contiguous -- i.e. the decoded data MUST NOT contain any gap between them. If there is a gap in the stream, the frames around the gap MUST NOT be in the same Block. Lacing is only useful for small contiguous data to save space. This is usually the case for audio tracks and not the case for video -- which use a lot of data -- or subtitle tracks -- which have long Lhomme, et al. Expires 13 February 2024 [Page 94] Internet-Draft Matroska Format August 2023 gaps. For audio, there is usually a fixed output sampling frequency for the whole track. So the decoder should be able to recover the timestamp of each sample, knowing each output sample is contiguous with a fixed frequency. For subtitles this is usually not the case so lacing SHOULD NOT be used. 10.4. Random Access Points Random Access Points (RAP) are positions where the parser can seek to and start playback without decoding of what was before. In Matroska BlockGroups and SimpleBlocks can be RAPs. To seek to these elements it is still necessary to seek to the Cluster containing them, read the Cluster Timestamp and start playback from the BlockGroup or SimpleBlock that is a RAP. Because a Matroska File is usually composed of multiple tracks playing at the same time -- video, audio and subtitles -- to seek properly to a RAP, each selected track must be taken in account. Usually all audio and subtitle BlockGroup or SimpleBlock are RAP. They are independent of each other and can be played randomly. Video tracks on the other hand often use references to previous and future frames for better coding efficiency. Frames with such reference MUST either contain one or more ReferenceBlock Elements in their BlockGroup or MUST be marked as non-keyframe in a SimpleBlock; see Section 10.2. * BlockGroup with a frame that references another frame, with the EBML tree shown as XML: 123456 -40 ... * SimpleBlock with a frame that references another frame, with the EBML tree shown as XML: 123456 (octet 3 bit 0 not set) ... Lhomme, et al. Expires 13 February 2024 [Page 95] Internet-Draft Matroska Format August 2023 Frames that are RAP -- i.e. they don't depend on other frames -- MUST set the keyframe flag if they are in a SimpleBlock or their parent BlockGroup MUST NOT contain a ReferenceBlock. * BlockGroup with a frame that references no other frame, with the EBML tree shown as XML: 123456 ... * SimpleBlock with a frame that references no other frame, with the EBML tree shown as XML: 123456 (octet 3 bit 0 set) ... There may be cases where the use of BlockGroup is necessary, as the frame may need a BlockDuration, BlockAdditions, CodecState or a DiscardPadding element. For thoses cases a SimpleBlock MUST NOT be used, the reference information SHOULD be recovered for non-RAP frames. * SimpleBlock with a frame that references another frame, with the EBML tree shown as XML: 123456 (octet 3 bit 0 not set) ... * Same frame that references another frame put inside a BlockGroup to add BlockDuration, with the EBML tree shown as XML: Lhomme, et al. Expires 13 February 2024 [Page 96] Internet-Draft Matroska Format August 2023 123456 -40 20 ... When a frame in a BlockGroup is not a RAP, the BlockGroup MUST contain at least a ReferenceBlock. The ReferenceBlocks MUST be used in one of the following ways: * each reference frame listed as a ReferenceBlock, * some referenced frame listed as a ReferenceBlock, even if the timestamp value is accurate, * or one ReferenceBlock with the timestamp value "0" corresponding to a self or unknown reference. The lack of ReferenceBlock would mean such a frame is a RAP and seeking on that frame that actually depends on other frames may create bogus output or even crash. * Same frame that references another frame put inside a BlockGroup but the reference could not be recovered, with the EBML tree shown as XML: 123456 0 20 ... * BlockGroup with a frame that references two other frames, with the EBML tree shown as XML: Lhomme, et al. Expires 13 February 2024 [Page 97] Internet-Draft Matroska Format August 2023 123456 -80 40 ... Intra-only video frames, such as the ones found in AV1 or VP9, can be decoded without any other frame, but they don't reset the codec state. So seeking to these frames is not possible as the next frames may need frames that are not known from this seeking point. Such intra-only frames MUST NOT be considered as keyframes so the keyframe flag MUST NOT be set in the SimpleBlock or a ReferenceBlock MUST be used to signify the frame is not a RAP. The timestamp value of the ReferenceBlock MUST be "0", meaning it's referencing itself. * Intra-only frame not an RAP, with the EBML tree shown as XML: 123456 0 ... Because a video SimpleBlock has less references information than a video BlockGroup, it is possible to remux a video track using BlockGroup into a SimpleBlock, as long as it doesn't use any other BlockGroup features than ReferenceBlock. 11. Timestamps Historically timestamps in Matroska were mistakenly called timecodes. The Timestamp Element was called Timecode, the TimestampScale Element was called TimecodeScale, the TrackTimestampScale Element was called TrackTimecodeScale and the ReferenceTimestamp Element was called ReferenceTimeCode. Lhomme, et al. Expires 13 February 2024 [Page 98] Internet-Draft Matroska Format August 2023 11.1. Timestamp Ticks All timestamp values in Matroska are expressed in multiples of a tick. They are usually stored as integers. There are three types of ticks possible: 11.1.1. Matroska Ticks For such elements, the timestamp value is stored directly in nanoseconds. The elements storing values in Matroska Ticks/nanoseconds are: * TrackEntry\DefaultDuration; defined in Section 5.1.4.1.13 * TrackEntry\DefaultDecodedFieldDuration; defined in Section 5.1.4.1.14 * TrackEntry\SeekPreRoll; defined in Section 5.1.4.1.26 * TrackEntry\CodecDelay; defined in Section 5.1.4.1.25 * BlockGroup\DiscardPadding; defined in Section 5.1.3.5.7 * ChapterAtom\ChapterTimeStart; defined in Section 5.1.7.1.4.3 * ChapterAtom\ChapterTimeEnd; defined in Section 5.1.7.1.4.4 * CuePoint\CueTime; defined in Section 5.1.5.1.1 * CueReference\CueRefTime; defined in Section 5.1.5.1.1 11.1.2. Segment Ticks Elements in Segment Ticks involve the use of the TimestampScale Element of the Segment to get the timestamp in nanoseconds of the element, with the following formula: timestamp in nanosecond = element value * TimestampScale This allows storing smaller integer values in the elements. When using the default value of TimestampScale of "1,000,000", one Segment Tick represents one millisecond. The elements storing values in Segment Ticks are: * Cluster\Timestamp; defined in Section 5.1.3.1 * Info\Duration is stored as a floating-point but the same formula applies; defined in Section 5.1.2.10 * CuePoint\CueTrackPositions\CueDuration; defined in Section 5.1.5.1.2.4 Lhomme, et al. Expires 13 February 2024 [Page 99] Internet-Draft Matroska Format August 2023 11.1.3. Track Ticks Elements in Track Ticks involve the use of the TimestampScale Element of the Segment and the TrackTimestampScale Element of the Track to get the timestamp in nanoseconds of the element, with the following formula: timestamp in nanoseconds = element value * TrackTimestampScale * TimestampScale This allows storing smaller integer values in the elements. The resulting floating-point values of the timestamps are still expressed in nanoseconds. When using the default values for TimestampScale and TrackTimestampScale of "1,000,000" and of "1.0" respectively, one Track Tick represents one millisecond. The elements storing values in Track Ticks are: * Cluster\BlockGroup\Block and Cluster\SimpleBlock timestamps; detailed in Section 11.2 * Cluster\BlockGroup\BlockDuration; defined in Section 5.1.3.5.3 * Cluster\BlockGroup\ReferenceBlock; defined in Section 5.1.3.5.5 When the TrackTimestampScale is interpreted as "1.0", Track Ticks are equivalent to Segment Ticks and give an integer value in nanoseconds. This is the most common case as TrackTimestampScale is usually omitted. A value of TrackTimestampScale other than "1.0" MAY be used to scale the timestamps more in tune with each Track sampling frequency. For historical reasons, a lot of Matroska readers don't take the TrackTimestampScale value in account. So using a value other than "1.0" might not work in many places. 11.2. Block Timestamps A Block Element and SimpleBlock Element timestamp is the time when the decoded data of the first frame in the Block/SimpleBlock MUST be presented, if the track of that Block/SimpleBlock is selected for playback. This is also known as the Presentation Timestamp (PTS). The Block Element and SimpleBlock Element store their timestamps as signed integers, relative to the Cluster\Timestamp value of the Cluster they are stored in. To get the timestamp of a Block or SimpleBlock in nanoseconds you have to use the following formula: Lhomme, et al. Expires 13 February 2024 [Page 100] Internet-Draft Matroska Format August 2023 ( Cluster\Timestamp + ( block timestamp * TrackTimestampScale ) ) * TimestampScale The Block Element and SimpleBlock Element store their timestamps as 16bit signed integers, allowing a range from "-32768" to "+32767" Track Ticks. Although these values can be negative, when added to the Cluster\Timestamp, the resulting frame timestamp SHOULD NOT be negative. When a CodecDelay Element is set, its value MUST be substracted from each Block timestamp of that track. To get the timestamp in nanoseconds of the first frame in a Block or SimpleBlock, the formula becomes: ( ( Cluster\Timestamp + ( block timestamp * TrackTimestampScale ) ) * TimestampScale ) - CodecDelay The resulting frame timestamp SHOULD NOT be negative. During playback, when a frame has a negative timestamp, the content MUST be decoded by the decoder but not played to the user. 11.3. TimestampScale Rounding The default Track Tick duration is one millisecond. The TimestampScale is a floating-point value, which is usually 1.0. But when it's not, the multiplied Block Timestamp is a floating-point value in nanoseconds. The Matroska Reader SHOULD use the nearest rounding value in nanosecond to get the proper nanosecond timestamp of a Block. This allows some clever TimestampScale values to have more refined timestamp precision per frame. 12. Language Codes Matroska from version 1 through 3 uses language codes that can be either the 3 letters bibliographic ISO-639-2 form [ISO639-2] (like "fre" for French), or such a language code followed by a dash and a country code for specialities in languages (like "fre-ca" for Canadian French). The ISO 639-2 Language Elements are "Language Element", "TagLanguage Element", and "ChapLanguage Element". Lhomme, et al. Expires 13 February 2024 [Page 101] Internet-Draft Matroska Format August 2023 Starting in Matroska version 4, either [ISO639-2] or [BCP47] MAY be used, although BCP 47 is RECOMMENDED. The BCP 47 Language Elements are "LanguageBCP47 Element", "TagLanguageBCP47 Element", and "ChapLanguageBCP47 Element". If a BCP 47 Language Element and an ISO 639-2 Language Element are used within the same Parent Element, then the ISO 639-2 Language Element MUST be ignored and precedence given to the BCP 47 Language Element. 13. Country Codes Country codes are the [BCP47] two-letter region subtag, without the UK exception. 14. Encryption This Matroska specification provides no interoperable solution for securing the data container with any assurances of confidentiality, integrity, authenticity, or to provide authorization. The ContentEncryption Element (Section 5.1.4.1.31.8) and associated sub- fields (Section 5.1.4.1.31.9 to Section 5.1.4.1.31.12) are defined only for the benefit of implementers to construct their own proprietary solution or as the basis for further standardization activities. How to use these fields to secure a Matroska data container is out of scope, as are any related issues such as key management and distribution. A Matroska Reader who encounters containers that use the fields defined in this section MUST rely on out-of-scope guidance to decode the associated content. Because encryption occurs within the Block Element, it is possible to manipulate encrypted streams without decrypting them. The streams could potentially be copied, deleted, cut, appended, or any number of other possible editing techniques without decryption. The data can be used without having to expose it or go through the decrypting process. Encryption can also be layered within Matroska. This means that two completely different types of encryption can be used, requiring two separate keys to be able to decrypt a stream. Encryption information is stored in the ContentEncodings Element under the ContentEncryption Element. For encryption systems sharing public/private keys, the creation of the keys and the exchange of keys are not covered by this document. They have to be handled by the system using Matroska. Lhomme, et al. Expires 13 February 2024 [Page 102] Internet-Draft Matroska Format August 2023 The algorithms described in Table 26 support different modes of operations and key sizes. The specification of these parameters is required for a complete solution, but is out of scope of this document and left to the proprietary implementations using them or subsequent profiles of this document. The ContentEncodingScope Element gives an idea of which part of the track are encrypted. But each ContentEncAlgo Element and its sub elements like AESSettingsCipherMode really define how the encrypted should be exactly interpreted. An example of an extension that builds upon these security-related fields in this specification is [WebM-Enc]. It uses AES-CTR, ContentEncAlgo = 5 (Section 5.1.4.1.31.9) and AESSettingsCipherMode = 1 (Section 5.1.4.1.31.12). A Matroska Writer MUST NOT use insecure cryptographic algorithms to create new archives or streams, but a Matroska Reader MAY support these algorithms to read previously made archives or stream. 15. Image Presentation 15.1. Cropping The PixelCrop Elements (PixelCropTop, PixelCropBottom, PixelCropRight, and PixelCropLeft) indicate when, and by how much, encoded videos frames SHOULD be cropped for display. These Elements allow edges of the frame that are not intended for display, such as the sprockets of a full-frame film scan or the VANC area of a digitized analog videotape, to be stored but hidden. PixelCropTop and PixelCropBottom store an integer of how many rows of pixels SHOULD be cropped from the top and bottom of the image (respectively). PixelCropLeft and PixelCropRight store an integer of how many columns of pixels SHOULD be cropped from the left and right of the image (respectively). For example, a pillar-boxed video that stores a 1440x1080 visual image within the center of a padded 1920x1080 encoded image may set both PixelCropLeft and PixelCropRight to "240", so that a Matroska Player should crop off 240 columns of pixels from the left and right of the encoded image to present the image with the pillar-boxes hidden. Cropping has to be performed before resizing and the display dimensions given by DisplayWidth, DisplayHeight and DisplayUnit apply to the already cropped image. Lhomme, et al. Expires 13 February 2024 [Page 103] Internet-Draft Matroska Format August 2023 15.2. Rotation The ProjectionPoseRoll Element (see Section 5.1.4.1.28.46) can be used to indicate that the image from the associated video track SHOULD be rotated for presentation. For instance, the following representation of the Projection Element Section 5.1.4.1.28.41) and the ProjectionPoseRoll Element represents a video track where the image SHOULD be presented with a 90-degree counter-clockwise rotation, with the EBML tree shown as XML : 90 Figure 15: Rotation example. 16. Segment Position The Segment Position of an Element refers to the position of the first octet of the Element ID of that Element, measured in octets, from the beginning of the Element Data section of the containing Segment Element. In other words, the Segment Position of an Element is the distance in octets from the beginning of its containing Segment Element minus the size of the Element ID and Element Data Size of that Segment Element. The Segment Position of the first Child Element of the Segment Element is 0. An Element which is not stored within a Segment Element, such as the Elements of the EBML Header, do not have a Segment Position. 16.1. Segment Position Exception Elements that are defined to store a Segment Position MAY define reserved values to indicate a special meaning. 16.2. Example of Segment Position This table presents an example of Segment Position by showing a hexadecimal representation of a very small Matroska file with labels to show the offsets in octets. The file contains a Segment Element with an Element ID of "0x18538067" and a MuxingApp Element with an Element ID of "0x4D80". Lhomme, et al. Expires 13 February 2024 [Page 104] Internet-Draft Matroska Format August 2023 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ 0 |1A|45|DF|A3|8B|42|82|88|6D|61|74|72|6F|73|6B|61| ^ EBML Header 0 | |18|53|80|67| ^ Segment ID 20 |93| ^ Segment Data Size 20 | |15|49|A9|66|8E|4D|80|84|69|65|74|66|57|41|84|69|65|74|66| ^ Start of Segment data 20 | |4D|80|84|69|65|74|66|57|41|84|69|65|74|66| ^ MuxingApp start In the above example, the Element ID of the Segment Element is stored at offset 16, the Element Data Size of the Segment Element is stored at offset 20, and the Element Data of the Segment Element is stored at offset 21. The MuxingApp Element is stored at offset 26. Since the Segment Position of an Element is calculated by subtracting the position of the Element Data of the containing Segment Element from the position of that Element, the Segment Position of MuxingApp Element in the above example is '26 - 21' or '5'. 17. Linked Segments Matroska provides several methods to link two or more Segment Elements together to create a Linked Segment. A Linked Segment is a set of multiple Segments linked together into a single presentation by using Hard Linking or Medium Linking. All Segments within a Linked Segment MUST have a SegmentUUID. All Segments within a Linked Segment SHOULD be stored within the same directory or be accessible quickly based on their SegmentUUID in order to have seamless transition between segments. All Segments within a Linked Segment MAY set a SegmentFamily with a common value to make it easier for a Matroska Player to know which Segments are meant to be played together. The SegmentFilename, PrevFilename and NextFilename elements MAY also give hints on the original filenames that were used when the Segment links were created, in case some SegmentUUID are damaged. Lhomme, et al. Expires 13 February 2024 [Page 105] Internet-Draft Matroska Format August 2023 17.1. Hard Linking Hard Linking, also called splitting, is the process of creating a Linked Segment by linking multiple Segment Elements using the NextUUID and PrevUUID Elements. All Segments within a Hard Linked Segment MUST use the same Tracks list and TimestampScale. Within a Linked Segment, the timestamps of Block and SimpleBlock MUST follow consecutively the timestamps of Block and SimpleBlock from the previous Segment in linking order. With Hard Linking, the chapters of any Segment within the Linked Segment MUST only reference the current Segment. The NextUUID and PrevUUID reference the respective SegmentUUID values of the next and previous Segments. The first Segment of a Linked Segment MUST NOT have a PrevUUID Element. The last Segment of a Linked Segment MUST NOT have a NextUUID Element. For each node of the chain of Segments of a Linked Segment at least one Segment MUST reference the other Segment within the chain. In a chain of Segments of a Linked Segment the NextUUID always takes precedence over the PrevUUID. So if SegmentA has a NextUUID to SegmentB and SegmentB has a PrevUUID to SegmentC, the link to use is NextUUID between SegmentA and SegmentB, SegmentC is not part of the Linked Segment. If SegmentB has a PrevUUID to SegmentA but SegmentA has no NextUUID, then the Matroska Player MAY consider these two Segments linked as SegmentA followed by SegmentB. As an example, three Segments can be Hard Linked as a Linked Segment through cross-referencing each other with SegmentUUID, PrevUUID, and NextUUID, as in this table: Lhomme, et al. Expires 13 February 2024 [Page 106] Internet-Draft Matroska Format August 2023 +==========+================+==================+==================+ |file name |SegmentUUID | PrevUUID | NextUUID | +==========+================+==================+==================+ |start.mkv |71000c23cd310998| Invalid | a77b3598941cb803 | | |53fbc94dd984a5dd| | eac0fcdafe44fac9 | +----------+----------------+------------------+------------------+ |middle.mkv|a77b3598941cb803| 71000c23cd310998 | 6c92285fa6d3e827 | | |eac0fcdafe44fac9| 53fbc94dd984a5dd | b198d120ea3ac674 | +----------+----------------+------------------+------------------+ |end.mkv |6c92285fa6d3e827| a77b3598941cb803 | Invalid | | |b198d120ea3ac674| eac0fcdafe44fac9 | | +----------+----------------+------------------+------------------+ Table 41: Usual Hard Linking UIDs An other example where only the NextUUID Element is used: +============+==================+==========+==================+ | file name | SegmentUUID | PrevUUID | NextUUID | +============+==================+==========+==================+ | start.mkv | 71000c23cd310998 | Invalid | a77b3598941cb803 | | | 53fbc94dd984a5dd | | eac0fcdafe44fac9 | +------------+------------------+----------+------------------+ | middle.mkv | a77b3598941cb803 | n/a | 6c92285fa6d3e827 | | | eac0fcdafe44fac9 | | b198d120ea3ac674 | +------------+------------------+----------+------------------+ | end.mkv | 6c92285fa6d3e827 | n/a | Invalid | | | b198d120ea3ac674 | | | +------------+------------------+----------+------------------+ Table 42: Hard Linking without PrevUUID An example where only the PrevUUID Element is used: +============+==================+==================+==========+ | file name | SegmentUUID | PrevUUID | NextUUID | +============+==================+==================+==========+ | start.mkv | 71000c23cd310998 | Invalid | n/a | | | 53fbc94dd984a5dd | | | +------------+------------------+------------------+----------+ | middle.mkv | a77b3598941cb803 | 71000c23cd310998 | n/a | | | eac0fcdafe44fac9 | 53fbc94dd984a5dd | | +------------+------------------+------------------+----------+ | end.mkv | 6c92285fa6d3e827 | a77b3598941cb803 | Invalid | | | b198d120ea3ac674 | eac0fcdafe44fac9 | | +------------+------------------+------------------+----------+ Table 43: Hard Linking without NextUUID Lhomme, et al. Expires 13 February 2024 [Page 107] Internet-Draft Matroska Format August 2023 In this example only the middle.mkv is using the PrevUUID and NextUUID Elements: +==========+================+==================+==================+ |file name |SegmentUUID | PrevUUID | NextUUID | +==========+================+==================+==================+ |start.mkv |71000c23cd310998| Invalid | n/a | | |53fbc94dd984a5dd| | | +----------+----------------+------------------+------------------+ |middle.mkv|a77b3598941cb803| 71000c23cd310998 | 6c92285fa6d3e827 | | |eac0fcdafe44fac9| 53fbc94dd984a5dd | b198d120ea3ac674 | +----------+----------------+------------------+------------------+ |end.mkv |6c92285fa6d3e827| n/a | Invalid | | |b198d120ea3ac674| | | +----------+----------------+------------------+------------------+ Table 44: Hard Linking with mixed UID links 17.2. Medium Linking Medium Linking creates relationships between Segments using Ordered Chapters (Section 20.1.3) and the ChapterSegmentUUID Element. A Chapter Edition with Ordered Chapters MAY contain Chapter elements that reference timestamp ranges from other Segments. The Segment referenced by the Ordered Chapter via the ChapterSegmentUUID Element SHOULD be played as part of a Linked Segment. The timestamps of Segment content referenced by Ordered Chapters MUST be adjusted according to the cumulative duration of the previous Ordered Chapters. As an example a file named intro.mkv could have a SegmentUUID of "0xb16a58609fc7e60653a60c984fc11ead". Another file called program.mkv could use a Chapter Edition that contains two Ordered Chapters. The first chapter references the Segment of intro.mkv with the use of a ChapterSegmentUUID, ChapterSegmentEditionUID, ChapterTimeStart, and optionally a ChapterTimeEnd element. The second chapter references content within the Segment of program.mkv. A Matroska Player SHOULD recognize the Linked Segment created by the use of ChapterSegmentUUID in an enabled Edition and present the reference content of the two Segments as a single presentation. The ChapterSegmentUUID represents the Segment that holds the content to play in place of the Linked Chapter. The ChapterSegmentUUID MUST NOT be the SegmentUUID of its own Segment. There are 2 ways to use a chapter link: Lhomme, et al. Expires 13 February 2024 [Page 108] Internet-Draft Matroska Format August 2023 * Linked-Duration linking, * Linked-Edition linking 17.2.1. Linked-Duration A Matroska Player MUST play the content of the linked Segment from the ChapterTimeStart until ChapterTimeEnd timestamp in place of the Linked Chapter. ChapterTimeStart and ChapterTimeEnd represent timestamps in the Linked Segment matching the value of ChapterSegmentUUID. Their values MUST be in the range of the linked Segment duration. The ChapterTimeEnd value MUST be set when using linked-duration chapter linking. ChapterSegmentEditionUID MUST NOT be set. 17.2.2. Linked-Edition A Matroska Player MUST play the whole linked Edition of the linked Segment in place of the Linked Chapter. ChapterSegmentEditionUID represents a valid Edition from the Linked Segment matching the value of ChapterSegmentUUID. When using linked-edition chapter linking. ChapterTimeEnd is OPTIONAL. 18. Track Flags 18.1. Default flag The "default track" flag is a hint for a Matroska Player indicating that a given track SHOULD be eligible to be automatically selected as the default track for a given language. If no tracks in a given language have the default track flag set, then all tracks in that language are eligible for automatic selection. This can be used to indicate that a track provides "regular service" suitable for users with default settings, as opposed to specialized services, such as commentary, hearing-impaired captions, or descriptive audio. The Matroska Player MAY override the "default track" flag for any reason, including user preferences to prefer tracks providing accessibility services. Lhomme, et al. Expires 13 February 2024 [Page 109] Internet-Draft Matroska Format August 2023 18.2. Forced flag The "forced" flag tells the Matroska Player that it SHOULD display this subtitle track, even if user preferences usually would not call for any subtitles to be displayed alongside the current selected audio track. This can be used to indicate that a track contains translations of onscreen text, or of dialogue spoken in a different language than the track's primary one. 18.3. Hearing-impaired flag The "hearing impaired" flag tells the Matroska Player that it SHOULD prefer this track when selecting a default track for a hearing- impaired user, and that it MAY prefer to select a different track when selecting a default track for a non-hearing-impaired user. 18.4. Visual-impaired flag The "visual impaired" flag tells the Matroska Player that it SHOULD prefer this track when selecting a default track for a visually- impaired user, and that it MAY prefer to select a different track when selecting a default track for a non-visually-impaired user. 18.5. Descriptions flag The "descriptions" flag tells the Matroska Player that this track is suitable to play via a text-to-speech system for a visually-impaired user, and that it SHOULD NOT automatically select this track when selecting a default track for a non-visually-impaired user. 18.6. Original flag The "original" flag tells the Matroska Player that this track is in the original language, and that it SHOULD prefer it if configured to prefer original-language tracks of this track's type. 18.7. Commentary flag The "commentary" flag tells the Matroska Player that this track contains commentary on the content. 18.8. Track Operation TrackOperation allows combining multiple tracks to make a virtual one. It uses two separate system to combine tracks. One to create a 3D "composition" (left/right/background planes) and one to simplify join two tracks together to make a single track. Lhomme, et al. Expires 13 February 2024 [Page 110] Internet-Draft Matroska Format August 2023 A track created with TrackOperation is a proper track with a UID and all its flags. However, the codec ID is meaningless because each "sub" track needs to be decoded by its own decoder before the "operation" is applied. The Cues Elements corresponding to such a virtual track SHOULD be the union of the Cues Elements for each of the tracks it's composed of (when the Cues are defined per track). In the case of TrackJoinBlocks, the Block Elements (from BlockGroup and SimpleBlock) of all the tracks SHOULD be used as if they were defined for this new virtual Track. When two Block Elements have overlapping start or end timestamps, it's up to the underlying system to either drop some of these frames or render them the way they overlap. This situation SHOULD be avoided when creating such tracks as you can never be sure of the end result on different platforms. 18.9. Overlay Track Overlay tracks SHOULD be rendered in the same channel as the track it's linked to. When content is found in such a track, it SHOULD be played on the rendering channel instead of the original track. 18.10. Multi-planar and 3D videos There are two different ways to compress 3D videos: have each eye track in a separate track and have one track have both eyes combined inside (which is more efficient, compression-wise). Matroska supports both ways. For the single track variant, there is the StereoMode Element, which defines how planes are assembled in the track (mono or left-right combined). Odd values of StereoMode means the left plane comes first for more convenient reading. The pixel count of the track (PixelWidth/PixelHeight) is the raw amount of pixels, for example 3840x1080 for full HD side by side, and the DisplayWidth/ DisplayHeight in pixels is the amount of pixels for one plane (1920x1080 for that full HD stream). Old stereo 3D were displayed using anaglyph (cyan and red colors separated). For compatibility with such movies, there is a value of the StereoMode that corresponds to AnaGlyph. There is also a "packed" mode (values 13 and 14) which consists of packing two frames together in a Block using lacing. The first frame is the left eye and the other frame is the right eye (or vice versa). The frames SHOULD be decoded in that order and are possibly dependent on each other (P and B frames). Lhomme, et al. Expires 13 February 2024 [Page 111] Internet-Draft Matroska Format August 2023 For separate tracks, Matroska needs to define exactly which track does what. TrackOperation with TrackCombinePlanes do that. For more details look at Section 18.8 on how TrackOperation works. The 3D support is still in infancy and may evolve to support more features. The StereoMode used to be part of Matroska v2 but it didn't meet the requirement for multiple tracks. There was also a bug in libmatroska prior to 0.9.0 that would save/read it as 0x53B9 instead of 0x53B8; see OldStereoMode (Section 5.1.4.1.28.5). Matroska Readers MAY support these legacy files by checking Matroska v2 or 0x53B9. The older values of StereoMode were 0: mono, 1: right eye, 2: left eye, 3: both eyes, the only values that can be found in OldStereoMode. They are not compatible with the StereoMode values found in Matroska v3 and above. 19. Default track selection This section provides some example sets of Tracks and hypothetical user settings, along with indications of which ones a similarly- configured Matroska Player SHOULD automatically select for playback by default in such a situation. A player MAY provide additional settings with more detailed controls for more nuanced scenarios. These examples are provided as guidelines to illustrate the intended usages of the various supported Track flags, and their expected behaviors. Track names are shown in English for illustrative purposes; actual files may have titles in the language of each track, or provide titles in multiple languages. 19.1. Audio Selection Example track set: Lhomme, et al. Expires 13 February 2024 [Page 112] Internet-Draft Matroska Format August 2023 +===+=====+====+======+========+=======+===============+===========+ |No.|Type |Lang|Layout|Original|Default|Other flags |Name | +===+=====+====+======+========+=======+===============+===========+ |1 |Video|und |N/A |N/A |N/A |None | | +---+-----+----+------+--------+-------+---------------+-----------+ |2 |Audio|eng |5.1 |1 |1 |None | | +---+-----+----+------+--------+-------+---------------+-----------+ |3 |Audio|eng |2.0 |1 |1 |None | | +---+-----+----+------+--------+-------+---------------+-----------+ |4 |Audio|eng |2.0 |1 |0 |Visual-impaired|Descriptive| | | | | | | | |audio | +---+-----+----+------+--------+-------+---------------+-----------+ |5 |Audio|esp |5.1 |0 |1 |None | | +---+-----+----+------+--------+-------+---------------+-----------+ |6 |Audio|esp |2.0 |0 |0 |Visual-impaired|Descriptive| | | | | | | | |audio | +---+-----+----+------+--------+-------+---------------+-----------+ |7 |Audio|eng |2.0 |1 |0 |Commentary |Director's | | | | | | | | |Commentary | +---+-----+----+------+--------+-------+---------------+-----------+ |8 |Audio|eng |2.0 |1 |0 |None |Karaoke | +---+-----+----+------+--------+-------+---------------+-----------+ Table 45: Audio Tracks for default selection Here we have a file with 7 audio tracks, of which 5 are in English and 2 are in Spanish. The English tracks all have the Original flag, indicating that English is the original content language. Generally the player will first consider the track languages: if the player has an option to prefer original-language audio and the user has enabled it, then it should prefer one of the Original-flagged tracks. If configured to specifically prefer audio tracks in English or Spanish, the player should select one of the tracks in the corresponding language. The player may also wish to prefer an Original-flagged track if no tracks matching any of the user's explicitly-preferred languages are available. Two of the tracks have the Visual-impaired flag. If the player has been configured to prefer such tracks, it should select one; otherwise, it should avoid them if possible. If selecting an English track, when other settings have left multiple possible options, it may be useful to exclude the tracks that lack the Default flag: here, one provides descriptive service for the visually impaired (which has its own flag and may be automatically Lhomme, et al. Expires 13 February 2024 [Page 113] Internet-Draft Matroska Format August 2023 selected by user configuration, but is unsuitable for users with default-configured players), one is a commentary track (which has its own flag, which the player may or may not have specialized handling for), and the last contains karaoke versions of the music that plays during the film, which is an unusual specialized audio service that Matroska has no built-in support for indicating, so it's indicated in the track name instead. By not setting the Default flag on these specialized tracks, the file's author hints that they should not be automatically selected by a default-configured player. Having narrowed its choices down, our example player now may have to select between tracks 2 and 3. The only difference between these tracks is their channel layouts: 2 is 5.1 surround, while 3 is stereo. If the player is aware that the output device is a pair of headphones or stereo speakers, it may wish to prefer the stereo mix automatically. On the other hand, if it knows that the device is a surround system, it may wish to prefer the surround mix. If the player finishes analyzing all of the available audio tracks and finds that multiple seems equally and maximally preferable, it SHOULD default to the first of the group. 19.2. Subtitle selection Example track set: Lhomme, et al. Expires 13 February 2024 [Page 114] Internet-Draft Matroska Format August 2023 +===+===========+====+========+=======+======+==========+==========+ |No.| Type |Lang|Original|Default|Forced| Other | Name | | | | | | | | flags | | +===+===========+====+========+=======+======+==========+==========+ |1 | Video |und |N/A |N/A |N/A | None | | +---+-----------+----+--------+-------+------+----------+----------+ |2 | Audio |fra |1 |1 |N/A | None | | +---+-----------+----+--------+-------+------+----------+----------+ |3 | Audio |por |0 |1 |N/A | None | | +---+-----------+----+--------+-------+------+----------+----------+ |4 | Subtitles |fra |1 |1 |0 | None | | +---+-----------+----+--------+-------+------+----------+----------+ |5 | Subtitles |fra |1 |0 |0 | Hearing- | Captions | | | | | | | | impaired | for the | | | | | | | | | hearing- | | | | | | | | | impaired | +---+-----------+----+--------+-------+------+----------+----------+ |6 | Subtitles |por |0 |1 |0 | None | | +---+-----------+----+--------+-------+------+----------+----------+ |7 | Subtitles |por |0 |0 |1 | None | Signs | +---+-----------+----+--------+-------+------+----------+----------+ |8 | Subtitles |por |0 |0 |0 | Hearing- | SDH | | | | | | | | impaired | | +---+-----------+----+--------+-------+------+----------+----------+ Table 46: Subtitle Tracks for default selection Here we have 2 audio tracks and 5 subtitle tracks. As we can see, French is the original language. We'll start by discussing the case where the user prefers French (or Original-language) audio (or has explicitly selected the French audio track), and also prefers French subtitles. In this case, if the player isn't configured to display captions when the audio matches their preferred subtitle languages, the player doesn't need to select a subtitle track at all. If the user _has_ indicated that they want captions to be displayed, the selection simply comes down to whether Hearing-impaired subtitles are preferred. The situation for a user who prefers Portuguese subtitles starts out somewhat analogous. If they select the original French audio (either by explicit audio language preference, preference for Original- language tracks, or by explicitly selecting that track), then the selection once again comes down to the hearing-impaired preference. Lhomme, et al. Expires 13 February 2024 [Page 115] Internet-Draft Matroska Format August 2023 However, the case where the Portuguese audio track is selected has an important catch: a Forced track in Portuguese is present. This may contain translations of onscreen text from the video track, or of portions of the audio that are not translated (music, for instance). This means that even if the user's preferences wouldn't normally call for captions here, the Forced track should be selected nonetheless, rather than selecting no track at all. On the other hand, if the user's preferences _do_ call for captions, the non-Forced tracks should be preferred, as the Forced track will not contain captioning for the dialogue. 20. Chapters The Matroska Chapters system can have multiple Editions and each Edition can consist of Simple Chapters where a chapter start time is used as marker in the timeline only. An Edition can be more complex with Ordered Chapters where a chapter end time stamp is additionally used or much more complex with Linked Chapters. The Matroska Chapters system can also have a menu structure, borrowed from the DVD menu system [DVD-Video], or have its own built-in Matroska menu structure. 20.1. EditionEntry The EditionEntry is also called an Edition. An Edition contains a set of Edition flags and MUST contain at least one ChapterAtom Element. Chapters are always inside an Edition (or a Chapter itself part of an Edition). Multiple Editions are allowed. Some of these Editions MAY be ordered and others not. 20.1.1. EditionFlagDefault Only one Edition SHOULD have an EditionFlagDefault flag set to true. 20.1.2. Default Edition The Default Edition is the Edition that a Matroska Player SHOULD use for playback by default. The first Edition with the EditionFlagDefault flag set to true is the Default Edition. When all EditionFlagDefault flags are set to false, then the first Edition is the Default Edition. Lhomme, et al. Expires 13 February 2024 [Page 116] Internet-Draft Matroska Format August 2023 +===========+=============+=================+ | Edition | FlagDefault | Default Edition | +===========+=============+=================+ | Edition 1 | true | X | +-----------+-------------+-----------------+ | Edition 2 | true | | +-----------+-------------+-----------------+ | Edition 3 | true | | +-----------+-------------+-----------------+ Table 47: Default edition, all default +===========+=============+=================+ | Edition | FlagDefault | Default Edition | +===========+=============+=================+ | Edition 1 | false | X | +-----------+-------------+-----------------+ | Edition 2 | false | | +-----------+-------------+-----------------+ | Edition 3 | false | | +-----------+-------------+-----------------+ Table 48: Default edition, no default +===========+=============+=================+ | Edition | FlagDefault | Default Edition | +===========+=============+=================+ | Edition 1 | false | | +-----------+-------------+-----------------+ | Edition 2 | true | X | +-----------+-------------+-----------------+ | Edition 3 | false | | +-----------+-------------+-----------------+ Table 49: Default edition, with default 20.1.3. EditionFlagOrdered The EditionFlagOrdered Flag is a significant feature as it enables an Edition of Ordered Chapters which defines and arranges a virtual timeline rather than simply labeling points within the timeline. For example, with Editions of Ordered Chapters a single Matroska file can present multiple edits of a film without duplicating content. Alternatively, if a videotape is digitized in full, one Ordered Edition could present the full content (including colorbars, countdown, slate, a feature presentation, and black frames), while another Edition of Ordered Chapters can use Chapters that only mark the intended presentation with the colorbars and other ancillary Lhomme, et al. Expires 13 February 2024 [Page 117] Internet-Draft Matroska Format August 2023 visual information excluded. If an Edition of Ordered Chapters is enabled, then the Matroska Player MUST play those Chapters in their stored order from the timestamp marked in the ChapterTimeStart Element to the timestamp marked in to ChapterTimeEnd Element. If the EditionFlagOrdered Flag evaluates to "0", Simple Chapters are used and only the ChapterTimeStart of a Chapter is used as chapter mark to jump to the predefined point in the timeline. With Simple Chapters, a Matroska Player MUST ignore certain Chapter Elements. In that case these elements are informational only. The following list shows the different Chapter elements only found in Ordered Chapters. +======================================+ | Ordered Chapter elements | +======================================+ | ChapterAtom/ChapterSegmentUUID | +--------------------------------------+ | ChapterAtom/ChapterSegmentEditionUID | +--------------------------------------+ | ChapterAtom/ChapterTrack | +--------------------------------------+ | ChapterAtom/ChapProcess | +--------------------------------------+ | Info/ChapterTranslate | +--------------------------------------+ | TrackEntry/TrackTranslate | +--------------------------------------+ Table 50: elements only found in ordered chapters Furthermore, there are other EBML Elements which could be used if the EditionFlagOrdered evaluates to "1". 20.1.3.1. Ordered-Edition and Matroska Segment-Linking * Hard Linking: Ordered-Chapters supersedes the Hard Linking. * Medium Linking: Ordered Chapters are used in a normal way and can be combined with the ChapterSegmentUUID element which establishes a link to another Segment. See Section 17 on the Linked Segments for more information about Hard Linking and Medium Linking. Lhomme, et al. Expires 13 February 2024 [Page 118] Internet-Draft Matroska Format August 2023 20.2. ChapterAtom The ChapterAtom is also called a Chapter. 20.2.1. ChapterTimeStart The timestamp of the start of Chapter with nanosecond accuracy, not scaled by TimestampScale. For Simple Chapters this is the position of the chapter markers in the timeline. 20.2.2. ChapterTimeEnd The timestamp of the end of Chapter with nanosecond accuracy, not scaled by TimestampScale. The timestamp defined by the ChapterTimeEnd is not part of the Chapter. A Matroska Player calculates the duration of this Chapter using the difference between the ChapterTimeEnd and ChapterTimeStart. The end timestamp MUST be greater than or equal to the start timestamp. When the ChapterTimeEnd timestamp is equal to the ChapterTimeStart timestamp, the timestamps is included in the Chapter. It can be useful to put markers in a file or add chapter commands with ordered chapter commands without having to play anything; see Section 5.1.7.1.4.14. +===========+=================+===============+===============+ | Chapter | Start timestamp | End timestamp | Duration | +===========+=================+===============+===============+ | Chapter 1 | 0 | 1000000000 | 1000000000 | +-----------+-----------------+---------------+---------------+ | Chapter 2 | 1000000000 | 5000000000 | 4000000000 | +-----------+-----------------+---------------+---------------+ | Chapter 3 | 6000000000 | 6000000000 | 0 | +-----------+-----------------+---------------+---------------+ | Chapter 4 | 9000000000 | 8000000000 | Invalid | | | | | (-1000000000) | +-----------+-----------------+---------------+---------------+ Table 51: ChapterTimeEnd usage possibilities 20.2.3. Nested Chapters A ChapterAtom element can contain other ChapterAtom elements. That element is a Parent Chapter and the ChapterAtom elements it contains are Nested Chapters. Lhomme, et al. Expires 13 February 2024 [Page 119] Internet-Draft Matroska Format August 2023 Nested Chapters can be useful to tag small parts of a Segment that already have tags or add Chapter Codec commands on smaller parts of a Segment that already have Chapter Codec commands. The ChapterTimeStart of a Nested Chapter MUST be greater than or equal to the ChapterTimeStart its Parent Chapter. If the Parent Chapter of a Nested Chapter has a ChapterTimeEnd, the ChapterTimeStart of that Nested Chapter MUST be smaller than or equal to the ChapterTimeEnd of the Parent Chapter. 20.2.4. Nested Chapters in Ordered Chapters The ChapterTimeEnd of the lowest level of Nested Chapters MUST be set for Ordered Chapters. When used with Ordered Chapters, the ChapterTimeEnd value of a Parent Chapter is useless for playback as the proper playback sections are described in its Nested Chapters. The ChapterTimeEnd SHOULD NOT be set in Parent Chapters and MUST be ignored for playback. 20.2.5. ChapterFlagHidden Each Chapter ChapterFlagHidden flag works independently of parent chapters. A Nested Chapter with a ChapterFlagHidden that evaluates to "0" remains visible in the user interface even if the Parent Chapter ChapterFlagHidden flag is set to "1". +==========================+===================+=========+ | Chapter + Nested Chapter | ChapterFlagHidden | visible | +==========================+===================+=========+ | Chapter 1 | 0 | yes | +--------------------------+-------------------+---------+ | Nested Chapter 1.1 | 0 | yes | +--------------------------+-------------------+---------+ | Nested Chapter 1.2 | 1 | no | +--------------------------+-------------------+---------+ | Chapter 2 | 1 | no | +--------------------------+-------------------+---------+ | Nested Chapter 2.1 | 0 | yes | +--------------------------+-------------------+---------+ | Nested Chapter 2.2 | 1 | no | +--------------------------+-------------------+---------+ Table 52: ChapterFlagHidden nested visibility Lhomme, et al. Expires 13 February 2024 [Page 120] Internet-Draft Matroska Format August 2023 20.3. Menu features The menu features are handled like a chapter codec. That means each codec has a type, some private data and some data in the chapters. The type of the menu system is defined by the ChapProcessCodecID parameter. For now, only 2 values are supported : 0 matroska script, 1 menu borrowed from the DVD [DVD-Video]. The private data depend on the type of menu system (stored in ChapProcessPrivate), idem for the data in the chapters (stored in ChapProcessData). The menu system, as well as Chapter Codecs in general, can do actions on the Matroska Player like jumping to another Chapter or Edition, selecting different tracks and possibly more. The scope of all the possibilities of Chapter Codecs is not covered in this document as it depends on the Chapter Codec features and its integration in a Matroska Player. 20.4. Physical Types Each level can have different meanings for audio and video. The ORIGINAL_MEDIA_TYPE tag [MatroskaTags] can be used to specify a string for ChapterPhysicalEquiv = 60. Here is the list of possible levels for both audio and video: Lhomme, et al. Expires 13 February 2024 [Page 121] Internet-Draft Matroska Format August 2023 +=======+=======================+=============+=====================+ | Value | Audio | Video | Comment | +=======+=======================+=============+=====================+ | 70 | SET / PACKAGE | SET / | the collection of | | | | PACKAGE | different media | +-------+-----------------------+-------------+---------------------+ | 60 | CD / 12" / 10" / 7" / | DVD / VHS | the physical medium | | | TAPE / MINIDISC / DAT | / | like a CD or a DVD | | | | LASERDISC | | +-------+-----------------------+-------------+---------------------+ | 50 | SIDE | SIDE | when the original | | | | | medium (LP/DVD) has | | | | | different sides | +-------+-----------------------+-------------+---------------------+ | 40 | - | LAYER | another physical | | | | | level on DVDs | +-------+-----------------------+-------------+---------------------+ | 30 | SESSION | SESSION | as found on CDs and | | | | | DVDs | +-------+-----------------------+-------------+---------------------+ | 20 | TRACK | - | as found on audio | | | | | CDs | +-------+-----------------------+-------------+---------------------+ | 10 | INDEX | - | the first logical | | | | | level of the side/ | | | | | medium | +-------+-----------------------+-------------+---------------------+ Table 53: ChapterPhysicalEquiv meaning per track type 20.5. Chapter Examples 20.5.1. Example 1 : basic chaptering In this example a movie is split in different chapters. It could also just be an audio file (album) on which each track corresponds to a chapter. * 00000 ms - 05000 ms : Intro * 05000 ms - 25000 ms : Before the crime * 25000 ms - 27500 ms : The crime * 27500 ms - 38000 ms : The killer arrested * 38000 ms - 43000 ms : Credits This would translate in the following matroska form, with the EBML tree shown as XML : Lhomme, et al. Expires 13 February 2024 [Page 122] Internet-Draft Matroska Format August 2023 16603393396715046047 1193046 0 5000000000 Intro 2311527 5000000000 25000000000 Before the crime Avant le crime fra 3430008 25000000000 27500000000 The crime Le crime fra 4548489 27500000000 38000000000 After the crime Apres le crime fra Lhomme, et al. Expires 13 February 2024 [Page 123] Internet-Draft Matroska Format August 2023 5666960 38000000000 43000000000 Credits Generique fra Figure 16: Basic Chapters Example. 20.5.2. Example 2 : nested chapters In this example an (existing) album is split into different chapters, and one of them contains another splitting. 20.5.2.1. The Micronauts "Bleep To Bleep" * 00:00 - 12:28 : Baby Wants To Bleep/Rock - 00:00 - 04:38 : Baby wants to bleep (pt.1) - 04:38 - 07:12 : Baby wants to rock - 07:12 - 10:33 : Baby wants to bleep (pt.2) - 10:33 - 12:28 : Baby wants to bleep (pt.3) * 12:30 - 19:38 : Bleeper_O+2 * 19:40 - 22:20 : Baby wants to bleep (pt.4) * 22:22 - 25:18 : Bleep to bleep * 25:20 - 33:35 : Baby wants to bleep (k) * 33:37 - 44:28 : Bleeper This would translate in the following matroska form, with the EBML tree shown as XML : 1281690858003401414 1 0 748000000 Baby wants to Bleep/Rock Lhomme, et al. Expires 13 February 2024 [Page 124] Internet-Draft Matroska Format August 2023 2 0 278000000 Baby wants to bleep (pt.1) 3 278000000 432000000 Baby wants to rock 4 432000000 633000000 Baby wants to bleep (pt.2) 5 633000000 748000000 Baby wants to bleep (pt.3) 6 750000000 1178500000 Bleeper_O+2 7 1180500000 1340000000 Baby wants to bleep (pt.4) Lhomme, et al. Expires 13 February 2024 [Page 125] Internet-Draft Matroska Format August 2023 8 1342000000 1518000000 Bleep to bleep 9 1520000000 2015000000 Baby wants to bleep (k) 10 2017000000 2668000000 Bleeper Figure 17: Nested Chapters Example. 21. Attachments Matroska supports storage of related files and data in the Attachments Element (a Top-Level Element). Attachment Elements can be used to store related cover art, font files, transcripts, reports, error recovery files, picture, or text-based annotations, copies of specifications, or other ancillary files related to the Segment. Matroska Readers MUST NOT execute files stored as Attachment Elements. 21.1. Cover Art This section defines a set of guidelines for the storage of cover art in Matroska files. A Matroska Reader MAY use embedded cover art to display a representational still-image depiction of the multimedia contents of the Matroska file. Lhomme, et al. Expires 13 February 2024 [Page 126] Internet-Draft Matroska Format August 2023 Only [JPEG] and PNG [RFC2083] image formats SHOULD be used for cover art pictures. There can be two different covers for a movie/album: a portrait style (e.g., a DVD case) and a landscape style (e.g., a wide banner ad). There can be two versions of the same cover, the normal cover and the small cover. The dimension of the normal cover SHOULD be 600 pixels on the smallest side -- for example, 960x600 for landscape, 600x800 for portrait, or 600x600 for square. The dimension of the small cover SHOULD be 120 pixels on the smallest side -- for example, 192x120 or 120x160. Versions of cover art can be differentiated by the filename, which is stored in the FileName Element. The default filename of the normal cover in square or portrait mode is cover.(jpg|png). When stored, the normal cover SHOULD be the first Attachment in storage order. The small cover SHOULD be prefixed with "small_", such as small_cover.(jpg|png). The landscape variant SHOULD be suffixed with "_land", such as cover_land.(jpg|png). The filenames are case- sensitive. The following table provides examples of file names for cover art in Attachments. +======================+===================+=================+ | FileName | Image Orientation | Pixel Length of | | | | Smallest Side | +======================+===================+=================+ | cover.jpg | Portrait or | 600 | | | square | | +----------------------+-------------------+-----------------+ | small_cover.png | Portrait or | 120 | | | square | | +----------------------+-------------------+-----------------+ | cover_land.png | Landscape | 600 | +----------------------+-------------------+-----------------+ | small_cover_land.jpg | Landscape | 120 | +----------------------+-------------------+-----------------+ Table 54: Cover Art Filenames Lhomme, et al. Expires 13 February 2024 [Page 127] Internet-Draft Matroska Format August 2023 21.2. Font files Font files MAY be added to a Matroska file as Attachments so that the font file may be used to display an associated subtitle track. This allows the presentation of a Matroska file to be consistent in various environments where the needed fonts might not be available on the local system. Depending on the font format in question, each font file can contain multiple font variants. Each font variant has a name which will be referred to as Font Name from now on. This Font Name can be different from the Attachment's FileName, even when disregarding the extension. In order to select a font for display, a Matroska player SHOULD consider both the Font Name and the base name of the Attachment's FileName, preferring the former when there are multiple matches. Subtitle codecs, such as SubStation Alpha (SSA/ASS), usually refer to a font by its Font Name, not by its filename. If none of the Attachments are a match for the Font Name, the Matroska player SHOULD attempt to find a system font whose Font Name matches the one used in the subtitle track. Since loading fonts temporarily can take a while, a Matroska player usually loads or installs all the fonts found in attachments so they are ready to be used during playback. Failure to use the font attachment might result in incorrect rendering of the subtitles. If a selected subtitle track has some AttachmentLink elements, the player MAY restrict its font rendering to use only these fonts. A Matroska player SHOULD handle the official font media types from [RFC8081] when the system can handle the type: * font/sfnt: Generic SFNT Font Type, * font/ttf: TTF Font Type, * font/otf: OpenType Layout (OTF) Font Type, * font/collection: Collection Font Type, * font/woff: WOFF 1.0, * font/woff2: WOFF 2.0. Lhomme, et al. Expires 13 February 2024 [Page 128] Internet-Draft Matroska Format August 2023 Fonts in Matroska existed long before [RFC8081]. A few unofficial media types for fonts were used in existing files. Therefore, it is RECOMMENDED for a Matroska player to support the following legacy media types for font attachments: * application/x-truetype-font: Truetype fonts, equivalent to font/ ttf and sometimes font/otf, * application/x-font-ttf: TTF fonts, equivalent to font/ttf, * application/vnd.ms-opentype: OpenType Layout fonts, equivalent to font/otf * application/font-sfnt: Generic SFNT Font Type, equivalent to font/ sfnt * application/font-woff: WOFF 1.0, equivalent to font/woff There may also be some font attachments with the application/octet- stream media type. In that case the Matroska player MAY try to guess the font type by checking the file extension of the AttachedFile\FileName string. Common file extensions for fonts are: * .ttf for Truetype fonts, equivalent to font/ttf, * .otf for OpenType Layout fonts, equivalent to font/otf, * .ttc for Collection fonts, equivalent to font/collection The file extension check MUST be case-insensitive. Matroska writers SHOULD use a valid font media type from [RFC8081] in the AttachedFile\FileMediaType of the font attachment. They MAY use the media types found in older files when compatibility with older players is necessary. 22. Cues The Cues Element provides an index of certain Cluster Elements to allow for optimized seeking to absolute timestamps within the Segment. The Cues Element contains one or many CuePoint Elements which each MUST reference an absolute timestamp (via the CueTime Element), a Track (via the CueTrack Element), and a Segment Position (via the CueClusterPosition Element). Additional non-mandated Elements are part of the CuePoint Element such as CueDuration, CueRelativePosition, CueCodecState and others which provide any Matroska Reader with additional information to use in the optimization of seeking performance. Lhomme, et al. Expires 13 February 2024 [Page 129] Internet-Draft Matroska Format August 2023 22.1. Recommendations The following recommendations are provided to optimize Matroska performance. * Unless Matroska is used as a live stream, it SHOULD contain a Cues Element. * For each video track, each keyframe SHOULD be referenced by a CuePoint Element. * It is RECOMMENDED to not reference non-keyframes of video tracks in Cues unless it references a Cluster Element which contains a CodecState Element but no keyframes. * For each subtitle track present, each subtitle frame SHOULD be referenced by a CuePoint Element with a CueDuration Element. * References to audio tracks MAY be skipped in CuePoint Elements if a video track is present. When included the CuePoint Elements SHOULD reference audio keyframes at most once every 500 milliseconds. * If the referenced frame is not stored within the first SimpleBlock, or first BlockGroup within its Cluster Element, then the CueRelativePosition Element SHOULD be written to reference where in the Cluster the reference frame is stored. * If a CuePoint Element references Cluster Element that includes a CodecState Element, then that CuePoint Element MUST use a CueCodecState Element. * CuePoint Elements SHOULD be numerically sorted in storage order by the value of the CueTime Element. 23. Matroska Streaming In Matroska, there are two kinds of streaming: file access and livestreaming. 23.1. File Access File access can simply be reading a file located on your computer, but also includes accessing a file from an HTTP (web) server or CIFS (Windows share) server. These protocols are usually safe from reading errors and seeking in the stream is possible. However, when a file is stored far away or on a slow server, seeking can be an expensive operation and should be avoided. The guidelines in Lhomme, et al. Expires 13 February 2024 [Page 130] Internet-Draft Matroska Format August 2023 Section 25, when followed, help reduce the number of seeking operations for regular playback and also have the playback start quickly without a lot of data needed to read first (like a Cues Element, Attachment Element or SeekHead Element). Matroska, having a small overhead, is well suited for storing music/ videos on file servers without a big impact on the bandwidth used. Matroska does not require the index to be loaded before playing, which allows playback to start very quickly. The index can be loaded only when seeking is requested the first time. 23.2. Livestreaming Livestreaming is the equivalent of television broadcasting on the internet. There are 2 families of servers for livestreaming: RTP/ RTSP and HTTP. Matroska is not meant to be used over RTP. RTP already has timing and channel mechanisms that would be wasted if doubled in Matroska. Additionally, having the same information at the RTP and Matroska level would be a source of confusion if they do not match. Livestreaming of Matroska over file-like protocols like HTTP, QUIC, etc. is possible. A live Matroska stream is different from a file because it usually has no known end (only ending when the client disconnects). For this, all bits of the "size" portion of the Segment Element MUST be set to 1. Another option is to concatenate Segment Elements with known sizes, one after the other. This solution allows a change of codec/resolution between each segment. For example, this allows for a switch between 4:3 and 16:9 in a television program. When Segment Elements are continuous, certain Elements, like SeekHead, Cues, Chapters, and Attachments, MUST NOT be used. It is possible for a Matroska Player to detect that a stream is not seekable. If the stream has neither a SeekHead list nor a Cues list at the beginning of the stream, it SHOULD be considered non-seekable. Even though it is possible to seek forward in the stream, it is NOT RECOMMENDED. In the context of live radio or web TV, it is possible to "tag" the content while it is playing. The Tags Element can be placed between Clusters each time it is necessary. In that case, the new Tags Element MUST reset the previously encountered Tags Elements and use the new values instead. Lhomme, et al. Expires 13 February 2024 [Page 131] Internet-Draft Matroska Format August 2023 24. Tags 24.1. Tags Precedence Tags allow tagging all kinds of Matroska parts with very detailed metadata in multiple languages. Some Matroska elements also contain their own string value like the Track Name (Section 5.1.4.1.18) or the Chapter String (Section 5.1.7.1.4.10). The following Matroska elements can also be defined with tags: * The Track Name Element (Section 5.1.4.1.18) corresponds to a tag with the TagTrackUID (Section 5.1.8.1.1.3) set to the given track, a TagName of TITLE (Section 5.1.8.1.2.1) and a TagLanguage (Section 5.1.8.1.2.2) or TagLanguageBCP47 (Section 5.1.8.1.2.3) of "und". * The Chapter String Element (Section 5.1.7.1.4.10) corresponds to a tag with the TagChapterUID (Section 5.1.8.1.1.5) set to the same chapter UID, a TagName of TITLE (Section 5.1.8.1.2.1) and a TagLanguage (Section 5.1.8.1.2.2) or TagLanguageBCP47 (Section 5.1.8.1.2.3) matching the ChapLanguage (Section 5.1.7.1.4.11) or ChapLanguageBCP47 (Section 5.1.7.1.4.12) respectively. * The FileDescription Element (Section 5.1.6.1.1) of an attachment corresponds to a tag with the TagAttachmentUID (Section 5.1.8.1.1.6) set to the given attachment, a TagName of TITLE (Section 5.1.8.1.2.1) and a TagLanguage (Section 5.1.8.1.2.2) or TagLanguageBCP47 (Section 5.1.8.1.2.3) of "und". When both values exist in the file, the value found in Tags takes precedence over the value found in original location of the element. For example, if you have a TrackEntry\Name element and Tag TITLE for that track in a Matroska Segment, the Tag string SHOULD be used and not the TrackEntry\Name string to identify the track. As the Tag element is optional, a lot of Matroska Readers do not handle it and will not use the tags value when it's found. So for maximum compatibility, it's usually better to put the strings in the TrackEntry, ChapterAtom and Attachment and keep the tags matching these values if tags are also used. Lhomme, et al. Expires 13 February 2024 [Page 132] Internet-Draft Matroska Format August 2023 24.2. Tag Levels Tag elements allow tagging information on multiple levels, each level having a TargetTypeValue Section 5.1.8.1.1.1. An element for a given TargetTypeValue also applies to the lower levels denoted by smaller TargetTypeValue values. If an upper value doesn't apply to a level but the actual value to use is not known, an empty TagString (Section 5.1.8.1.2.5) or an empty TagBinary (Section 5.1.8.1.2.6) element MUST be used as the tag value for this level. See [MatroskaTags] for more details on common tag names, types and descriptions. 25. Implementation Recommendations 25.1. Cluster It is RECOMMENDED that each individual Cluster Element contains no more than 5 seconds or 5 megabytes of content. 25.2. SeekHead It is RECOMMENDED that the first SeekHead Element be followed by a Void Element to allow for the SeekHead Element to be expanded to cover new Top-Level Elements that could be added to the Matroska file, such as Tags, Chapters, and Attachments Elements. The size of this Void Element should be adjusted depending on the Matroska file already having Tags, Chapters, and Attachments Elements. 25.3. Optimum Layouts While there can be Top-Level Elements in any order, some ordering of Elements are better than others. Here are few optimum layouts for different use case: 25.3.1. Optimum layout for a muxer This is the basic layout muxers should be using for an efficient playback experience. * SeekHead * Info * Tracks * Chapters * Attachments * Tags Lhomme, et al. Expires 13 February 2024 [Page 133] Internet-Draft Matroska Format August 2023 * Clusters * Cues 25.3.2. Optimum layout after editing tags When tags from the previous layout need to be extended, they are moved to the end with the extra information. The location where the old tags were located is voided. * SeekHead * Info * Tracks * Chapters * Attachments * Void * Clusters * Cues * Tags 25.3.3. Optimum layout with Cues at the front Cues are usually a big chunk of data referencing a lot of locations in the file. For players that want to seek in the file they need to seek to the end of the file to access these locations. It is often better if they are placed early in the file. On the other hand that means players that don't intend to seek will have to read/skip these data no matter what. Because the Cues reference locations further in the file, it's often complicated to allocate the proper space for that element before all the locations are known. Therefore, this layout is rarely used. * SeekHead * Info * Tracks * Chapters * Attachments * Tags * Cues * Clusters 25.3.4. Optimum layout for livestreaming In Livestreaming (Section 23.2) only a few elements make sense. SeekHead and Cues are useless for example. All elements other than the Clusters MUST be placed before the Clusters. * Info Lhomme, et al. Expires 13 February 2024 [Page 134] Internet-Draft Matroska Format August 2023 * Tracks * Attachments (rare) * Tags * Clusters 26. Security Considerations Matroska inherits security considerations from EBML. Attacks on a Matroska Reader could include: * Storage of an arbitrary and potentially executable data within an Attachment Element. Matroska Readers that extract or use data from Matroska Attachments SHOULD check that the data adheres to expectations or not use the attachement. * A Matroska Attachment with an inaccurate media type. * Damage to the Encryption and Compression fields (Section 14) that would result in bogus binary data interpreted by the decoder. * Chapter Codecs running unwanted commands on the host system. The same error handling done for EBML applies to Matroska files. Particular error handling is not covered in this specification as this is depends on the goal of the Matroska Readers. It is up to the decision of the Matroska Readers on how to handle the errors if they are recoverable in their code or not. For example, if the checksum of the \Segment\Tracks is invalid some could decide to try to read the data anyway, some will just reject the file, most will not even check it. Matroska Reader implementations need to be robust against malicious payloads. Those related to denial of service are outlined in Section 2.1 of [RFC4732]. Although rarer, the same may apply to a Matroska Writer. Malicious stream data must not cause the Writer to misbehave, as this might allow an attacker access to transcoding gateways. As an audio and visual container format, a Matroska file or stream will potentially encapsulate numerous byte streams created with a variety of codecs. Implementers will need to consider the security considerations of these encapsulated formats. 27. IANA Considerations Lhomme, et al. Expires 13 February 2024 [Page 135] Internet-Draft Matroska Format August 2023 27.1. Matroska Element IDs Registry This document creates a new IANA registry called the "Matroska Element IDs" registry. To register a new Element ID in this registry, one needs an Element ID, a Change Controller (IETF or email of registrant) and an optional Reference to a document describing the Element ID. Element IDs are encoded using the VINT mechanism described in Section 4 of [RFC8794] and can be between one and five octets long. Five-octet-long Element IDs are possible only if declared in the EBML header. Element IDs are described in Section 5 of [RFC8794] with errata 7189 and 7191. One-octet Matroska Element IDs are to be allocated according to the "RFC Required" policy [RFC8126]. Two-octet Matroska Element IDs are to be allocated according to the "Specification Required" policy [RFC8126]. Three-octet and four-octet Matroska Element IDs are to be allocated according to the "First Come First Served" policy [RFC8126]. The allowed values in the Elements IDs registry are similar to the ones found in the EBML Element IDs registry defined in Section 17.1 of [RFC8794]. EBML IDs defined for the EBML Header -- as defined in Section 17.1 of [RFC8794] -- MUST NOT be used as Matroska Element IDs. Given the scarcity of the One-octet Element IDs, they should only be created to save space for elements found many times in a file. For example, within a BlockGroup or Chapters. The Four-octet Element IDs are mostly for synchronization of large elements. They should only be used for such high level elements. Elements that are not expected to be used often should use Three-octet Element IDs. Elements found in Section 28 have an assigned Matroska Element ID for historical reasons. These elements are not in use and SHOULD NOT be reused unless there is no other IDs available with the desired size. Such IDs are considered as reclaimed to the IANA registry as they could be used for other things in the future. Matroska Element IDs Values found in this document are assigned as initial values as follows: Lhomme, et al. Expires 13 February 2024 [Page 136] Internet-Draft Matroska Format August 2023 +============+=============================+======================+ | Element ID | Element Name | Reference | +============+=============================+======================+ | 0x80 | ChapterDisplay | Described in | | | | Section 5.1.7.1.4.9 | +------------+-----------------------------+----------------------+ | 0x83 | TrackType | Described in | | | | Section 5.1.4.1.3 | +------------+-----------------------------+----------------------+ | 0x85 | ChapString | Described in | | | | Section 5.1.7.1.4.10 | +------------+-----------------------------+----------------------+ | 0x86 | CodecID | Described in | | | | Section 5.1.4.1.21 | +------------+-----------------------------+----------------------+ | 0x88 | FlagDefault | Described in | | | | Section 5.1.4.1.5 | +------------+-----------------------------+----------------------+ | 0x8E | Slices | Reclaimed | | | | (Section 28.5) | +------------+-----------------------------+----------------------+ | 0x91 | ChapterTimeStart | Described in | | | | Section 5.1.7.1.4.3 | +------------+-----------------------------+----------------------+ | 0x92 | ChapterTimeEnd | Described in | | | | Section 5.1.7.1.4.4 | +------------+-----------------------------+----------------------+ | 0x96 | CueRefTime | Described in | | | | Section 5.1.5.1.2.8 | +------------+-----------------------------+----------------------+ | 0x97 | CueRefCluster | Reclaimed | | | | (Section 28.37) | +------------+-----------------------------+----------------------+ | 0x98 | ChapterFlagHidden | Described in | | | | Section 5.1.7.1.4.5 | +------------+-----------------------------+----------------------+ | 0x9A | FlagInterlaced | Described in | | | | Section 5.1.4.1.28.1 | +------------+-----------------------------+----------------------+ | 0x9B | BlockDuration | Described in | | | | Section 5.1.3.5.3 | +------------+-----------------------------+----------------------+ | 0x9C | FlagLacing | Described in | | | | Section 5.1.4.1.12 | +------------+-----------------------------+----------------------+ | 0x9D | FieldOrder | Described in | | | | Section 5.1.4.1.28.2 | +------------+-----------------------------+----------------------+ Lhomme, et al. Expires 13 February 2024 [Page 137] Internet-Draft Matroska Format August 2023 | 0x9F | Channels | Described in | | | | Section 5.1.4.1.29.3 | +------------+-----------------------------+----------------------+ | 0xA0 | BlockGroup | Described in | | | | Section 5.1.3.5 | +------------+-----------------------------+----------------------+ | 0xA1 | Block | Described in | | | | Section 5.1.3.5.1 | +------------+-----------------------------+----------------------+ | 0xA2 | BlockVirtual | Reclaimed | | | | (Section 28.3) | +------------+-----------------------------+----------------------+ | 0xA3 | SimpleBlock | Described in | | | | Section 5.1.3.4 | +------------+-----------------------------+----------------------+ | 0xA4 | CodecState | Described in | | | | Section 5.1.3.5.6 | +------------+-----------------------------+----------------------+ | 0xA5 | BlockAdditional | Described in | | | | Section 5.1.3.5.2.2 | +------------+-----------------------------+----------------------+ | 0xA6 | BlockMore | Described in | | | | Section 5.1.3.5.2.1 | +------------+-----------------------------+----------------------+ | 0xA7 | Position | Described in | | | | Section 5.1.3.2 | +------------+-----------------------------+----------------------+ | 0xAA | CodecDecodeAll | Reclaimed | | | | (Section 28.22) | +------------+-----------------------------+----------------------+ | 0xAB | PrevSize | Described in | | | | Section 5.1.3.3 | +------------+-----------------------------+----------------------+ | 0xAE | TrackEntry | Described in | | | | Section 5.1.4.1 | +------------+-----------------------------+----------------------+ | 0xAF | EncryptedBlock | Reclaimed | | | | (Section 28.15) | +------------+-----------------------------+----------------------+ | 0xB0 | PixelWidth | Described in | | | | Section 5.1.4.1.28.6 | +------------+-----------------------------+----------------------+ | 0xB2 | CueDuration | Described in | | | | Section 5.1.5.1.2.4 | +------------+-----------------------------+----------------------+ | 0xB3 | CueTime | Described in | | | | Section 5.1.5.1.1 | +------------+-----------------------------+----------------------+ Lhomme, et al. Expires 13 February 2024 [Page 138] Internet-Draft Matroska Format August 2023 | 0xB5 | SamplingFrequency | Described in | | | | Section 5.1.4.1.29.1 | +------------+-----------------------------+----------------------+ | 0xB6 | ChapterAtom | Described in | | | | Section 5.1.7.1.4 | +------------+-----------------------------+----------------------+ | 0xB7 | CueTrackPositions | Described in | | | | Section 5.1.5.1.2 | +------------+-----------------------------+----------------------+ | 0xB9 | FlagEnabled | Described in | | | | Section 5.1.4.1.4 | +------------+-----------------------------+----------------------+ | 0xBA | PixelHeight | Described in | | | | Section 5.1.4.1.28.7 | +------------+-----------------------------+----------------------+ | 0xBB | CuePoint | Described in | | | | Section 5.1.5.1 | +------------+-----------------------------+----------------------+ | 0xC0 | TrickTrackUID | Reclaimed | | | | (Section 28.28) | +------------+-----------------------------+----------------------+ | 0xC1 | TrickTrackSegmentUID | Reclaimed | | | | (Section 28.29) | +------------+-----------------------------+----------------------+ | 0xC4 | TrickMasterTrackSegmentUID | Reclaimed | | | | (Section 28.32) | +------------+-----------------------------+----------------------+ | 0xC6 | TrickTrackFlag | Reclaimed | | | | (Section 28.30) | +------------+-----------------------------+----------------------+ | 0xC7 | TrickMasterTrackUID | Reclaimed | | | | (Section 28.31) | +------------+-----------------------------+----------------------+ | 0xC8 | ReferenceFrame | Reclaimed | | | | (Section 28.12) | +------------+-----------------------------+----------------------+ | 0xC9 | ReferenceOffset | Reclaimed | | | | (Section 28.13) | +------------+-----------------------------+----------------------+ | 0xCA | ReferenceTimestamp | Reclaimed | | | | (Section 28.14) | +------------+-----------------------------+----------------------+ | 0xCB | BlockAdditionID | Reclaimed | | | | (Section 28.9) | +------------+-----------------------------+----------------------+ | 0xCC | LaceNumber | Reclaimed | | | | (Section 28.7) | +------------+-----------------------------+----------------------+ Lhomme, et al. Expires 13 February 2024 [Page 139] Internet-Draft Matroska Format August 2023 | 0xCD | FrameNumber | Reclaimed | | | | (Section 28.8) | +------------+-----------------------------+----------------------+ | 0xCE | Delay | Reclaimed | | | | (Section 28.10) | +------------+-----------------------------+----------------------+ | 0xCF | SliceDuration | Reclaimed | | | | (Section 28.11) | +------------+-----------------------------+----------------------+ | 0xD7 | TrackNumber | Described in | | | | Section 5.1.4.1.1 | +------------+-----------------------------+----------------------+ | 0xDB | CueReference | Described in | | | | Section 5.1.5.1.2.7 | +------------+-----------------------------+----------------------+ | 0xE0 | Video | Described in | | | | Section 5.1.4.1.28 | +------------+-----------------------------+----------------------+ | 0xE1 | Audio | Described in | | | | Section 5.1.4.1.29 | +------------+-----------------------------+----------------------+ | 0xE2 | TrackOperation | Described in | | | | Section 5.1.4.1.30 | +------------+-----------------------------+----------------------+ | 0xE3 | TrackCombinePlanes | Described in | | | | Section 5.1.4.1.30.1 | +------------+-----------------------------+----------------------+ | 0xE4 | TrackPlane | Described in | | | | Section 5.1.4.1.30.2 | +------------+-----------------------------+----------------------+ | 0xE5 | TrackPlaneUID | Described in | | | | Section 5.1.4.1.30.3 | +------------+-----------------------------+----------------------+ | 0xE6 | TrackPlaneType | Described in | | | | Section 5.1.4.1.30.4 | +------------+-----------------------------+----------------------+ | 0xE7 | Timestamp | Described in | | | | Section 5.1.3.1 | +------------+-----------------------------+----------------------+ | 0xE8 | TimeSlice | Reclaimed | | | | (Section 28.6) | +------------+-----------------------------+----------------------+ | 0xE9 | TrackJoinBlocks | Described in | | | | Section 5.1.4.1.30.5 | +------------+-----------------------------+----------------------+ | 0xEA | CueCodecState | Described in | | | | Section 5.1.5.1.2.6 | +------------+-----------------------------+----------------------+ Lhomme, et al. Expires 13 February 2024 [Page 140] Internet-Draft Matroska Format August 2023 | 0xEB | CueRefCodecState | Reclaimed | | | | (Section 28.39) | +------------+-----------------------------+----------------------+ | 0xED | TrackJoinUID | Described in | | | | Section 5.1.4.1.30.6 | +------------+-----------------------------+----------------------+ | 0xEE | BlockAddID | Described in | | | | Section 5.1.3.5.2.3 | +------------+-----------------------------+----------------------+ | 0xF0 | CueRelativePosition | Described in | | | | Section 5.1.5.1.2.3 | +------------+-----------------------------+----------------------+ | 0xF1 | CueClusterPosition | Described in | | | | Section 5.1.5.1.2.2 | +------------+-----------------------------+----------------------+ | 0xF7 | CueTrack | Described in | | | | Section 5.1.5.1.2.1 | +------------+-----------------------------+----------------------+ | 0xFA | ReferencePriority | Described in | | | | Section 5.1.3.5.4 | +------------+-----------------------------+----------------------+ | 0xFB | ReferenceBlock | Described in | | | | Section 5.1.3.5.5 | +------------+-----------------------------+----------------------+ | 0xFD | ReferenceVirtual | Reclaimed | | | | (Section 28.4) | +------------+-----------------------------+----------------------+ | 0x41A4 | BlockAddIDName | Described in | | | | Section 5.1.4.1.17.2 | +------------+-----------------------------+----------------------+ | 0x41E4 | BlockAdditionMapping | Described in | | | | Section 5.1.4.1.17 | +------------+-----------------------------+----------------------+ | 0x41E7 | BlockAddIDType | Described in | | | | Section 5.1.4.1.17.3 | +------------+-----------------------------+----------------------+ | 0x41ED | BlockAddIDExtraData | Described in | | | | Section 5.1.4.1.17.4 | +------------+-----------------------------+----------------------+ | 0x41F0 | BlockAddIDValue | Described in | | | | Section 5.1.4.1.17.1 | +------------+-----------------------------+----------------------+ | 0x4254 | ContentCompAlgo | Described in | | | | Section 5.1.4.1.31.6 | +------------+-----------------------------+----------------------+ | 0x4255 | ContentCompSettings | Described in | | | | Section 5.1.4.1.31.7 | +------------+-----------------------------+----------------------+ Lhomme, et al. Expires 13 February 2024 [Page 141] Internet-Draft Matroska Format August 2023 | 0x437C | ChapLanguage | Described in | | | | Section 5.1.7.1.4.11 | +------------+-----------------------------+----------------------+ | 0x437D | ChapLanguageBCP47 | Described in | | | | Section 5.1.7.1.4.12 | +------------+-----------------------------+----------------------+ | 0x437E | ChapCountry | Described in | | | | Section 5.1.7.1.4.13 | +------------+-----------------------------+----------------------+ | 0x4444 | SegmentFamily | Described in | | | | Section 5.1.2.7 | +------------+-----------------------------+----------------------+ | 0x4461 | DateUTC | Described in | | | | Section 5.1.2.11 | +------------+-----------------------------+----------------------+ | 0x447A | TagLanguage | Described in | | | | Section 5.1.8.1.2.2 | +------------+-----------------------------+----------------------+ | 0x447B | TagLanguageBCP47 | Described in | | | | Section 5.1.8.1.2.3 | +------------+-----------------------------+----------------------+ | 0x4484 | TagDefault | Described in | | | | Section 5.1.8.1.2.4 | +------------+-----------------------------+----------------------+ | 0x4485 | TagBinary | Described in | | | | Section 5.1.8.1.2.6 | +------------+-----------------------------+----------------------+ | 0x4487 | TagString | Described in | | | | Section 5.1.8.1.2.5 | +------------+-----------------------------+----------------------+ | 0x4489 | Duration | Described in | | | | Section 5.1.2.10 | +------------+-----------------------------+----------------------+ | 0x44B4 | TagDefaultBogus | Reclaimed | | | | (Section 28.43) | +------------+-----------------------------+----------------------+ | 0x450D | ChapProcessPrivate | Described in | | | | Section 5.1.7.1.4.16 | +------------+-----------------------------+----------------------+ | 0x45A3 | TagName | Described in | | | | Section 5.1.8.1.2.1 | +------------+-----------------------------+----------------------+ | 0x45B9 | EditionEntry | Described in | | | | Section 5.1.7.1 | +------------+-----------------------------+----------------------+ | 0x45BC | EditionUID | Described in | | | | Section 5.1.7.1.1 | +------------+-----------------------------+----------------------+ Lhomme, et al. Expires 13 February 2024 [Page 142] Internet-Draft Matroska Format August 2023 | 0x45DB | EditionFlagDefault | Described in | | | | Section 5.1.7.1.2 | +------------+-----------------------------+----------------------+ | 0x45DD | EditionFlagOrdered | Described in | | | | Section 5.1.7.1.3 | +------------+-----------------------------+----------------------+ | 0x465C | FileData | Described in | | | | Section 5.1.6.1.4 | +------------+-----------------------------+----------------------+ | 0x4660 | FileMediaType | Described in | | | | Section 5.1.6.1.3 | +------------+-----------------------------+----------------------+ | 0x4661 | FileUsedStartTime | Reclaimed | | | | (Section 28.41) | +------------+-----------------------------+----------------------+ | 0x4662 | FileUsedEndTime | Reclaimed | | | | (Section 28.42) | +------------+-----------------------------+----------------------+ | 0x466E | FileName | Described in | | | | Section 5.1.6.1.2 | +------------+-----------------------------+----------------------+ | 0x4675 | FileReferral | Reclaimed | | | | (Section 28.40) | +------------+-----------------------------+----------------------+ | 0x467E | FileDescription | Described in | | | | Section 5.1.6.1.1 | +------------+-----------------------------+----------------------+ | 0x46AE | FileUID | Described in | | | | Section 5.1.6.1.5 | +------------+-----------------------------+----------------------+ | 0x47E1 | ContentEncAlgo | Described in | | | | Section 5.1.4.1.31.9 | +------------+-----------------------------+----------------------+ | 0x47E2 | ContentEncKeyID | Described in Section | | | | 5.1.4.1.31.10 | +------------+-----------------------------+----------------------+ | 0x47E3 | ContentSignature | Reclaimed | | | | (Section 28.33) | +------------+-----------------------------+----------------------+ | 0x47E4 | ContentSigKeyID | Reclaimed | | | | (Section 28.34) | +------------+-----------------------------+----------------------+ | 0x47E5 | ContentSigAlgo | Reclaimed | | | | (Section 28.35) | +------------+-----------------------------+----------------------+ | 0x47E6 | ContentSigHashAlgo | Reclaimed | | | | (Section 28.36) | +------------+-----------------------------+----------------------+ Lhomme, et al. Expires 13 February 2024 [Page 143] Internet-Draft Matroska Format August 2023 | 0x47E7 | ContentEncAESSettings | Described in Section | | | | 5.1.4.1.31.11 | +------------+-----------------------------+----------------------+ | 0x47E8 | AESSettingsCipherMode | Described in Section | | | | 5.1.4.1.31.12 | +------------+-----------------------------+----------------------+ | 0x4D80 | MuxingApp | Described in | | | | Section 5.1.2.13 | +------------+-----------------------------+----------------------+ | 0x4DBB | Seek | Described in | | | | Section 5.1.1.1 | +------------+-----------------------------+----------------------+ | 0x5031 | ContentEncodingOrder | Described in | | | | Section 5.1.4.1.31.2 | +------------+-----------------------------+----------------------+ | 0x5032 | ContentEncodingScope | Described in | | | | Section 5.1.4.1.31.3 | +------------+-----------------------------+----------------------+ | 0x5033 | ContentEncodingType | Described in | | | | Section 5.1.4.1.31.4 | +------------+-----------------------------+----------------------+ | 0x5034 | ContentCompression | Described in | | | | Section 5.1.4.1.31.5 | +------------+-----------------------------+----------------------+ | 0x5035 | ContentEncryption | Described in | | | | Section 5.1.4.1.31.8 | +------------+-----------------------------+----------------------+ | 0x535F | CueRefNumber | Reclaimed | | | | (Section 28.38) | +------------+-----------------------------+----------------------+ | 0x536E | Name | Described in | | | | Section 5.1.4.1.18 | +------------+-----------------------------+----------------------+ | 0x5378 | CueBlockNumber | Described in | | | | Section 5.1.5.1.2.5 | +------------+-----------------------------+----------------------+ | 0x537F | TrackOffset | Reclaimed | | | | (Section 28.18) | +------------+-----------------------------+----------------------+ | 0x53AB | SeekID | Described in | | | | Section 5.1.1.1.1 | +------------+-----------------------------+----------------------+ | 0x53AC | SeekPosition | Described in | | | | Section 5.1.1.1.2 | +------------+-----------------------------+----------------------+ | 0x53B8 | StereoMode | Described in | | | | Section 5.1.4.1.28.3 | +------------+-----------------------------+----------------------+ Lhomme, et al. Expires 13 February 2024 [Page 144] Internet-Draft Matroska Format August 2023 | 0x53B9 | OldStereoMode | Described in | | | | Section 5.1.4.1.28.5 | +------------+-----------------------------+----------------------+ | 0x53C0 | AlphaMode | Described in | | | | Section 5.1.4.1.28.4 | +------------+-----------------------------+----------------------+ | 0x54AA | PixelCropBottom | Described in | | | | Section 5.1.4.1.28.8 | +------------+-----------------------------+----------------------+ | 0x54B0 | DisplayWidth | Described in Section | | | | 5.1.4.1.28.12 | +------------+-----------------------------+----------------------+ | 0x54B2 | DisplayUnit | Described in Section | | | | 5.1.4.1.28.14 | +------------+-----------------------------+----------------------+ | 0x54B3 | AspectRatioType | Reclaimed | | | | (Section 28.24) | +------------+-----------------------------+----------------------+ | 0x54BA | DisplayHeight | Described in Section | | | | 5.1.4.1.28.13 | +------------+-----------------------------+----------------------+ | 0x54BB | PixelCropTop | Described in | | | | Section 5.1.4.1.28.9 | +------------+-----------------------------+----------------------+ | 0x54CC | PixelCropLeft | Described in Section | | | | 5.1.4.1.28.10 | +------------+-----------------------------+----------------------+ | 0x54DD | PixelCropRight | Described in Section | | | | 5.1.4.1.28.11 | +------------+-----------------------------+----------------------+ | 0x55AA | FlagForced | Described in | | | | Section 5.1.4.1.6 | +------------+-----------------------------+----------------------+ | 0x55AB | FlagHearingImpaired | Described in | | | | Section 5.1.4.1.7 | +------------+-----------------------------+----------------------+ | 0x55AC | FlagVisualImpaired | Described in | | | | Section 5.1.4.1.8 | +------------+-----------------------------+----------------------+ | 0x55AD | FlagTextDescriptions | Described in | | | | Section 5.1.4.1.9 | +------------+-----------------------------+----------------------+ | 0x55AE | FlagOriginal | Described in | | | | Section 5.1.4.1.10 | +------------+-----------------------------+----------------------+ | 0x55AF | FlagCommentary | Described in | | | | Section 5.1.4.1.11 | +------------+-----------------------------+----------------------+ Lhomme, et al. Expires 13 February 2024 [Page 145] Internet-Draft Matroska Format August 2023 | 0x55B0 | Colour | Described in Section | | | | 5.1.4.1.28.16 | +------------+-----------------------------+----------------------+ | 0x55B1 | MatrixCoefficients | Described in Section | | | | 5.1.4.1.28.17 | +------------+-----------------------------+----------------------+ | 0x55B2 | BitsPerChannel | Described in Section | | | | 5.1.4.1.28.18 | +------------+-----------------------------+----------------------+ | 0x55B3 | ChromaSubsamplingHorz | Described in Section | | | | 5.1.4.1.28.19 | +------------+-----------------------------+----------------------+ | 0x55B4 | ChromaSubsamplingVert | Described in Section | | | | 5.1.4.1.28.20 | +------------+-----------------------------+----------------------+ | 0x55B5 | CbSubsamplingHorz | Described in Section | | | | 5.1.4.1.28.21 | +------------+-----------------------------+----------------------+ | 0x55B6 | CbSubsamplingVert | Described in Section | | | | 5.1.4.1.28.22 | +------------+-----------------------------+----------------------+ | 0x55B7 | ChromaSitingHorz | Described in Section | | | | 5.1.4.1.28.23 | +------------+-----------------------------+----------------------+ | 0x55B8 | ChromaSitingVert | Described in Section | | | | 5.1.4.1.28.24 | +------------+-----------------------------+----------------------+ | 0x55B9 | Range | Described in Section | | | | 5.1.4.1.28.25 | +------------+-----------------------------+----------------------+ | 0x55BA | TransferCharacteristics | Described in Section | | | | 5.1.4.1.28.26 | +------------+-----------------------------+----------------------+ | 0x55BB | Primaries | Described in Section | | | | 5.1.4.1.28.27 | +------------+-----------------------------+----------------------+ | 0x55BC | MaxCLL | Described in Section | | | | 5.1.4.1.28.28 | +------------+-----------------------------+----------------------+ | 0x55BD | MaxFALL | Described in Section | | | | 5.1.4.1.28.29 | +------------+-----------------------------+----------------------+ | 0x55D0 | MasteringMetadata | Described in Section | | | | 5.1.4.1.28.30 | +------------+-----------------------------+----------------------+ | 0x55D1 | PrimaryRChromaticityX | Described in Section | | | | 5.1.4.1.28.31 | +------------+-----------------------------+----------------------+ Lhomme, et al. Expires 13 February 2024 [Page 146] Internet-Draft Matroska Format August 2023 | 0x55D2 | PrimaryRChromaticityY | Described in Section | | | | 5.1.4.1.28.32 | +------------+-----------------------------+----------------------+ | 0x55D3 | PrimaryGChromaticityX | Described in Section | | | | 5.1.4.1.28.33 | +------------+-----------------------------+----------------------+ | 0x55D4 | PrimaryGChromaticityY | Described in Section | | | | 5.1.4.1.28.34 | +------------+-----------------------------+----------------------+ | 0x55D5 | PrimaryBChromaticityX | Described in Section | | | | 5.1.4.1.28.35 | +------------+-----------------------------+----------------------+ | 0x55D6 | PrimaryBChromaticityY | Described in Section | | | | 5.1.4.1.28.36 | +------------+-----------------------------+----------------------+ | 0x55D7 | WhitePointChromaticityX | Described in Section | | | | 5.1.4.1.28.37 | +------------+-----------------------------+----------------------+ | 0x55D8 | WhitePointChromaticityY | Described in Section | | | | 5.1.4.1.28.38 | +------------+-----------------------------+----------------------+ | 0x55D9 | LuminanceMax | Described in Section | | | | 5.1.4.1.28.39 | +------------+-----------------------------+----------------------+ | 0x55DA | LuminanceMin | Described in Section | | | | 5.1.4.1.28.40 | +------------+-----------------------------+----------------------+ | 0x55EE | MaxBlockAdditionID | Described in | | | | Section 5.1.4.1.16 | +------------+-----------------------------+----------------------+ | 0x5654 | ChapterStringUID | Described in | | | | Section 5.1.7.1.4.2 | +------------+-----------------------------+----------------------+ | 0x56AA | CodecDelay | Described in | | | | Section 5.1.4.1.25 | +------------+-----------------------------+----------------------+ | 0x56BB | SeekPreRoll | Described in | | | | Section 5.1.4.1.26 | +------------+-----------------------------+----------------------+ | 0x5741 | WritingApp | Described in | | | | Section 5.1.2.14 | +------------+-----------------------------+----------------------+ | 0x5854 | SilentTracks | Reclaimed | | | | (Section 28.1) | +------------+-----------------------------+----------------------+ | 0x58D7 | SilentTrackNumber | Reclaimed | | | | (Section 28.2) | +------------+-----------------------------+----------------------+ Lhomme, et al. Expires 13 February 2024 [Page 147] Internet-Draft Matroska Format August 2023 | 0x61A7 | AttachedFile | Described in | | | | Section 5.1.6.1 | +------------+-----------------------------+----------------------+ | 0x6240 | ContentEncoding | Described in | | | | Section 5.1.4.1.31.1 | +------------+-----------------------------+----------------------+ | 0x6264 | BitDepth | Described in | | | | Section 5.1.4.1.29.4 | +------------+-----------------------------+----------------------+ | 0x63A2 | CodecPrivate | Described in | | | | Section 5.1.4.1.22 | +------------+-----------------------------+----------------------+ | 0x63C0 | Targets | Described in | | | | Section 5.1.8.1.1 | +------------+-----------------------------+----------------------+ | 0x63C3 | ChapterPhysicalEquiv | Described in | | | | Section 5.1.7.1.4.8 | +------------+-----------------------------+----------------------+ | 0x63C4 | TagChapterUID | Described in | | | | Section 5.1.8.1.1.5 | +------------+-----------------------------+----------------------+ | 0x63C5 | TagTrackUID | Described in | | | | Section 5.1.8.1.1.3 | +------------+-----------------------------+----------------------+ | 0x63C6 | TagAttachmentUID | Described in | | | | Section 5.1.8.1.1.6 | +------------+-----------------------------+----------------------+ | 0x63C9 | TagEditionUID | Described in | | | | Section 5.1.8.1.1.4 | +------------+-----------------------------+----------------------+ | 0x63CA | TargetType | Described in | | | | Section 5.1.8.1.1.2 | +------------+-----------------------------+----------------------+ | 0x6624 | TrackTranslate | Described in | | | | Section 5.1.4.1.27 | +------------+-----------------------------+----------------------+ | 0x66A5 | TrackTranslateTrackID | Described in | | | | Section 5.1.4.1.27.1 | +------------+-----------------------------+----------------------+ | 0x66BF | TrackTranslateCodec | Described in | | | | Section 5.1.4.1.27.2 | +------------+-----------------------------+----------------------+ | 0x66FC | TrackTranslateEditionUID | Described in | | | | Section 5.1.4.1.27.3 | +------------+-----------------------------+----------------------+ | 0x67C8 | SimpleTag | Described in | | | | Section 5.1.8.1.2 | +------------+-----------------------------+----------------------+ Lhomme, et al. Expires 13 February 2024 [Page 148] Internet-Draft Matroska Format August 2023 | 0x68CA | TargetTypeValue | Described in | | | | Section 5.1.8.1.1.1 | +------------+-----------------------------+----------------------+ | 0x6911 | ChapProcessCommand | Described in | | | | Section 5.1.7.1.4.17 | +------------+-----------------------------+----------------------+ | 0x6922 | ChapProcessTime | Described in | | | | Section 5.1.7.1.4.18 | +------------+-----------------------------+----------------------+ | 0x6924 | ChapterTranslate | Described in | | | | Section 5.1.2.8 | +------------+-----------------------------+----------------------+ | 0x6933 | ChapProcessData | Described in | | | | Section 5.1.7.1.4.19 | +------------+-----------------------------+----------------------+ | 0x6944 | ChapProcess | Described in | | | | Section 5.1.7.1.4.14 | +------------+-----------------------------+----------------------+ | 0x6955 | ChapProcessCodecID | Described in | | | | Section 5.1.7.1.4.15 | +------------+-----------------------------+----------------------+ | 0x69A5 | ChapterTranslateID | Described in | | | | Section 5.1.2.8.1 | +------------+-----------------------------+----------------------+ | 0x69BF | ChapterTranslateCodec | Described in | | | | Section 5.1.2.8.2 | +------------+-----------------------------+----------------------+ | 0x69FC | ChapterTranslateEditionUID | Described in | | | | Section 5.1.2.8.3 | +------------+-----------------------------+----------------------+ | 0x6D80 | ContentEncodings | Described in | | | | Section 5.1.4.1.31 | +------------+-----------------------------+----------------------+ | 0x6DE7 | MinCache | Reclaimed | | | | (Section 28.16) | +------------+-----------------------------+----------------------+ | 0x6DF8 | MaxCache | Reclaimed | | | | (Section 28.17) | +------------+-----------------------------+----------------------+ | 0x6E67 | ChapterSegmentUUID | Described in | | | | Section 5.1.7.1.4.6 | +------------+-----------------------------+----------------------+ | 0x6EBC | ChapterSegmentEditionUID | Described in | | | | Section 5.1.7.1.4.7 | +------------+-----------------------------+----------------------+ | 0x6FAB | TrackOverlay | Reclaimed | | | | (Section 28.23) | +------------+-----------------------------+----------------------+ Lhomme, et al. Expires 13 February 2024 [Page 149] Internet-Draft Matroska Format August 2023 | 0x7373 | Tag | Described in | | | | Section 5.1.8.1 | +------------+-----------------------------+----------------------+ | 0x7384 | SegmentFilename | Described in | | | | Section 5.1.2.2 | +------------+-----------------------------+----------------------+ | 0x73A4 | SegmentUUID | Described in | | | | Section 5.1.2.1 | +------------+-----------------------------+----------------------+ | 0x73C4 | ChapterUID | Described in | | | | Section 5.1.7.1.4.1 | +------------+-----------------------------+----------------------+ | 0x73C5 | TrackUID | Described in | | | | Section 5.1.4.1.2 | +------------+-----------------------------+----------------------+ | 0x7446 | AttachmentLink | Described in | | | | Section 5.1.4.1.24 | +------------+-----------------------------+----------------------+ | 0x75A1 | BlockAdditions | Described in | | | | Section 5.1.3.5.2 | +------------+-----------------------------+----------------------+ | 0x75A2 | DiscardPadding | Described in | | | | Section 5.1.3.5.7 | +------------+-----------------------------+----------------------+ | 0x7670 | Projection | Described in Section | | | | 5.1.4.1.28.41 | +------------+-----------------------------+----------------------+ | 0x7671 | ProjectionType | Described in Section | | | | 5.1.4.1.28.42 | +------------+-----------------------------+----------------------+ | 0x7672 | ProjectionPrivate | Described in Section | | | | 5.1.4.1.28.43 | +------------+-----------------------------+----------------------+ | 0x7673 | ProjectionPoseYaw | Described in Section | | | | 5.1.4.1.28.44 | +------------+-----------------------------+----------------------+ | 0x7674 | ProjectionPosePitch | Described in Section | | | | 5.1.4.1.28.45 | +------------+-----------------------------+----------------------+ | 0x7675 | ProjectionPoseRoll | Described in Section | | | | 5.1.4.1.28.46 | +------------+-----------------------------+----------------------+ | 0x78B5 | OutputSamplingFrequency | Described in | | | | Section 5.1.4.1.29.2 | +------------+-----------------------------+----------------------+ | 0x7BA9 | Title | Described in | | | | Section 5.1.2.12 | +------------+-----------------------------+----------------------+ Lhomme, et al. Expires 13 February 2024 [Page 150] Internet-Draft Matroska Format August 2023 | 0x7D7B | ChannelPositions | Reclaimed | | | | (Section 28.27) | +------------+-----------------------------+----------------------+ | 0x22B59C | Language | Described in | | | | Section 5.1.4.1.19 | +------------+-----------------------------+----------------------+ | 0x22B59D | LanguageBCP47 | Described in | | | | Section 5.1.4.1.20 | +------------+-----------------------------+----------------------+ | 0x23314F | TrackTimestampScale | Described in | | | | Section 5.1.4.1.15 | +------------+-----------------------------+----------------------+ | 0x234E7A | DefaultDecodedFieldDuration | Described in | | | | Section 5.1.4.1.14 | +------------+-----------------------------+----------------------+ | 0x2383E3 | FrameRate | Reclaimed | | | | (Section 28.26) | +------------+-----------------------------+----------------------+ | 0x23E383 | DefaultDuration | Described in | | | | Section 5.1.4.1.13 | +------------+-----------------------------+----------------------+ | 0x258688 | CodecName | Described in | | | | Section 5.1.4.1.23 | +------------+-----------------------------+----------------------+ | 0x26B240 | CodecDownloadURL | Reclaimed | | | | (Section 28.21) | +------------+-----------------------------+----------------------+ | 0x2AD7B1 | TimestampScale | Described in | | | | Section 5.1.2.9 | +------------+-----------------------------+----------------------+ | 0x2EB524 | UncompressedFourCC | Described in Section | | | | 5.1.4.1.28.15 | +------------+-----------------------------+----------------------+ | 0x2FB523 | GammaValue | Reclaimed | | | | (Section 28.25) | +------------+-----------------------------+----------------------+ | 0x3A9697 | CodecSettings | Reclaimed | | | | (Section 28.19) | +------------+-----------------------------+----------------------+ | 0x3B4040 | CodecInfoURL | Reclaimed | | | | (Section 28.20) | +------------+-----------------------------+----------------------+ | 0x3C83AB | PrevFilename | Described in | | | | Section 5.1.2.4 | +------------+-----------------------------+----------------------+ | 0x3CB923 | PrevUUID | Described in | | | | Section 5.1.2.3 | +------------+-----------------------------+----------------------+ Lhomme, et al. Expires 13 February 2024 [Page 151] Internet-Draft Matroska Format August 2023 | 0x3E83BB | NextFilename | Described in | | | | Section 5.1.2.6 | +------------+-----------------------------+----------------------+ | 0x3EB923 | NextUUID | Described in | | | | Section 5.1.2.5 | +------------+-----------------------------+----------------------+ | 0x1043A770 | Chapters | Described in | | | | Section 5.1.7 | +------------+-----------------------------+----------------------+ | 0x114D9B74 | SeekHead | Described in | | | | Section 5.1.1 | +------------+-----------------------------+----------------------+ | 0x1254C367 | Tags | Described in | | | | Section 5.1.8 | +------------+-----------------------------+----------------------+ | 0x1549A966 | Info | Described in | | | | Section 5.1.2 | +------------+-----------------------------+----------------------+ | 0x1654AE6B | Tracks | Described in | | | | Section 5.1.4 | +------------+-----------------------------+----------------------+ | 0x18538067 | Segment | Described in | | | | Section 5.1 | +------------+-----------------------------+----------------------+ | 0x1941A469 | Attachments | Described in | | | | Section 5.1.6 | +------------+-----------------------------+----------------------+ | 0x1C53BB6B | Cues | Described in | | | | Section 5.1.5 | +------------+-----------------------------+----------------------+ | 0x1F43B675 | Cluster | Described in | | | | Section 5.1.3 | +------------+-----------------------------+----------------------+ Table 55: IDs and Names for Matroska Element IDs assigned by this document 27.2. Chapter Codec IDs Registry This document creates a new IANA registry called the "Matroska Chapter Codec IDs" registry. The values correspond to the unsigned integer ChapProcessCodecID value described in Section 5.1.7.1.4.15. To register a new Chapter Codec ID in this registry, one needs a Chapter Codec ID, a Change Controller (IETF or email of registrant) and an optional Reference to a document describing the Chapter Codec ID. Lhomme, et al. Expires 13 February 2024 [Page 152] Internet-Draft Matroska Format August 2023 The Chapter Codec IDs are to be allocated according to the "First Come First Served" policy [RFC8126]. ChapProcessCodecID values of "0" and "1" are RESERVED to the IETF for future use. 27.3. Media Types Matroska files and streams are found in three main forms: audio-video files, audio-only and occasionally with stereoscopic video tracks. Historically Matroska files and streams have used the following media types with a "x-" prefix. For better compatibility a system SHOULD be able to handle both formats. Newer systems SHOULD NOT use the historic format and use the format that follows the [RFC6838] format instead. Please register three media types, the [RFC6838] templates are below: 27.3.1. For files containing video tracks Type name: video Subtype name: matroska Required parameters: N/A Optional parameters: N/A Encoding considerations: as per this document and RFC8794 Security considerations: See Section 26. Interoperability considerations: Due to the extensibility of Matroska, it is possible to encounter files with unknown but valid EBML Elements. Readers should be ready to handle this case. The fixed byte order, octet boundaries and UTF-8 usage allow for broad interoparability. Published specification: THISRFC Applications that use this media type: FFmpeg, VLC, ... Fragment identifier considerations: N/A Additional information: * Deprecated alias names for this type: video/x-matroska * Magic number(s): N/A * File extension(s): mkv * Macintosh file type code(s): N/A Person & email address to contact for further information: IETF CELLAR WG cellar@ietf.org Lhomme, et al. Expires 13 February 2024 [Page 153] Internet-Draft Matroska Format August 2023 Intended usage: COMMON Restrictions on usage: None Author: IETF CELLAR WG Change controller: IETF Provisional registration? (standards tree only): No 27.3.2. For files containing audio tracks with no video tracks Type name: audio Subtype name: matroska Required parameters: N/A Optional parameters: N/A Encoding considerations: as per this document and RFC8794 Security considerations: See Section 26. Interoperability considerations: Due to the extensibility of Matroska, it is possible to encounter files with unknown but valid EBML Elements. Readers should be ready to handle this case. The fixed byte order, octet boundaries and UTF-8 usage allow for broad interoparability. Published specification: THISRFC Applications that use this media type: FFmpeg, VLC, ... Fragment identifier considerations: N/A Additional information: * Deprecated alias names for this type: audio/x-matroska * Magic number(s): N/A * File extension(s): mka * Macintosh file type code(s): N/A Person & email address to contact for further information: IETF CELLAR WG cellar@ietf.org Intended usage: COMMON Restrictions on usage: None Author: IETF CELLAR WG Change controller: IETF Provisional registration? (standards tree only): No 27.3.3. For files containing a stereoscopic video track Type name: video Subtype name: matroska-3d Required parameters: N/A Optional parameters: N/A Encoding considerations: as per this document and RFC8794 Lhomme, et al. Expires 13 February 2024 [Page 154] Internet-Draft Matroska Format August 2023 Security considerations: See Section 26. Interoperability considerations: Due to the extensibility of Matroska, it is possible to encounter files with unknown but valid EBML Elements. Readers should be ready to handle this case. The fixed byte order, octet boundaries and UTF-8 usage allow for broad interoparability. Published specification: THISRFC Applications that use this media type: FFmpeg, VLC, ... Fragment identifier considerations: N/A Additional information: * Deprecated alias names for this type: video/x-matroska-3d * Magic number(s): N/A * File extension(s): mk3d * Macintosh file type code(s): N/A Person & email address to contact for further information: IETF CELLAR WG cellar@ietf.org Intended usage: COMMON Restrictions on usage: None Author: IETF CELLAR WG Change controller: IETF Provisional registration? (standards tree only): No 28. Annex A: Historic Deprecated Elements As Matroska evolved since 2002 many parts that were considered for use in the format were never used and often incorrectly designed. Many of the elements that were then defined are not found in any known files but were part of public specs. DivX also had a few custom elements that were designed for custom features. We list these elements that have a known ID that SHOULD NOT be reused to avoid colliding with existing files. They might be reassigned by IANA in the future if there are no more IDs for a given size. A short description of what each ID was used for is included, but the text is not normative. 28.1. SilentTracks Element type / id: master / 0x5854 path: \Segment\Cluster\SilentTracks documentation: The list of tracks that are not used in that part of Lhomme, et al. Expires 13 February 2024 [Page 155] Internet-Draft Matroska Format August 2023 the stream. It is useful when using overlay tracks on seeking or to decide what track to use. 28.2. SilentTrackNumber Element type / id: uinteger / 0x58D7 path: \Segment\Cluster\SilentTracks\SilentTrackNumber documentation: One of the track number that are not used from now on in the stream. It could change later if not specified as silent in a further Cluster. 28.3. BlockVirtual Element type / id: binary / 0xA2 path: \Segment\Cluster\BlockGroup\BlockVirtual documentation: A Block with no data. It must be stored in the stream at the place the real Block would be in display order. 28.4. ReferenceVirtual Element type / id: integer / 0xFD path: \Segment\Cluster\BlockGroup\ReferenceVirtual documentation: The Segment Position of the data that would otherwise be in position of the virtual block. 28.5. Slices Element type / id: master / 0x8E path: \Segment\Cluster\BlockGroup\Slices documentation: Contains slices description. 28.6. TimeSlice Element type / id: master / 0xE8 path: \Segment\Cluster\BlockGroup\Slices\TimeSlice documentation: Contains extra time information about the data contained in the Block. Being able to interpret this Element is not required for playback. 28.7. LaceNumber Element type / id: uinteger / 0xCC path: \Segment\Cluster\BlockGroup\Slices\TimeSlice\LaceNumber documentation: The reverse number of the frame in the lace (0 is the last frame, 1 is the next to last, etc.). Being able to interpret this Element is not required for playback. Lhomme, et al. Expires 13 February 2024 [Page 156] Internet-Draft Matroska Format August 2023 28.8. FrameNumber Element type / id: uinteger / 0xCD path: \Segment\Cluster\BlockGroup\Slices\TimeSlice\FrameNumber documentation: The number of the frame to generate from this lace with this delay (allow you to generate many frames from the same Block/Frame). 28.9. BlockAdditionID Element type / id: uinteger / 0xCB path: \Segment\Cluster\BlockGroup\Slices\TimeSlice\BlockAdditionID documentation: The ID of the BlockAdditional Element (0 is the main Block). 28.10. Delay Element type / id: uinteger / 0xCE path: \Segment\Cluster\BlockGroup\Slices\TimeSlice\Delay documentation: The delay to apply to the Element, expressed in Track Ticks; see Section 11.1. 28.11. SliceDuration Element type / id: uinteger / 0xCF path: \Segment\Cluster\BlockGroup\Slices\TimeSlice\SliceDuration documentation: The duration to apply to the Element, expressed in Track Ticks; see Section 11.1. 28.12. ReferenceFrame Element type / id: master / 0xC8 path: \Segment\Cluster\BlockGroup\ReferenceFrame documentation: Contains information about the last reference frame. See [DivXTrickTrack]. 28.13. ReferenceOffset Element type / id: uinteger / 0xC9 path: \Segment\Cluster\BlockGroup\ReferenceFrame\ReferenceOffset documentation: The relative offset, in bytes, from the previous BlockGroup element for this Smooth FF/RW video track to the containing BlockGroup element. See [DivXTrickTrack]. 28.14. ReferenceTimestamp Element type / id: uinteger / 0xCA path: \Segment\Cluster\BlockGroup\ReferenceFrame\ReferenceTimestamp Lhomme, et al. Expires 13 February 2024 [Page 157] Internet-Draft Matroska Format August 2023 documentation: The timestamp of the BlockGroup pointed to by ReferenceOffset, expressed in Track Ticks; see Section 11.1. See [DivXTrickTrack]. 28.15. EncryptedBlock Element type / id: binary / 0xAF path: \Segment\Cluster\EncryptedBlock documentation: Similar to SimpleBlock, see Section 10.2, but the data inside the Block are Transformed (encrypt and/or signed). 28.16. MinCache Element type / id: uinteger / 0x6DE7 path: \Segment\Tracks\TrackEntry\MinCache documentation: The minimum number of frames a player should be able to cache during playback. If set to 0, the reference pseudo-cache system is not used. 28.17. MaxCache Element type / id: uinteger / 0x6DF8 path: \Segment\Tracks\TrackEntry\MaxCache documentation: The maximum cache size necessary to store referenced frames in and the current frame. 0 means no cache is needed. 28.18. TrackOffset Element type / id: integer / 0x537F path: \Segment\Tracks\TrackEntry\TrackOffset documentation: A value to add to the Block's Timestamp, expressed in Matroska Ticks -- i.e., in nanoseconds; see Section 11.1. This can be used to adjust the playback offset of a track. 28.19. CodecSettings Element type / id: utf-8 / 0x3A9697 path: \Segment\Tracks\TrackEntry\CodecSettings documentation: A string describing the encoding setting used. 28.20. CodecInfoURL Element type / id: string / 0x3B4040 path: \Segment\Tracks\TrackEntry\CodecInfoURL documentation: A URL to find information about the codec used. Lhomme, et al. Expires 13 February 2024 [Page 158] Internet-Draft Matroska Format August 2023 28.21. CodecDownloadURL Element type / id: string / 0x26B240 path: \Segment\Tracks\TrackEntry\CodecDownloadURL documentation: A URL to download about the codec used. 28.22. CodecDecodeAll Element type / id: uinteger / 0xAA path: \Segment\Tracks\TrackEntry\CodecDecodeAll documentation: Set to 1 if the codec can decode potentially damaged data. 28.23. TrackOverlay Element type / id: uinteger / 0x6FAB path: \Segment\Tracks\TrackEntry\TrackOverlay documentation: Specify that this track is an overlay track for the Track specified (in the u-integer). That means when this track has a gap on SilentTracks, the overlay track should be used instead. The order of multiple TrackOverlay matters, the first one is the one that should be used. If not found it should be the second, etc. 28.24. AspectRatioType Element type / id: uinteger / 0x54B3 path: \Segment\Tracks\TrackEntry\Video\AspectRatioType documentation: Specify the possible modifications to the aspect ratio. 28.25. GammaValue Element type / id: float / 0x2FB523 path: \Segment\Tracks\TrackEntry\Video\GammaValue documentation: Gamma Value. 28.26. FrameRate Element type / id: float / 0x2383E3 path: \Segment\Tracks\TrackEntry\Video\FrameRate documentation: Number of frames per second. This value is Informational only. It is intended for constant frame rate streams, and should not be used for a variable frame rate TrackEntry. Lhomme, et al. Expires 13 February 2024 [Page 159] Internet-Draft Matroska Format August 2023 28.27. ChannelPositions Element type / id: binary / 0x7D7B path: \Segment\Tracks\TrackEntry\Audio\ChannelPositions documentation: Table of horizontal angles for each successive channel. 28.28. TrickTrackUID Element type / id: uinteger / 0xC0 path: \Segment\Tracks\TrackEntry\TrickTrackUID documentation: The TrackUID of the Smooth FF/RW video in the paired EBML structure corresponding to this video track. See [DivXTrickTrack]. 28.29. TrickTrackSegmentUID Element type / id: binary / 0xC1 path: \Segment\Tracks\TrackEntry\TrickTrackSegmentUID documentation: The SegmentUID of the Segment containing the track identified by TrickTrackUID. See [DivXTrickTrack]. 28.30. TrickTrackFlag Element type / id: uinteger / 0xC6 path: \Segment\Tracks\TrackEntry\TrickTrackFlag documentation: Set to 1 if this video track is a Smooth FF/RW track. If set to 1, MasterTrackUID and MasterTrackSegUID should be present and BlockGroups for this track must contain ReferenceFrame structures. Otherwise, TrickTrackUID and TrickTrackSegUID must be present if this track has a corresponding Smooth FF/RW track. See [DivXTrickTrack]. 28.31. TrickMasterTrackUID Element type / id: uinteger / 0xC7 path: \Segment\Tracks\TrackEntry\TrickMasterTrackUID documentation: The TrackUID of the video track in the paired EBML structure that corresponds to this Smooth FF/RW track. See [DivXTrickTrack]. 28.32. TrickMasterTrackSegmentUID Element type / id: binary / 0xC4 path: \Segment\Tracks\TrackEntry\TrickMasterTrackSegmentUID documentation: The SegmentUID of the Segment containing the track identified by MasterTrackUID. See [DivXTrickTrack]. Lhomme, et al. Expires 13 February 2024 [Page 160] Internet-Draft Matroska Format August 2023 28.33. ContentSignature Element type / id: binary / 0x47E3 path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co ntentEncryption\ContentSignature documentation: A cryptographic signature of the contents. 28.34. ContentSigKeyID Element type / id: binary / 0x47E4 path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co ntentEncryption\ContentSigKeyID documentation: This is the ID of the private key the data was signed with. 28.35. ContentSigAlgo Element type / id: uinteger / 0x47E5 path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co ntentEncryption\ContentSigAlgo documentation: The algorithm used for the signature. 28.36. ContentSigHashAlgo Element type / id: uinteger / 0x47E6 path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co ntentEncryption\ContentSigHashAlgo documentation: The hash algorithm used for the signature. 28.37. CueRefCluster Element type / id: uinteger / 0x97 path: \Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefCl uster documentation: The Segment Position of the Cluster containing the referenced Block. 28.38. CueRefNumber Element type / id: uinteger / 0x535F path: \Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefNu mber documentation: Number of the referenced Block of Track X in the specified Cluster. 28.39. CueRefCodecState Element type / id: uinteger / 0xEB Lhomme, et al. Expires 13 February 2024 [Page 161] Internet-Draft Matroska Format August 2023 path: \Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefCo decState documentation: The Segment Position of the Codec State corresponding to this referenced Element. 0 means that the data is taken from the initial Track Entry. 28.40. FileReferral Element type / id: binary / 0x4675 path: \Segment\Attachments\AttachedFile\FileReferral documentation: A binary value that a track/codec can refer to when the attachment is needed. 28.41. FileUsedStartTime Element type / id: uinteger / 0x4661 path: \Segment\Attachments\AttachedFile\FileUsedStartTime documentation: The timestamp at which this optimized font attachment comes into context, expressed in Segment Ticks which is based on TimestampScale. See [DivXWorldFonts]. 28.42. FileUsedEndTime Element type / id: uinteger / 0x4662 path: \Segment\Attachments\AttachedFile\FileUsedEndTime documentation: The timestamp at which this optimized font attachment goes out of context, expressed in Segment Ticks which is based on TimestampScale. See [DivXWorldFonts]. 28.43. TagDefaultBogus Element type / id: uinteger / 0x44B4 path: \Segment\Tags\Tag\+SimpleTag\TagDefaultBogus documentation: A variant of the TagDefault element with a bogus Element ID; see Section 5.1.8.1.2.4. 29. Normative References [BCP47] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646, September 2009, . [CIE-1931] Commission Internationale de l'Eclairage, "CIE 1931 Standard Colorimetric System", 1931, . Lhomme, et al. Expires 13 February 2024 [Page 162] Internet-Draft Matroska Format August 2023 [ISO639-2] United States Library Of Congress, "Codes for the Representation of Names of Languages", ISO 639-2:1998, 21 December 2017, . [ISO9899] International Organization for Standardization, "Information technology -- Programming languages -- C", ISO/IEC 9899:2011, 2011, . [ITU-H.273] International Telecommunication Union, "Coding-independent code points for video signal type identification", ITU H.273, 24 September 2021, . [RFC1950] Deutsch, P. and J. Gailly, "ZLIB Compressed Data Format Specification version 3.3", RFC 1950, DOI 10.17487/RFC1950, May 1996, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally Unique IDentifier (UUID) URN Namespace", RFC 4122, DOI 10.17487/RFC4122, July 2005, . [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type Specifications and Registration Procedures", BCP 13, RFC 6838, DOI 10.17487/RFC6838, January 2013, . [RFC8081] Lilley, C., "The "font" Top-Level Media Type", RFC 8081, DOI 10.17487/RFC8081, February 2017, . [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . Lhomme, et al. Expires 13 February 2024 [Page 163] Internet-Draft Matroska Format August 2023 [RFC8794] Lhomme, S., Rice, D., and M. Bunkus, "Extensible Binary Meta Language", RFC 8794, DOI 10.17487/RFC8794, July 2020, . 30. Informative References [AVIFormat] Microsoft, "AVI RIFF File Reference", 31 May 2018, . [Blowfish] Schneier, B., "The Blowfish Encryption Algorithm", 1993, . [BZIP2] Seward, J., "bzip2", 18 July 1996, . [DivXTrickTrack] "DivX Trick Track Extensions", 14 December 2010, . [DivXWorldFonts] "DivX World Fonts Extensions", 14 December 2010, . [DVD-Video] DVD Forum, "DVD-Books: Part 3 DVD-Video Book", 1 November 1995, . [FIPS.197] US National Institute of Standards and Technology, "Advanced Encryption Standard (AES)", FIPS PUB 197, DOI 10.6028/NIST.FIPS.197, 26 November 2001, . [FIPS.46-3] US National Institute of Standards and Technology, "Data Encryption Standard (DES)", FIPS PUB 46, 25 October 1999, . [FourCC-RGB] Silicon.dk ApS, "RGB Pixel Format FourCCs", . Lhomme, et al. Expires 13 February 2024 [Page 164] Internet-Draft Matroska Format August 2023 [FourCC-YUV] Silicon.dk ApS, "YUV Pixel Format FourCCs", . [JPEG] International Telegraph and Telephone Consultative Committee, "Digital Compression and Coding of Continuous- Tone Still Images", ITU T.81, September 1992, . [LZO] Tarreau, W., Rodgman, R., and M. Oberhumer, "Lempel-Ziv- Oberhumer compression", 30 October 2018, . [MatroskaCodec] Lhomme, S., Bunkus, M., and D. Rice, "Media Container Codec Specifications", Work in Progress, Internet-Draft, draft-ietf-cellar-codec-10, 12 April 2021, . [MatroskaTags] Lhomme, S., Bunkus, M., and D. Rice, "Matroska Media Container Tag Specifications", Work in Progress, Internet- Draft, draft-ietf-cellar-tags-10, 12 April 2021, . [MCF] "Media Container Format", 17 July 2002, . [MSRGB] Microsoft, "WMF Compression Enumeration", . [MSYUV16] Microsoft, "10-bit and 16-bit YUV Video Formats", . [MSYUV8] Microsoft, "Recommended 8-Bit YUV Formats for Video Rendering", . [RFC0959] Postel, J. and J. Reynolds, "File Transfer Protocol", STD 9, RFC 959, DOI 10.17487/RFC0959, October 1985, . Lhomme, et al. Expires 13 February 2024 [Page 165] Internet-Draft Matroska Format August 2023 [RFC2083] Boutell, T., "PNG (Portable Network Graphics) Specification Version 1.0", RFC 2083, DOI 10.17487/RFC2083, March 1997, . [RFC3533] Pfeiffer, S., "The Ogg Encapsulation Format Version 0", RFC 3533, DOI 10.17487/RFC3533, May 2003, . [RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, Ed., "HTTP Semantics", STD 97, RFC 9110, DOI 10.17487/RFC9110, June 2022, . [SMB-CIFS] Microsoft Corporation, "Common Internet File System (CIFS) Protocol", 1 October 2020, . [SP.800-38A] US National Institute of Standards and Technology, "Recommendation for Block Cipher Modes of Operation: Methods and Techniques", DOI 10.6028/NIST.SP.800-38A, 1 December 2001, . [SP.800-67] US National Institute of Standards and Technology, "Recommendation for the Triple Data Encryption Algorithm (TDEA) Block Cipher", DOI 10.6028/10.6028/NIST.SP.800-67r2, 1 November 2017, . [Twofish] Schneier, B., Kelsey, J., Whiting, D., Wagner, D., Hall, C., and N. Ferguson, "Twofish: A 128-Bit Block Cipher", 15 June 1998, . [WebM-Enc] Galligan, F., "WebM Encryption", 19 September 2016, . [WebVTT] Pieters, S., Pfeiffer, S., Ed., Jaegenstedt, P., and I. Hickson, "WebVTT Cue Identifier", 4 April 2019, . Authors' Addresses Lhomme, et al. Expires 13 February 2024 [Page 166] Internet-Draft Matroska Format August 2023 Steve Lhomme Email: slhomme@matroska.org Moritz Bunkus Email: moritz@bunkus.org Dave Rice Email: dave@dericed.com Lhomme, et al. Expires 13 February 2024 [Page 167]