cellar S. Lhomme Internet-Draft Intended status: Informational M. Bunkus Expires: 29 April 2020 D. Rice 27 October 2019 Matroska Specifications draft-ietf-cellar-matroska-04 Abstract This document defines the Matroska audiovisual container, including definitions of its structural elements, as well as its terminology, vocabulary, and application. 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 29 April 2020. Copyright Notice Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved. 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 Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Lhomme, et al. Expires 29 April 2020 [Page 1] Internet-Draft Matroska October 2019 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Status of this document . . . . . . . . . . . . . . . . . . . 5 3. Security Considerations . . . . . . . . . . . . . . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5. Notation and Conventions . . . . . . . . . . . . . . . . . . 6 6. Basis in EBML . . . . . . . . . . . . . . . . . . . . . . . . 6 6.1. Added Constraints on EBML . . . . . . . . . . . . . . . . 6 6.2. Matroska Design . . . . . . . . . . . . . . . . . . . . . 7 6.2.1. Language Codes . . . . . . . . . . . . . . . . . . . 7 6.2.2. Physical Types . . . . . . . . . . . . . . . . . . . 7 6.2.3. Block Structure . . . . . . . . . . . . . . . . . . . 8 6.2.4. Lacing . . . . . . . . . . . . . . . . . . . . . . . 10 7. Matroska Structure . . . . . . . . . . . . . . . . . . . . . 14 8. Matroska Additions to Schema Element Attributes . . . . . . . 23 9. Matroska Schema . . . . . . . . . . . . . . . . . . . . . . . 24 9.1. EBMLMaxIDLength Element . . . . . . . . . . . . . . . . . 24 9.2. EBMLMaxSizeLength Element . . . . . . . . . . . . . . . . 24 9.3. Segment Element . . . . . . . . . . . . . . . . . . . . . 25 9.3.1. SeekHead Element . . . . . . . . . . . . . . . . . . 25 9.3.2. Info Element . . . . . . . . . . . . . . . . . . . . 26 9.3.3. Cluster Element . . . . . . . . . . . . . . . . . . . 33 9.3.4. Tracks Element . . . . . . . . . . . . . . . . . . . 45 9.3.5. Cues Element . . . . . . . . . . . . . . . . . . . . 106 9.3.6. Attachments Element . . . . . . . . . . . . . . . . . 112 9.3.7. Chapters Element . . . . . . . . . . . . . . . . . . 115 9.3.8. Tags Element . . . . . . . . . . . . . . . . . . . . 127 10. Matroska Element Ordering . . . . . . . . . . . . . . . . . . 134 10.1. Top-Level Elements . . . . . . . . . . . . . . . . . . . 134 10.2. CRC-32 . . . . . . . . . . . . . . . . . . . . . . . . . 135 10.3. SeekHead . . . . . . . . . . . . . . . . . . . . . . . . 135 10.4. Cues (index) . . . . . . . . . . . . . . . . . . . . . . 135 10.5. Info . . . . . . . . . . . . . . . . . . . . . . . . . . 135 10.6. Chapters Element . . . . . . . . . . . . . . . . . . . . 136 10.7. Attachments . . . . . . . . . . . . . . . . . . . . . . 136 10.8. Tags . . . . . . . . . . . . . . . . . . . . . . . . . . 136 10.9. Optimum layout from a muxer . . . . . . . . . . . . . . 136 10.10. Optimum layout after editing tags . . . . . . . . . . . 137 10.11. Optimum layout with Cues at the front . . . . . . . . . 137 10.12. Cluster Timestamp . . . . . . . . . . . . . . . . . . . 137 11. Chapters . . . . . . . . . . . . . . . . . . . . . . . . . . 138 11.1. Edition and Chapter Flags . . . . . . . . . . . . . . . 138 11.1.1. Chapter Flags . . . . . . . . . . . . . . . . . . . 138 11.1.2. Edition Flags . . . . . . . . . . . . . . . . . . . 138 11.2. Menu features . . . . . . . . . . . . . . . . . . . . . 140 11.2.1. Matroska Script (0) . . . . . . . . . . . . . . . . 140 11.2.2. DVD menu (1) . . . . . . . . . . . . . . . . . . . . 141 Lhomme, et al. Expires 29 April 2020 [Page 2] Internet-Draft Matroska October 2019 11.3. Example 1 : basic chaptering . . . . . . . . . . . . . . 142 11.4. Example 2 : nested chapters . . . . . . . . . . . . . . 142 11.4.1. The Micronauts "Bleep To Bleep" . . . . . . . . . . 143 12. Attachments . . . . . . . . . . . . . . . . . . . . . . . . . 143 12.1. Cover Art . . . . . . . . . . . . . . . . . . . . . . . 143 13. Cues . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 13.1. Recommendations . . . . . . . . . . . . . . . . . . . . 144 14. Matroska Streaming . . . . . . . . . . . . . . . . . . . . . 145 14.1. File Access . . . . . . . . . . . . . . . . . . . . . . 145 14.2. Livestreaming . . . . . . . . . . . . . . . . . . . . . 146 15. Menu Specifications . . . . . . . . . . . . . . . . . . . . . 146 15.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 147 15.1.1. Highlights/Hotspots . . . . . . . . . . . . . . . . 147 15.1.2. Playback features . . . . . . . . . . . . . . . . . 148 15.1.3. Player requirements . . . . . . . . . . . . . . . . 148 15.2. Working Graph . . . . . . . . . . . . . . . . . . . . . 148 16. Unknown elements . . . . . . . . . . . . . . . . . . . . . . 149 17. Default Values . . . . . . . . . . . . . . . . . . . . . . . 149 18. DefaultDecodedFieldDuration . . . . . . . . . . . . . . . . . 149 19. Encryption . . . . . . . . . . . . . . . . . . . . . . . . . 150 20. Image Presentation . . . . . . . . . . . . . . . . . . . . . 150 20.1. Cropping . . . . . . . . . . . . . . . . . . . . . . . . 150 20.2. Rotation . . . . . . . . . . . . . . . . . . . . . . . . 151 21. Matroska versioning . . . . . . . . . . . . . . . . . . . . . 151 22. MIME Types . . . . . . . . . . . . . . . . . . . . . . . . . 152 23. Segment Position . . . . . . . . . . . . . . . . . . . . . . 152 23.1. Segment Position Exception . . . . . . . . . . . . . . . 152 23.2. Example of Segment Position . . . . . . . . . . . . . . 152 24. Linked Segments . . . . . . . . . . . . . . . . . . . . . . . 153 24.1. Hard Linking . . . . . . . . . . . . . . . . . . . . . . 153 24.2. Medium Linking . . . . . . . . . . . . . . . . . . . . . 155 24.3. Soft Linking . . . . . . . . . . . . . . . . . . . . . . 155 25. Track Flags . . . . . . . . . . . . . . . . . . . . . . . . . 156 25.1. Default flag . . . . . . . . . . . . . . . . . . . . . . 156 25.2. Forced flag . . . . . . . . . . . . . . . . . . . . . . 156 25.3. Track Operation . . . . . . . . . . . . . . . . . . . . 156 25.4. Overlay Track . . . . . . . . . . . . . . . . . . . . . 157 25.5. Multi-planar and 3D videos . . . . . . . . . . . . . . . 157 26. Timestamps . . . . . . . . . . . . . . . . . . . . . . . . . 158 26.1. Timestamp Types . . . . . . . . . . . . . . . . . . . . 158 26.2. Block Timestamps . . . . . . . . . . . . . . . . . . . . 158 26.3. Raw Timestamp . . . . . . . . . . . . . . . . . . . . . 158 26.4. TimestampScale . . . . . . . . . . . . . . . . . . . . . 159 26.5. TimestampScale Rounding . . . . . . . . . . . . . . . . 159 26.6. TrackTimestampScale . . . . . . . . . . . . . . . . . . 161 27. Normative References . . . . . . . . . . . . . . . . . . . . 163 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 163 Lhomme, et al. Expires 29 April 2020 [Page 3] Internet-Draft Matroska October 2019 1. Introduction Matroska aims to become THE standard of multimedia container formats. It was derived from a project called MCF (http://mukoli.free.fr/mcf/ mcf.html), but differentiates from it significantly because it is based on EBML (https://github.com/Matroska-Org/ebml- specification/blob/master/specification.markdown) (Extensible Binary Meta Language), a binary derivative of XML. EBML enables 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 for 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 like: * 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, CIFS, FTP, etc) * Menus (like DVDs have) Matroska is an open standards project. This means for personal use it is absolutely free to use and that the technical specifications describing the bitstream are open to everybody, even to companies that would like to support it in their products. Lhomme, et al. Expires 29 April 2020 [Page 4] Internet-Draft Matroska October 2019 2. Status of this document This document is a work-in-progress specification defining the Matroska file format as part of the IETF Cellar working group (https://datatracker.ietf.org/wg/cellar/charter/). But since it's quite complete it is used as a reference for the development of libmatroska. Legacy versions of the specification can be found here (https://matroska.org/files/matroska.pdf) (PDF doc by Alexander Noe -- outdated). For a simplified diagram of the layout of a Matroska file, see the Diagram page (diagram.md). A more refined and detailed version of the EBML specifications is being worked on here (https://github.com/Matroska-Org/ebml- specification/blob/master/specification.markdown). The table found below is now generated from the "source" of the Matroska specification. This XML file (https://github.com/Matroska- Org/foundation-source/blob/master/spectool/specdata.xml) is also used to generate the semantic data used in libmatroska and libmatroska2. We encourage anyone to use and monitor its changes so your code is spec-proof and always up to date. Note that versions 1, 2 and 3 have been finalized. Version 4 is currently work in progress. There MAY be further additions to v4. 3. Security Considerations Matroska inherits security considerations from EBML. Attacks on a "Matroska Reader" could include: * Storage of a 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. * A "Matroska Attachment" with an inaccurate mime-type. 4. IANA Considerations To be determined. Lhomme, et al. Expires 29 April 2020 [Page 5] Internet-Draft Matroska October 2019 5. 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 "Matroska Reader" is a data parser that interprets the semantics of a Matroska document and creates a way for programs to use "Matroska". "Matroska Player": A "Matroska Player" is a "Matroska Reader" with a primary purpose of playing audiovisual files, including "Matroska" documents. 6. Basis in EBML Matroska is a Document Type of EBML (Extensible Binary Meta Language). This specification is dependent on the EBML Specification (https://github.com/Matroska-Org/ebml-specification/blob/master/ specification.markdown). For an understanding of Matroska's EBML Schema, see in particular the sections of the EBML Specification covering EBML Element Types (https://github.com/Matroska-Org/ebml- specification/blob/master/specification.markdown#ebml-element-types), EBML Schema (https://github.com/Matroska-Org/ebml- specification/blob/master/specification.markdown#ebml-schema), and EBML Structure (https://github.com/Matroska-Org/ebml- specification/blob/master/specification.markdown#structure). 6.1. Added Constraints on EBML 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 29 April 2020 [Page 6] Internet-Draft Matroska October 2019 6.2. Matroska Design All top-levels elements (Segment and direct sub-elements) are coded on 4 octets, i.e. class D elements. 6.2.1. Language Codes Matroska from version 1 through 3 uses language codes that can be either the 3 letters bibliographic ISO-639-2 (https://www.loc.gov/standards/iso639-2/php/English_list.php) form (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". Starting in Matroska version 4, either "ISO 639-2" or BCP 47 (https://tools.ietf.org/html/bcp47) MAY be used, although "BCP 47" is RECOMMENDED. The "BCP 47 Language Elements" are "LanguageIETF Element", "TagLanguageIETF Element", and "ChapLanguageIETF 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". Country codes are the same as used for internet domains (https://www.iana.org/domains/root/db). 6.2.2. Physical Types Each level can have different meanings for audio and video. The ORIGINAL_MEDIUM tag 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 29 April 2020 [Page 7] Internet-Draft Matroska October 2019 +----------------------+------------+-----------+-----------------+ | ChapterPhysicalEquiv | Audio | Video | Comment | +======================+============+===========+=================+ | 70 | SET / | SET / | the collection | | | PACKAGE | PACKAGE | of different | | | | | media | +----------------------+------------+-----------+-----------------+ | 60 | CD / 12" / | DVD / VHS | the physical | | | 10" / 7" / | / | medium like a | | | TAPE / | LASERDISC | CD or a DVD | | | MINIDISC / | | | | | DAT | | | +----------------------+------------+-----------+-----------------+ | 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 1 6.2.3. Block Structure Bit 0 is the most significant bit. 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. There can be many Blocks in a BlockGroup provided they all have the Lhomme, et al. Expires 29 April 2020 [Page 8] Internet-Draft Matroska October 2019 same timestamp. It is used with different parts of a frame with different priorities. 6.2.3.1. Block Header +--------+--------+---------------------------------------------+ | Offset | Player | Description | +========+========+=============================================+ | 0x00+ | MUST | Track Number (Track Entry). It is coded in | | | | EBML like form (1 octet if the value is < | | | | 0x80, 2 if < 0x4000, etc) (most significant | | | | bits set to increase the range). | +--------+--------+---------------------------------------------+ | 0x01+ | MUST | Timestamp (relative to Cluster timestamp, | | | | signed int16) | +--------+--------+---------------------------------------------+ Table 2 6.2.3.2. Block Header Flags +--------+-----+--------+------------------------------------+ | Offset | Bit | Player | Description | +========+=====+========+====================================+ | 0x03+ | 0-3 | - | Reserved, set to 0 | +--------+-----+--------+------------------------------------+ | 0x03+ | 4 | - | Invisible, the codec SHOULD decode | | | | | this frame but not display it | +--------+-----+--------+------------------------------------+ | 0x03+ | 5-6 | MUST | Lacing | +--------+-----+--------+------------------------------------+ | | | | * 00 : no lacing | +--------+-----+--------+------------------------------------+ | | | | * 01 : Xiph lacing | +--------+-----+--------+------------------------------------+ | | | | * 11 : EBML lacing | +--------+-----+--------+------------------------------------+ | | | | * 10 : fixed-size lacing | +--------+-----+--------+------------------------------------+ | 0x03+ | 7 | - | not used | +--------+-----+--------+------------------------------------+ Table 3 Lhomme, et al. Expires 29 April 2020 [Page 9] Internet-Draft Matroska October 2019 6.2.4. 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). There are 3 types of lacing: 1. Xiph, inspired by what is found in the Ogg container 2. EBML, which is the same with sizes coded differently 3. fixed-size, where the size is not coded 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. They will then be stored in the same block as follows: 6.2.4.1. Xiph lacing * Block head (with lacing bits set to 01) * Lacing head: Number of frames in the lace -1, i.e. 2 (the 800 and 500 octets one) * Lacing sizes: only the 2 first ones will be coded, 800 gives 255;255;255;35, 500 gives 255;245. The size of the last frame is deduced from the total size of the Block. * Data in frame 1 * Data in frame 2 * Data in frame 3 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. 6.2.4.2. EBML lacing In this case, the size is not coded as blocks of 255 bytes, but as a difference with the previous size and this size is coded as in EBML. The first size in the lace is unsigned as in EBML. The others use a range shifting to get a sign on each value: Lhomme, et al. Expires 29 April 2020 [Page 10] Internet-Draft Matroska October 2019 +--------------------------+---------------------------------------+ | Bit Representation | Value | +==========================+=======================================+ | 1xxx xxxx | value -(2^6-1) to 2^6-1 (ie 0 to | | | 2^7-2 minus 2^6-1, half of the range) | +--------------------------+---------------------------------------+ | 01xx xxxx xxxx xxxx | value -(2^13-1) to 2^(13-1) | +--------------------------+---------------------------------------+ | 001x xxxx xxxx xxxx xxxx | value -(2^20-1) to 2^(20-1) | | xxxx | | +--------------------------+---------------------------------------+ | 0001 xxxx xxxx xxxx xxxx | value -(2^27-1) to 2^(27-1) | | xxxx xxxx xxxx | | +--------------------------+---------------------------------------+ | 0000 1xxx xxxx xxxx xxxx | value -(2^34-1) to 2^(34-1) | | xxxx xxxx xxxx xxxx xxxx | | +--------------------------+---------------------------------------+ | 0000 01xx xxxx xxxx xxxx | value -(2^41-1) to 2^(41-1) | | xxxx xxxx xxxx xxxx xxxx | | | xxxx xxxx | | +--------------------------+---------------------------------------+ | 0000 001x xxxx xxxx xxxx | value -(2^48-1) to 2^(48-1) | | xxxx xxxx xxxx xxxx xxxx | | | xxxx xxxx xxxx xxxx | | +--------------------------+---------------------------------------+ Table 4 * Block head (with lacing bits set to 11) * Lacing head: Number of frames in the lace -1, i.e. 2 (the 800 and 500 octets one) * Lacing sizes: only the 2 first ones will be coded, 800 gives 0x320 0x4000 = 0x4320, 500 is coded as -300 : - 0x12C + 0x1FFF + 0x4000 = 0x5ED3. The size of the last frame is deduced from the total size of the Block. * Data in frame 1 * Data in frame 2 * Data in frame 3 Lhomme, et al. Expires 29 April 2020 [Page 11] Internet-Draft Matroska October 2019 6.2.4.3. Fixed-size lacing In this case, only the number of frames in the lace is saved, the size of each frame is deduced from the total size of the Block. For example, for 3 frames of 800 octets each: * Block head (with lacing bits set to 10) * Lacing head: Number of frames in the lace -1, i.e. 2 * Data in frame 1 * Data in frame 2 * Data in frame 3 6.2.4.4. SimpleBlock Structure The "SimpleBlock" is inspired by the Block structure (#block- structure). The main differences are the added Keyframe flag and Discardable flag. Otherwise everything is the same. Bit 0 is the most significant bit. 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. There can be many "Block Elements" in a "BlockGroup" provided they all have the same timestamp. It is used with different parts of a frame with different priorities. Lhomme, et al. Expires 29 April 2020 [Page 12] Internet-Draft Matroska October 2019 6.2.4.4.1. SimpleBlock Header +--------+--------+---------------------------------------------+ | Offset | Player | Description | +========+========+=============================================+ | 0x00+ | MUST | Track Number (Track Entry). It is coded in | | | | EBML like form (1 octet if the value is < | | | | 0x80, 2 if < 0x4000, etc) (most significant | | | | bits set to increase the range). | +--------+--------+---------------------------------------------+ | 0x01+ | MUST | Timestamp (relative to Cluster timestamp, | | | | signed int16) | +--------+--------+---------------------------------------------+ Table 5 6.2.4.4.2. SimpleBlock Header Flags +--------+-----+--------+------------------------------------------+ | Offset | Bit | Player | Description | +========+=====+========+==========================================+ | 0x03+ | 0 | - | Keyframe, set when the Block contains | | | | | only keyframes | +--------+-----+--------+------------------------------------------+ | 0x03+ | 1-3 | - | Reserved, set to 0 | +--------+-----+--------+------------------------------------------+ | 0x03+ | 4 | - | Invisible, the codec SHOULD decode this | | | | | frame but not display it | +--------+-----+--------+------------------------------------------+ | 0x03+ | 5-6 | MUST | Lacing | +--------+-----+--------+------------------------------------------+ | | | | * 00 : no lacing | +--------+-----+--------+------------------------------------------+ | | | | * 01 : Xiph lacing | +--------+-----+--------+------------------------------------------+ | | | | * 11 : EBML lacing | +--------+-----+--------+------------------------------------------+ | | | | * 10 : fixed-size lacing | +--------+-----+--------+------------------------------------------+ | 0x03+ | 7 | - | Discardable, the frames of the Block can | | | | | be discarded during playing if needed | +--------+-----+--------+------------------------------------------+ Table 6 Lhomme, et al. Expires 29 April 2020 [Page 13] Internet-Draft Matroska October 2019 6.2.4.5. Laced Data When lacing bit is set. +--------+--------+---------------------------------------------+ | Offset | Player | Description | +========+========+=============================================+ | 0x00 | MUST | Number of frames in the lace-1 (uint8) | +--------+--------+---------------------------------------------+ | 0x01 / | MUST* | Lace-coded size of each frame of the lace, | | 0xXX | | except for the last one (multiple uint8). | | | | *This is not used with Fixed-size lacing as | | | | it is calculated automatically from (total | | | | size of lace) / (number of frames in lace). | +--------+--------+---------------------------------------------+ Table 7 For (possibly) Laced Data +--------+--------+--------------------------+ | Offset | Player | Description | +========+========+==========================+ | 0x00 | MUST | Consecutive laced frames | +--------+--------+--------------------------+ Table 8 7. Matroska Structure 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" Lhomme, et al. Expires 29 April 2020 [Page 14] Internet-Draft Matroska October 2019 * "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 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 | +---------------------------+ The Matroska "EBML Schema" defines eight "Top Level Elements": "SeekHead", "Info", "Tracks", "Chapters", "Cluster", "Cues", "Attachments", and "Tags". 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 29 April 2020 [Page 15] Internet-Draft Matroska October 2019 +--------------------------------+ | SeekHead | Seek | SeekID | | | |--------------| | | | SeekPosition | +--------------------------------+ Figure 1: 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 | SegmentUID | | |------------------| | | SegmentFilename | | |------------------| | | PrevUID | | |------------------| | | PrevFilename | | |------------------| | | NextUID | | |------------------| | | NextFilename | | |------------------| | | SegmentFamily | | |------------------| | | ChapterTranslate | | |------------------| | | TimestampScale | | |------------------| | | Duration | | |------------------| | | DateUTC | | |------------------| | | Title | | |------------------| | | MuxingApp | | |------------------| | | WritingApp | |-------------------------| Figure 2: Representation of an "Info Element" and its "Child Elements". The "Tracks Element" defines the technical details for each track and can store the name, number, unique identifier, language and type Lhomme, et al. Expires 29 April 2020 [Page 16] Internet-Draft Matroska October 2019 (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 29 April 2020 [Page 17] Internet-Draft Matroska October 2019 +------------------------------------+ | 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 3: Representation of the "Tracks Element" and a selection of its "Descendant Elements". Lhomme, et al. Expires 29 April 2020 [Page 18] Internet-Draft Matroska October 2019 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 |--------------------| | | | EditionFlagHidden | | | |--------------------| | | | EditionFlagDefault | | | |--------------------| | | | EditionFlagOrdered | | | |---------------------------------+ | | | ChapterAtom | ChapterUID | | | | |-------------------| | | | | ChapterStringUID | | | | |-------------------| | | | | ChapterTimeStart | | | | |-------------------| | | | | ChapterTimeEnd | | | | |-------------------| | | | | ChapterFlagHidden | | | | |-------------------------------+ | | | | ChapterDisplay | ChapString | | | | | |--------------| | | | | | ChapLanguage | +------------------------------------------------------------------+ Figure 4: 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". The "Cluster Element" helps to break up "SimpleBlock" or "BlockGroup Elements" and helps with seeking and error protection. It is RECOMMENDED that the size of each individual "Cluster Element" be limited to store no more than 5 seconds or 5 megabytes. Every "Cluster Element" MUST contain a "Timestamp Element". This SHOULD be the "Timestamp Element" used to play the first "Block" in the "Cluster Element". There SHOULD be one or more "BlockGroup" or "SimpleBlock Element" in each "Cluster Element". A "BlockGroup Element" MAY contain a "Block" of data and any information relating directly to that "Block". Lhomme, et al. Expires 29 April 2020 [Page 19] Internet-Draft Matroska October 2019 +--------------------------+ | Cluster | Timestamp | | |----------------| | | SilentTracks | | |----------------| | | Position | | |----------------| | | PrevSize | | |----------------| | | SimpleBlock | | |----------------| | | BlockGroup | | |----------------| | | EncryptedBlock | +--------------------------+ Figure 5: 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 6: 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". 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 Lhomme, et al. Expires 29 April 2020 [Page 20] Internet-Draft Matroska October 2019 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. For video files, it is RECOMMENDED to index at least the keyframes of the video track. +-------------------------------------+ | Cues | CuePoint | CueTime | | | |-------------------| | | | CueTrackPositions | | |------------------------------| | | CuePoint | CueTime | | | |-------------------| | | | CueTrackPositions | +-------------------------------------+ Figure 7: 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, webpages, programs, or even the codec needed to play back the file. Lhomme, et al. Expires 29 April 2020 [Page 21] Internet-Draft Matroska October 2019 +------------------------------------------------+ | Attachments | AttachedFile | FileDescription | | | |-------------------| | | | FileName | | | |-------------------| | | | FileMimeType | | | |-------------------| | | | FileData | | | |-------------------| | | | FileUID | | | |-------------------| | | | FileName | | | |-------------------| | | | FileReferral | | | |-------------------| | | | FileUsedStartTime | | | |-------------------| | | | FileUsedEndTime | +------------------------------------------------+ Figure 8: Representation of a "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 29 April 2020 [Page 22] Internet-Draft Matroska October 2019 +-------------------------------------------+ | Tags | Tag | Targets | TargetTypeValue | | | | |------------------| | | | | TargetType | | | | |------------------| | | | | TagTrackUID | | | | |------------------| | | | | TagEditionUID | | | | |------------------| | | | | TagChapterUID | | | | |------------------| | | | | TagAttachmentUID | | | |------------------------------| | | | SimpleTag | TagName | | | | |------------------| | | | | TagLanguage | | | | |------------------| | | | | TagDefault | | | | |------------------| | | | | TagString | | | | |------------------| | | | | TagBinary | | | | |------------------| | | | | SimpleTag | +-------------------------------------------+ Figure 9: Representation of a "Tags Element" and three levels of its "Children Elements". 8. Matroska Additions to Schema Element Attributes In addition to the EBML Schema definition provided by the EBML Specification, Matroska adds the following additional attributes: +-----------+----------+----------------------------------------+ | attribute | required | definition | | name | | | +===========+==========+========================================+ | webm | No | A boolean to express if the Matroska | | | | Element is also supported within | | | | version 2 of the "webm" specification. | | | | Please consider the webm specification | | | | (http://www.webmproject.org/docs/ | | | | container/) as the authoritative on | | | | "webm". | +-----------+----------+----------------------------------------+ Table 9 Lhomme, et al. Expires 29 April 2020 [Page 23] Internet-Draft Matroska October 2019 9. Matroska Schema This specification includes an "EBML Schema" which defines the Elements and structure of Matroska as an EBML Document Type. 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. 9.1. EBMLMaxIDLength Element name: "EBMLMaxIDLength" path: "1*1(\EBML\EBMLMaxIDLength)" id: "0x42F2" minOccurs: "1" maxOccurs: "1" range: "4" default: "4" type: "uinteger" 9.2. EBMLMaxSizeLength Element name: "EBMLMaxSizeLength" path: "1*1(\EBML\EBMLMaxSizeLength)" id: "0x42F3" minOccurs: "1" maxOccurs: "1" range: "1-8" default: "8" type: "uinteger" Lhomme, et al. Expires 29 April 2020 [Page 24] Internet-Draft Matroska October 2019 9.3. Segment Element name: "Segment" path: "1*1(\Segment)" id: "0x18538067" minOccurs: "1" maxOccurs: "1" type: "master" unknownsizeallowed: "1" definition: The Root Element that contains all other Top-Level Elements (Elements defined only at Level 1). A Matroska file is composed of 1 Segment. 9.3.1. SeekHead Element name: "SeekHead" path: "0*2(\Segment\SeekHead)" id: "0x114D9B74" maxOccurs: "2" type: "master" definition: Contains the Segment Position of other Top-Level Elements. 9.3.1.1. Seek Element name: "Seek" path: "1*(\Segment\SeekHead\Seek)" id: "0x4DBB" minOccurs: "1" type: "master" definition: Contains a single seek entry to an EBML Element. Lhomme, et al. Expires 29 April 2020 [Page 25] Internet-Draft Matroska October 2019 9.3.1.1.1. SeekID Element name: "SeekID" path: "1*1(\Segment\SeekHead\Seek\SeekID)" id: "0x53AB" minOccurs: "1" maxOccurs: "1" type: "binary" definition: The binary ID corresponding to the Element name. 9.3.1.1.2. SeekPosition Element name: "SeekPosition" path: "1*1(\Segment\SeekHead\Seek\SeekPosition)" id: "0x53AC" minOccurs: "1" maxOccurs: "1" type: "uinteger" definition: The Segment Position of the Element. 9.3.2. Info Element name: "Info" path: "1*(\Segment\Info)" id: "0x1549A966" minOccurs: "1" type: "master" recurring: "1" definition: Contains general information about the Segment. Lhomme, et al. Expires 29 April 2020 [Page 26] Internet-Draft Matroska October 2019 9.3.2.1. SegmentUID Element name: "SegmentUID" path: "0*1(\Segment\Info\SegmentUID)" id: "0x73A4" maxOccurs: "1" range: "not 0" type: "binary" definition: A randomly generated unique ID to identify the Segment amongst many others (128 bits). usage notes: If the Segment is a part of a Linked Segment then this Element is REQUIRED. 9.3.2.2. SegmentFilename Element name: "SegmentFilename" path: "0*1(\Segment\Info\SegmentFilename)" id: "0x7384" maxOccurs: "1" type: "utf-8" definition: A filename corresponding to this Segment. 9.3.2.3. PrevUID Element name: "PrevUID" path: "0*1(\Segment\Info\PrevUID)" id: "0x3CB923" maxOccurs: "1" type: "binary" definition: A unique ID to identify the previous Segment of a Linked Segment (128 bits). Lhomme, et al. Expires 29 April 2020 [Page 27] Internet-Draft Matroska October 2019 usage notes: If the Segment is a part of a Linked Segment that uses Hard Linking then either the PrevUID or the NextUID Element is REQUIRED. If a Segment contains a PrevUID but not a NextUID then it MAY be considered as the last Segment of the Linked Segment. The PrevUID MUST NOT be equal to the SegmentUID. 9.3.2.4. PrevFilename Element name: "PrevFilename" path: "0*1(\Segment\Info\PrevFilename)" id: "0x3C83AB" maxOccurs: "1" type: "utf-8" definition: A filename corresponding to the file of the previous Linked Segment. usage notes: Provision of the previous filename is for display convenience, but PrevUID SHOULD be considered authoritative for identifying the previous Segment in a Linked Segment. 9.3.2.5. NextUID Element name: "NextUID" path: "0*1(\Segment\Info\NextUID)" id: "0x3EB923" maxOccurs: "1" type: "binary" definition: A unique ID to identify the next Segment of a Linked Segment (128 bits). usage notes: If the Segment is a part of a Linked Segment that uses Hard Linking then either the PrevUID or the NextUID Element is REQUIRED. If a Segment contains a NextUID but not a PrevUID then it MAY be considered as the first Segment of the Linked Segment. The NextUID MUST NOT be equal to the SegmentUID. Lhomme, et al. Expires 29 April 2020 [Page 28] Internet-Draft Matroska October 2019 9.3.2.6. NextFilename Element name: "NextFilename" path: "0*1(\Segment\Info\NextFilename)" id: "0x3E83BB" maxOccurs: "1" type: "utf-8" definition: A filename corresponding to the file of the next Linked Segment. usage notes: Provision of the next filename is for display convenience, but NextUID SHOULD be considered authoritative for identifying the Next Segment. 9.3.2.7. SegmentFamily Element name: "SegmentFamily" path: "0*(\Segment\Info\SegmentFamily)" id: "0x4444" type: "binary" definition: A randomly generated unique ID that all Segments of a Linked Segment MUST share (128 bits). usage notes: If the Segment is a part of a Linked Segment that uses Soft Linking then this Element is REQUIRED. 9.3.2.8. ChapterTranslate Element name: "ChapterTranslate" path: "0*(\Segment\Info\ChapterTranslate)" id: "0x6924" type: "master" definition: A tuple of corresponding ID used by chapter codecs to represent this Segment. Lhomme, et al. Expires 29 April 2020 [Page 29] Internet-Draft Matroska October 2019 9.3.2.8.1. ChapterTranslateEditionUID Element name: "ChapterTranslateEditionUID" path: "0*(\Segment\Info\ChapterTranslate\ChapterTranslateEditionUID)" id: "0x69FC" type: "uinteger" definition: Specify an edition UID on which this correspondence applies. When not specified, it means for all editions found in the Segment. 9.3.2.8.2. ChapterTranslateCodec Element name: "ChapterTranslateCodec" path: "1*1(\Segment\Info\ChapterTranslate\ChapterTranslateCodec)" id: "0x69BF" minOccurs: "1" maxOccurs: "1" type: "uinteger" definition: The chapter codec restrictions: +-------+-----------------+ | value | label | +=======+=================+ | "0" | Matroska Script | +-------+-----------------+ | "1" | DVD-menu | +-------+-----------------+ Table 10 9.3.2.8.3. ChapterTranslateID Element name: "ChapterTranslateID" path: "1*1(\Segment\Info\ChapterTranslate\ChapterTranslateID)" Lhomme, et al. Expires 29 April 2020 [Page 30] Internet-Draft Matroska October 2019 id: "0x69A5" minOccurs: "1" maxOccurs: "1" type: "binary" definition: The binary value used to represent this Segment in the chapter codec data. The format depends on the ChapProcessCodecID used. 9.3.2.9. TimestampScale Element name: "TimestampScale" path: "1*1(\Segment\Info\TimestampScale)" id: "0x2AD7B1" minOccurs: "1" maxOccurs: "1" range: "not 0" default: "1000000" type: "uinteger" definition: Timestamp scale in nanoseconds (1.000.000 means all timestamps in the Segment are expressed in milliseconds). 9.3.2.10. Duration Element name: "Duration" path: "0*1(\Segment\Info\Duration)" id: "0x4489" maxOccurs: "1" range: "> 0x0p+0" type: "float" Lhomme, et al. Expires 29 April 2020 [Page 31] Internet-Draft Matroska October 2019 definition: Duration of the Segment in nanoseconds based on TimestampScale. 9.3.2.11. DateUTC Element name: "DateUTC" path: "0*1(\Segment\Info\DateUTC)" id: "0x4461" maxOccurs: "1" type: "date" definition: The date and time that the Segment was created by the muxing application or library. 9.3.2.12. Title Element name: "Title" path: "0*1(\Segment\Info\Title)" id: "0x7BA9" maxOccurs: "1" type: "utf-8" definition: General name of the Segment. 9.3.2.13. MuxingApp Element name: "MuxingApp" path: "1*1(\Segment\Info\MuxingApp)" id: "0x4D80" minOccurs: "1" maxOccurs: "1" type: "utf-8" definition: Muxing application or library (example: "libmatroska- 0.4.3"). Lhomme, et al. Expires 29 April 2020 [Page 32] Internet-Draft Matroska October 2019 usage notes: Include the full name of the application or library followed by the version number. 9.3.2.14. WritingApp Element name: "WritingApp" path: "1*1(\Segment\Info\WritingApp)" id: "0x5741" minOccurs: "1" maxOccurs: "1" type: "utf-8" definition: Writing application (example: "mkvmerge-0.3.3"). usage notes: Include the full name of the application followed by the version number. 9.3.3. Cluster Element name: "Cluster" path: "0*(\Segment\Cluster)" id: "0x1F43B675" type: "master" unknownsizeallowed: "1" definition: The Top-Level Element containing the (monolithic) Block structure. 9.3.3.1. Timestamp Element name: "Timestamp" path: "1*1(\Segment\Cluster\Timestamp)" id: "0xE7" minOccurs: "1" maxOccurs: "1" Lhomme, et al. Expires 29 April 2020 [Page 33] Internet-Draft Matroska October 2019 type: "uinteger" definition: Absolute timestamp of the cluster (based on TimestampScale). 9.3.3.2. SilentTracks Element name: "SilentTracks" path: "0*1(\Segment\Cluster\SilentTracks)" id: "0x5854" maxOccurs: "1" type: "master" definition: The list of tracks that are not used in that part of the stream. It is useful when using overlay tracks on seeking or to decide what track to use. 9.3.3.2.1. SilentTrackNumber Element name: "SilentTrackNumber" path: "0*(\Segment\Cluster\SilentTracks\SilentTrackNumber)" id: "0x58D7" type: "uinteger" definition: 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. 9.3.3.3. Position Element name: "Position" path: "0*1(\Segment\Cluster\Position)" id: "0xA7" maxOccurs: "1" type: "uinteger" Lhomme, et al. Expires 29 April 2020 [Page 34] Internet-Draft Matroska October 2019 definition: The Segment Position of the Cluster in the Segment (0 in live streams). It might help to resynchronise offset on damaged streams. 9.3.3.4. PrevSize Element name: "PrevSize" path: "0*1(\Segment\Cluster\PrevSize)" id: "0xAB" maxOccurs: "1" type: "uinteger" definition: Size of the previous Cluster, in octets. Can be useful for backward playing. 9.3.3.5. SimpleBlock Element name: "SimpleBlock" path: "0*(\Segment\Cluster\SimpleBlock)" id: "0xA3" type: "binary" minver: "2" definition: Similar to Block but without all the extra information, mostly used to reduced overhead when no extra feature is needed. (see SimpleBlock Structure) 9.3.3.6. BlockGroup Element name: "BlockGroup" path: "0*(\Segment\Cluster\BlockGroup)" id: "0xA0" type: "master" definition: Basic container of information containing a single Block and information specific to that Block. Lhomme, et al. Expires 29 April 2020 [Page 35] Internet-Draft Matroska October 2019 9.3.3.6.1. Block Element name: "Block" path: "1*1(\Segment\Cluster\BlockGroup\Block)" id: "0xA1" minOccurs: "1" maxOccurs: "1" type: "binary" definition: Block containing the actual data to be rendered and a timestamp relative to the Cluster Timestamp. (see Block Structure) 9.3.3.6.2. BlockVirtual Element name: "BlockVirtual" path: "0*1(\Segment\Cluster\BlockGroup\BlockVirtual)" id: "0xA2" maxOccurs: "1" type: "binary" minver: "0" maxver: "0" definition: A Block with no data. It MUST be stored in the stream at the place the real Block would be in display order. (see Block Virtual) 9.3.3.6.3. BlockAdditions Element name: "BlockAdditions" path: "0*1(\Segment\Cluster\BlockGroup\BlockAdditions)" id: "0x75A1" maxOccurs: "1" type: "master" Lhomme, et al. Expires 29 April 2020 [Page 36] Internet-Draft Matroska October 2019 definition: Contain additional blocks to complete the main one. An EBML parser that has no knowledge of the Block structure could still see and use/skip these data. 9.3.3.6.3.1. BlockMore Element name: "BlockMore" path: "1*(\Segment\Cluster\BlockGroup\BlockAdditions\BlockMore)" id: "0xA6" minOccurs: "1" type: "master" definition: Contain the BlockAdditional and some parameters. 9.3.3.6.3.2. BlockAddID Element name: "BlockAddID" path: "1*1(\Segment\Cluster\BlockGroup\BlockAdditions\BlockMore\Block AddID)" id: "0xEE" minOccurs: "1" maxOccurs: "1" range: "not 0" default: "1" type: "uinteger" definition: An ID to identify the BlockAdditional level. A value of 1 means the BlockAdditional data is interpreted as additional data passed to the codec with the Block data. 9.3.3.6.3.3. BlockAdditional Element name: "BlockAdditional" path: "1*1(\Segment\Cluster\BlockGroup\BlockAdditions\BlockMore\Block Additional)" Lhomme, et al. Expires 29 April 2020 [Page 37] Internet-Draft Matroska October 2019 id: "0xA5" minOccurs: "1" maxOccurs: "1" type: "binary" definition: Interpreted by the codec as it wishes (using the BlockAddID). 9.3.3.6.4. BlockDuration Element name: "BlockDuration" path: "0*1(\Segment\Cluster\BlockGroup\BlockDuration)" id: "0x9B" minOccurs: see implementation notes maxOccurs: "1" default: see implementation notes type: "uinteger" definition: The duration of the Block (based on TimestampScale). 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. implementation notes: Lhomme, et al. Expires 29 April 2020 [Page 38] Internet-Draft Matroska October 2019 +-----------+---------------------------------------------------+ | 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 11 9.3.3.6.5. ReferencePriority Element name: "ReferencePriority" path: "1*1(\Segment\Cluster\BlockGroup\ReferencePriority)" id: "0xFA" minOccurs: "1" maxOccurs: "1" default: "0" type: "uinteger" definition: This frame is referenced and has the specified cache 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. 9.3.3.6.6. ReferenceBlock Element name: "ReferenceBlock" path: "0*(\Segment\Cluster\BlockGroup\ReferenceBlock)" id: "0xFB" type: "integer" definition: Timestamp of another frame used as a reference (ie: B or P frame). The timestamp is relative to the block it's attached to. Lhomme, et al. Expires 29 April 2020 [Page 39] Internet-Draft Matroska October 2019 9.3.3.6.7. ReferenceVirtual Element name: "ReferenceVirtual" path: "0*1(\Segment\Cluster\BlockGroup\ReferenceVirtual)" id: "0xFD" maxOccurs: "1" type: "integer" minver: "0" maxver: "0" definition: The Segment Position of the data that would otherwise be in position of the virtual block. 9.3.3.6.8. CodecState Element name: "CodecState" path: "0*1(\Segment\Cluster\BlockGroup\CodecState)" id: "0xA4" maxOccurs: "1" type: "binary" 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. 9.3.3.6.9. DiscardPadding Element name: "DiscardPadding" path: "0*1(\Segment\Cluster\BlockGroup\DiscardPadding)" id: "0x75A2" maxOccurs: "1" type: "integer" Lhomme, et al. Expires 29 April 2020 [Page 40] Internet-Draft Matroska October 2019 minver: "4" definition: Duration in nanoseconds of the silent data added to the Block (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. 9.3.3.6.10. Slices Element name: "Slices" path: "0*1(\Segment\Cluster\BlockGroup\Slices)" id: "0x8E" maxOccurs: "1" type: "master" definition: Contains slices description. 9.3.3.6.10.1. TimeSlice Element name: "TimeSlice" path: "0*(\Segment\Cluster\BlockGroup\Slices\TimeSlice)" id: "0xE8" type: "master" maxver: "1" definition: Contains extra time information about the data contained in the Block. Being able to interpret this Element is not REQUIRED for playback. 9.3.3.6.10.2. LaceNumber Element name: "LaceNumber" path: "0*1(\Segment\Cluster\BlockGroup\Slices\TimeSlice\LaceNumber)" id: "0xCC" maxOccurs: "1" Lhomme, et al. Expires 29 April 2020 [Page 41] Internet-Draft Matroska October 2019 default: "0" type: "uinteger" maxver: "1" definition: 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. 9.3.3.6.10.3. FrameNumber Element name: "FrameNumber" path: "0*1(\Segment\Cluster\BlockGroup\Slices\TimeSlice\FrameNumber)" id: "0xCD" maxOccurs: "1" default: "0" type: "uinteger" minver: "0" maxver: "0" definition: The number of the frame to generate from this lace with this delay (allow you to generate many frames from the same Block/ Frame). 9.3.3.6.10.4. BlockAdditionID Element name: "BlockAdditionID" path: "0*1(\Segment\Cluster\BlockGroup\Slices\TimeSlice\BlockAdditionID)" id: "0xCB" maxOccurs: "1" default: "0" type: "uinteger" minver: "0" Lhomme, et al. Expires 29 April 2020 [Page 42] Internet-Draft Matroska October 2019 maxver: "0" definition: The ID of the BlockAdditional Element (0 is the main Block). 9.3.3.6.10.5. Delay Element name: "Delay" path: "0*1(\Segment\Cluster\BlockGroup\Slices\TimeSlice\Delay)" id: "0xCE" maxOccurs: "1" default: "0" type: "uinteger" minver: "0" maxver: "0" definition: The (scaled) delay to apply to the Element. 9.3.3.6.10.6. SliceDuration Element name: "SliceDuration" path: "0*1(\Segment\Cluster\BlockGroup\Slices\TimeSlice\SliceDuration)" id: "0xCF" maxOccurs: "1" default: "0" type: "uinteger" minver: "0" maxver: "0" definition: The (scaled) duration to apply to the Element. Lhomme, et al. Expires 29 April 2020 [Page 43] Internet-Draft Matroska October 2019 9.3.3.6.11. ReferenceFrame Element name: "ReferenceFrame" path: "0*1(\Segment\Cluster\BlockGroup\ReferenceFrame)" id: "0xC8" maxOccurs: "1" type: "master" minver: "0" maxver: "0" definition: DivX trick track extensions 9.3.3.6.11.1. ReferenceOffset Element name: "ReferenceOffset" path: "1*1(\Segment\Cluster\BlockGroup\ReferenceFrame\ReferenceOffset)" id: "0xC9" minOccurs: "1" maxOccurs: "1" type: "uinteger" minver: "0" maxver: "0" definition: DivX trick track extensions 9.3.3.6.11.2. ReferenceTimestamp Element name: "ReferenceTimestamp" path: "1*1(\Segment\Cluster\BlockGroup\ReferenceFrame\ReferenceTimestamp)" id: "0xCA" Lhomme, et al. Expires 29 April 2020 [Page 44] Internet-Draft Matroska October 2019 minOccurs: "1" maxOccurs: "1" type: "uinteger" minver: "0" maxver: "0" definition: DivX trick track extensions 9.3.3.7. EncryptedBlock Element name: "EncryptedBlock" path: "0*(\Segment\Cluster\EncryptedBlock)" id: "0xAF" type: "binary" minver: "0" maxver: "0" definition: Similar to SimpleBlock but the data inside the Block are Transformed (encrypt and/or signed). (see EncryptedBlock Structure) 9.3.4. Tracks Element name: "Tracks" path: "0*(\Segment\Tracks)" id: "0x1654AE6B" type: "master" recurring: "1" definition: A Top-Level Element of information with many tracks described. 9.3.4.1. TrackEntry Element name: "TrackEntry" Lhomme, et al. Expires 29 April 2020 [Page 45] Internet-Draft Matroska October 2019 path: "1*(\Segment\Tracks\TrackEntry)" id: "0xAE" minOccurs: "1" type: "master" definition: Describes a track with all Elements. 9.3.4.1.1. TrackNumber Element name: "TrackNumber" path: "1*1(\Segment\Tracks\TrackEntry\TrackNumber)" id: "0xD7" minOccurs: "1" maxOccurs: "1" range: "not 0" type: "uinteger" definition: The track number as used in the Block Header (using more than 127 tracks is not encouraged, though the design allows an unlimited number). 9.3.4.1.2. TrackUID Element name: "TrackUID" path: "1*1(\Segment\Tracks\TrackEntry\TrackUID)" id: "0x73C5" minOccurs: "1" maxOccurs: "1" range: "not 0" type: "uinteger" definition: A unique ID to identify the Track. This SHOULD be kept Lhomme, et al. Expires 29 April 2020 [Page 46] Internet-Draft Matroska October 2019 the same when making a direct stream copy of the Track to another file. 9.3.4.1.3. TrackType Element name: "TrackType" path: "1*1(\Segment\Tracks\TrackEntry\TrackType)" id: "0x83" minOccurs: "1" maxOccurs: "1" range: "1-254" type: "uinteger" definition: A set of track types coded on 8 bits. restrictions: +-------+----------+ | value | label | +=======+==========+ | "1" | video | +-------+----------+ | "2" | audio | +-------+----------+ | "3" | complex | +-------+----------+ | "16" | logo | +-------+----------+ | "17" | subtitle | +-------+----------+ | "18" | buttons | +-------+----------+ | "32" | control | +-------+----------+ | "33" | metadata | +-------+----------+ Table 12 Lhomme, et al. Expires 29 April 2020 [Page 47] Internet-Draft Matroska October 2019 9.3.4.1.4. FlagEnabled Element name: "FlagEnabled" path: "1*1(\Segment\Tracks\TrackEntry\FlagEnabled)" id: "0xB9" minOccurs: "1" maxOccurs: "1" range: "0-1" default: "1" type: "uinteger" minver: "2" definition: Set if the track is usable. (1 bit) 9.3.4.1.5. FlagDefault Element name: "FlagDefault" path: "1*1(\Segment\Tracks\TrackEntry\FlagDefault)" id: "0x88" minOccurs: "1" maxOccurs: "1" range: "0-1" default: "1" type: "uinteger" definition: Set if that track (audio, video or subs) SHOULD be active if no language found matches the user preference. (1 bit) 9.3.4.1.6. FlagForced Element name: "FlagForced" path: "1*1(\Segment\Tracks\TrackEntry\FlagForced)" Lhomme, et al. Expires 29 April 2020 [Page 48] Internet-Draft Matroska October 2019 id: "0x55AA" minOccurs: "1" maxOccurs: "1" range: "0-1" default: "0" type: "uinteger" definition: Set if that track MUST be active during playback. There can be many forced track for a kind (audio, video or subs), the player SHOULD select the one which language matches the user preference or the default + forced track. Overlay MAY happen between a forced and non-forced track of the same kind. (1 bit) 9.3.4.1.7. FlagLacing Element name: "FlagLacing" path: "1*1(\Segment\Tracks\TrackEntry\FlagLacing)" id: "0x9C" minOccurs: "1" maxOccurs: "1" range: "0-1" default: "1" type: "uinteger" definition: Set if the track MAY contain blocks using lacing. (1 bit) 9.3.4.1.8. MinCache Element name: "MinCache" path: "1*1(\Segment\Tracks\TrackEntry\MinCache)" id: "0x6DE7" minOccurs: "1" Lhomme, et al. Expires 29 April 2020 [Page 49] Internet-Draft Matroska October 2019 maxOccurs: "1" default: "0" type: "uinteger" definition: 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. 9.3.4.1.9. MaxCache Element name: "MaxCache" path: "0*1(\Segment\Tracks\TrackEntry\MaxCache)" id: "0x6DF8" maxOccurs: "1" type: "uinteger" definition: The maximum cache size necessary to store referenced frames in and the current frame. 0 means no cache is needed. 9.3.4.1.10. DefaultDuration Element name: "DefaultDuration" path: "0*1(\Segment\Tracks\TrackEntry\DefaultDuration)" id: "0x23E383" maxOccurs: "1" range: "not 0" type: "uinteger" definition: Number of nanoseconds (not scaled via TimestampScale) per frame ('frame' in the Matroska sense -- one Element put into a (Simple)Block). 9.3.4.1.11. DefaultDecodedFieldDuration Element name: "DefaultDecodedFieldDuration" path: "0*1(\Segment\Tracks\TrackEntry\DefaultDecodedFieldDuration)" Lhomme, et al. Expires 29 April 2020 [Page 50] Internet-Draft Matroska October 2019 id: "0x234E7A" maxOccurs: "1" range: "not 0" type: "uinteger" minver: "4" definition: The period in nanoseconds (not scaled by TimestampScale) between two successive fields at the output of the decoding process (see the notes) 9.3.4.1.12. TrackTimestampScale Element name: "TrackTimestampScale" path: "1*1(\Segment\Tracks\TrackEntry\TrackTimestampScale)" id: "0x23314F" minOccurs: "1" maxOccurs: "1" range: "> 0x0p+0" default: "0x1p+0" type: "float" maxver: "3" definition: DEPRECATED, DO NOT USE. 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). 9.3.4.1.13. TrackOffset Element name: "TrackOffset" path: "0*1(\Segment\Tracks\TrackEntry\TrackOffset)" id: "0x537F" maxOccurs: "1" Lhomme, et al. Expires 29 April 2020 [Page 51] Internet-Draft Matroska October 2019 default: "0" type: "integer" minver: "0" maxver: "0" definition: A value to add to the Block's Timestamp. This can be used to adjust the playback offset of a track. 9.3.4.1.14. MaxBlockAdditionID Element name: "MaxBlockAdditionID" path: "1*1(\Segment\Tracks\TrackEntry\MaxBlockAdditionID)" id: "0x55EE" minOccurs: "1" maxOccurs: "1" default: "0" type: "uinteger" definition: The maximum value of BlockAddID. A value 0 means there is no BlockAdditions for this track. 9.3.4.1.15. BlockAdditionMapping Element name: "BlockAdditionMapping" path: "0*(\Segment\Tracks\TrackEntry\BlockAdditionMapping)" id: "0x41E4" type: "master" minver: "4" definition: Contains elements that describe each value of BlockAddID found in the Track. Lhomme, et al. Expires 29 April 2020 [Page 52] Internet-Draft Matroska October 2019 9.3.4.1.15.1. BlockAddIDValue Element name: "BlockAddIDValue" path: "1*1(\Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddID Value)" id: "0x41F0" minOccurs: "1" maxOccurs: "1" range: ">=2" type: "uinteger" minver: "4" definition: The BlockAddID value being described. To keep MaxBlockAdditionID as low as possible, small values SHOULD be used. 9.3.4.1.15.2. BlockAddIDName Element name: "BlockAddIDName" path: "0*1(\Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDName)" id: "0x41A4" maxOccurs: "1" type: "string" minver: "4" definition: A human-friendly name describing the type of BlockAdditional data as defined by the associated Block Additional Mapping. 9.3.4.1.15.3. BlockAddIDType Element name: "BlockAddIDType" path: "1*1(\Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDType)" Lhomme, et al. Expires 29 April 2020 [Page 53] Internet-Draft Matroska October 2019 id: "0x41E7" minOccurs: "1" maxOccurs: "1" default: "0" type: "uinteger" minver: "4" definition: Stores the registered identifer of the Block Additional Mapping to define how the BlockAdditional data should be handled. 9.3.4.1.15.4. BlockAddIDExtraData Element name: "BlockAddIDExtraData" path: "0*1(\Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddID ExtraData)" id: "0x41E7" maxOccurs: "1" type: "binary" minver: "4" definition: Extra binary data that the BlockAddIDType can use to interpret the BlockAdditional data. The intepretation of the binary data depends on the BlockAddIDType value and the corresponding Block Additional Mapping. 9.3.4.1.16. Name Element name: "Name" path: "0*1(\Segment\Tracks\TrackEntry\Name)" id: "0x536E" maxOccurs: "1" type: "utf-8" definition: A human-readable track name. Lhomme, et al. Expires 29 April 2020 [Page 54] Internet-Draft Matroska October 2019 9.3.4.1.17. Language Element name: "Language" path: "0*1(\Segment\Tracks\TrackEntry\Language)" id: "0x22B59C" maxOccurs: "1" default: "eng" type: "string" definition: Specifies the language of the track in the Matroska languages form. This Element MUST be ignored if the LanguageIETF Element is used in the same TrackEntry. 9.3.4.1.18. LanguageIETF Element name: "LanguageIETF" path: "0*1(\Segment\Tracks\TrackEntry\LanguageIETF)" id: "0x22B59D" maxOccurs: "1" type: "string" minver: "4" definition: Specifies the language of the track according to BCP 47 and using the IANA Language Subtag Registry. If this Element is used, then any Language Elements used in the same TrackEntry MUST be ignored. 9.3.4.1.19. CodecID Element name: "CodecID" path: "1*1(\Segment\Tracks\TrackEntry\CodecID)" id: "0x86" minOccurs: "1" maxOccurs: "1" Lhomme, et al. Expires 29 April 2020 [Page 55] Internet-Draft Matroska October 2019 type: "string" definition: An ID corresponding to the codec, see the codec page for more info. 9.3.4.1.20. CodecPrivate Element name: "CodecPrivate" path: "0*1(\Segment\Tracks\TrackEntry\CodecPrivate)" id: "0x63A2" maxOccurs: "1" type: "binary" definition: Private data only known to the codec. 9.3.4.1.21. CodecName Element name: "CodecName" path: "0*1(\Segment\Tracks\TrackEntry\CodecName)" id: "0x258688" maxOccurs: "1" type: "utf-8" definition: A human-readable string specifying the codec. 9.3.4.1.22. AttachmentLink Element name: "AttachmentLink" path: "0*1(\Segment\Tracks\TrackEntry\AttachmentLink)" id: "0x7446" maxOccurs: "1" range: "not 0" type: "uinteger" maxver: "3" Lhomme, et al. Expires 29 April 2020 [Page 56] Internet-Draft Matroska October 2019 definition: The UID of an attachment that is used by this codec. 9.3.4.1.23. CodecSettings Element name: "CodecSettings" path: "0*1(\Segment\Tracks\TrackEntry\CodecSettings)" id: "0x3A9697" maxOccurs: "1" type: "utf-8" minver: "0" maxver: "0" definition: A string describing the encoding setting used. 9.3.4.1.24. CodecInfoURL Element name: "CodecInfoURL" path: "0*(\Segment\Tracks\TrackEntry\CodecInfoURL)" id: "0x3B4040" type: "string" minver: "0" maxver: "0" definition: A URL to find information about the codec used. 9.3.4.1.25. CodecDownloadURL Element name: "CodecDownloadURL" path: "0*(\Segment\Tracks\TrackEntry\CodecDownloadURL)" id: "0x26B240" type: "string" minver: "0" Lhomme, et al. Expires 29 April 2020 [Page 57] Internet-Draft Matroska October 2019 maxver: "0" definition: A URL to download about the codec used. 9.3.4.1.26. CodecDecodeAll Element name: "CodecDecodeAll" path: "1*1(\Segment\Tracks\TrackEntry\CodecDecodeAll)" id: "0xAA" minOccurs: "1" maxOccurs: "1" range: "0-1" default: "1" type: "uinteger" minver: "2" definition: The codec can decode potentially damaged data (1 bit). 9.3.4.1.27. TrackOverlay Element name: "TrackOverlay" path: "0*(\Segment\Tracks\TrackEntry\TrackOverlay)" id: "0x6FAB" type: "uinteger" definition: Specify that this track is an overlay track for the Track specified (in the u-integer). That means when this track has a gap (see 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. 9.3.4.1.28. CodecDelay Element name: "CodecDelay" path: "0*1(\Segment\Tracks\TrackEntry\CodecDelay)" Lhomme, et al. Expires 29 April 2020 [Page 58] Internet-Draft Matroska October 2019 id: "0x56AA" maxOccurs: "1" default: "0" type: "uinteger" minver: "4" definition: CodecDelay is The codec-built-in delay in nanoseconds. This value MUST be subtracted from each block timestamp in order to get the actual timestamp. The value SHOULD be small so the muxing of tracks with the same actual timestamp are in the same Cluster. 9.3.4.1.29. SeekPreRoll Element name: "SeekPreRoll" path: "1*1(\Segment\Tracks\TrackEntry\SeekPreRoll)" id: "0x56BB" minOccurs: "1" maxOccurs: "1" default: "0" type: "uinteger" minver: "4" definition: After a discontinuity, SeekPreRoll is the duration in nanoseconds of the data the decoder MUST decode before the decoded data is valid. 9.3.4.1.30. TrackTranslate Element name: "TrackTranslate" path: "0*(\Segment\Tracks\TrackEntry\TrackTranslate)" id: "0x6624" type: "master" definition: The track identification for the given Chapter Codec. Lhomme, et al. Expires 29 April 2020 [Page 59] Internet-Draft Matroska October 2019 9.3.4.1.30.1. TrackTranslateEditionUID Element name: "TrackTranslateEditionUID" path: "0*(\Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateEdi tionUID)" id: "0x66FC" type: "uinteger" definition: Specify an edition UID on which this translation applies. When not specified, it means for all editions found in the Segment. 9.3.4.1.30.2. TrackTranslateCodec Element name: "TrackTranslateCodec" path: "1*1(\Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateCodec)" id: "0x66BF" minOccurs: "1" maxOccurs: "1" type: "uinteger" definition: The chapter codec. restrictions: +-------+-----------------+ | value | label | +=======+=================+ | "0" | Matroska Script | +-------+-----------------+ | "1" | DVD-menu | +-------+-----------------+ Table 13 9.3.4.1.30.3. TrackTranslateTrackID Element name: "TrackTranslateTrackID" Lhomme, et al. Expires 29 April 2020 [Page 60] Internet-Draft Matroska October 2019 path: "1*1(\Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateTr ackID)" id: "0x66A5" minOccurs: "1" maxOccurs: "1" type: "binary" definition: The binary value used to represent this track in the chapter codec data. The format depends on the ChapProcessCodecID used. 9.3.4.1.31. Video Element name: "Video" path: "0*1(\Segment\Tracks\TrackEntry\Video)" id: "0xE0" maxOccurs: "1" type: "master" definition: Video settings. 9.3.4.1.31.1. FlagInterlaced Element name: "FlagInterlaced" path: "1*1(\Segment\Tracks\TrackEntry\Video\FlagInterlaced)" id: "0x9A" minOccurs: "1" maxOccurs: "1" range: "0-2" default: "0" type: "uinteger" minver: "2" Lhomme, et al. Expires 29 April 2020 [Page 61] Internet-Draft Matroska October 2019 definition: A flag to declare if the video is known to be progressive or interlaced and if applicable to declare details about the interlacement. restrictions: +-------+--------------+ | value | label | +=======+==============+ | "0" | undetermined | +-------+--------------+ | "1" | interlaced | +-------+--------------+ | "2" | progressive | +-------+--------------+ Table 14 9.3.4.1.31.2. FieldOrder Element name: "FieldOrder" path: "1*1(\Segment\Tracks\TrackEntry\Video\FieldOrder)" id: "0x9D" minOccurs: "1" maxOccurs: "1" range: "0-14" default: "2" type: "uinteger" minver: "4" definition: Declare the field ordering of the video. If FlagInterlaced is not set to 1, this Element MUST be ignored. restrictions: Lhomme, et al. Expires 29 April 2020 [Page 62] Internet-Draft Matroska October 2019 +-------+--------------+-----------------------------------------+ | value | label | documentation | +=======+==============+=========================================+ | "0" | progressive | | +-------+--------------+-----------------------------------------+ | "1" | tff | Top field displayed first. Top field | | | | stored first. | +-------+--------------+-----------------------------------------+ | "2" | undetermined | | +-------+--------------+-----------------------------------------+ | "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 15 9.3.4.1.31.3. StereoMode Element name: "StereoMode" path: "0*1(\Segment\Tracks\TrackEntry\Video\StereoMode)" id: "0x53B8" maxOccurs: "1" default: "0" type: "uinteger" minver: "3" definition: Stereo-3D video mode. There are some more details on 3D support in the Specification Notes. restrictions: Lhomme, et al. Expires 29 April 2020 [Page 63] Internet-Draft Matroska October 2019 +-------+---------------------------------------------------+ | 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 16 9.3.4.1.31.4. AlphaMode Element name: "AlphaMode" path: "0*1(\Segment\Tracks\TrackEntry\Video\AlphaMode)" id: "0x53C0" maxOccurs: "1" default: "0" Lhomme, et al. Expires 29 April 2020 [Page 64] Internet-Draft Matroska October 2019 type: "uinteger" minver: "3" definition: Alpha Video Mode. Presence of this Element indicates that the BlockAdditional Element could contain Alpha data. 9.3.4.1.31.5. OldStereoMode Element name: "OldStereoMode" path: "0*1(\Segment\Tracks\TrackEntry\Video\OldStereoMode)" id: "0x53B9" maxOccurs: "1" type: "uinteger" maxver: "0" definition: DEPRECATED, DO NOT USE. Bogus StereoMode value used in old versions of libmatroska. restrictions: +-------+-----------+ | value | label | +=======+===========+ | "0" | mono | +-------+-----------+ | "1" | right eye | +-------+-----------+ | "2" | left eye | +-------+-----------+ | "3" | both eyes | +-------+-----------+ Table 17 9.3.4.1.31.6. PixelWidth Element name: "PixelWidth" path: "1*1(\Segment\Tracks\TrackEntry\Video\PixelWidth)" id: "0xB0" Lhomme, et al. Expires 29 April 2020 [Page 65] Internet-Draft Matroska October 2019 minOccurs: "1" maxOccurs: "1" range: "not 0" type: "uinteger" definition: Width of the encoded video frames in pixels. 9.3.4.1.31.7. PixelHeight Element name: "PixelHeight" path: "1*1(\Segment\Tracks\TrackEntry\Video\PixelHeight)" id: "0xBA" minOccurs: "1" maxOccurs: "1" range: "not 0" type: "uinteger" definition: Height of the encoded video frames in pixels. 9.3.4.1.31.8. PixelCropBottom Element name: "PixelCropBottom" path: "0*1(\Segment\Tracks\TrackEntry\Video\PixelCropBottom)" id: "0x54AA" maxOccurs: "1" default: "0" type: "uinteger" definition: The number of video pixels to remove at the bottom of the image. Lhomme, et al. Expires 29 April 2020 [Page 66] Internet-Draft Matroska October 2019 9.3.4.1.31.9. PixelCropTop Element name: "PixelCropTop" path: "0*1(\Segment\Tracks\TrackEntry\Video\PixelCropTop)" id: "0x54BB" maxOccurs: "1" default: "0" type: "uinteger" definition: The number of video pixels to remove at the top of the image. 9.3.4.1.31.10. PixelCropLeft Element name: "PixelCropLeft" path: "0*1(\Segment\Tracks\TrackEntry\Video\PixelCropLeft)" id: "0x54CC" maxOccurs: "1" default: "0" type: "uinteger" definition: The number of video pixels to remove on the left of the image. 9.3.4.1.31.11. PixelCropRight Element name: "PixelCropRight" path: "0*1(\Segment\Tracks\TrackEntry\Video\PixelCropRight)" id: "0x54DD" maxOccurs: "1" default: "0" type: "uinteger" Lhomme, et al. Expires 29 April 2020 [Page 67] Internet-Draft Matroska October 2019 definition: The number of video pixels to remove on the right of the image. 9.3.4.1.31.12. DisplayWidth Element name: "DisplayWidth" path: "0*1(\Segment\Tracks\TrackEntry\Video\DisplayWidth)" id: "0x54B0" maxOccurs: "1" range: "not 0" default: see implementation notes type: "uinteger" definition: Width of the video frames to display. Applies to the video frame after cropping (PixelCrop* Elements). implementation notes: +-----------+-------------------------------------------------+ | attribute | note | +===========+=================================================+ | default | If the DisplayUnit of the same TrackEntry is 0, | | | then the default value for DisplayWidth is | | | equal to PixelWidth - PixelCropLeft - | | | PixelCropRight, else there is no default value. | +-----------+-------------------------------------------------+ Table 18 9.3.4.1.31.13. DisplayHeight Element name: "DisplayHeight" path: "0*1(\Segment\Tracks\TrackEntry\Video\DisplayHeight)" id: "0x54BA" maxOccurs: "1" range: "not 0" default: see implementation notes Lhomme, et al. Expires 29 April 2020 [Page 68] Internet-Draft Matroska October 2019 type: "uinteger" definition: Height of the video frames to display. Applies to the video frame after cropping (PixelCrop* Elements). implementation notes: +-----------+--------------------------------------------------+ | attribute | note | +===========+==================================================+ | default | If the DisplayUnit of the same TrackEntry is 0, | | | then the default value for DisplayHeight is | | | equal to PixelHeight - PixelCropTop - | | | PixelCropBottom, else there is no default value. | +-----------+--------------------------------------------------+ Table 19 9.3.4.1.31.14. DisplayUnit Element name: "DisplayUnit" path: "0*1(\Segment\Tracks\TrackEntry\Video\DisplayUnit)" id: "0x54B2" maxOccurs: "1" default: "0" type: "uinteger" definition: How DisplayWidth & DisplayHeight are interpreted. restrictions: Lhomme, et al. Expires 29 April 2020 [Page 69] Internet-Draft Matroska October 2019 +-------+----------------------+ | value | label | +=======+======================+ | "0" | pixels | +-------+----------------------+ | "1" | centimeters | +-------+----------------------+ | "2" | inches | +-------+----------------------+ | "3" | display aspect ratio | +-------+----------------------+ | "4" | unknown | +-------+----------------------+ Table 20 9.3.4.1.31.15. AspectRatioType Element name: "AspectRatioType" path: "0*1(\Segment\Tracks\TrackEntry\Video\AspectRatioType)" id: "0x54B3" maxOccurs: "1" default: "0" type: "uinteger" definition: Specify the possible modifications to the aspect ratio. restrictions: +-------+-------------------+ | value | label | +=======+===================+ | "0" | free resizing | +-------+-------------------+ | "1" | keep aspect ratio | +-------+-------------------+ | "2" | fixed | +-------+-------------------+ Table 21 Lhomme, et al. Expires 29 April 2020 [Page 70] Internet-Draft Matroska October 2019 9.3.4.1.31.16. ColourSpace Element name: "ColourSpace" path: "0*1(\Segment\Tracks\TrackEntry\Video\ColourSpace)" id: "0x2EB524" minOccurs: see implementation notes maxOccurs: "1" type: "binary" definition: Specify the pixel format used for the Track's data as a FourCC. This value is similar in scope to the biCompression value of AVI's BITMAPINFOHEADER. implementation notes: +-----------+--------------------------------------------+ | attribute | note | +===========+============================================+ | minOccurs | ColourSpace MUST be set (minOccurs=1) in | | | TrackEntry when the CodecID Element of the | | | TrackEntry is set to "V_UNCOMPRESSED". | +-----------+--------------------------------------------+ Table 22 9.3.4.1.31.17. GammaValue Element name: "GammaValue" path: "0*1(\Segment\Tracks\TrackEntry\Video\GammaValue)" id: "0x2FB523" maxOccurs: "1" range: "> 0x0p+0" type: "float" minver: "0" maxver: "0" Lhomme, et al. Expires 29 April 2020 [Page 71] Internet-Draft Matroska October 2019 definition: Gamma Value. 9.3.4.1.31.18. FrameRate Element name: "FrameRate" path: "0*1(\Segment\Tracks\TrackEntry\Video\FrameRate)" id: "0x2383E3" maxOccurs: "1" range: "> 0x0p+0" type: "float" minver: "0" maxver: "0" definition: Number of frames per second. Informational only. 9.3.4.1.31.19. Colour Element name: "Colour" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour)" id: "0x55B0" maxOccurs: "1" type: "master" minver: "4" definition: Settings describing the colour format. 9.3.4.1.31.20. MatrixCoefficients Element name: "MatrixCoefficients" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MatrixCoefficients)" id: "0x55B1" maxOccurs: "1" Lhomme, et al. Expires 29 April 2020 [Page 72] Internet-Draft Matroska October 2019 default: "2" type: "uinteger" 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 ISO/IEC 23001-8:2016 or ITU-T H.273. restrictions: +-------+---------------------------------------+ | 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 23 Lhomme, et al. Expires 29 April 2020 [Page 73] Internet-Draft Matroska October 2019 9.3.4.1.31.21. BitsPerChannel Element name: "BitsPerChannel" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\BitsPerChannel)" id: "0x55B2" maxOccurs: "1" default: "0" type: "uinteger" minver: "4" definition: Number of decoded bits per channel. A value of 0 indicates that the BitsPerChannel is unspecified. 9.3.4.1.31.22. ChromaSubsamplingHorz Element name: "ChromaSubsamplingHorz" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\ChromaSubsamplingHorz)" id: "0x55B3" maxOccurs: "1" type: "uinteger" 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. 9.3.4.1.31.23. ChromaSubsamplingVert Element name: "ChromaSubsamplingVert" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\ChromaSubsamplingVert)" id: "0x55B4" Lhomme, et al. Expires 29 April 2020 [Page 74] Internet-Draft Matroska October 2019 maxOccurs: "1" type: "uinteger" 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. 9.3.4.1.31.24. CbSubsamplingHorz Element name: "CbSubsamplingHorz" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\CbSubsamplingHorz)" id: "0x55B5" maxOccurs: "1" type: "uinteger" 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. 9.3.4.1.31.25. CbSubsamplingVert Element name: "CbSubsamplingVert" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\CbSubsamplingVert)" id: "0x55B6" maxOccurs: "1" type: "uinteger" minver: "4" Lhomme, et al. Expires 29 April 2020 [Page 75] Internet-Draft Matroska October 2019 definition: The amount of pixels to remove in the Cb channel for every pixel not removed vertically. This is additive with ChromaSubsamplingVert. 9.3.4.1.31.26. ChromaSitingHorz Element name: "ChromaSitingHorz" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\ChromaSitingHorz)" id: "0x55B7" maxOccurs: "1" default: "0" type: "uinteger" minver: "4" definition: How chroma is subsampled horizontally. restrictions: +-------+-----------------+ | value | label | +=======+=================+ | "0" | unspecified | +-------+-----------------+ | "1" | left collocated | +-------+-----------------+ | "2" | half | +-------+-----------------+ Table 24 9.3.4.1.31.27. ChromaSitingVert Element name: "ChromaSitingVert" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\ChromaSitingVert)" id: "0x55B8" maxOccurs: "1" default: "0" Lhomme, et al. Expires 29 April 2020 [Page 76] Internet-Draft Matroska October 2019 type: "uinteger" minver: "4" definition: How chroma is subsampled vertically. restrictions: +-------+----------------+ | value | label | +=======+================+ | "0" | unspecified | +-------+----------------+ | "1" | top collocated | +-------+----------------+ | "2" | half | +-------+----------------+ Table 25 9.3.4.1.31.28. Range Element name: "Range" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\Range)" id: "0x55B9" maxOccurs: "1" default: "0" type: "uinteger" minver: "4" definition: Clipping of the color ranges. restrictions: Lhomme, et al. Expires 29 April 2020 [Page 77] Internet-Draft Matroska October 2019 +-------+-------------------------------------------------------+ | value | label | +=======+=======================================================+ | "0" | unspecified | +-------+-------------------------------------------------------+ | "1" | broadcast range | +-------+-------------------------------------------------------+ | "2" | full range (no clipping) | +-------+-------------------------------------------------------+ | "3" | defined by MatrixCoefficients/TransferCharacteristics | +-------+-------------------------------------------------------+ Table 26 9.3.4.1.31.29. TransferCharacteristics Element name: "TransferCharacteristics" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\TransferCharacteri stics)" id: "0x55BA" maxOccurs: "1" default: "2" type: "uinteger" minver: "4" definition: The transfer characteristics of the video. For clarity, the value and meanings for TransferCharacteristics are adopted from Table 3 of ISO/IEC 23091-4 or ITU-T H.273. restrictions: Lhomme, et al. Expires 29 April 2020 [Page 78] Internet-Draft Matroska October 2019 +-------+---------------------------------------+ | value | label | +=======+=======================================+ | "0" | reserved | +-------+---------------------------------------+ | "1" | ITU-R BT.709 | +-------+---------------------------------------+ | "2" | unspecified | +-------+---------------------------------------+ | "3" | reserved | +-------+---------------------------------------+ | "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 27 9.3.4.1.31.30. Primaries Element name: "Primaries" Lhomme, et al. Expires 29 April 2020 [Page 79] Internet-Draft Matroska October 2019 path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\Primaries)" id: "0x55BB" maxOccurs: "1" default: "2" type: "uinteger" minver: "4" definition: The colour primaries of the video. For clarity, the value and meanings for Primaries are adopted from Table 2 of ISO/IEC 23091-4 or ITU-T H.273. restrictions: Lhomme, et al. Expires 29 April 2020 [Page 80] Internet-Draft Matroska October 2019 +-------+----------------------------------------+ | value | label | +=======+========================================+ | "0" | reserved | +-------+----------------------------------------+ | "1" | ITU-R BT.709 | +-------+----------------------------------------+ | "2" | unspecified | +-------+----------------------------------------+ | "3" | reserved | +-------+----------------------------------------+ | "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 28 9.3.4.1.31.31. MaxCLL Element name: "MaxCLL" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MaxCLL)" id: "0x55BC" maxOccurs: "1" type: "uinteger" minver: "4" Lhomme, et al. Expires 29 April 2020 [Page 81] Internet-Draft Matroska October 2019 definition: Maximum brightness of a single pixel (Maximum Content Light Level) in candelas per square meter (cd/m^2). 9.3.4.1.31.32. MaxFALL Element name: "MaxFALL" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MaxFALL)" id: "0x55BD" maxOccurs: "1" type: "uinteger" minver: "4" definition: Maximum brightness of a single full frame (Maximum Frame- Average Light Level) in candelas per square meter (cd/m^2). 9.3.4.1.31.33. MasteringMetadata Element name: "MasteringMetadata" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata)" id: "0x55D0" maxOccurs: "1" type: "master" minver: "4" definition: SMPTE 2086 mastering data. 9.3.4.1.31.34. PrimaryRChromaticityX Element name: "PrimaryRChromaticityX" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\ PrimaryRChromaticityX)" id: "0x55D1" maxOccurs: "1" Lhomme, et al. Expires 29 April 2020 [Page 82] Internet-Draft Matroska October 2019 range: "0-1" type: "float" minver: "4" definition: Red X chromaticity coordinate as defined by CIE 1931. 9.3.4.1.31.35. PrimaryRChromaticityY Element name: "PrimaryRChromaticityY" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\ PrimaryRChromaticityY)" id: "0x55D2" maxOccurs: "1" range: "0-1" type: "float" minver: "4" definition: Red Y chromaticity coordinate as defined by CIE 1931. 9.3.4.1.31.36. PrimaryGChromaticityX Element name: "PrimaryGChromaticityX" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\ PrimaryGChromaticityX)" id: "0x55D3" maxOccurs: "1" range: "0-1" type: "float" minver: "4" definition: Green X chromaticity coordinate as defined by CIE 1931. Lhomme, et al. Expires 29 April 2020 [Page 83] Internet-Draft Matroska October 2019 9.3.4.1.31.37. PrimaryGChromaticityY Element name: "PrimaryGChromaticityY" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\ PrimaryGChromaticityY)" id: "0x55D4" maxOccurs: "1" range: "0-1" type: "float" minver: "4" definition: Green Y chromaticity coordinate as defined by CIE 1931. 9.3.4.1.31.38. PrimaryBChromaticityX Element name: "PrimaryBChromaticityX" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\ PrimaryBChromaticityX)" id: "0x55D5" maxOccurs: "1" range: "0-1" type: "float" minver: "4" definition: Blue X chromaticity coordinate as defined by CIE 1931. 9.3.4.1.31.39. PrimaryBChromaticityY Element name: "PrimaryBChromaticityY" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\ PrimaryBChromaticityY)" id: "0x55D6" maxOccurs: "1" Lhomme, et al. Expires 29 April 2020 [Page 84] Internet-Draft Matroska October 2019 range: "0-1" type: "float" minver: "4" definition: Blue Y chromaticity coordinate as defined by CIE 1931. 9.3.4.1.31.40. WhitePointChromaticityX Element name: "WhitePointChromaticityX" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\ WhitePointChromaticityX)" id: "0x55D7" maxOccurs: "1" range: "0-1" type: "float" minver: "4" definition: White X chromaticity coordinate as defined by CIE 1931. 9.3.4.1.31.41. WhitePointChromaticityY Element name: "WhitePointChromaticityY" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\ WhitePointChromaticityY)" id: "0x55D8" maxOccurs: "1" range: "0-1" type: "float" minver: "4" definition: White Y chromaticity coordinate as defined by CIE 1931. Lhomme, et al. Expires 29 April 2020 [Page 85] Internet-Draft Matroska October 2019 9.3.4.1.31.42. LuminanceMax Element name: "LuminanceMax" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\ LuminanceMax)" id: "0x55D9" maxOccurs: "1" range: ">= 0x0p+0" type: "float" minver: "4" definition: Maximum luminance. Represented in candelas per square meter (cd/m^2). 9.3.4.1.31.43. LuminanceMin Element name: "LuminanceMin" path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\ LuminanceMin)" id: "0x55DA" maxOccurs: "1" range: ">= 0x0p+0" type: "float" minver: "4" definition: Minimum luminance. Represented in candelas per square meter (cd/m^2). 9.3.4.1.31.44. Projection Element name: "Projection" path: "0*1(\Segment\Tracks\TrackEntry\Video\Projection)" id: "0x7670" Lhomme, et al. Expires 29 April 2020 [Page 86] Internet-Draft Matroska October 2019 maxOccurs: "1" type: "master" minver: "4" definition: Describes the video projection details. Used to render spherical and VR videos. 9.3.4.1.31.45. ProjectionType Element name: "ProjectionType" path: "1*1(\Segment\Tracks\TrackEntry\Video\Projection\ProjectionType)" id: "0x7671" minOccurs: "1" maxOccurs: "1" range: "0-3" default: "0" type: "uinteger" minver: "4" definition: Describes the projection used for this video track. restrictions: +-------+-----------------+ | value | label | +=======+=================+ | "0" | rectangular | +-------+-----------------+ | "1" | equirectangular | +-------+-----------------+ | "2" | cubemap | +-------+-----------------+ | "3" | mesh | +-------+-----------------+ Table 29 Lhomme, et al. Expires 29 April 2020 [Page 87] Internet-Draft Matroska October 2019 9.3.4.1.31.46. ProjectionPrivate Element name: "ProjectionPrivate" path: "0*1(\Segment\Tracks\TrackEntry\Video\Projection\ProjectionPrivate)" id: "0x7672" maxOccurs: "1" type: "binary" minver: "4" definition: Private data that only applies to a specific projection.SemanticsIf 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').Note: 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. 9.3.4.1.31.47. ProjectionPoseYaw Element name: "ProjectionPoseYaw" path: "1*1(\Segment\Tracks\TrackEntry\Video\Projection\ProjectionPoseYaw)" id: "0x7673" minOccurs: "1" maxOccurs: "1" default: "0x0p+0" type: "float" Lhomme, et al. Expires 29 April 2020 [Page 88] Internet-Draft Matroska October 2019 minver: "4" definition: Specifies a yaw rotation to the projection.SemanticsValue 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 field should be in the -180 to 180 degree range. 9.3.4.1.31.48. ProjectionPosePitch Element name: "ProjectionPosePitch" path: "1*1(\Segment\Tracks\TrackEntry\Video\Projection\ProjectionPose Pitch)" id: "0x7674" minOccurs: "1" maxOccurs: "1" default: "0x0p+0" type: "float" minver: "4" definition: Specifies a pitch rotation to the projection.SemanticsValue 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 field should be in the -90 to 90 degree range. 9.3.4.1.31.49. ProjectionPoseRoll Element name: "ProjectionPoseRoll" path: "1*1(\Segment\Tracks\TrackEntry\Video\Projection\ProjectionPoseRoll)" id: "0x7675" minOccurs: "1" maxOccurs: "1" default: "0x0p+0" Lhomme, et al. Expires 29 April 2020 [Page 89] Internet-Draft Matroska October 2019 type: "float" minver: "4" definition: Specifies a roll rotation to the projection.SemanticsValue 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 field should be in the -180 to 180 degree range. 9.3.4.1.32. Audio Element name: "Audio" path: "0*1(\Segment\Tracks\TrackEntry\Audio)" id: "0xE1" maxOccurs: "1" type: "master" definition: Audio settings. 9.3.4.1.32.1. SamplingFrequency Element name: "SamplingFrequency" path: "1*1(\Segment\Tracks\TrackEntry\Audio\SamplingFrequency)" id: "0xB5" minOccurs: "1" maxOccurs: "1" range: "> 0x0p+0" default: "0x1.f4p+12" type: "float" definition: Sampling frequency in Hz. 9.3.4.1.32.2. OutputSamplingFrequency Element name: "OutputSamplingFrequency" Lhomme, et al. Expires 29 April 2020 [Page 90] Internet-Draft Matroska October 2019 path: "0*1(\Segment\Tracks\TrackEntry\Audio\OutputSamplingFrequency)" id: "0x78B5" maxOccurs: "1" range: "> 0x0p+0" default: see implementation notes type: "float" definition: Real output sampling frequency in Hz (used for SBR techniques). implementation notes: +-----------+------------------------------------------------------+ | attribute | note | +===========+======================================================+ | default | The default value for OutputSamplingFrequency of the | | | same TrackEntry is equal to the SamplingFrequency. | +-----------+------------------------------------------------------+ Table 30 9.3.4.1.32.3. Channels Element name: "Channels" path: "1*1(\Segment\Tracks\TrackEntry\Audio\Channels)" id: "0x9F" minOccurs: "1" maxOccurs: "1" range: "not 0" default: "1" type: "uinteger" definition: Numbers of channels in the track. Lhomme, et al. Expires 29 April 2020 [Page 91] Internet-Draft Matroska October 2019 9.3.4.1.32.4. ChannelPositions Element name: "ChannelPositions" path: "0*1(\Segment\Tracks\TrackEntry\Audio\ChannelPositions)" id: "0x7D7B" maxOccurs: "1" type: "binary" minver: "0" maxver: "0" definition: Table of horizontal angles for each successive channel, see appendix. 9.3.4.1.32.5. BitDepth Element name: "BitDepth" path: "0*1(\Segment\Tracks\TrackEntry\Audio\BitDepth)" id: "0x6264" maxOccurs: "1" range: "not 0" type: "uinteger" definition: Bits per sample, mostly used for PCM. 9.3.4.1.33. TrackOperation Element name: "TrackOperation" path: "0*1(\Segment\Tracks\TrackEntry\TrackOperation)" id: "0xE2" maxOccurs: "1" type: "master" minver: "3" Lhomme, et al. Expires 29 April 2020 [Page 92] Internet-Draft Matroska October 2019 definition: Operation that needs to be applied on tracks to create this virtual track. For more details look at the Specification Notes on the subject. 9.3.4.1.33.1. TrackCombinePlanes Element name: "TrackCombinePlanes" path: "0*1(\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes)" id: "0xE3" maxOccurs: "1" type: "master" minver: "3" definition: Contains the list of all video plane tracks that need to be combined to create this 3D track 9.3.4.1.33.2. TrackPlane Element name: "TrackPlane" path: "1*(\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlane s\TrackPlane)" id: "0xE4" minOccurs: "1" type: "master" minver: "3" definition: Contains a video plane track that need to be combined to create this 3D track 9.3.4.1.33.3. TrackPlaneUID Element name: "TrackPlaneUID" path: "1*1(\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlan es\TrackPlane\TrackPlaneUID)" id: "0xE5" Lhomme, et al. Expires 29 April 2020 [Page 93] Internet-Draft Matroska October 2019 minOccurs: "1" maxOccurs: "1" range: "not 0" type: "uinteger" minver: "3" definition: The trackUID number of the track representing the plane. 9.3.4.1.33.4. TrackPlaneType Element name: "TrackPlaneType" path: "1*1(\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlan es\TrackPlane\TrackPlaneType)" id: "0xE6" minOccurs: "1" maxOccurs: "1" type: "uinteger" minver: "3" definition: The kind of plane this track corresponds to. restrictions: +-------+------------+ | value | label | +=======+============+ | "0" | left eye | +-------+------------+ | "1" | right eye | +-------+------------+ | "2" | background | +-------+------------+ Table 31 Lhomme, et al. Expires 29 April 2020 [Page 94] Internet-Draft Matroska October 2019 9.3.4.1.33.5. TrackJoinBlocks Element name: "TrackJoinBlocks" path: "0*1(\Segment\Tracks\TrackEntry\TrackOperation\TrackJoinBlocks)" id: "0xE9" maxOccurs: "1" type: "master" minver: "3" definition: Contains the list of all tracks whose Blocks need to be combined to create this virtual track 9.3.4.1.33.6. TrackJoinUID Element name: "TrackJoinUID" path: "1*(\Segment\Tracks\TrackEntry\TrackOperation\TrackJoinBlocks\T rackJoinUID)" id: "0xED" minOccurs: "1" range: "not 0" type: "uinteger" minver: "3" definition: The trackUID number of a track whose blocks are used to create this virtual track. 9.3.4.1.34. TrickTrackUID Element name: "TrickTrackUID" path: "0*1(\Segment\Tracks\TrackEntry\TrickTrackUID)" id: "0xC0" maxOccurs: "1" Lhomme, et al. Expires 29 April 2020 [Page 95] Internet-Draft Matroska October 2019 type: "uinteger" minver: "0" maxver: "0" definition: DivX trick track extensions 9.3.4.1.35. TrickTrackSegmentUID Element name: "TrickTrackSegmentUID" path: "0*1(\Segment\Tracks\TrackEntry\TrickTrackSegmentUID)" id: "0xC1" maxOccurs: "1" type: "binary" minver: "0" maxver: "0" definition: DivX trick track extensions 9.3.4.1.36. TrickTrackFlag Element name: "TrickTrackFlag" path: "0*1(\Segment\Tracks\TrackEntry\TrickTrackFlag)" id: "0xC6" maxOccurs: "1" default: "0" type: "uinteger" minver: "0" maxver: "0" definition: DivX trick track extensions Lhomme, et al. Expires 29 April 2020 [Page 96] Internet-Draft Matroska October 2019 9.3.4.1.37. TrickMasterTrackUID Element name: "TrickMasterTrackUID" path: "0*1(\Segment\Tracks\TrackEntry\TrickMasterTrackUID)" id: "0xC7" maxOccurs: "1" type: "uinteger" minver: "0" maxver: "0" definition: DivX trick track extensions 9.3.4.1.38. TrickMasterTrackSegmentUID Element name: "TrickMasterTrackSegmentUID" path: "0*1(\Segment\Tracks\TrackEntry\TrickMasterTrackSegmentUID)" id: "0xC4" maxOccurs: "1" type: "binary" minver: "0" maxver: "0" definition: DivX trick track extensions 9.3.4.1.39. ContentEncodings Element name: "ContentEncodings" path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings)" id: "0x6D80" maxOccurs: "1" type: "master" Lhomme, et al. Expires 29 April 2020 [Page 97] Internet-Draft Matroska October 2019 definition: Settings for several content encoding mechanisms like compression or encryption. 9.3.4.1.39.1. ContentEncoding Element name: "ContentEncoding" path: "1*(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding)" id: "0x6240" minOccurs: "1" type: "master" definition: Settings for one content encoding like compression or encryption. 9.3.4.1.39.2. ContentEncodingOrder Element name: "ContentEncodingOrder" path: "1*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin g\ContentEncodingOrder)" id: "0x5031" minOccurs: "1" maxOccurs: "1" default: "0" type: "uinteger" definition: Tells when this modification was used during encoding/ muxing starting with 0 and counting upwards. The decoder/demuxer has to start with the highest order number it finds and work its way down. This value has to be unique over all ContentEncodingOrder Elements in the TrackEntry that contains this ContentEncodingOrder element. 9.3.4.1.39.3. ContentEncodingScope Element name: "ContentEncodingScope" Lhomme, et al. Expires 29 April 2020 [Page 98] Internet-Draft Matroska October 2019 path: "1*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin g\ContentEncodingScope)" id: "0x5032" minOccurs: "1" maxOccurs: "1" range: "not 0" default: "1" type: "uinteger" definition: A bit field that describes which Elements have been modified in this way. Values (big endian) can be OR'ed. restrictions: +-------+--------------------------------------------------+ | value | label | +=======+==================================================+ | "1" | All frame contents, excluding lacing data | +-------+--------------------------------------------------+ | "2" | The track's private data | +-------+--------------------------------------------------+ | "4" | The next ContentEncoding (next | | | "ContentEncodingOrder". Either the data inside | | | "ContentCompression" and/or "ContentEncryption") | +-------+--------------------------------------------------+ Table 32 9.3.4.1.39.4. ContentEncodingType Element name: "ContentEncodingType" path: "1*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin g\ContentEncodingType)" id: "0x5033" minOccurs: "1" maxOccurs: "1" default: "0" Lhomme, et al. Expires 29 April 2020 [Page 99] Internet-Draft Matroska October 2019 type: "uinteger" definition: A value describing what kind of transformation is applied. restrictions: +-------+-------------+ | value | label | +=======+=============+ | "0" | Compression | +-------+-------------+ | "1" | Encryption | +-------+-------------+ Table 33 9.3.4.1.39.5. ContentCompression Element name: "ContentCompression" path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin g\ContentCompression)" id: "0x5034" maxOccurs: "1" type: "master" 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. 9.3.4.1.39.6. ContentCompAlgo Element name: "ContentCompAlgo" path: "1*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin g\ContentCompression\ContentCompAlgo)" id: "0x4254" minOccurs: "1" maxOccurs: "1" Lhomme, et al. Expires 29 April 2020 [Page 100] Internet-Draft Matroska October 2019 default: "0" type: "uinteger" definition: The compression algorithm used. restrictions: +-------+------------------+ | value | label | +=======+==================+ | "0" | zlib | +-------+------------------+ | "1" | bzlib | +-------+------------------+ | "2" | lzo1x | +-------+------------------+ | "3" | Header Stripping | +-------+------------------+ Table 34 9.3.4.1.39.7. ContentCompSettings Element name: "ContentCompSettings" path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin g\ContentCompression\ContentCompSettings)" id: "0x4255" maxOccurs: "1" type: "binary" 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. 9.3.4.1.39.8. ContentEncryption Element name: "ContentEncryption" path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin g\ContentEncryption)" id: "0x5035" Lhomme, et al. Expires 29 April 2020 [Page 101] Internet-Draft Matroska October 2019 maxOccurs: "1" type: "master" definition: Settings describing the encryption used. This Element MUST be present if the value of "ContentEncodingType" is 1 (encryption) and MUST be ignored otherwise. 9.3.4.1.39.9. ContentEncAlgo Element name: "ContentEncAlgo" path: "1*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin g\ContentEncryption\ContentEncAlgo)" id: "0x47E1" minOccurs: "1" maxOccurs: "1" default: "0" type: "uinteger" definition: The encryption algorithm used. The value '0' means that the contents have not been encrypted but only signed. restrictions: +-------+-----------------------+ | value | label | +=======+=======================+ | "0" | Not encrypted | +-------+-----------------------+ | "1" | DES - FIPS 46-3 | +-------+-----------------------+ | "2" | Triple DES - RFC 1851 | +-------+-----------------------+ | "3" | Twofish | +-------+-----------------------+ | "4" | Blowfish | +-------+-----------------------+ | "5" | AES - FIPS 187 | +-------+-----------------------+ Table 35 Lhomme, et al. Expires 29 April 2020 [Page 102] Internet-Draft Matroska October 2019 9.3.4.1.39.10. ContentEncKeyID Element name: "ContentEncKeyID" path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin g\ContentEncryption\ContentEncKeyID)" id: "0x47E2" maxOccurs: "1" type: "binary" definition: For public key algorithms this is the ID of the public key the the data was encrypted with. 9.3.4.1.39.11. ContentEncAESSettings Element name: "ContentEncAESSettings" path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin g\ContentEncryption\ContentEncAESSettings)" id: "0x47E7" maxOccurs: "1" type: "master" minver: "4" definition: Settings describing the encryption algorithm used. If "ContentEncAlgo" != 5 this MUST be ignored. 9.3.4.1.39.12. AESSettingsCipherMode Element name: "AESSettingsCipherMode" path: "1*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin g\ContentEncryption\ContentEncAESSettings\AESSettingsCipherMode)" id: "0x47E8" minOccurs: "1" maxOccurs: "1" type: "uinteger" Lhomme, et al. Expires 29 April 2020 [Page 103] Internet-Draft Matroska October 2019 minver: "4" definition: The AES cipher mode used in the encryption. restrictions: +-------+--------------------------------------------------+ | value | label | +=======+==================================================+ | "1" | AES-CTR / Counter, NIST SP 800-38A | +-------+--------------------------------------------------+ | "2" | AES-CBC / Cipher Block Chaining, NIST SP 800-38A | +-------+--------------------------------------------------+ Table 36 9.3.4.1.39.13. ContentSignature Element name: "ContentSignature" path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin g\ContentEncryption\ContentSignature)" id: "0x47E3" maxOccurs: "1" type: "binary" definition: A cryptographic signature of the contents. 9.3.4.1.39.14. ContentSigKeyID Element name: "ContentSigKeyID" path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin g\ContentEncryption\ContentSigKeyID)" id: "0x47E4" maxOccurs: "1" type: "binary" definition: This is the ID of the private key the data was signed with. Lhomme, et al. Expires 29 April 2020 [Page 104] Internet-Draft Matroska October 2019 9.3.4.1.39.15. ContentSigAlgo Element name: "ContentSigAlgo" path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin g\ContentEncryption\ContentSigAlgo)" id: "0x47E5" maxOccurs: "1" default: "0" type: "uinteger" definition: The algorithm used for the signature. restrictions: +-------+------------+ | value | label | +=======+============+ | "0" | Not signed | +-------+------------+ | "1" | RSA | +-------+------------+ Table 37 9.3.4.1.39.16. ContentSigHashAlgo Element name: "ContentSigHashAlgo" path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin g\ContentEncryption\ContentSigHashAlgo)" id: "0x47E6" maxOccurs: "1" default: "0" type: "uinteger" definition: The hash algorithm used for the signature. restrictions: Lhomme, et al. Expires 29 April 2020 [Page 105] Internet-Draft Matroska October 2019 +-------+------------+ | value | label | +=======+============+ | "0" | Not signed | +-------+------------+ | "1" | SHA1-160 | +-------+------------+ | "2" | MD5 | +-------+------------+ Table 38 9.3.5. Cues Element name: "Cues" path: "0*1(\Segment\Cues)" id: "0x1C53BB6B" minOccurs: see implementation notes maxOccurs: "1" type: "master" definition: A Top-Level Element to speed seeking access. All entries are local to the Segment. implementation notes: +-----------+----------------------------------------------------+ | attribute | note | +===========+====================================================+ | minOccurs | This Element SHOULD be set when the Segment is not | | | transmitted as a live stream (see #livestreaming). | +-----------+----------------------------------------------------+ Table 39 9.3.5.1. CuePoint Element name: "CuePoint" path: "1*(\Segment\Cues\CuePoint)" id: "0xBB" Lhomme, et al. Expires 29 April 2020 [Page 106] Internet-Draft Matroska October 2019 minOccurs: "1" type: "master" definition: Contains all information relative to a seek point in the Segment. 9.3.5.1.1. CueTime Element name: "CueTime" path: "1*1(\Segment\Cues\CuePoint\CueTime)" id: "0xB3" minOccurs: "1" maxOccurs: "1" type: "uinteger" definition: Absolute timestamp according to the Segment time base. 9.3.5.1.2. CueTrackPositions Element name: "CueTrackPositions" path: "1*(\Segment\Cues\CuePoint\CueTrackPositions)" id: "0xB7" minOccurs: "1" type: "master" definition: Contain positions for different tracks corresponding to the timestamp. 9.3.5.1.2.1. CueTrack Element name: "CueTrack" path: "1*1(\Segment\Cues\CuePoint\CueTrackPositions\CueTrack)" id: "0xF7" minOccurs: "1" Lhomme, et al. Expires 29 April 2020 [Page 107] Internet-Draft Matroska October 2019 maxOccurs: "1" range: "not 0" type: "uinteger" definition: The track for which a position is given. 9.3.5.1.2.2. CueClusterPosition Element name: "CueClusterPosition" path: "1*1(\Segment\Cues\CuePoint\CueTrackPositions\CueClusterPosition)" id: "0xF1" minOccurs: "1" maxOccurs: "1" type: "uinteger" definition: The Segment Position of the Cluster containing the associated Block. 9.3.5.1.2.3. CueRelativePosition Element name: "CueRelativePosition" path: "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueRelativePosition)" id: "0xF0" maxOccurs: "1" type: "uinteger" 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. Lhomme, et al. Expires 29 April 2020 [Page 108] Internet-Draft Matroska October 2019 9.3.5.1.2.4. CueDuration Element name: "CueDuration" path: "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueDuration)" id: "0xB2" maxOccurs: "1" type: "uinteger" minver: "4" definition: The duration of the block according to the Segment time base. If missing the track's DefaultDuration does not apply and no duration information is available in terms of the cues. 9.3.5.1.2.5. CueBlockNumber Element name: "CueBlockNumber" path: "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueBlockNumber)" id: "0x5378" maxOccurs: "1" range: "not 0" default: "1" type: "uinteger" definition: Number of the Block in the specified Cluster. 9.3.5.1.2.6. CueCodecState Element name: "CueCodecState" path: "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueCodecState)" id: "0xEA" maxOccurs: "1" default: "0" Lhomme, et al. Expires 29 April 2020 [Page 109] Internet-Draft Matroska October 2019 type: "uinteger" minver: "2" definition: The Segment Position of the Codec State corresponding to this Cue Element. 0 means that the data is taken from the initial Track Entry. 9.3.5.1.2.7. CueReference Element name: "CueReference" path: "0*(\Segment\Cues\CuePoint\CueTrackPositions\CueReference)" id: "0xDB" type: "master" minver: "2" definition: The Clusters containing the referenced Blocks. 9.3.5.1.2.8. CueRefTime Element name: "CueRefTime" path: "1*1(\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueR efTime)" id: "0x96" minOccurs: "1" maxOccurs: "1" type: "uinteger" minver: "2" definition: Timestamp of the referenced Block. 9.3.5.1.2.9. CueRefCluster Element name: "CueRefCluster" path: "1*1(\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueR efCluster)" Lhomme, et al. Expires 29 April 2020 [Page 110] Internet-Draft Matroska October 2019 id: "0x97" minOccurs: "1" maxOccurs: "1" type: "uinteger" minver: "0" maxver: "0" definition: The Segment Position of the Cluster containing the referenced Block. 9.3.5.1.2.10. CueRefNumber Element name: "CueRefNumber" path: "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueR efNumber)" id: "0x535F" maxOccurs: "1" range: "not 0" default: "1" type: "uinteger" minver: "0" maxver: "0" definition: Number of the referenced Block of Track X in the specified Cluster. 9.3.5.1.2.11. CueRefCodecState Element name: "CueRefCodecState" path: "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueR efCodecState)" id: "0xEB" Lhomme, et al. Expires 29 April 2020 [Page 111] Internet-Draft Matroska October 2019 maxOccurs: "1" default: "0" type: "uinteger" minver: "0" maxver: "0" definition: The Segment Position of the Codec State corresponding to this referenced Element. 0 means that the data is taken from the initial Track Entry. 9.3.6. Attachments Element name: "Attachments" path: "0*1(\Segment\Attachments)" id: "0x1941A469" maxOccurs: "1" type: "master" definition: Contain attached files. 9.3.6.1. AttachedFile Element name: "AttachedFile" path: "1*(\Segment\Attachments\AttachedFile)" id: "0x61A7" minOccurs: "1" type: "master" definition: An attached file. 9.3.6.1.1. FileDescription Element name: "FileDescription" path: "0*1(\Segment\Attachments\AttachedFile\FileDescription)" Lhomme, et al. Expires 29 April 2020 [Page 112] Internet-Draft Matroska October 2019 id: "0x467E" maxOccurs: "1" type: "utf-8" definition: A human-friendly name for the attached file. 9.3.6.1.2. FileName Element name: "FileName" path: "1*1(\Segment\Attachments\AttachedFile\FileName)" id: "0x466E" minOccurs: "1" maxOccurs: "1" type: "utf-8" definition: Filename of the attached file. 9.3.6.1.3. FileMimeType Element name: "FileMimeType" path: "1*1(\Segment\Attachments\AttachedFile\FileMimeType)" id: "0x4660" minOccurs: "1" maxOccurs: "1" type: "string" definition: MIME type of the file. 9.3.6.1.4. FileData Element name: "FileData" path: "1*1(\Segment\Attachments\AttachedFile\FileData)" id: "0x465C" Lhomme, et al. Expires 29 April 2020 [Page 113] Internet-Draft Matroska October 2019 minOccurs: "1" maxOccurs: "1" type: "binary" definition: The data of the file. 9.3.6.1.5. FileUID Element name: "FileUID" path: "1*1(\Segment\Attachments\AttachedFile\FileUID)" id: "0x46AE" minOccurs: "1" maxOccurs: "1" range: "not 0" type: "uinteger" definition: Unique ID representing the file, as random as possible. 9.3.6.1.6. FileReferral Element name: "FileReferral" path: "0*1(\Segment\Attachments\AttachedFile\FileReferral)" id: "0x4675" maxOccurs: "1" type: "binary" minver: "0" maxver: "0" definition: A binary value that a track/codec can refer to when the attachment is needed. Lhomme, et al. Expires 29 April 2020 [Page 114] Internet-Draft Matroska October 2019 9.3.6.1.7. FileUsedStartTime Element name: "FileUsedStartTime" path: "0*1(\Segment\Attachments\AttachedFile\FileUsedStartTime)" id: "0x4661" maxOccurs: "1" type: "uinteger" minver: "0" maxver: "0" definition: DivX font extension 9.3.6.1.8. FileUsedEndTime Element name: "FileUsedEndTime" path: "0*1(\Segment\Attachments\AttachedFile\FileUsedEndTime)" id: "0x4662" maxOccurs: "1" type: "uinteger" minver: "0" maxver: "0" definition: DivX font extension 9.3.7. Chapters Element name: "Chapters" path: "0*1(\Segment\Chapters)" id: "0x1043A770" maxOccurs: "1" type: "master" Lhomme, et al. Expires 29 April 2020 [Page 115] Internet-Draft Matroska October 2019 recurring: "1" definition: A system to define basic menus and partition data. For more detailed information, look at the Chapters Explanation. 9.3.7.1. EditionEntry Element name: "EditionEntry" path: "1*(\Segment\Chapters\EditionEntry)" id: "0x45B9" minOccurs: "1" type: "master" definition: Contains all information about a Segment edition. 9.3.7.1.1. EditionUID Element name: "EditionUID" path: "0*1(\Segment\Chapters\EditionEntry\EditionUID)" id: "0x45BC" maxOccurs: "1" range: "not 0" type: "uinteger" definition: A unique ID to identify the edition. It's useful for tagging an edition. 9.3.7.1.2. EditionFlagHidden Element name: "EditionFlagHidden" path: "1*1(\Segment\Chapters\EditionEntry\EditionFlagHidden)" id: "0x45BD" minOccurs: "1" maxOccurs: "1" Lhomme, et al. Expires 29 April 2020 [Page 116] Internet-Draft Matroska October 2019 range: "0-1" default: "0" type: "uinteger" definition: If an edition is hidden (1), it SHOULD NOT be available to the user interface (but still to Control Tracks; see flag notes). (1 bit) 9.3.7.1.3. EditionFlagDefault Element name: "EditionFlagDefault" path: "1*1(\Segment\Chapters\EditionEntry\EditionFlagDefault)" id: "0x45DB" minOccurs: "1" maxOccurs: "1" range: "0-1" default: "0" type: "uinteger" definition: If a flag is set (1) the edition SHOULD be used as the default one. (1 bit) 9.3.7.1.4. EditionFlagOrdered Element name: "EditionFlagOrdered" path: "0*1(\Segment\Chapters\EditionEntry\EditionFlagOrdered)" id: "0x45DD" maxOccurs: "1" range: "0-1" default: "0" type: "uinteger" Lhomme, et al. Expires 29 April 2020 [Page 117] Internet-Draft Matroska October 2019 definition: Specify if the chapters can be defined multiple times and the order to play them is enforced. (1 bit) 9.3.7.1.5. ChapterAtom Element name: "ChapterAtom" path: "1*(\Segment\Chapters\EditionEntry(1*(\ChapterAtom)))" id: "0xB6" minOccurs: "1" type: "master" definition: Contains the atom information to use as the chapter atom (apply to all tracks). 9.3.7.1.5.1. ChapterUID Element name: "ChapterUID" path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterUID)" id: "0x73C4" minOccurs: "1" maxOccurs: "1" range: "not 0" type: "uinteger" definition: A unique ID to identify the Chapter. 9.3.7.1.5.2. ChapterStringUID Element name: "ChapterStringUID" path: "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterStringUID)" id: "0x5654" maxOccurs: "1" type: "utf-8" Lhomme, et al. Expires 29 April 2020 [Page 118] Internet-Draft Matroska October 2019 minver: "3" definition: A unique string ID to identify the Chapter. Use for WebVTT cue identifier storage. 9.3.7.1.5.3. ChapterTimeStart Element name: "ChapterTimeStart" path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterTimeStart)" id: "0x91" minOccurs: "1" maxOccurs: "1" type: "uinteger" definition: Timestamp of the start of Chapter (not scaled). 9.3.7.1.5.4. ChapterTimeEnd Element name: "ChapterTimeEnd" path: "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterTimeEnd)" id: "0x92" maxOccurs: "1" type: "uinteger" definition: Timestamp of the end of Chapter (timestamp excluded, not scaled). 9.3.7.1.5.5. ChapterFlagHidden Element name: "ChapterFlagHidden" path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterFlagHidden)" id: "0x98" minOccurs: "1" Lhomme, et al. Expires 29 April 2020 [Page 119] Internet-Draft Matroska October 2019 maxOccurs: "1" range: "0-1" default: "0" type: "uinteger" definition: If a chapter is hidden (1), it SHOULD NOT be available to the user interface (but still to Control Tracks; see flag notes). (1 bit) 9.3.7.1.5.6. ChapterFlagEnabled Element name: "ChapterFlagEnabled" path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterFlagEnabled)" id: "0x4598" minOccurs: "1" maxOccurs: "1" range: "0-1" default: "1" type: "uinteger" definition: Specify whether the chapter is enabled. It can be enabled/disabled by a Control Track. When disabled, the movie SHOULD skip all the content between the TimeStart and TimeEnd of this chapter (see flag notes). (1 bit) 9.3.7.1.5.7. ChapterSegmentUID Element name: "ChapterSegmentUID" path: "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterSegmentUID)" id: "0x6E67" minOccurs: see implementation notes maxOccurs: "1" Lhomme, et al. Expires 29 April 2020 [Page 120] Internet-Draft Matroska October 2019 range: ">0" type: "binary" definition: The SegmentUID of another Segment to play during this chapter. implementation notes: +-----------+---------------------------------------------+ | attribute | note | +===========+=============================================+ | minOccurs | ChapterSegmentUID MUST be set (minOccurs=1) | | | if ChapterSegmentEditionUID is used. | +-----------+---------------------------------------------+ Table 40 9.3.7.1.5.8. ChapterSegmentEditionUID Element name: "ChapterSegmentEditionUID" path: "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterSegmentE ditionUID)" id: "0x6EBC" maxOccurs: "1" range: "not 0" type: "uinteger" definition: The EditionUID to play from the Segment linked in ChapterSegmentUID. If ChapterSegmentEditionUID is undeclared then no Edition of the linked Segment is used. 9.3.7.1.5.9. ChapterPhysicalEquiv Element name: "ChapterPhysicalEquiv" path: "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterPhysical Equiv)" id: "0x63C3" maxOccurs: "1" Lhomme, et al. Expires 29 April 2020 [Page 121] Internet-Draft Matroska October 2019 type: "uinteger" definition: Specify the physical equivalent of this ChapterAtom like "DVD" (60) or "SIDE" (50), see complete list of values. 9.3.7.1.5.10. ChapterTrack Element name: "ChapterTrack" path: "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterTrack)" id: "0x8F" maxOccurs: "1" type: "master" definition: List of tracks on which the chapter applies. If this Element is not present, all tracks apply 9.3.7.1.5.11. ChapterTrackUID Element name: "ChapterTrackUID" path: "1*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterTrack\Cha pterTrackUID)" id: "0x89" minOccurs: "1" range: "not 0" type: "uinteger" definition: UID of the Track to apply this chapter too. In the absence of a control track, choosing this chapter will select the listed Tracks and deselect unlisted tracks. Absence of this Element indicates that the Chapter SHOULD be applied to any currently used Tracks. 9.3.7.1.5.12. ChapterDisplay Element name: "ChapterDisplay" path: "0*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterDisplay)" id: "0x80" Lhomme, et al. Expires 29 April 2020 [Page 122] Internet-Draft Matroska October 2019 type: "master" definition: Contains all possible strings to use for the chapter display. 9.3.7.1.5.13. ChapString Element name: "ChapString" path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterDisplay\ ChapString)" id: "0x85" minOccurs: "1" maxOccurs: "1" type: "utf-8" definition: Contains the string to use as the chapter atom. 9.3.7.1.5.14. ChapLanguage Element name: "ChapLanguage" path: "1*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterDisplay\C hapLanguage)" id: "0x437C" minOccurs: "1" default: "eng" type: "string" definition: The languages corresponding to the string, in the bibliographic ISO-639-2 form. This Element MUST be ignored if the ChapLanguageIETF Element is used within the same ChapterDisplay Element. 9.3.7.1.5.15. ChapLanguageIETF Element name: "ChapLanguageIETF" path: "0*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterDisplay\C hapLanguageIETF)" Lhomme, et al. Expires 29 April 2020 [Page 123] Internet-Draft Matroska October 2019 id: "0x437D" type: "string" minver: "4" definition: Specifies the language used in the ChapString according to BCP 47 and using the IANA Language Subtag Registry. If this Element is used, then any ChapLanguage Elements used in the same ChapterDisplay MUST be ignored. 9.3.7.1.5.16. ChapCountry Element name: "ChapCountry" path: "0*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterDisplay\C hapCountry)" id: "0x437E" type: "string" definition: The countries corresponding to the string, same 2 octets as in Internet domains. This Element MUST be ignored if the ChapLanguageIETF Element is used within the same ChapterDisplay Element. 9.3.7.1.5.17. ChapProcess Element name: "ChapProcess" path: "0*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess)" id: "0x6944" type: "master" definition: Contains all the commands associated to the Atom. 9.3.7.1.5.18. ChapProcessCodecID Element name: "ChapProcessCodecID" path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess\Cha pProcessCodecID)" id: "0x6955" Lhomme, et al. Expires 29 April 2020 [Page 124] Internet-Draft Matroska October 2019 minOccurs: "1" maxOccurs: "1" default: "0" type: "uinteger" definition: Contains the type of the codec used for the processing. A value of 0 means native Matroska processing (to be defined), a value of 1 means the DVD command set is used. More codec IDs can be added later. 9.3.7.1.5.19. ChapProcessPrivate Element name: "ChapProcessPrivate" path: "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess\Cha pProcessPrivate)" id: "0x450D" maxOccurs: "1" type: "binary" definition: Some optional data attached to the ChapProcessCodecID information. For ChapProcessCodecID = 1, it is the "DVD level" equivalent. 9.3.7.1.5.20. ChapProcessCommand Element name: "ChapProcessCommand" path: "0*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess\Chap ProcessCommand)" id: "0x6911" type: "master" definition: Contains all the commands associated to the Atom. 9.3.7.1.5.21. ChapProcessTime Element name: "ChapProcessTime" Lhomme, et al. Expires 29 April 2020 [Page 125] Internet-Draft Matroska October 2019 path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess\Cha pProcessCommand\ChapProcessTime)" id: "0x6922" minOccurs: "1" maxOccurs: "1" type: "uinteger" 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 41 9.3.7.1.5.22. ChapProcessData Element name: "ChapProcessData" path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess\Cha pProcessCommand\ChapProcessData)" id: "0x6933" minOccurs: "1" maxOccurs: "1" type: "binary" 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. Lhomme, et al. Expires 29 April 2020 [Page 126] Internet-Draft Matroska October 2019 9.3.8. Tags Element name: "Tags" path: "0*(\Segment\Tags)" id: "0x1254C367" type: "master" definition: Element containing metadata describing Tracks, Editions, Chapters, Attachments, or the Segment as a whole. A list of valid tags can be found here. 9.3.8.1. Tag Element name: "Tag" path: "1*(\Segment\Tags\Tag)" id: "0x7373" minOccurs: "1" type: "master" definition: A single metadata descriptor. 9.3.8.1.1. Targets Element name: "Targets" path: "1*1(\Segment\Tags\Tag\Targets)" id: "0x63C0" minOccurs: "1" maxOccurs: "1" type: "master" definition: Specifies which other elements the metadata represented by the Tag applies to. If empty or not present, then the Tag describes everything in the Segment. Lhomme, et al. Expires 29 April 2020 [Page 127] Internet-Draft Matroska October 2019 9.3.8.1.1.1. TargetTypeValue Element name: "TargetTypeValue" path: "0*1(\Segment\Tags\Tag\Targets\TargetTypeValue)" id: "0x68CA" maxOccurs: "1" default: "50" type: "uinteger" definition: A number to indicate the logical level of the target. restrictions: +-------+--------------------------+--------------------------------+ | value | label | documentation | +=======+==========================+================================+ | "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 / CONCERT | 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 | | | CHAPTER | or movie. | +-------+--------------------------+--------------------------------+ | "20" | SUBTRACK / PART / | Corresponds to parts of a | | | MOVEMENT / SCENE | track for audio (like a | | | | movement). | +-------+--------------------------+--------------------------------+ | "10" | SHOT | The lowest hierarchy found in | | | | music or movies. | +-------+--------------------------+--------------------------------+ Table 42 Lhomme, et al. Expires 29 April 2020 [Page 128] Internet-Draft Matroska October 2019 9.3.8.1.1.2. TargetType Element name: "TargetType" path: "0*1(\Segment\Tags\Tag\Targets\TargetType)" id: "0x63CA" maxOccurs: "1" type: "string" definition: An informational string that can be used to display the logical level of the target like "ALBUM", "TRACK", "MOVIE", "CHAPTER", etc (see TargetType). restrictions: +--------------+------------+ | value | label | +==============+============+ | "COLLECTION" | COLLECTION | +--------------+------------+ | "EDITION" | EDITION | +--------------+------------+ | "ISSUE" | ISSUE | +--------------+------------+ | "VOLUME" | VOLUME | +--------------+------------+ | "OPUS" | OPUS | +--------------+------------+ | "SEASON" | SEASON | +--------------+------------+ | "SEQUEL" | SEQUEL | +--------------+------------+ | "ALBUM" | ALBUM | +--------------+------------+ | "OPERA" | OPERA | +--------------+------------+ | "CONCERT" | CONCERT | +--------------+------------+ | "MOVIE" | MOVIE | +--------------+------------+ | "EPISODE" | EPISODE | +--------------+------------+ | "PART" | PART | +--------------+------------+ | "SESSION" | SESSION | Lhomme, et al. Expires 29 April 2020 [Page 129] Internet-Draft Matroska October 2019 +--------------+------------+ | "TRACK" | TRACK | +--------------+------------+ | "SONG" | SONG | +--------------+------------+ | "CHAPTER" | CHAPTER | +--------------+------------+ | "SUBTRACK" | SUBTRACK | +--------------+------------+ | "PART" | PART | +--------------+------------+ | "MOVEMENT" | MOVEMENT | +--------------+------------+ | "SCENE" | SCENE | +--------------+------------+ | "SHOT" | SHOT | +--------------+------------+ Table 43 9.3.8.1.1.3. TagTrackUID Element name: "TagTrackUID" path: "0*(\Segment\Tags\Tag\Targets\TagTrackUID)" id: "0x63C5" default: "0" type: "uinteger" definition: A unique ID to identify the Track(s) the tags belong to. If the value is 0 at this level, the tags apply to all tracks in the Segment. 9.3.8.1.1.4. TagEditionUID Element name: "TagEditionUID" path: "0*(\Segment\Tags\Tag\Targets\TagEditionUID)" id: "0x63C9" default: "0" type: "uinteger" Lhomme, et al. Expires 29 April 2020 [Page 130] Internet-Draft Matroska October 2019 definition: A unique ID to identify the EditionEntry(s) the tags belong to. If the value is 0 at this level, the tags apply to all editions in the Segment. 9.3.8.1.1.5. TagChapterUID Element name: "TagChapterUID" path: "0*(\Segment\Tags\Tag\Targets\TagChapterUID)" id: "0x63C4" default: "0" type: "uinteger" definition: A unique ID to identify the Chapter(s) the tags belong to. If the value is 0 at this level, the tags apply to all chapters in the Segment. 9.3.8.1.1.6. TagAttachmentUID Element name: "TagAttachmentUID" path: "0*(\Segment\Tags\Tag\Targets\TagAttachmentUID)" id: "0x63C6" default: "0" type: "uinteger" definition: A unique ID to identify the Attachment(s) the tags belong to. If the value is 0 at this level, the tags apply to all the attachments in the Segment. 9.3.8.1.2. SimpleTag Element name: "SimpleTag" path: "1*(\Segment\Tags\Tag(1*(\SimpleTag)))" id: "0x67C8" minOccurs: "1" type: "master" Lhomme, et al. Expires 29 April 2020 [Page 131] Internet-Draft Matroska October 2019 definition: Contains general information about the target. 9.3.8.1.2.1. TagName Element name: "TagName" path: "1*1(\Segment\Tags\Tag\SimpleTag\TagName)" id: "0x45A3" minOccurs: "1" maxOccurs: "1" type: "utf-8" definition: The name of the Tag that is going to be stored. 9.3.8.1.2.2. TagLanguage Element name: "TagLanguage" path: "1*1(\Segment\Tags\Tag\SimpleTag\TagLanguage)" id: "0x447A" minOccurs: "1" maxOccurs: "1" default: "und" type: "string" definition: Specifies the language of the tag specified, in the Matroska languages form. This Element MUST be ignored if the TagLanguageIETF Element is used within the same SimpleTag Element. 9.3.8.1.2.3. TagLanguageIETF Element name: "TagLanguageIETF" path: "0*1(\Segment\Tags\Tag\SimpleTag\TagLanguageIETF)" id: "0x447B" maxOccurs: "1" Lhomme, et al. Expires 29 April 2020 [Page 132] Internet-Draft Matroska October 2019 type: "string" minver: "4" definition: Specifies the language used in the TagString according to BCP 47 and using the IANA Language Subtag Registry. If this Element is used, then any TagLanguage Elements used in the same SimpleTag MUST be ignored. 9.3.8.1.2.4. TagDefault Element name: "TagDefault" path: "1*1(\Segment\Tags\Tag\SimpleTag\TagDefault)" id: "0x4484" minOccurs: "1" maxOccurs: "1" range: "0-1" default: "1" type: "uinteger" definition: A boolean value to indicate if this is the default/ original language to use for the given tag. 9.3.8.1.2.5. TagString Element name: "TagString" path: "0*1(\Segment\Tags\Tag\SimpleTag\TagString)" id: "0x4487" maxOccurs: "1" type: "utf-8" definition: The value of the Tag. 9.3.8.1.2.6. TagBinary Element name: "TagBinary" Lhomme, et al. Expires 29 April 2020 [Page 133] Internet-Draft Matroska October 2019 path: "0*1(\Segment\Tags\Tag\SimpleTag\TagBinary)" id: "0x4485" maxOccurs: "1" type: "binary" definition: The values of the Tag if it is binary. Note that this cannot be used in the same SimpleTag as TagString. 10. 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". The Matroska 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. 10.1. 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". 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; therefore, it is RECOMMENDED to use "Void Elements" as padding in between "Top-Level Elements". Lhomme, et al. Expires 29 April 2020 [Page 134] Internet-Draft Matroska October 2019 10.2. 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". The Matroska specification recommends that "CRC-32 Elements" SHOULD NOT be used as an immediate "Child Element" of the "Segment Element"; however all "Top-Level Elements" of an "EBML Document" SHOULD include a "CRC-32 Element" as a "Child Element". 10.3. SeekHead If used, the first "SeekHead Element" SHOULD 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". 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". 10.4. 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". 10.5. 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 29 April 2020 [Page 135] Internet-Draft Matroska October 2019 10.6. 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 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". 10.7. 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". 10.8. Tags The "Tags Element" is most subject to changes after the file was originally created. For easier editing, the "Tags Element" SHOULD 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 size will only marginally change. 10.9. Optimum layout from a muxer * SeekHead * Info * Tracks * Chapters * Attachments * Tags Lhomme, et al. Expires 29 April 2020 [Page 136] Internet-Draft Matroska October 2019 * Clusters * Cues 10.10. Optimum layout after editing tags * SeekHead * Info * Tracks * Chapters * Attachments * Void * Clusters * Cues * Tags 10.11. Optimum layout with Cues at the front * SeekHead * Info * Tracks * Chapters * Attachments * Tags * Cues * Clusters 10.12. Cluster Timestamp The "Timestamp Element" MUST occur as in storage order before any "SimpleBlock", "BlockGroup", or "EncryptedBlock" within the "Cluster Element". Lhomme, et al. Expires 29 April 2020 [Page 137] Internet-Draft Matroska October 2019 11. Chapters 11.1. Edition and Chapter Flags 11.1.1. Chapter Flags Two "Chapter Flags" are defined to describe the behavior of the "ChapterAtom Element": "ChapterFlagHidden" and "ChapterFlagEnabled". If a "ChapterAtom Element" is the "Child Element" of another "ChapterAtom Element" with a "Chapter Flag" set to "true", then the "Child ChapterAtom Element" MUST be interpreted as having its same "Chapter Flag" set to "true". If a "ChapterAtom Element" is the "Child Element" of another "ChapterAtom Element" with a "Chapter Flag" set to "false" or if the "ChapterAtom Element" does not have a "ChapterAtom Element" as its "Parent Element", then it MUST be interpreted according to its own "Chapter Flag". As an example, consider a "Parent ChapterAtom Element" that has its "ChapterFlagHidden" set to "true" and also contains two child "ChapterAtoms", the first with "ChapterFlagHidden" set to "true" and the second with "ChapterFlagHidden" either set to "false" or not present at all (in which case the default value of the Element applies, which is "false"). Since the parent "ChapterAtom" has its "ChapterFlagHidden" set to "true" then all of its children "ChapterAtoms" MUST also be interpreted as if their "ChapterFlagHidden" is also set to "true". However, if a "Control Track" toggles the parent's "ChapterFlagHidden" flag to "false", then only the parent "ChapterAtom" and its second child "ChapterAtom" MUST be interpreted as if "ChapterFlagHidden" is set to "false". The first child "ChapterAtom" which has the "ChapterFlagHidden" flag set to "true" retains its value until its value is toggled to "false" by a "Control Track". 11.1.2. Edition Flags Three "Edition Flags" are defined to describe the behavior of the "EditionEntry Element": "EditionFlagHidden", "EditionFlagDefault" and "EditionFlagOrdered". 11.1.2.1. EditionFlagHidden The "EditionFlagHidden Flag" behaves similarly to the "ChapterFlagHidden Flag": if "EditionFlagHidden" is set to "true", its "Child ChapterAtoms Elements" MUST also be interpreted as if their "ChapterFlagHidden" is also set to "true", regardless of their own "ChapterFlagHidden Flags". If "EditionFlagHidden" is toggled by a "Control Track" to "false", the "ChapterFlagHidden Flags" of the Lhomme, et al. Expires 29 April 2020 [Page 138] Internet-Draft Matroska October 2019 "Child ChapterAtoms Elements" SHALL determine whether the "ChapterAtom" is hidden or not. 11.1.2.2. EditionFlagDefault It is RECOMMENDED that no more than one "Edition" have an "EditionFlagDefault Flag" set to "true". The first "Edition" with both the "EditionFlagDefault Flag" set to "true" and the "EditionFlagHidden Flag" set to "false" is the "Default Edition". When all "EditionFlagDefault Flags" are set to "false", then the first "Edition" is the "Default Edition". 11.1.2.3. 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 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" is set to "false", "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". All these elements are now informational only. The following list shows the different usage of "Chapter Elements" between an ordered and non-ordered "Edition". Chapter elements / ordered Edition | False | True ChapterUID | X | X ChapterStringUID | X | X ChapterTimeStart | X | X ChapterTimeEnd | - | X ChapterFlagHidden | X | X ChapterFlagEnabled | X | X ChapterSegmentUID | - | X ChapterSegmentEditionUID | - | X ChapterPhysicalEquiv | X | X ChapterTrack | - | X ChapterDisplay | X | X ChapProcess | - | X Furthermore there are other EBML "Elements" which could be used if the "EditionFlagOrdered Flag" is set to "true". Lhomme, et al. Expires 29 April 2020 [Page 139] Internet-Draft Matroska October 2019 Other elements / ordered Edition | False | True Info/SegmentFamily | - | X Info/ChapterTranslate | - | X Track/TrackTranslate | - | X These other "Elements" belong to the Matroska DVD menu system and are only used when the "ChapProcessCodecID Element" is set to 1. 11.1.2.3.1. Ordered-Edition and Matroska Segment-Linking * Hard Linking: "Ordered-Chapters" supersedes the "Hard Linking". * Soft Linking: In this complex system "Ordered Chapters" are REQUIRED and a "Chapter CODEC" MUST interpret the "ChapProcess" of all chapters. * Medium Linking: "Ordered Chapters" are used in a normal way and can be combined with the "ChapterSegmentUID" element which establishes a link to another Matroska file/Segment. See the section on the Linked Segments (#linked-segments)) for more information about "Hard Linking", "Soft Linking" and "Medium Linking". 11.2. 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. The private data depend on the type of menu system (stored in ChapProcessPrivate), idem for the data in the chapters (stored in ChapProcessData). 11.2.1. Matroska Script (0) This is the case when "ChapProcessCodecID" = 0. This is a script language build for Matroska purposes. The inspiration comes from ActionScript, javascript and other similar scripting languages. The commands are stored as text commands, in UTF-8. The syntax is C like, with commands spanned on many lines, each terminating with a ";". You can also include comments at the end of lines with "//" or comment many lines using "/* */". The scripts are stored in ChapProcessData. For the moment ChapProcessPrivate is not used. The one and only command existing for the moment is "GotoAndPlay( ChapterUID );". As the same suggests, it means that when this command is encountered, the "Matroska Player" SHOULD jump to the "Chapter" specified by the UID and play it. Lhomme, et al. Expires 29 April 2020 [Page 140] Internet-Draft Matroska October 2019 11.2.2. DVD menu (1) This is the case when "ChapProcessCodecID" = 1. Each level of a chapter corresponds to a logical level in the DVD system that is stored in the first octet of the ChapProcessPrivate. This DVD hierarchy is as follows: ChapProcessPrivate | DVD Name | Hierarchy | Commands Possible | Comment 0x30 | SS | DVD domain | - | First Play, Video Manager, Video Title 0x2A | LU | Language Unit | - | Contains only PGCs 0x28 | TT | Title | - | Contains only PGCs 0x20 | PGC | Program Group Chain (PGC) | * | 0x18 | PG | Program 1 / Program 2 / Program 3 | - | 0x10 | PTT | Part Of Title 1 / Part Of Title 2 | - | Equivalent to the chapters on the sleeve. 0x08 | CN | Cell 1 / Cell 2 / Cell 3 / Cell 4 / Cell 5 / Cell 6 | - | You can also recover wether a Segment is a Video Manager (VMG), Video Title Set (VTS) or Video Title Set Menu (VTSM) from the ChapterTranslateID element found in the Segment Info. This field uses 2 octets as follows: 1. Domain Type: 0 for VMG, the domain number for VTS and VTSM 2. Domain Value: 0 for VMG and VTSM, 1 for the VTS source. For instance, the menu part from VTS_01_0.VOB would be coded [1,0] and the content part from VTS_02_3.VOB would be [2,1]. The VMG is always [0,0] The following octets of ChapProcessPrivate are as follows: Octet 1 | DVD Name | Following Octets 0x30 | SS | Domain name code (1: 0x00= First play, 0xC0= VMG, 0x40= VTSM, 0x80= VTS) + VTS(M) number (2) 0x2A | LU | Language code (2) + Language extension (1) 0x28 | TT | global Title number (2) + corresponding TTN of the VTS (1) 0x20 | PGC | PGC number (2) + Playback Type (1) + Disabled User Operations (4) 0x18 | PG | Program number (2) 0x10 | PTT | PTT- chapter number (1) 0x08 | CN | Cell number [VOB ID(2)][Cell ID(1)][Angle Num(1)] If the level specified in ChapProcessPrivate is a PGC (0x20), there is an octet called the Playback Type, specifying the kind of PGC defined: * 0x00: entry only/basic PGC * 0x82: Title+Entry Menu (only found in the Video Manager domain) Lhomme, et al. Expires 29 April 2020 [Page 141] Internet-Draft Matroska October 2019 * 0x83: Root Menu (only found in the VTSM domain) * 0x84: Subpicture Menu (only found in the VTSM domain) * 0x85: Audio Menu (only found in the VTSM domain) * 0x86: Angle Menu (only found in the VTSM domain) * 0x87: Chapter Menu (only found in the VTSM domain) The next 4 following octets correspond to the User Operation flags (http://dvd.sourceforge.net/dvdinfo/uops.html) in the standard PGC. When a bit is set, the command SHOULD be disabled. ChapProcessData contains the pre/post/cell commands in binary format as there are stored on a DVD. There is just an octet preceding these data to specify the number of commands in the element. As follows: [# of commands(1)][command 1 (8)][command 2 (8)][command 3 (8)]. More information on the DVD commands and format on DVD-replica (http://www.dvd-replica.com/DVD/), where we got most of the info about it. You can also get information on DVD from the DVDinfo project (http://dvd.sourceforge.net/dvdinfo/). 11.3. 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. * 00000ms - 05000ms : Intro * 05000ms - 25000ms : Before the crime * 25000ms - 27500ms : The crime * 27500ms - 38000ms : The killer arrested * 38000ms - 43000ms : Credits This would translate in the following matroska form : 16603393396715046047 1193046 0 5000000000 Intro eng 0 1 2311527 5000000000 25000000000 Before the crime eng Avant le crime fra 0 1 3430008 25000000000 27500000000 The crime eng Le crime fra 0 1 4548489 27500000000 38000000000 After the crime eng Apres le crime fra 0 1 5666960 38000000000 43000000000 Credits eng Generique fra 0 1 0 0 11.4. Example 2 : nested chapters In this example an (existing) album is split into different chapters, and one of them contain another splitting. Lhomme, et al. Expires 29 April 2020 [Page 142] Internet-Draft Matroska October 2019 11.4.1. 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 1281690858003401414 1 0 748000000 Baby wants to Bleep/Rock eng 2 0 278000000 Baby wants to bleep (pt.1) eng 0 1 3 278000000 432000000 Baby wants to rock eng 0 1 4 432000000 633000000 Baby wants to bleep (pt.2) eng 0 1 5 633000000 748000000 Baby wants to bleep (pt.3) eng 0 1 0 1 6 750000000 1178500000 Bleeper_O+2 eng 0 1 7 1180500000 1340000000 Baby wants to bleep (pt.4) eng 0 1 8 1342000000 1518000000 Bleep to bleep eng 0 1 9 1520000000 2015000000 Baby wants to bleep (k) eng 0 1 10 2017000000 2668000000 Bleeper eng 0 1 0 0 12. 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". 12.1. 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. Only JPEG and PNG 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). Lhomme, et al. Expires 29 April 2020 [Page 143] Internet-Draft Matroska October 2019 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 square | 600 small_cover.png | Portrait or square | 120 cover_land.png | Landscape | 600 small_cover_land.jpg | Landscape | 120 13. 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. 13.1. 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". Lhomme, et al. Expires 29 April 2020 [Page 144] Internet-Draft Matroska October 2019 * 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". 14. Matroska Streaming In Matroska, there are two kinds of streaming: file access and livestreaming. 14.1. 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 following guidelines, 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. Lhomme, et al. Expires 29 April 2020 [Page 145] Internet-Draft Matroska October 2019 14.2. 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 HTTP (or any other plain protocol based on TCP) 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 "MetaSeek", "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 "MetaSeek" list or a "Cues" list at the beginning of the stream, it SHOULD be considered non- seekable. Even though it is possible to seek blindly 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. 15. Menu Specifications This document is a _draft of the Menu system_ that will be the default one in "Matroska". As it will just be composed of a Control Track, it will be seen as a "codec" and could be replaced later by something else if needed. A menu is like what you see on DVDs, when you have some screens to select the audio format, subtitles or scene selection. Lhomme, et al. Expires 29 April 2020 [Page 146] Internet-Draft Matroska October 2019 15.1. Requirements What we'll try to have is a system that can do almost everything done on a DVD, or more, or better, or drop the unused features if necessary. As the name suggests, a Control Track is a track that can control the playback of the file and/or all the playback features. To make it as simple as possible for "Matroska Players", the Control Track will just give orders to the "Matroska Player" and get the actions associated with the highlights/hotspots. 15.1.1. Highlights/Hotspots A highlight is basically a rectangle/key associated with an action UID. When that rectangle/key is activated, the "Matroska Player" send the UID of the action to the Control Track handler (codec). The fact that it can also be a key means that even for audio only files, a keyboard shortcut or button panel could be used for menus. But in that case, the hotspot will have to be associated with a name to display. This highlight is sent from the Control Track to the "Matroska Player". Then the "Matroska Player" has to handle that highlight until it's deactivated (see Playback Features (#playback-features)). The highlight contains a UID of the action, a displayable name (UTF- 8), an associated key (list of keys to be defined, probably up/down/left/right/select), a screen position/range and an image to display. The image will be displayed either when the user place the mouse over the rectangle (or any other shape), or when an option of the screen is selected (not activated). There could be a second image used when the option is activated. And there could be a third image that can serve as background. This way you could have a still image (like in some DVDs) for the menu and behind that image blank video (small bitrate). When a highlight is activated by the user, the "Matroska Player" has to send the UID of the action to the Control Track. Then the Control Track codec will handle the action and possibly give new orders to the "Matroska Player". The format used for storing images SHOULD be extensible. For the moment we'll use PNG and BMP, both with alpha channel. Lhomme, et al. Expires 29 April 2020 [Page 147] Internet-Draft Matroska October 2019 15.1.2. Playback features All the following features will be sent from the Control Track to the "Matroska Player" : * Jump to chapter (UID, prev, next, number) * Disable all tracks of a kind (audio, video, subtitle) * Enable track UID (the kind doesn't matter) * Define/Disable a highlight * Enable/Disable jumping * Enable/Disable track selection of a kind * Select Edition ID (see chapters) * Pause playback * Stop playback * Enable/Disable a Chapter UID * Hide/Unhide a Chapter UID All the actions will be written in a normal Matroska track, with a timestamp. A "Menu Frame" SHOULD be able to contain more that one action/highlight for a given timestamp. (to be determined, EBML format structure) 15.1.3. Player requirements Some "Matroska Players" might not support the control track. That mean they will play the active/looped parts as part of the data. So I suggest putting the active/looped parts of a movie at the end of a movie. When a Menu-aware "Matroska Player" encounter the default Control Track of a "Matroska" file, the first order SHOULD be to jump at the start of the active/looped part of the movie. 15.2. Working Graph Matroska Source file -> Control Track <-> Player. -> other tracks -> rendered Lhomme, et al. Expires 29 April 2020 [Page 148] Internet-Draft Matroska October 2019 16. Unknown elements 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). For example, 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". 17. Default Values The default value of an "Element" is assumed when not present in the data stream. It is assumed only in the scope of its "Parent Element". For example, the "Language Element" is in the scope of the "Track Element". If the "Parent Element" is not present or assumed, then the "Child Element" cannot be assumed. 18. 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, then the period between two successive fields at the output of the decoding process equals "DefaultDecodedFieldDuration". For video sequences signaled as progressive, it is twice the value of "DefaultDecodedFieldDuration". 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: 1000000000ns/(48/1.001) = 20854167ns * PAL broadcast/DVD: 1000000000ns/(50/1.000) = 20000000ns Lhomme, et al. Expires 29 April 2020 [Page 149] Internet-Draft Matroska October 2019 * N/ATSC broadcast: 1000000000ns/(60/1.001) = 16683333ns * hard-telecined DVD: 1000000000ns/(60/1.001) = 16683333ns (60 encoded interlaced fields per second) * soft-telecined DVD: 1000000000ns/(60/1.001) = 16683333ns (48 encoded interlaced fields per second, with "repeat_first_field = 1") 19. Encryption Encryption in Matroska is designed in a very generic style to allow people to implement whatever form of encryption is best for them. It is possible to use the encryption framework in Matroska as a type of DRM (Digital Rights Management). 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". 20. Image Presentation 20.1. 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 Lhomme, et al. Expires 29 April 2020 [Page 150] Internet-Draft Matroska October 2019 off 240 columns of pixels from the left and right of the encoded image to present the image with the pillar-boxes hidden. 20.2. Rotation The ProjectionPoseRoll Element (see Section 9.3.4.1.31.49) 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 9.3.4.1.31.44) and the ProjectionPoseRoll Element represents a video track where the image SHOULD be presentation with a 90 degree counter-clockwise rotation. 90 21. Matroska versioning 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" MUST have a "DocTypeVersion" equal to or greater than 2. A file containing "CueRelativePosition" Elements 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. "DocTypeVersion" MUST always be equal to or greater than "DocTypeReadVersion". A reading application supporting Matroska version "V" MUST NOT refuse to read an application with "DocReadTypeVersion" equal to or lower than "V" even if "DocTypeVersion" is greater than "V". See also the note about Unknown Elements (#unknown-elements). Lhomme, et al. Expires 29 April 2020 [Page 151] Internet-Draft Matroska October 2019 22. MIME Types There is no IETF endorsed MIME type for Matroska files. These definitions can be used: * .mka : Matroska audio "audio/x-matroska" * .mkv : Matroska video "video/x-matroska" * .mk3d : Matroska 3D video "video/x-matroska-3d" 23. 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". 23.1. Segment Position Exception "Elements" that are defined to store a "Segment Position" MAY define reserved values to indicate a special meaning. 23.2. 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". 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|18|53|80|67| 20 |93|15|49|A9|66|8E|4D|80|84|69|65|74|66|57|41|84|69|65|74|66| 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. Lhomme, et al. Expires 29 April 2020 [Page 152] Internet-Draft Matroska October 2019 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". 24. Linked Segments Matroska provides several methods to link two or many "Segment Elements" together to create a "Linked Segment". A "Linked Segment" is a set of multiple "Segments" related together into a single presentation by using Hard Linking, Medium Linking, or Soft Linking. All "Segments" within a "Linked Segment" MUST utilize the same track numbers and timescale. All "Segments" within a "Linked Segment" MUST be stored within the same directory. All "Segments" within a "Linked Segment" MUST store a "SegmentUID". 24.1. Hard Linking Hard Linking (also called splitting) is the process of creating a "Linked Segment" by relating multiple "Segment Elements" using the "NextUID" and "PrevUID" Elements. Within a "Linked Segment", the timestamps of each "Segment" MUST follow consecutively in linking order. With Hard Linking, the chapters of any "Segment" within the "Linked Segment" MUST only reference the current "Segment". With Hard Linking, the "NextUID" and "PrevUID" MUST reference the respective "SegmentUID" values of the next and previous "Segments". The first "Segment" of a "Linked Segment" SHOULD have a "NextUID Element" and MUST NOT have a "PrevUID Element". The last "Segment" of a "Linked Segment" SHOULD have a "PrevUID Element" and MUST NOT have a "NextUID Element". The middle "Segments" of a "Linked Segment" SHOULD have both a "NextUID Element" and a "PrevUID Element". In a chain of "Linked Segments" the "NextUID" always takes precedence over the "PrevUID". So if SegmentA has a NextUID to SegmentB and SegmentB has a PrevUID to SegmentC, the link to use is SegmentA to SegmentB. If SegmentB has a PrevUID to SegmentA but SegmentA has no NextUID, 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 "SegmentUID", "PrevUID", and "NextUID", as in this table. Lhomme, et al. Expires 29 April 2020 [Page 153] Internet-Draft Matroska October 2019 +------------+----------------+------------------+------------------+ | file name | "SegmentUID" | "PrevUID" | "NextUID" | +============+================+==================+==================+ |"start.mkv" |71000c23cd310998| n/a | a77b3598941cb803 | | |53fbc94dd984a5dd| | eac0fcdafe44fac9 | +------------+----------------+------------------+------------------+ |"middle.mkv"|a77b3598941cb803| 71000c23cd310998 | 6c92285fa6d3e827 | | |eac0fcdafe44fac9| 53fbc94dd984a5dd | b198d120ea3ac674 | +------------+----------------+------------------+------------------+ | "end.mkv" |6c92285fa6d3e827| a77b3598941cb803 | n/a | | |b198d120ea3ac674| eac0fcdafe44fac9 | | +------------+----------------+------------------+------------------+ Table 44 An other example where only the "NextUID" Element is used. +--------------+------------------+-----------+------------------+ | file name | "SegmentUID" | "PrevUID" | "NextUID" | +==============+==================+===========+==================+ | "start.mkv" | 71000c23cd310998 | n/a | a77b3598941cb803 | | | 53fbc94dd984a5dd | | eac0fcdafe44fac9 | +--------------+------------------+-----------+------------------+ | "middle.mkv" | a77b3598941cb803 | n/a | 6c92285fa6d3e827 | | | eac0fcdafe44fac9 | | b198d120ea3ac674 | +--------------+------------------+-----------+------------------+ | "end.mkv" | 6c92285fa6d3e827 | n/a | n/a | | | b198d120ea3ac674 | | | +--------------+------------------+-----------+------------------+ Table 45 A next example where only the "PrevUID" Element is used. +--------------+------------------+------------------+-----------+ | file name | "SegmentUID" | "PrevUID" | "NextUID" | +==============+==================+==================+===========+ | "start.mkv" | 71000c23cd310998 | n/a | n/a | | | 53fbc94dd984a5dd | | | +--------------+------------------+------------------+-----------+ | "middle.mkv" | a77b3598941cb803 | 71000c23cd310998 | n/a | | | eac0fcdafe44fac9 | 53fbc94dd984a5dd | | +--------------+------------------+------------------+-----------+ | "end.mkv" | 6c92285fa6d3e827 | a77b3598941cb803 | n/a | | | b198d120ea3ac674 | eac0fcdafe44fac9 | | +--------------+------------------+------------------+-----------+ Table 46 Lhomme, et al. Expires 29 April 2020 [Page 154] Internet-Draft Matroska October 2019 In this example only the "middle.mkv" is using the "PrevUID" and "NextUID" Elements. +------------+----------------+------------------+------------------+ | file name | "SegmentUID" | "PrevUID" | "NextUID" | +============+================+==================+==================+ |"start.mkv" |71000c23cd310998| n/a | n/a | | |53fbc94dd984a5dd| | | +------------+----------------+------------------+------------------+ |"middle.mkv"|a77b3598941cb803| 71000c23cd310998 | 6c92285fa6d3e827 | | |eac0fcdafe44fac9| 53fbc94dd984a5dd | b198d120ea3ac674 | +------------+----------------+------------------+------------------+ | "end.mkv" |6c92285fa6d3e827| n/a | n/a | | |b198d120ea3ac674| | | +------------+----------------+------------------+------------------+ Table 47 24.2. Medium Linking Medium Linking creates relationships between "Segments" using Ordered Chapters and the "ChapterSegmentUID Element". A "Segment Edition" with Ordered Chapters MAY contain "Chapter Elements" that reference timestamp ranges from other "Segments". The "Segment" referenced by the Ordered Chapter via the "ChapterSegmentUID 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 the previous Ordered Chapters. As an example a file named "intro.mkv" could have a "SegmentUID" 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 "ChapterSegmentUID", "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 "ChapterSegmentUID" in an enabled "Edition" and present the reference content of the two "Segments" together. 24.3. Soft Linking Soft Linking is used by codec chapters. They can reference another "Segment" and jump to that "Segment". The way the "Segments" are described are internal to the chapter codec and unknown to the Matroska level. But there are "Elements" within the "Info Element" (such as "ChapterTranslate") that can translate a value representing Lhomme, et al. Expires 29 April 2020 [Page 155] Internet-Draft Matroska October 2019 a "Segment" in the chapter codec and to the current "SegmentUID". All "Segments" that could be used in a "Linked Segment" in this way SHOULD be marked as members of the same family via the "SegmentFamily Element", so that the "Matroska Player" can quickly switch from one to the other. 25. Track Flags 25.1. Default flag The "default track" flag is a hint for a "Matroska Player" and SHOULD always be changeable by the user. If the user wants to see or hear a track of a certain kind (audio, video, subtitles) and hasn't chosen a specific track, the "Matroska Player" SHOULD use the first track of that kind whose "default track" flag is set to "1". If no such track is found then the first track of this kind SHOULD be chosen. Only one track of a kind MAY have its "default track" flag set in a segment. If a track entry does not contain the "default track" flag element then its default value "1" is to be used. 25.2. Forced flag The "forced" flag tells the "Matroska Player" that it MUST display/ play this track or another track of the same kind that also has its "forced" flag set. When there are multiple "forced" tracks, the "Matroska Player" SHOULD determine the track based upon the language of the forced flag or use the default flag if no track matches the use languages. Another track of the same kind without the "forced" flag may be use simultaneously with the "forced" track (like DVD subtitles for example). 25.3. 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. 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 sum 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 Lhomme, et al. Expires 29 April 2020 [Page 156] Internet-Draft Matroska October 2019 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. 25.4. Overlay Track Overlay tracks SHOULD be rendered in the same 'channel' as the track its linked to. When content is found in such a track, it SHOULD be played on the rendering channel instead of the original track. 25.5. 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 colours 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). For separate tracks, Matroska needs to define exactly which track does what. "TrackOperation" with "TrackCombinePlanes" do that. For more details look at how TrackOperation works (#track-operation). 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. Lhomme, et al. Expires 29 April 2020 [Page 157] Internet-Draft Matroska October 2019 "Matroska Readers" may support these legacy files by checking Matroska v2 or 0x53B9. The older values (http://www.matroska.org/node/1/revisions/74/view#StereoMode) were 0: mono, 1: right eye, 2: left eye, 3: both eyes. 26. 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. 26.1. Timestamp Types * Absolute Timestamp = Block+Cluster * Relative Timestamp = Block * Scaled Timestamp = Block+Cluster * Raw Timestamp = (Block+Cluster)*TimestampScale*TrackTimestampScale 26.2. Block Timestamps The "Block Element"'s timestamp MUST be a signed integer that represents the "Raw Timestamp" relative to the "Cluster"'s "Timestamp Element", multiplied by the "TimestampScale Element". See TimestampScale (#timestampscale) for more information. The "Block Element"'s timestamp MUST be represented by a 16bit signed integer (sint16). The "Block"'s timestamp has a range of -32768 to +32767 units. When using the default value of the "TimestampScale Element", each integer represents 1ms. The maximum time span of "Block Elements" in a "Cluster" using the default "TimestampScale Element" of 1ms is 65536ms. If a "Cluster"'s "Timestamp Element" is set to zero, it is possible to have "Block Elements" with a negative "Raw Timestamp". "Block Elements" with a negative "Raw Timestamp" are not valid. 26.3. Raw Timestamp The exact time of an object SHOULD be represented in nanoseconds. To find out a "Block"'s "Raw Timestamp", you need the "Block"'s "Timestamp Element", the "Cluster"'s "Timestamp Element", and the "TimestampScale Element". Lhomme, et al. Expires 29 April 2020 [Page 158] Internet-Draft Matroska October 2019 26.4. TimestampScale The "TimestampScale Element" is used to calculate the "Raw Timestamp" of a "Block". The timestamp is obtained by adding the "Block"'s timestamp to the "Cluster"'s "Timestamp Element", and then multiplying that result by the "TimestampScale". The result will be the "Block"'s "Raw Timestamp" in nanoseconds. The formula for this would look like: (a + b) * c a = `Block`'s Timestamp b = `Cluster`'s Timestamp c = `TimestampScale` For example, assume a "Cluster"'s "Timestamp" has a value of 564264, the "Block" has a "Timestamp" of 1233, and the "TimestampScale Element" is the default of 1000000. (1233 + 564264) * 1000000 = 565497000000 So, the "Block" in this example has a specific time of 565497000000 in nanoseconds. In milliseconds this would be 565497ms. 26.5. TimestampScale Rounding Because the default value of "TimestampScale" is 1000000, which makes each integer in the "Cluster" and "Block" "Timestamp Elements" equal 1ms, this is the most commonly used. When dealing with audio, this causes inaccuracy when seeking. When the audio is combined with video, this is not an issue. For most cases, the the synch of audio to video does not need to be more than 1ms accurate. This becomes obvious when one considers that sound will take 2-3ms to travel a single meter, so distance from your speakers will have a greater effect on audio/visual synch than this. However, when dealing with audio-only files, seeking accuracy can become critical. For instance, when storing a whole CD in a single track, a user will want to be able to seek to the exact sample that a song begins at. If seeking a few sample ahead or behind, a 'crack' or 'pop' may result as a few odd samples are rendered. Also, when performing precise editing, it may be very useful to have the audio accuracy down to a single sample. When storing timestamps for an audio stream, the "TimestampScale Element" SHOULD have an accuracy of at least that of the audio sample rate, otherwise there are rounding errors that prevent users from knowing the precise location of a sample. Here's how a program has Lhomme, et al. Expires 29 April 2020 [Page 159] Internet-Draft Matroska October 2019 to round each timestamp in order to be able to recreate the sample number accurately. Let's assume that the application has an audio track with a sample rate of 44100. As written above the "TimestampScale" MUST have at least the accuracy of the sample rate itself: 1000000000 / 44100 = 22675.7369614512. This value MUST always be truncated. Otherwise the accuracy will not suffice. So in this example the application will use 22675 for the "TimestampScale". The application could even use some lower value like 22674 which would allow it to be a little bit imprecise about the original timestamps. But more about that in a minute. Next the application wants to write sample number 52340 and calculates the timestamp. This is easy. In order to calculate the "Raw Timestamp" in ns all it has to do is calculate "Raw Timestamp = round(1000000000 * sample_number / sample_rate)". Rounding at this stage is very important! The application might skip it if it choses a slightly smaller value for the "TimestampScale" factor instead of the truncated one like shown above. Otherwise it has to round or the results won't be reversible. For our example we get "Raw Timestamp = round(1000000000 * 52340 / 44100) = round(1186848072.56236) = 1186848073". The next step is to calculate the "Absolute Timestamp" - that is the timestamp that will be stored in the Matroska file. Here the application has to divide the "Raw Timestamp" from the previous paragraph by the "TimestampScale" factor and round the result: "Absolute Timestamp = round(Raw Timestamp / TimestampScale_factor)" which will result in the following for our example: "Absolute Timestamp = round(1186848073 / 22675) = round(52341.7011245866) = 52342". This number is the one the application has to write to the file. Now our file is complete, and we want to play it back with another application. Its task is to find out which sample the first application wrote into the file. So it starts reading the Matroska file and finds the "TimestampScale" factor 22675 and the audio sample rate 44100. Later it finds a data block with the "Absolute Timestamp" of 52342. But how does it get the sample number from these numbers? First it has to calculate the "Raw Timestamp" of the block it has just read. Here's no rounding involved, just an integer multiplication: "Raw Timestamp = Absolute Timestamp * TimestampScale_factor". In our example: "Raw Timestamp = 52342 * 22675 = 1186854850". Lhomme, et al. Expires 29 April 2020 [Page 160] Internet-Draft Matroska October 2019 The conversion from the "Raw Timestamp" to the sample number again requires rounding: "sample_number = round(Raw Timestamp * sample_rate / 1000000000)". In our example: "sample_number = round(1186854850 * 44100 / 1000000000) = round(52340.298885) = 52340". This is exactly the sample number that the previous program started with. Some general notes for a program: 1. Always calculate the timestamps / sample numbers with floating point numbers of at least 64bit precision (called 'double' in most modern programming languages). If you're calculating with integers then make sure they're 64bit long, too. 2. Always round if you divide. Always! If you don't you'll end up with situations in which you have a timestamp in the Matroska file that does not correspond to the sample number that it started with. Using a slightly lower timestamp scale factor can help here in that it removes the need for proper rounding in the conversion from sample number to "Raw Timestamp". 26.6. TrackTimestampScale The "TrackTimestampScale Element" is used align tracks that would otherwise be played at different speeds. An example of this would be if you have a film that was originally recorded at 24fps video. When playing this back through a PAL broadcasting system, it is standard to speed up the film to 25fps to match the 25fps display speed of the PAL broadcasting standard. However, when broadcasting the video through NTSC, it is typical to leave the film at its original speed. If you wanted to make a single file where there was one video stream, and an audio stream used from the PAL broadcast, as well as an audio stream used from the NTSC broadcast, you would have the problem that the PAL audio stream would be 1/24th faster than the NTSC audio stream, quickly leading to problems. It is possible to stretch out the PAL audio track and re-encode it at a slower speed, however when dealing with lossy audio codecs, this often results in a loss of audio quality and/or larger file sizes. This is the type of problem that "TrackTimestampScale" was designed to fix. Using it, the video can be played back at a speed that will synch with either the NTSC or the PAL audio stream, depending on which is being used for playback. To continue the above example: Track 1: Video Track 2: NTSC Audio Track 3: PAL Audio Lhomme, et al. Expires 29 April 2020 [Page 161] Internet-Draft Matroska October 2019 Because the NTSC track is at the original speed, it will used as the default value of 1.0 for its "TrackTimestampScale". The video will also be aligned to the NTSC track with the default value of 1.0. The "TrackTimestampScale" value to use for the PAL track would be calculated by determining how much faster the PAL track is than the NTSC track. In this case, because we know the video for the NTSC audio is being played back at 24fps and the video for the PAL audio is being played back at 25fps, the calculation would be: 25/24 is almost 1.04166666666666666667 When writing a file that uses a non-default "TrackTimestampScale", the values of the "Block"'s timestamp are whatever they would be when normally storing the track with a default value for the "TrackTimestampScale". However, the data is interleaved a little differently. Data SHOULD be interleaved by its Raw Timestamp (#raw- timestamp) in the order handed back from the encoder. The "Raw Timestamp" of a "Block" from a track using "TrackTimestampScale" is calculated using: "(Block's Timestamp + Cluster's Timestamp) * TimestampScale * TrackTimestampScale" So, a Block from the PAL track above that had a Scaled Timestamp (#timestamp-types) of 100 seconds would have a "Raw Timestamp" of 104.66666667 seconds, and so would be stored in that part of the file. When playing back a track using the "TrackTimestampScale", if the track is being played by itself, there is no need to scale it. From the above example, when playing the Video with the NTSC Audio, neither are scaled. However, when playing back the Video with the PAL Audio, the timestamps from the PAL Audio track are scaled using the "TrackTimestampScale", resulting in the video playing back in synch with the audio. It would be possible for a "Matroska Player" to also adjust the audio's samplerate at the same time as adjusting the timestamps if you wanted to play the two audio streams synchronously. It would also be possible to adjust the video to match the audio's speed. However, for playback, the selected track(s) timestamps SHOULD be adjusted if they need to be scaled. While the above example deals specifically with audio tracks, this element can be used to align video, audio, subtitles, or any other type of track contained in a Matroska file. Lhomme, et al. Expires 29 April 2020 [Page 162] Internet-Draft Matroska October 2019 27. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . Authors' Addresses Steve Lhomme Email: slhomme@matroska.org Moritz Bunkus Email: moritz@bunkus.org Dave Rice Email: dave@dericed.com Lhomme, et al. Expires 29 April 2020 [Page 163]