Matroska Media Container Format Specifications
draft-ietf-cellar-matroska-07
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draft-ietf-cellar-matroska-07
cellar S. Lhomme
Internet-Draft
Intended status: Informational M. Bunkus
Expires: 14 October 2021
D. Rice
12 April 2021
Matroska Media Container Format Specifications
draft-ietf-cellar-matroska-07
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-
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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 14 October 2021.
Copyright Notice
Copyright (c) 2021 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.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Status of this document . . . . . . . . . . . . . . . . . . . 5
3. Security Considerations . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
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 . . . . . . . . . . . . . . . . . . . . . . . 9
7. Matroska Structure . . . . . . . . . . . . . . . . . . . . . 14
8. Matroska Schema . . . . . . . . . . . . . . . . . . . . . . . 22
8.1. EBMLMaxIDLength Element . . . . . . . . . . . . . . . . . 22
8.2. EBMLMaxSizeLength Element . . . . . . . . . . . . . . . . 23
9. Segment Element . . . . . . . . . . . . . . . . . . . . . . . 23
9.1. SeekHead Element . . . . . . . . . . . . . . . . . . . . 24
9.1.1. Seek Element . . . . . . . . . . . . . . . . . . . . 24
9.2. Info Element . . . . . . . . . . . . . . . . . . . . . . 25
9.2.1. SegmentUID Element . . . . . . . . . . . . . . . . . 25
9.2.2. SegmentFilename Element . . . . . . . . . . . . . . . 26
9.2.3. PrevUID Element . . . . . . . . . . . . . . . . . . . 26
9.2.4. PrevFilename Element . . . . . . . . . . . . . . . . 26
9.2.5. NextUID Element . . . . . . . . . . . . . . . . . . . 27
9.2.6. NextFilename Element . . . . . . . . . . . . . . . . 27
9.2.7. SegmentFamily Element . . . . . . . . . . . . . . . . 28
9.2.8. ChapterTranslate Element . . . . . . . . . . . . . . 28
9.2.9. TimestampScale Element . . . . . . . . . . . . . . . 30
9.2.10. Duration Element . . . . . . . . . . . . . . . . . . 30
9.2.11. DateUTC Element . . . . . . . . . . . . . . . . . . . 30
9.2.12. Title Element . . . . . . . . . . . . . . . . . . . . 31
9.2.13. MuxingApp Element . . . . . . . . . . . . . . . . . . 31
9.2.14. WritingApp Element . . . . . . . . . . . . . . . . . 31
9.3. Cluster Element . . . . . . . . . . . . . . . . . . . . . 32
9.3.1. Timestamp Element . . . . . . . . . . . . . . . . . . 32
9.3.2. SilentTracks Element . . . . . . . . . . . . . . . . 32
9.3.3. Position Element . . . . . . . . . . . . . . . . . . 33
9.3.4. PrevSize Element . . . . . . . . . . . . . . . . . . 33
9.3.5. SimpleBlock Element . . . . . . . . . . . . . . . . . 34
9.3.6. BlockGroup Element . . . . . . . . . . . . . . . . . 34
9.3.7. EncryptedBlock Element . . . . . . . . . . . . . . . 43
9.4. Tracks Element . . . . . . . . . . . . . . . . . . . . . 44
9.4.1. TrackEntry Element . . . . . . . . . . . . . . . . . 44
9.5. Cues Element . . . . . . . . . . . . . . . . . . . . . . 108
9.5.1. CuePoint Element . . . . . . . . . . . . . . . . . . 109
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9.6. Attachments Element . . . . . . . . . . . . . . . . . . . 114
9.6.1. AttachedFile Element . . . . . . . . . . . . . . . . 114
9.7. Chapters Element . . . . . . . . . . . . . . . . . . . . 118
9.7.1. EditionEntry Element . . . . . . . . . . . . . . . . 118
9.8. Tags Element . . . . . . . . . . . . . . . . . . . . . . 127
9.8.1. Tag Element . . . . . . . . . . . . . . . . . . . . . 128
10. Matroska Element Ordering . . . . . . . . . . . . . . . . . . 135
10.1. Top-Level Elements . . . . . . . . . . . . . . . . . . . 135
10.2. CRC-32 . . . . . . . . . . . . . . . . . . . . . . . . . 135
10.3. SeekHead . . . . . . . . . . . . . . . . . . . . . . . . 136
10.4. Cues (index) . . . . . . . . . . . . . . . . . . . . . . 136
10.5. Info . . . . . . . . . . . . . . . . . . . . . . . . . . 136
10.6. Chapters Element . . . . . . . . . . . . . . . . . . . . 136
10.7. Attachments . . . . . . . . . . . . . . . . . . . . . . 137
10.8. Tags . . . . . . . . . . . . . . . . . . . . . . . . . . 137
10.9. Optimum layout from a muxer . . . . . . . . . . . . . . 137
10.10. Optimum layout after editing tags . . . . . . . . . . . 137
10.11. Optimum layout with Cues at the front . . . . . . . . . 138
10.12. Cluster Timestamp . . . . . . . . . . . . . . . . . . . 138
11. Chapters . . . . . . . . . . . . . . . . . . . . . . . . . . 138
11.1. EditionEntry . . . . . . . . . . . . . . . . . . . . . . 139
11.1.1. EditionFlagDefault . . . . . . . . . . . . . . . . . 139
11.1.2. Default Edition . . . . . . . . . . . . . . . . . . 139
11.1.3. EditionFlagOrdered . . . . . . . . . . . . . . . . . 140
11.1.4. ChapterSegmentUID . . . . . . . . . . . . . . . . . 141
11.2. ChapterAtom . . . . . . . . . . . . . . . . . . . . . . 142
11.2.1. ChapterTimeStart . . . . . . . . . . . . . . . . . . 142
11.2.2. ChapterTimeEnd . . . . . . . . . . . . . . . . . . . 142
11.2.3. ChapterFlagHidden . . . . . . . . . . . . . . . . . 143
11.3. Menu features . . . . . . . . . . . . . . . . . . . . . 143
11.4. Chapter Examples . . . . . . . . . . . . . . . . . . . . 144
11.4.1. Example 1 : basic chaptering . . . . . . . . . . . . 144
11.4.2. Example 2 : nested chapters . . . . . . . . . . . . 146
12. Attachments . . . . . . . . . . . . . . . . . . . . . . . . . 149
12.1. Cover Art . . . . . . . . . . . . . . . . . . . . . . . 149
13. Cues . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
13.1. Recommendations . . . . . . . . . . . . . . . . . . . . 150
14. Matroska Streaming . . . . . . . . . . . . . . . . . . . . . 151
14.1. File Access . . . . . . . . . . . . . . . . . . . . . . 151
14.2. Livestreaming . . . . . . . . . . . . . . . . . . . . . 152
15. Unknown elements . . . . . . . . . . . . . . . . . . . . . . 152
16. Default Values . . . . . . . . . . . . . . . . . . . . . . . 153
17. DefaultDecodedFieldDuration . . . . . . . . . . . . . . . . . 153
18. Encryption . . . . . . . . . . . . . . . . . . . . . . . . . 154
19. Image Presentation . . . . . . . . . . . . . . . . . . . . . 154
19.1. Cropping . . . . . . . . . . . . . . . . . . . . . . . . 154
19.2. Rotation . . . . . . . . . . . . . . . . . . . . . . . . 155
20. Matroska versioning . . . . . . . . . . . . . . . . . . . . . 155
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21. MIME Types . . . . . . . . . . . . . . . . . . . . . . . . . 155
22. Segment Position . . . . . . . . . . . . . . . . . . . . . . 156
22.1. Segment Position Exception . . . . . . . . . . . . . . . 156
22.2. Example of Segment Position . . . . . . . . . . . . . . 156
23. Linked Segments . . . . . . . . . . . . . . . . . . . . . . . 157
23.1. Hard Linking . . . . . . . . . . . . . . . . . . . . . . 157
23.2. Medium Linking . . . . . . . . . . . . . . . . . . . . . 159
23.3. Soft Linking . . . . . . . . . . . . . . . . . . . . . . 160
24. Track Flags . . . . . . . . . . . . . . . . . . . . . . . . . 160
24.1. Default flag . . . . . . . . . . . . . . . . . . . . . . 160
24.2. Forced flag . . . . . . . . . . . . . . . . . . . . . . 160
24.3. Hearing-impaired flag . . . . . . . . . . . . . . . . . 160
24.4. Visual-impaired flag . . . . . . . . . . . . . . . . . . 161
24.5. Descriptions flag . . . . . . . . . . . . . . . . . . . 161
24.6. Original flag . . . . . . . . . . . . . . . . . . . . . 161
24.7. Commentary flag . . . . . . . . . . . . . . . . . . . . 161
24.8. Track Operation . . . . . . . . . . . . . . . . . . . . 161
24.9. Overlay Track . . . . . . . . . . . . . . . . . . . . . 162
24.10. Multi-planar and 3D videos . . . . . . . . . . . . . . . 162
25. Default track selection . . . . . . . . . . . . . . . . . . . 163
25.1. Audio Selection . . . . . . . . . . . . . . . . . . . . 163
25.2. Subtitle selection . . . . . . . . . . . . . . . . . . . 164
26. Timestamps . . . . . . . . . . . . . . . . . . . . . . . . . 166
26.1. Timestamp Types . . . . . . . . . . . . . . . . . . . . 166
26.2. Block Timestamps . . . . . . . . . . . . . . . . . . . . 166
26.3. Raw Timestamp . . . . . . . . . . . . . . . . . . . . . 167
26.4. TimestampScale . . . . . . . . . . . . . . . . . . . . . 167
26.5. TimestampScale Rounding . . . . . . . . . . . . . . . . 167
26.6. TrackTimestampScale . . . . . . . . . . . . . . . . . . 169
27. Normative References . . . . . . . . . . . . . . . . . . . . 171
28. Informative References . . . . . . . . . . . . . . . . . . . 172
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 172
1. Introduction
Matroska aims to become THE standard of multimedia container formats.
It was derived from a project called [MCF], but differentiates from
it significantly because it is based on EBML (Extensible Binary Meta
Language) [RFC8794], 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)
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* 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.
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.
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:
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* 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.
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 data parser that interprets the semantics of a
Matroska document and creates a way for programs to use
"Matroska".
"Matroska Player": A "Matroska Reader" with a primary purpose of
playing audiovisual files, including "Matroska" documents.
6. Basis in EBML
Matroska is a Document Type of EBML (Extensible Binary Meta
Language). This specification is dependent on the EBML Specification
[RFC8794]. For an understanding of Matroska's EBML Schema, see in
particular the sections of the EBML Specification covering EBML
Element Types (Section 7), EBML Schema (Section 11.1), and EBML
Structure (Section 3).
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".
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* The "EBMLMaxIDLength" of the "EBML Header" MUST be "4".
* The "EBMLMaxSizeLength" of the "EBML Header" MUST be between "1"
and "8" inclusive.
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 form [ISO639-2] (like
"fre" for french), or such a language code followed by a dash and a
country code for specialities in languages (like "fre-ca" for
Canadian French). The "ISO 639-2 Language Elements" are "Language
Element", "TagLanguage Element", and "ChapLanguage Element".
Starting in Matroska version 4, either [ISO639-2] or [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 2 octets country-codes as in Internet
domains [IANADomains] based on [ISO3166-1] alpha-2 codes.
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:
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+======================+============+===========+=================+
| 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.
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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
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
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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:
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+==========================+=============================+
| 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 |
| xxxx | 2^(20)-1 |
+--------------------------+-----------------------------+
| 0001 xxxx xxxx xxxx xxxx | value -(2^(27)-1) to |
| xxxx xxxx xxxx | 2^(27)-1 |
+--------------------------+-----------------------------+
| 0000 1xxx xxxx xxxx xxxx | value -(2^(34)-1) to |
| xxxx xxxx xxxx xxxx xxxx | 2^(34)-1 |
+--------------------------+-----------------------------+
| 0000 01xx xxxx xxxx xxxx | value -(2^(41)-1) to |
| xxxx xxxx xxxx xxxx xxxx | 2^(41)-1 |
| xxxx xxxx | |
+--------------------------+-----------------------------+
| 0000 001x xxxx xxxx xxxx | value -(2^(48)-1) to |
| xxxx xxxx xxxx xxxx xxxx | 2^(48)-1 |
| 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
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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; see
Section 6.2.3. 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.
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
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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
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
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+========+========+==========================+
| 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"
* "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.
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+-------------+
| 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".
+--------------------------------+
| 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".
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+-------------------------+
| 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
(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.
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+------------------------------------+
| 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".
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The "Chapters Element" lists all of the chapters. Chapters are a way
to set predefined points to jump to in video or audio.
+-----------------------------------------+
| Chapters | Edition | EditionUID |
| | Entry |--------------------|
| | | EditionFlagDefault |
| | |--------------------|
| | | EditionFlagOrdered |
| | |---------------------------------+
| | | ChapterAtom | ChapterUID |
| | | |-------------------|
| | | | ChapterStringUID |
| | | |-------------------|
| | | | ChapterTimeStart |
| | | |-------------------|
| | | | ChapterTimeEnd |
| | | |-------------------|
| | | | ChapterFlagHidden |
| | | |-------------------------------+
| | | | ChapterDisplay | ChapString |
| | | | |--------------|
| | | | | ChapLanguage |
+------------------------------------------------------------------+
Figure 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".
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+--------------------------+
| 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
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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.
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+------------------------------------------------+
| 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.
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+-------------------------------------------+
| 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 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.
8.1. EBMLMaxIDLength Element
name: EBMLMaxIDLength
path: "\EBML\EBMLMaxIDLength"
id: 0x42F2
minOccurs: 1
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maxOccurs: 1
range: 4
default: 4
type: uinteger
8.2. EBMLMaxSizeLength Element
name: EBMLMaxSizeLength
path: "\EBML\EBMLMaxSizeLength"
id: 0x42F3
minOccurs: 1
maxOccurs: 1
range: 1-8
default: 8
type: uinteger
9. Segment Element
name: Segment
path: "\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.
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9.1. SeekHead Element
name: SeekHead
path: "\Segment\SeekHead"
id: 0x114D9B74
maxOccurs: 2
type: master
definition: Contains the Segment Position of other Top-Level
Elements.
9.1.1. Seek Element
name: Seek
path: "\Segment\SeekHead\Seek"
id: 0x4DBB
minOccurs: 1
type: master
definition: Contains a single seek entry to an EBML Element.
9.1.1.1. SeekID Element
name: SeekID
path: "\Segment\SeekHead\Seek\SeekID"
id: 0x53AB
minOccurs: 1
maxOccurs: 1
type: binary
definition: The binary ID corresponding to the Element name.
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9.1.1.2. SeekPosition Element
name: SeekPosition
path: "\Segment\SeekHead\Seek\SeekPosition"
id: 0x53AC
minOccurs: 1
maxOccurs: 1
type: uinteger
definition: The Segment Position of the Element.
9.2. Info Element
name: Info
path: "\Segment\Info"
id: 0x1549A966
minOccurs: 1
maxOccurs: 1
type: master
recurring: 1
definition: Contains general information about the Segment.
9.2.1. SegmentUID Element
name: SegmentUID
path: "\Segment\Info\SegmentUID"
id: 0x73A4
maxOccurs: 1
range: not 0
type: binary
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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.
9.2.2. SegmentFilename Element
name: SegmentFilename
path: "\Segment\Info\SegmentFilename"
id: 0x7384
maxOccurs: 1
type: utf-8
definition: A filename corresponding to this Segment.
9.2.3. PrevUID Element
name: PrevUID
path: "\Segment\Info\PrevUID"
id: 0x3CB923
maxOccurs: 1
type: binary
definition: A unique ID to identify the previous 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 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.
9.2.4. PrevFilename Element
name: PrevFilename
path: "\Segment\Info\PrevFilename"
id: 0x3C83AB
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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.
9.2.5. NextUID Element
name: NextUID
path: "\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.
9.2.6. NextFilename Element
name: NextFilename
path: "\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
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convenience, but NextUID SHOULD be considered authoritative for
identifying the Next Segment.
9.2.7. SegmentFamily Element
name: SegmentFamily
path: "\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.
9.2.8. ChapterTranslate Element
name: ChapterTranslate
path: "\Segment\Info\ChapterTranslate"
id: 0x6924
type: master
definition: A tuple of corresponding ID used by chapter codecs to
represent this Segment.
9.2.8.1. ChapterTranslateEditionUID Element
name: ChapterTranslateEditionUID
path: "\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.
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9.2.8.2. ChapterTranslateCodec Element
name: ChapterTranslateCodec
path: "\Segment\Info\ChapterTranslate\ChapterTranslateCodec"
id: 0x69BF
minOccurs: 1
maxOccurs: 1
type: uinteger
definition: The chapter codec; see Section 9.7.1.4.10.1.
restrictions:
+=======+=================+
| value | label |
+=======+=================+
| 0 | Matroska Script |
+-------+-----------------+
| 1 | DVD-menu |
+-------+-----------------+
Table 9
9.2.8.3. ChapterTranslateID Element
name: ChapterTranslateID
path: "\Segment\Info\ChapterTranslate\ChapterTranslateID"
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; see Section 9.7.1.4.10.1.
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9.2.9. TimestampScale Element
name: TimestampScale
path: "\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).
9.2.10. Duration Element
name: Duration
path: "\Segment\Info\Duration"
id: 0x4489
maxOccurs: 1
range: > 0x0p+0
type: float
definition: Duration of the Segment in nanoseconds based on
TimestampScale.
9.2.11. DateUTC Element
name: DateUTC
path: "\Segment\Info\DateUTC"
id: 0x4461
maxOccurs: 1
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type: date
definition: The date and time that the Segment was created by the
muxing application or library.
9.2.12. Title Element
name: Title
path: "\Segment\Info\Title"
id: 0x7BA9
maxOccurs: 1
type: utf-8
definition: General name of the Segment.
9.2.13. MuxingApp Element
name: MuxingApp
path: "\Segment\Info\MuxingApp"
id: 0x4D80
minOccurs: 1
maxOccurs: 1
type: utf-8
definition: Muxing application or library (example: "libmatroska-
0.4.3").
usage notes: Include the full name of the application or library
followed by the version number.
9.2.14. WritingApp Element
name: WritingApp
path: "\Segment\Info\WritingApp"
id: 0x5741
minOccurs: 1
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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. Cluster Element
name: Cluster
path: "\Segment\Cluster"
id: 0x1F43B675
type: master
unknownsizeallowed: 1
definition: The Top-Level Element containing the (monolithic) Block
structure.
9.3.1. Timestamp Element
name: Timestamp
path: "\Segment\Cluster\Timestamp"
id: 0xE7
minOccurs: 1
maxOccurs: 1
type: uinteger
definition: Absolute timestamp of the cluster (based on
TimestampScale).
9.3.2. SilentTracks Element
name: SilentTracks
path: "\Segment\Cluster\SilentTracks"
id: 0x5854
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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.
9.3.2.1. SilentTrackNumber Element
name: SilentTrackNumber
path: "\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. Position Element
name: Position
path: "\Segment\Cluster\Position"
id: 0xA7
maxOccurs: 1
type: uinteger
definition: The Segment Position of the Cluster in the Segment (0 in
live streams). It might help to resynchronise offset on damaged
streams.
9.3.4. PrevSize Element
name: PrevSize
path: "\Segment\Cluster\PrevSize"
id: 0xAB
maxOccurs: 1
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type: uinteger
definition: Size of the previous Cluster, in octets. Can be useful
for backward playing.
9.3.5. SimpleBlock Element
name: SimpleBlock
path: "\Segment\Cluster\SimpleBlock"
id: 0xA3
type: binary
minver: 2
definition: Similar to Block, see Section 6.2.3, but without all the
extra information, mostly used to reduced overhead when no extra
feature is needed; see Section 6.2.4.4 on SimpleBlock Structure.
9.3.6. BlockGroup Element
name: BlockGroup
path: "\Segment\Cluster\BlockGroup"
id: 0xA0
type: master
definition: Basic container of information containing a single Block
and information specific to that Block.
9.3.6.1. Block Element
name: Block
path: "\Segment\Cluster\BlockGroup\Block"
id: 0xA1
minOccurs: 1
maxOccurs: 1
type: binary
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definition: Block containing the actual data to be rendered and a
timestamp relative to the Cluster Timestamp; see Section 6.2.3 on
Block Structure.
9.3.6.2. BlockVirtual Element
name: BlockVirtual
path: "\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.
9.3.6.3. BlockAdditions Element
name: BlockAdditions
path: "\Segment\Cluster\BlockGroup\BlockAdditions"
id: 0x75A1
maxOccurs: 1
type: master
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.
9.3.6.3.1. BlockMore Element
name: BlockMore
path: "\Segment\Cluster\BlockGroup\BlockAdditions\BlockMore"
id: 0xA6
minOccurs: 1
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type: master
definition: Contain the BlockAdditional and some parameters.
9.3.6.3.1.1. BlockAddID Element
name: BlockAddID
path: "\Segment\Cluster\BlockGroup\BlockAdditions\BlockMore\BlockAdd
ID"
id: 0xEE
minOccurs: 1
maxOccurs: 1
range: not 0
default: 1
type: uinteger
definition: An ID to identify the BlockAdditional level. If
BlockAddIDType of the corresponding block is 0, this value is also
the value of BlockAddIDType for the meaning of the content of
BlockAdditional.
9.3.6.3.1.2. BlockAdditional Element
name: BlockAdditional
path: "\Segment\Cluster\BlockGroup\BlockAdditions\BlockMore\BlockAdd
itional"
id: 0xA5
minOccurs: 1
maxOccurs: 1
type: binary
definition: Interpreted by the codec as it wishes (using the
BlockAddID).
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9.3.6.4. BlockDuration Element
name: BlockDuration
path: "\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:
+==========================+===============================+
| 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 10
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9.3.6.5. ReferencePriority Element
name: ReferencePriority
path: "\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.
9.3.6.6. ReferenceBlock Element
name: ReferenceBlock
path: "\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.
9.3.6.7. ReferenceVirtual Element
name: ReferenceVirtual
path: "\Segment\Cluster\BlockGroup\ReferenceVirtual"
id: 0xFD
maxOccurs: 1
type: integer
minver: 0
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maxver: 0
definition: The Segment Position of the data that would otherwise be
in position of the virtual block.
9.3.6.8. CodecState Element
name: CodecState
path: "\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.
9.3.6.9. DiscardPadding Element
name: DiscardPadding
path: "\Segment\Cluster\BlockGroup\DiscardPadding"
id: 0x75A2
maxOccurs: 1
type: integer
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.
9.3.6.10. Slices Element
name: Slices
path: "\Segment\Cluster\BlockGroup\Slices"
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id: 0x8E
maxOccurs: 1
type: master
definition: Contains slices description.
9.3.6.10.1. TimeSlice Element
name: TimeSlice
path: "\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.
9.3.6.10.1.1. LaceNumber Element
name: LaceNumber
path: "\Segment\Cluster\BlockGroup\Slices\TimeSlice\LaceNumber"
id: 0xCC
maxOccurs: 1
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.
9.3.6.10.1.2. FrameNumber Element
name: FrameNumber
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path: "\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).
9.3.6.10.1.3. BlockAdditionID Element
name: BlockAdditionID
path: "\Segment\Cluster\BlockGroup\Slices\TimeSlice\BlockAdditionID"
id: 0xCB
maxOccurs: 1
default: 0
type: uinteger
minver: 0
maxver: 0
definition: The ID of the BlockAdditional Element (0 is the main
Block).
9.3.6.10.1.4. Delay Element
name: Delay
path: "\Segment\Cluster\BlockGroup\Slices\TimeSlice\Delay"
id: 0xCE
maxOccurs: 1
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default: 0
type: uinteger
minver: 0
maxver: 0
definition: The (scaled) delay to apply to the Element.
9.3.6.10.1.5. SliceDuration Element
name: SliceDuration
path: "\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.
9.3.6.11. ReferenceFrame Element
name: ReferenceFrame
path: "\Segment\Cluster\BlockGroup\ReferenceFrame"
id: 0xC8
maxOccurs: 1
type: master
minver: 0
maxver: 0
definition: Contains information about the last reference frame.
See [DivXTrickTrack].
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9.3.6.11.1. ReferenceOffset Element
name: ReferenceOffset
path: "\Segment\Cluster\BlockGroup\ReferenceFrame\ReferenceOffset"
id: 0xC9
minOccurs: 1
maxOccurs: 1
type: uinteger
minver: 0
maxver: 0
definition: The relative offset, in bytes, from the previous
BlockGroup element for this Smooth FF/RW video track to the
containing BlockGroup element. See [DivXTrickTrack].
9.3.6.11.2. ReferenceTimestamp Element
name: ReferenceTimestamp
path: "\Segment\Cluster\BlockGroup\ReferenceFrame\ReferenceTimestamp
"
id: 0xCA
minOccurs: 1
maxOccurs: 1
type: uinteger
minver: 0
maxver: 0
definition: The timecode of the BlockGroup pointed to by
ReferenceOffset. See [DivXTrickTrack].
9.3.7. EncryptedBlock Element
name: EncryptedBlock
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path: "\Segment\Cluster\EncryptedBlock"
id: 0xAF
type: binary
minver: 0
maxver: 0
definition: Similar to SimpleBlock, see Section 6.2.4.4, but the
data inside the Block are Transformed (encrypt and/or signed).
9.4. Tracks Element
name: Tracks
path: "\Segment\Tracks"
id: 0x1654AE6B
maxOccurs: 1
type: master
recurring: 1
definition: A Top-Level Element of information with many tracks
described.
9.4.1. TrackEntry Element
name: TrackEntry
path: "\Segment\Tracks\TrackEntry"
id: 0xAE
minOccurs: 1
type: master
definition: Describes a track with all Elements.
9.4.1.1. TrackNumber Element
name: TrackNumber
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path: "\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).
9.4.1.2. TrackUID Element
name: TrackUID
path: "\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
the same when making a direct stream copy of the Track to another
file.
9.4.1.3. TrackType Element
name: TrackType
path: "\Segment\Tracks\TrackEntry\TrackType"
id: 0x83
minOccurs: 1
maxOccurs: 1
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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 11
9.4.1.4. FlagEnabled Element
name: FlagEnabled
path: "\Segment\Tracks\TrackEntry\FlagEnabled"
id: 0xB9
minOccurs: 1
maxOccurs: 1
range: 0-1
default: 1
type: uinteger
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minver: 2
definition: Set to 1 if the track is usable. It is possible to turn
a not usable track into a usable track using chapter codecs or
control tracks.
9.4.1.5. FlagDefault Element
name: FlagDefault
path: "\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
eligible for automatic selection by the player; see Section 25 for
more details.
9.4.1.6. FlagForced Element
name: FlagForced
path: "\Segment\Tracks\TrackEntry\FlagForced"
id: 0x55AA
minOccurs: 1
maxOccurs: 1
range: 0-1
default: 0
type: uinteger
definition: Applies only to subtitles. Set if that track SHOULD be
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eligible for automatic selection by the player if it matches the
user's language preference, even if the user's preferences would
normally not enable subtitles with the selected audio track; this
can be used for tracks containing only translations of foreign-
language audio or onscreen text. See Section 25 for more details.
9.4.1.7. FlagHearingImpaired Element
name: FlagHearingImpaired
path: "\Segment\Tracks\TrackEntry\FlagHearingImpaired"
id: 0x55AB
maxOccurs: 1
range: 0-1
type: uinteger
definition: Set to 1 if that track is suitable for users with
hearing impairments, set to 0 if it is unsuitable for users with
hearing impairments.
9.4.1.8. FlagVisualImpaired Element
name: FlagVisualImpaired
path: "\Segment\Tracks\TrackEntry\FlagVisualImpaired"
id: 0x55AC
maxOccurs: 1
range: 0-1
type: uinteger
definition: Set to 1 if that track is suitable for users with visual
impairments, set to 0 if it is unsuitable for users with visual
impairments.
9.4.1.9. FlagTextDescriptions Element
name: FlagTextDescriptions
path: "\Segment\Tracks\TrackEntry\FlagTextDescriptions"
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id: 0x55AD
maxOccurs: 1
range: 0-1
type: uinteger
definition: Set to 1 if that track contains textual descriptions of
video content, set to 0 if that track does not contain textual
descriptions of video content.
9.4.1.10. FlagOriginal Element
name: FlagOriginal
path: "\Segment\Tracks\TrackEntry\FlagOriginal"
id: 0x55AE
maxOccurs: 1
range: 0-1
type: uinteger
definition: Set to 1 if that track is in the content's original
language, set to 0 if it is a translation.
9.4.1.11. FlagCommentary Element
name: FlagCommentary
path: "\Segment\Tracks\TrackEntry\FlagCommentary"
id: 0x55AF
maxOccurs: 1
range: 0-1
type: uinteger
definition: Set to 1 if that track contains commentary, set to 0 if
it does not contain commentary.
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9.4.1.12. FlagLacing Element
name: FlagLacing
path: "\Segment\Tracks\TrackEntry\FlagLacing"
id: 0x9C
minOccurs: 1
maxOccurs: 1
range: 0-1
default: 1
type: uinteger
definition: Set to 1 if the track MAY contain blocks using lacing.
9.4.1.13. MinCache Element
name: MinCache
path: "\Segment\Tracks\TrackEntry\MinCache"
id: 0x6DE7
minOccurs: 1
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.
9.4.1.14. MaxCache Element
name: MaxCache
path: "\Segment\Tracks\TrackEntry\MaxCache"
id: 0x6DF8
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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.
9.4.1.15. DefaultDuration Element
name: DefaultDuration
path: "\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).
9.4.1.16. DefaultDecodedFieldDuration Element
name: DefaultDecodedFieldDuration
path: "\Segment\Tracks\TrackEntry\DefaultDecodedFieldDuration"
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 Section 17 for more information
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9.4.1.17. TrackTimestampScale Element
name: TrackTimestampScale
path: "\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).
9.4.1.18. TrackOffset Element
name: TrackOffset
path: "\Segment\Tracks\TrackEntry\TrackOffset"
id: 0x537F
maxOccurs: 1
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.
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9.4.1.19. MaxBlockAdditionID Element
name: MaxBlockAdditionID
path: "\Segment\Tracks\TrackEntry\MaxBlockAdditionID"
id: 0x55EE
minOccurs: 1
maxOccurs: 1
default: 0
type: uinteger
definition: The maximum value of BlockAddID (Section 9.3.6.3.1.1).
A value 0 means there is no BlockAdditions (Section 9.3.6.3) for
this track.
9.4.1.20. BlockAdditionMapping Element
name: BlockAdditionMapping
path: "\Segment\Tracks\TrackEntry\BlockAdditionMapping"
id: 0x41E4
type: master
minver: 4
definition: Contains elements that extend the track format, by
adding content either to each frame, with BlockAddID
(Section 9.3.6.3.1.1), or to the track as a whole with
BlockAddIDExtraData.
9.4.1.20.1. BlockAddIDValue Element
name: BlockAddIDValue
path: "\Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDVal
ue"
id: 0x41F0
maxOccurs: 1
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range: >=2
type: uinteger
minver: 4
definition: If the track format extension needs content beside
frames, the value refers to the BlockAddID (Section 9.3.6.3.1.1),
value being described. To keep MaxBlockAdditionID as low as
possible, small values SHOULD be used.
9.4.1.20.2. BlockAddIDName Element
name: BlockAddIDName
path: "\Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDNam
e"
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.
9.4.1.20.3. BlockAddIDType Element
name: BlockAddIDType
path: "\Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDTyp
e"
id: 0x41E7
minOccurs: 1
maxOccurs: 1
default: 0
type: uinteger
minver: 4
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definition: Stores the registered identifer of the Block Additional
Mapping to define how the BlockAdditional data should be handled.
9.4.1.20.4. BlockAddIDExtraData Element
name: BlockAddIDExtraData
path: "\Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDExt
raData"
id: 0x41ED
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.
9.4.1.21. Name Element
name: Name
path: "\Segment\Tracks\TrackEntry\Name"
id: 0x536E
maxOccurs: 1
type: utf-8
definition: A human-readable track name.
9.4.1.22. Language Element
name: Language
path: "\Segment\Tracks\TrackEntry\Language"
id: 0x22B59C
minOccurs: 1
maxOccurs: 1
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default: eng
type: string
definition: Specifies the language of the track in the Matroska
languages form; see Section 6.2.1 on language codes. This Element
MUST be ignored if the LanguageIETF Element is used in the same
TrackEntry.
9.4.1.23. LanguageIETF Element
name: LanguageIETF
path: "\Segment\Tracks\TrackEntry\LanguageIETF"
id: 0x22B59D
maxOccurs: 1
type: string
minver: 4
definition: Specifies the language of the track according to [BCP47]
and using the IANA Language Subtag Registry [IANALangRegistry].
If this Element is used, then any Language Elements used in the
same TrackEntry MUST be ignored.
9.4.1.24. CodecID Element
name: CodecID
path: "\Segment\Tracks\TrackEntry\CodecID"
id: 0x86
minOccurs: 1
maxOccurs: 1
type: string
definition: An ID corresponding to the codec, see
[I-D.ietf-cellar-codec] for more info.
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9.4.1.25. CodecPrivate Element
name: CodecPrivate
path: "\Segment\Tracks\TrackEntry\CodecPrivate"
id: 0x63A2
maxOccurs: 1
type: binary
definition: Private data only known to the codec.
9.4.1.26. CodecName Element
name: CodecName
path: "\Segment\Tracks\TrackEntry\CodecName"
id: 0x258688
maxOccurs: 1
type: utf-8
definition: A human-readable string specifying the codec.
9.4.1.27. AttachmentLink Element
name: AttachmentLink
path: "\Segment\Tracks\TrackEntry\AttachmentLink"
id: 0x7446
maxOccurs: 1
range: not 0
type: uinteger
maxver: 3
definition: The UID of an attachment that is used by this codec.
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9.4.1.28. CodecSettings Element
name: CodecSettings
path: "\Segment\Tracks\TrackEntry\CodecSettings"
id: 0x3A9697
maxOccurs: 1
type: utf-8
minver: 0
maxver: 0
definition: A string describing the encoding setting used.
9.4.1.29. CodecInfoURL Element
name: CodecInfoURL
path: "\Segment\Tracks\TrackEntry\CodecInfoURL"
id: 0x3B4040
type: string
minver: 0
maxver: 0
definition: A URL to find information about the codec used.
9.4.1.30. CodecDownloadURL Element
name: CodecDownloadURL
path: "\Segment\Tracks\TrackEntry\CodecDownloadURL"
id: 0x26B240
type: string
minver: 0
maxver: 0
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definition: A URL to download about the codec used.
9.4.1.31. CodecDecodeAll Element
name: CodecDecodeAll
path: "\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.
9.4.1.32. TrackOverlay Element
name: TrackOverlay
path: "\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 Section 9.3.2 on SilentTracks, the overlay track
SHOULD be used instead. The order of multiple TrackOverlay
matters, the first one is the one that SHOULD be used. If not
found it SHOULD be the second, etc.
9.4.1.33. CodecDelay Element
name: CodecDelay
path: "\Segment\Tracks\TrackEntry\CodecDelay"
id: 0x56AA
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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.
9.4.1.34. SeekPreRoll Element
name: SeekPreRoll
path: "\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.
9.4.1.35. TrackTranslate Element
name: TrackTranslate
path: "\Segment\Tracks\TrackEntry\TrackTranslate"
id: 0x6624
type: master
definition: The track identification for the given Chapter Codec.
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9.4.1.35.1. TrackTranslateEditionUID Element
name: TrackTranslateEditionUID
path: "\Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateEditi
onUID"
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.
9.4.1.35.2. TrackTranslateCodec Element
name: TrackTranslateCodec
path: "\Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateCodec
"
id: 0x66BF
minOccurs: 1
maxOccurs: 1
type: uinteger
definition: The chapter codec; see Section 9.7.1.4.10.1.
restrictions:
+=======+=================+
| value | label |
+=======+=================+
| 0 | Matroska Script |
+-------+-----------------+
| 1 | DVD-menu |
+-------+-----------------+
Table 12
9.4.1.35.3. TrackTranslateTrackID Element
name: TrackTranslateTrackID
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path: "\Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateTrack
ID"
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; see Section 9.7.1.4.10.1.
9.4.1.36. Video Element
name: Video
path: "\Segment\Tracks\TrackEntry\Video"
id: 0xE0
maxOccurs: 1
type: master
definition: Video settings.
9.4.1.36.1. FlagInterlaced Element
name: FlagInterlaced
path: "\Segment\Tracks\TrackEntry\Video\FlagInterlaced"
id: 0x9A
minOccurs: 1
maxOccurs: 1
range: 0-2
default: 0
type: uinteger
minver: 2
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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 13
9.4.1.36.2. FieldOrder Element
name: FieldOrder
path: "\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:
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+===================+==============+===============================+
| 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 14
9.4.1.36.3. StereoMode Element
name: StereoMode
path: "\Segment\Tracks\TrackEntry\Video\StereoMode"
id: 0x53B8
maxOccurs: 1
default: 0
type: uinteger
minver: 3
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definition: Stereo-3D video mode. There are some more details in
Section 24.10.
restrictions:
+=======+===================================================+
| 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 15
9.4.1.36.4. AlphaMode Element
name: AlphaMode
path: "\Segment\Tracks\TrackEntry\Video\AlphaMode"
id: 0x53C0
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maxOccurs: 1
default: 0
type: uinteger
minver: 3
definition: Alpha Video Mode. Presence of this Element indicates
that the BlockAdditional Element could contain Alpha data.
9.4.1.36.5. OldStereoMode Element
name: OldStereoMode
path: "\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 16
9.4.1.36.6. PixelWidth Element
name: PixelWidth
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path: "\Segment\Tracks\TrackEntry\Video\PixelWidth"
id: 0xB0
minOccurs: 1
maxOccurs: 1
range: not 0
type: uinteger
definition: Width of the encoded video frames in pixels.
9.4.1.36.7. PixelHeight Element
name: PixelHeight
path: "\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.
9.4.1.36.8. PixelCropBottom Element
name: PixelCropBottom
path: "\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.
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9.4.1.36.9. PixelCropTop Element
name: PixelCropTop
path: "\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.
9.4.1.36.10. PixelCropLeft Element
name: PixelCropLeft
path: "\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.
9.4.1.36.11. PixelCropRight Element
name: PixelCropRight
path: "\Segment\Tracks\TrackEntry\Video\PixelCropRight"
id: 0x54DD
maxOccurs: 1
default: 0
type: uinteger
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definition: The number of video pixels to remove on the right of the
image.
9.4.1.36.12. DisplayWidth Element
name: DisplayWidth
path: "\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 17
9.4.1.36.13. DisplayHeight Element
name: DisplayHeight
path: "\Segment\Tracks\TrackEntry\Video\DisplayHeight"
id: 0x54BA
maxOccurs: 1
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range: not 0
default: see implementation notes
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 18
9.4.1.36.14. DisplayUnit Element
name: DisplayUnit
path: "\Segment\Tracks\TrackEntry\Video\DisplayUnit"
id: 0x54B2
maxOccurs: 1
default: 0
type: uinteger
definition: How DisplayWidth & DisplayHeight are interpreted.
restrictions:
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+=======+======================+
| value | label |
+=======+======================+
| 0 | pixels |
+-------+----------------------+
| 1 | centimeters |
+-------+----------------------+
| 2 | inches |
+-------+----------------------+
| 3 | display aspect ratio |
+-------+----------------------+
| 4 | unknown |
+-------+----------------------+
Table 19
9.4.1.36.15. AspectRatioType Element
name: AspectRatioType
path: "\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 20
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9.4.1.36.16. ColourSpace Element
name: ColourSpace
path: "\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 21
9.4.1.36.17. GammaValue Element
name: GammaValue
path: "\Segment\Tracks\TrackEntry\Video\GammaValue"
id: 0x2FB523
maxOccurs: 1
range: > 0x0p+0
type: float
minver: 0
maxver: 0
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definition: Gamma Value.
9.4.1.36.18. FrameRate Element
name: FrameRate
path: "\Segment\Tracks\TrackEntry\Video\FrameRate"
id: 0x2383E3
maxOccurs: 1
range: > 0x0p+0
type: float
minver: 0
maxver: 0
definition: Number of frames per second. This value is
Informational only. It is intended for constant frame rate
streams, and SHOULD NOT be used for a variable frame rate
TrackEntry.
9.4.1.36.19. Colour Element
name: Colour
path: "\Segment\Tracks\TrackEntry\Video\Colour"
id: 0x55B0
maxOccurs: 1
type: master
minver: 4
definition: Settings describing the colour format.
9.4.1.36.19.1. MatrixCoefficients Element
name: MatrixCoefficients
path: "\Segment\Tracks\TrackEntry\Video\Colour\MatrixCoefficients"
id: 0x55B1
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maxOccurs: 1
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:
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+=======+=======================================+
| 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 22
9.4.1.36.19.2. BitsPerChannel Element
name: BitsPerChannel
path: "\Segment\Tracks\TrackEntry\Video\Colour\BitsPerChannel"
id: 0x55B2
maxOccurs: 1
default: 0
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type: uinteger
minver: 4
definition: Number of decoded bits per channel. A value of 0
indicates that the BitsPerChannel is unspecified.
9.4.1.36.19.3. ChromaSubsamplingHorz Element
name: ChromaSubsamplingHorz
path: "\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.
9.4.1.36.19.4. ChromaSubsamplingVert Element
name: ChromaSubsamplingVert
path: "\Segment\Tracks\TrackEntry\Video\Colour\ChromaSubsamplingVert
"
id: 0x55B4
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.
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9.4.1.36.19.5. CbSubsamplingHorz Element
name: CbSubsamplingHorz
path: "\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.
9.4.1.36.19.6. CbSubsamplingVert Element
name: CbSubsamplingVert
path: "\Segment\Tracks\TrackEntry\Video\Colour\CbSubsamplingVert"
id: 0x55B6
maxOccurs: 1
type: uinteger
minver: 4
definition: The amount of pixels to remove in the Cb channel for
every pixel not removed vertically. This is additive with
ChromaSubsamplingVert.
9.4.1.36.19.7. ChromaSitingHorz Element
name: ChromaSitingHorz
path: "\Segment\Tracks\TrackEntry\Video\Colour\ChromaSitingHorz"
id: 0x55B7
maxOccurs: 1
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default: 0
type: uinteger
minver: 4
definition: How chroma is subsampled horizontally.
restrictions:
+=======+=================+
| value | label |
+=======+=================+
| 0 | unspecified |
+-------+-----------------+
| 1 | left collocated |
+-------+-----------------+
| 2 | half |
+-------+-----------------+
Table 23
9.4.1.36.19.8. ChromaSitingVert Element
name: ChromaSitingVert
path: "\Segment\Tracks\TrackEntry\Video\Colour\ChromaSitingVert"
id: 0x55B8
maxOccurs: 1
default: 0
type: uinteger
minver: 4
definition: How chroma is subsampled vertically.
restrictions:
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+=======+================+
| value | label |
+=======+================+
| 0 | unspecified |
+-------+----------------+
| 1 | top collocated |
+-------+----------------+
| 2 | half |
+-------+----------------+
Table 24
9.4.1.36.19.9. Range Element
name: Range
path: "\Segment\Tracks\TrackEntry\Video\Colour\Range"
id: 0x55B9
maxOccurs: 1
default: 0
type: uinteger
minver: 4
definition: Clipping of the color ranges.
restrictions:
+=======+=========================================================+
| value | label |
+=======+=========================================================+
| 0 | unspecified |
+-------+---------------------------------------------------------+
| 1 | broadcast range |
+-------+---------------------------------------------------------+
| 2 | full range (no clipping) |
+-------+---------------------------------------------------------+
| 3 | defined by MatrixCoefficients / TransferCharacteristics |
+-------+---------------------------------------------------------+
Table 25
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9.4.1.36.19.10. TransferCharacteristics Element
name: TransferCharacteristics
path: "\Segment\Tracks\TrackEntry\Video\Colour\TransferCharacteristi
cs"
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:
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+=======+=======================================+
| 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 26
9.4.1.36.19.11. Primaries Element
name: Primaries
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path: "\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:
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+=======+========================================+
| 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 27
9.4.1.36.19.12. MaxCLL Element
name: MaxCLL
path: "\Segment\Tracks\TrackEntry\Video\Colour\MaxCLL"
id: 0x55BC
maxOccurs: 1
type: uinteger
minver: 4
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definition: Maximum brightness of a single pixel (Maximum Content
Light Level) in candelas per square meter (cd/m^(2)).
9.4.1.36.19.13. MaxFALL Element
name: MaxFALL
path: "\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)).
9.4.1.36.19.14. MasteringMetadata Element
name: MasteringMetadata
path: "\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata"
id: 0x55D0
maxOccurs: 1
type: master
minver: 4
definition: SMPTE 2086 mastering data.
9.4.1.36.19.15. PrimaryRChromaticityX Element
name: PrimaryRChromaticityX
path: "\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Pri
maryRChromaticityX"
id: 0x55D1
maxOccurs: 1
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range: 0-1
type: float
minver: 4
definition: Red X chromaticity coordinate, as defined by CIE 1931.
9.4.1.36.19.16. PrimaryRChromaticityY Element
name: PrimaryRChromaticityY
path: "\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Pri
maryRChromaticityY"
id: 0x55D2
maxOccurs: 1
range: 0-1
type: float
minver: 4
definition: Red Y chromaticity coordinate, as defined by CIE 1931.
9.4.1.36.19.17. PrimaryGChromaticityX Element
name: PrimaryGChromaticityX
path: "\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Pri
maryGChromaticityX"
id: 0x55D3
maxOccurs: 1
range: 0-1
type: float
minver: 4
definition: Green X chromaticity coordinate, as defined by CIE 1931.
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9.4.1.36.19.18. PrimaryGChromaticityY Element
name: PrimaryGChromaticityY
path: "\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Pri
maryGChromaticityY"
id: 0x55D4
maxOccurs: 1
range: 0-1
type: float
minver: 4
definition: Green Y chromaticity coordinate, as defined by CIE 1931.
9.4.1.36.19.19. PrimaryBChromaticityX Element
name: PrimaryBChromaticityX
path: "\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Pri
maryBChromaticityX"
id: 0x55D5
maxOccurs: 1
range: 0-1
type: float
minver: 4
definition: Blue X chromaticity coordinate, as defined by CIE 1931.
9.4.1.36.19.20. PrimaryBChromaticityY Element
name: PrimaryBChromaticityY
path: "\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Pri
maryBChromaticityY"
id: 0x55D6
maxOccurs: 1
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range: 0-1
type: float
minver: 4
definition: Blue Y chromaticity coordinate, as defined by CIE 1931.
9.4.1.36.19.21. WhitePointChromaticityX Element
name: WhitePointChromaticityX
path: "\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Whi
tePointChromaticityX"
id: 0x55D7
maxOccurs: 1
range: 0-1
type: float
minver: 4
definition: White X chromaticity coordinate, as defined by CIE 1931.
9.4.1.36.19.22. WhitePointChromaticityY Element
name: WhitePointChromaticityY
path: "\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Whi
tePointChromaticityY"
id: 0x55D8
maxOccurs: 1
range: 0-1
type: float
minver: 4
definition: White Y chromaticity coordinate, as defined by CIE 1931.
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9.4.1.36.19.23. LuminanceMax Element
name: LuminanceMax
path: "\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Lum
inanceMax"
id: 0x55D9
maxOccurs: 1
range: >= 0x0p+0
type: float
minver: 4
definition: Maximum luminance. Represented in candelas per square
meter (cd/m^(2)).
9.4.1.36.19.24. LuminanceMin Element
name: LuminanceMin
path: "\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Lum
inanceMin"
id: 0x55DA
maxOccurs: 1
range: >= 0x0p+0
type: float
minver: 4
definition: Minimum luminance. Represented in candelas per square
meter (cd/m^(2)).
9.4.1.36.20. Projection Element
name: Projection
path: "\Segment\Tracks\TrackEntry\Video\Projection"
id: 0x7670
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maxOccurs: 1
type: master
minver: 4
definition: Describes the video projection details. Used to render
spherical and VR videos.
9.4.1.36.20.1. ProjectionType Element
name: ProjectionType
path: "\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 28
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9.4.1.36.20.2. ProjectionPrivate Element
name: ProjectionPrivate
path: "\Segment\Tracks\TrackEntry\Video\Projection\ProjectionPrivate
"
id: 0x7672
maxOccurs: 1
type: binary
minver: 4
definition: Private data that only applies to a specific projection.
* If "ProjectionType" equals 0 (Rectangular), then this element must
not be present.
* If "ProjectionType" equals 1 (Equirectangular), then this element
must be present and contain the same binary data that would be
stored inside an ISOBMFF Equirectangular Projection Box ('equi').
* If "ProjectionType" equals 2 (Cubemap), then this element must be
present and contain the same binary data that would be stored
inside an ISOBMFF Cubemap Projection Box ('cbmp').
* If "ProjectionType" equals 3 (Mesh), then this element must be
present and contain the same binary data that would be stored
inside an ISOBMFF Mesh Projection Box ('mshp').
usage notes: ISOBMFF box size and fourcc fields are not included in
the binary data, but the FullBox version and flag fields are.
This is to avoid redundant framing information while preserving
versioning and semantics between the two container formats.
9.4.1.36.20.3. ProjectionPoseYaw Element
name: ProjectionPoseYaw
path: "\Segment\Tracks\TrackEntry\Video\Projection\ProjectionPoseYaw
"
id: 0x7673
minOccurs: 1
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maxOccurs: 1
default: 0x0p+0
type: float
minver: 4
definition: Specifies a yaw rotation to the projection.
Value represents a clockwise rotation, in degrees, around the up
vector. This rotation must be applied before any
"ProjectionPosePitch" or "ProjectionPoseRoll" rotations. The value
of this field should be in the -180 to 180 degree range.
9.4.1.36.20.4. ProjectionPosePitch Element
name: ProjectionPosePitch
path: "\Segment\Tracks\TrackEntry\Video\Projection\ProjectionPosePit
ch"
id: 0x7674
minOccurs: 1
maxOccurs: 1
default: 0x0p+0
type: float
minver: 4
definition: Specifies a pitch rotation to the projection.
Value represents a counter-clockwise rotation, in degrees, around the
right vector. This rotation must be applied after the
"ProjectionPoseYaw" rotation and before the "ProjectionPoseRoll"
rotation. The value of this field should be in the -90 to 90 degree
range.
9.4.1.36.20.5. ProjectionPoseRoll Element
name: ProjectionPoseRoll
path: "\Segment\Tracks\TrackEntry\Video\Projection\ProjectionPoseRol
l"
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id: 0x7675
minOccurs: 1
maxOccurs: 1
default: 0x0p+0
type: float
minver: 4
definition: Specifies a roll rotation to the projection.
Value represents a counter-clockwise rotation, in degrees, around the
forward vector. This rotation must be applied after the
"ProjectionPoseYaw" and "ProjectionPosePitch" rotations. The value
of this field should be in the -180 to 180 degree range.
9.4.1.37. Audio Element
name: Audio
path: "\Segment\Tracks\TrackEntry\Audio"
id: 0xE1
maxOccurs: 1
type: master
definition: Audio settings.
9.4.1.37.1. SamplingFrequency Element
name: SamplingFrequency
path: "\Segment\Tracks\TrackEntry\Audio\SamplingFrequency"
id: 0xB5
minOccurs: 1
maxOccurs: 1
range: > 0x0p+0
default: 0x1.f4p+12
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type: float
definition: Sampling frequency in Hz.
9.4.1.37.2. OutputSamplingFrequency Element
name: OutputSamplingFrequency
path: "\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 29
9.4.1.37.3. Channels Element
name: Channels
path: "\Segment\Tracks\TrackEntry\Audio\Channels"
id: 0x9F
minOccurs: 1
maxOccurs: 1
range: not 0
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default: 1
type: uinteger
definition: Numbers of channels in the track.
9.4.1.37.4. ChannelPositions Element
name: ChannelPositions
path: "\Segment\Tracks\TrackEntry\Audio\ChannelPositions"
id: 0x7D7B
maxOccurs: 1
type: binary
minver: 0
maxver: 0
definition: Table of horizontal angles for each successive channel.
9.4.1.37.5. BitDepth Element
name: BitDepth
path: "\Segment\Tracks\TrackEntry\Audio\BitDepth"
id: 0x6264
maxOccurs: 1
range: not 0
type: uinteger
definition: Bits per sample, mostly used for PCM.
9.4.1.38. TrackOperation Element
name: TrackOperation
path: "\Segment\Tracks\TrackEntry\TrackOperation"
id: 0xE2
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maxOccurs: 1
type: master
minver: 3
definition: Operation that needs to be applied on tracks to create
this virtual track. For more details look at Section 24.8.
9.4.1.38.1. TrackCombinePlanes Element
name: TrackCombinePlanes
path: "\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
9.4.1.38.1.1. TrackPlane Element
name: TrackPlane
path: "\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes\
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
9.4.1.38.1.2. TrackPlaneUID Element
name: TrackPlaneUID
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path: "\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes\
TrackPlane\TrackPlaneUID"
id: 0xE5
minOccurs: 1
maxOccurs: 1
range: not 0
type: uinteger
minver: 3
definition: The trackUID number of the track representing the plane.
9.4.1.38.1.3. TrackPlaneType Element
name: TrackPlaneType
path: "\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes\
TrackPlane\TrackPlaneType"
id: 0xE6
minOccurs: 1
maxOccurs: 1
type: uinteger
minver: 3
definition: The kind of plane this track corresponds to.
restrictions:
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+=======+============+
| value | label |
+=======+============+
| 0 | left eye |
+-------+------------+
| 1 | right eye |
+-------+------------+
| 2 | background |
+-------+------------+
Table 30
9.4.1.38.2. TrackJoinBlocks Element
name: TrackJoinBlocks
path: "\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
9.4.1.38.2.1. TrackJoinUID Element
name: TrackJoinUID
path: "\Segment\Tracks\TrackEntry\TrackOperation\TrackJoinBlocks\Tra
ckJoinUID"
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.
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9.4.1.39. TrickTrackUID Element
name: TrickTrackUID
path: "\Segment\Tracks\TrackEntry\TrickTrackUID"
id: 0xC0
maxOccurs: 1
type: uinteger
minver: 0
maxver: 0
definition: The TrackUID of the Smooth FF/RW video in the paired
EBML structure corresponding to this video track. See
[DivXTrickTrack].
9.4.1.40. TrickTrackSegmentUID Element
name: TrickTrackSegmentUID
path: "\Segment\Tracks\TrackEntry\TrickTrackSegmentUID"
id: 0xC1
maxOccurs: 1
type: binary
minver: 0
maxver: 0
definition: The SegmentUID of the Segment containing the track
identified by TrickTrackUID. See [DivXTrickTrack].
9.4.1.41. TrickTrackFlag Element
name: TrickTrackFlag
path: "\Segment\Tracks\TrackEntry\TrickTrackFlag"
id: 0xC6
maxOccurs: 1
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default: 0
type: uinteger
minver: 0
maxver: 0
definition: Set to 1 if this video track is a Smooth FF/RW track.
If set to 1, MasterTrackUID and MasterTrackSegUID should must be
present and BlockGroups for this track must contain ReferenceFrame
structures. Otherwise, TrickTrackUID and TrickTrackSegUID must be
present if this track has a corresponding Smooth FF/RW track. See
[DivXTrickTrack].
9.4.1.42. TrickMasterTrackUID Element
name: TrickMasterTrackUID
path: "\Segment\Tracks\TrackEntry\TrickMasterTrackUID"
id: 0xC7
maxOccurs: 1
type: uinteger
minver: 0
maxver: 0
definition: The TrackUID of the video track in the paired EBML
structure that corresponds to this Smooth FF/RW track. See
[DivXTrickTrack].
9.4.1.43. TrickMasterTrackSegmentUID Element
name: TrickMasterTrackSegmentUID
path: "\Segment\Tracks\TrackEntry\TrickMasterTrackSegmentUID"
id: 0xC4
maxOccurs: 1
type: binary
minver: 0
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maxver: 0
definition: The SegmentUID of the Segment containing the track
identified by MasterTrackUID. See [DivXTrickTrack].
9.4.1.44. ContentEncodings Element
name: ContentEncodings
path: "\Segment\Tracks\TrackEntry\ContentEncodings"
id: 0x6D80
maxOccurs: 1
type: master
definition: Settings for several content encoding mechanisms like
compression or encryption.
9.4.1.44.1. ContentEncoding Element
name: ContentEncoding
path: "\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding"
id: 0x6240
minOccurs: 1
type: master
definition: Settings for one content encoding like compression or
encryption.
9.4.1.44.1.1. ContentEncodingOrder Element
name: ContentEncodingOrder
path: "\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\C
ontentEncodingOrder"
id: 0x5031
minOccurs: 1
maxOccurs: 1
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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.
9.4.1.44.1.2. ContentEncodingScope Element
name: ContentEncodingScope
path: "\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\C
ontentEncodingScope"
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 31
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9.4.1.44.1.3. ContentEncodingType Element
name: ContentEncodingType
path: "\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\C
ontentEncodingType"
id: 0x5033
minOccurs: 1
maxOccurs: 1
default: 0
type: uinteger
definition: A value describing what kind of transformation is
applied.
restrictions:
+=======+=============+
| value | label |
+=======+=============+
| 0 | Compression |
+-------+-------------+
| 1 | Encryption |
+-------+-------------+
Table 32
9.4.1.44.1.4. ContentCompression Element
name: ContentCompression
path: "\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\C
ontentCompression"
id: 0x5034
maxOccurs: 1
type: master
definition: Settings describing the compression used. This Element
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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.
9.4.1.44.1.5. ContentCompAlgo Element
name: ContentCompAlgo
path: "\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\C
ontentCompression\ContentCompAlgo"
id: 0x4254
minOccurs: 1
maxOccurs: 1
default: 0
type: uinteger
definition: The compression algorithm used.
restrictions:
+=======+==================+
| value | label |
+=======+==================+
| 0 | zlib |
+-------+------------------+
| 1 | bzlib |
+-------+------------------+
| 2 | lzo1x |
+-------+------------------+
| 3 | Header Stripping |
+-------+------------------+
Table 33
9.4.1.44.1.6. ContentCompSettings Element
name: ContentCompSettings
path: "\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\C
ontentCompression\ContentCompSettings"
id: 0x4255
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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.
9.4.1.44.1.7. ContentEncryption Element
name: ContentEncryption
path: "\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\C
ontentEncryption"
id: 0x5035
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.
9.4.1.44.1.8. ContentEncAlgo Element
name: ContentEncAlgo
path: "\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\C
ontentEncryption\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:
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+=======+=======================+
| value | label |
+=======+=======================+
| 0 | Not encrypted |
+-------+-----------------------+
| 1 | DES - FIPS 46-3 |
+-------+-----------------------+
| 2 | Triple DES - RFC 1851 |
+-------+-----------------------+
| 3 | Twofish |
+-------+-----------------------+
| 4 | Blowfish |
+-------+-----------------------+
| 5 | AES - FIPS 187 |
+-------+-----------------------+
Table 34
9.4.1.44.1.9. ContentEncKeyID Element
name: ContentEncKeyID
path: "\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\C
ontentEncryption\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.
9.4.1.44.1.10. ContentEncAESSettings Element
name: ContentEncAESSettings
path: "\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\C
ontentEncryption\ContentEncAESSettings"
id: 0x47E7
maxOccurs: 1
type: master
minver: 4
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definition: Settings describing the encryption algorithm used. If
"ContentEncAlgo" != 5 this MUST be ignored.
9.4.1.44.1.11. AESSettingsCipherMode Element
name: AESSettingsCipherMode
path: "\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\C
ontentEncryption\ContentEncAESSettings\AESSettingsCipherMode"
id: 0x47E8
minOccurs: 1
maxOccurs: 1
type: uinteger
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 35
9.4.1.44.1.12. ContentSignature Element
name: ContentSignature
path: "\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\C
ontentEncryption\ContentSignature"
id: 0x47E3
maxOccurs: 1
type: binary
definition: A cryptographic signature of the contents.
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9.4.1.44.1.13. ContentSigKeyID Element
name: ContentSigKeyID
path: "\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\C
ontentEncryption\ContentSigKeyID"
id: 0x47E4
maxOccurs: 1
type: binary
definition: This is the ID of the private key the data was signed
with.
9.4.1.44.1.14. ContentSigAlgo Element
name: ContentSigAlgo
path: "\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\C
ontentEncryption\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 36
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9.4.1.44.1.15. ContentSigHashAlgo Element
name: ContentSigHashAlgo
path: "\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\C
ontentEncryption\ContentSigHashAlgo"
id: 0x47E6
maxOccurs: 1
default: 0
type: uinteger
definition: The hash algorithm used for the signature.
restrictions:
+=======+============+
| value | label |
+=======+============+
| 0 | Not signed |
+-------+------------+
| 1 | SHA1-160 |
+-------+------------+
| 2 | MD5 |
+-------+------------+
Table 37
9.5. Cues Element
name: Cues
path: "\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.
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implementation notes:
+===========+====================================================+
| attribute | note |
+===========+====================================================+
| minOccurs | This Element SHOULD be set when the Segment is not |
| | transmitted as a live stream (see #livestreaming). |
+-----------+----------------------------------------------------+
Table 38
9.5.1. CuePoint Element
name: CuePoint
path: "\Segment\Cues\CuePoint"
id: 0xBB
minOccurs: 1
type: master
definition: Contains all information relative to a seek point in the
Segment.
9.5.1.1. CueTime Element
name: CueTime
path: "\Segment\Cues\CuePoint\CueTime"
id: 0xB3
minOccurs: 1
maxOccurs: 1
type: uinteger
definition: Absolute timestamp according to the Segment time base.
9.5.1.2. CueTrackPositions Element
name: CueTrackPositions
path: "\Segment\Cues\CuePoint\CueTrackPositions"
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id: 0xB7
minOccurs: 1
type: master
definition: Contain positions for different tracks corresponding to
the timestamp.
9.5.1.2.1. CueTrack Element
name: CueTrack
path: "\Segment\Cues\CuePoint\CueTrackPositions\CueTrack"
id: 0xF7
minOccurs: 1
maxOccurs: 1
range: not 0
type: uinteger
definition: The track for which a position is given.
9.5.1.2.2. CueClusterPosition Element
name: CueClusterPosition
path: "\Segment\Cues\CuePoint\CueTrackPositions\CueClusterPosition"
id: 0xF1
minOccurs: 1
maxOccurs: 1
type: uinteger
definition: The Segment Position of the Cluster containing the
associated Block.
9.5.1.2.3. CueRelativePosition Element
name: CueRelativePosition
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path: "\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.
9.5.1.2.4. CueDuration Element
name: CueDuration
path: "\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.
9.5.1.2.5. CueBlockNumber Element
name: CueBlockNumber
path: "\Segment\Cues\CuePoint\CueTrackPositions\CueBlockNumber"
id: 0x5378
maxOccurs: 1
range: not 0
default: 1
type: uinteger
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definition: Number of the Block in the specified Cluster.
9.5.1.2.6. CueCodecState Element
name: CueCodecState
path: "\Segment\Cues\CuePoint\CueTrackPositions\CueCodecState"
id: 0xEA
maxOccurs: 1
default: 0
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.
9.5.1.2.7. CueReference Element
name: CueReference
path: "\Segment\Cues\CuePoint\CueTrackPositions\CueReference"
id: 0xDB
type: master
minver: 2
definition: The Clusters containing the referenced Blocks.
9.5.1.2.7.1. CueRefTime Element
name: CueRefTime
path: "\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefT
ime"
id: 0x96
minOccurs: 1
maxOccurs: 1
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type: uinteger
minver: 2
definition: Timestamp of the referenced Block.
9.5.1.2.7.2. CueRefCluster Element
name: CueRefCluster
path: "\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefC
luster"
id: 0x97
minOccurs: 1
maxOccurs: 1
type: uinteger
minver: 0
maxver: 0
definition: The Segment Position of the Cluster containing the
referenced Block.
9.5.1.2.7.3. CueRefNumber Element
name: CueRefNumber
path: "\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefN
umber"
id: 0x535F
maxOccurs: 1
range: not 0
default: 1
type: uinteger
minver: 0
maxver: 0
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definition: Number of the referenced Block of Track X in the
specified Cluster.
9.5.1.2.7.4. CueRefCodecState Element
name: CueRefCodecState
path: "\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefC
odecState"
id: 0xEB
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.
9.6. Attachments Element
name: Attachments
path: "\Segment\Attachments"
id: 0x1941A469
maxOccurs: 1
type: master
definition: Contain attached files.
9.6.1. AttachedFile Element
name: AttachedFile
path: "\Segment\Attachments\AttachedFile"
id: 0x61A7
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minOccurs: 1
type: master
definition: An attached file.
9.6.1.1. FileDescription Element
name: FileDescription
path: "\Segment\Attachments\AttachedFile\FileDescription"
id: 0x467E
maxOccurs: 1
type: utf-8
definition: A human-friendly name for the attached file.
9.6.1.2. FileName Element
name: FileName
path: "\Segment\Attachments\AttachedFile\FileName"
id: 0x466E
minOccurs: 1
maxOccurs: 1
type: utf-8
definition: Filename of the attached file.
9.6.1.3. FileMimeType Element
name: FileMimeType
path: "\Segment\Attachments\AttachedFile\FileMimeType"
id: 0x4660
minOccurs: 1
maxOccurs: 1
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type: string
definition: MIME type of the file.
9.6.1.4. FileData Element
name: FileData
path: "\Segment\Attachments\AttachedFile\FileData"
id: 0x465C
minOccurs: 1
maxOccurs: 1
type: binary
definition: The data of the file.
9.6.1.5. FileUID Element
name: FileUID
path: "\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.
9.6.1.6. FileReferral Element
name: FileReferral
path: "\Segment\Attachments\AttachedFile\FileReferral"
id: 0x4675
maxOccurs: 1
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type: binary
minver: 0
maxver: 0
definition: A binary value that a track/codec can refer to when the
attachment is needed.
9.6.1.7. FileUsedStartTime Element
name: FileUsedStartTime
path: "\Segment\Attachments\AttachedFile\FileUsedStartTime"
id: 0x4661
maxOccurs: 1
type: uinteger
minver: 0
maxver: 0
definition: The timecode at which this optimized font attachment
comes into context, based on the Segment TimecodeScale. This
element is reserved for future use and if written must be the
segment start time. See [DivXWorldFonts].
9.6.1.8. FileUsedEndTime Element
name: FileUsedEndTime
path: "\Segment\Attachments\AttachedFile\FileUsedEndTime"
id: 0x4662
maxOccurs: 1
type: uinteger
minver: 0
maxver: 0
definition: The timecode at which this optimized font attachment
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goes out of context, based on the Segment TimecodeScale. This
element is reserved for future use and if written must be the
segment end time. See [DivXWorldFonts].
9.7. Chapters Element
name: Chapters
path: "\Segment\Chapters"
id: 0x1043A770
maxOccurs: 1
type: master
recurring: 1
definition: A system to define basic menus and partition data. For
more detailed information, look at the Chapters explanation in
Section 11.
9.7.1. EditionEntry Element
name: EditionEntry
path: "\Segment\Chapters\EditionEntry"
id: 0x45B9
minOccurs: 1
type: master
definition: Contains all information about a Segment edition.
9.7.1.1. EditionUID Element
name: EditionUID
path: "\Segment\Chapters\EditionEntry\EditionUID"
id: 0x45BC
maxOccurs: 1
range: not 0
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type: uinteger
definition: A unique ID to identify the edition. It's useful for
tagging an edition.
9.7.1.2. EditionFlagDefault Element
name: EditionFlagDefault
path: "\Segment\Chapters\EditionEntry\EditionFlagDefault"
id: 0x45DB
minOccurs: 1
maxOccurs: 1
range: 0-1
default: 0
type: uinteger
definition: Set to 1 if the edition SHOULD be used as the default
one.
9.7.1.3. EditionFlagOrdered Element
name: EditionFlagOrdered
path: "\Segment\Chapters\EditionEntry\EditionFlagOrdered"
id: 0x45DD
maxOccurs: 1
range: 0-1
default: 0
type: uinteger
definition: Specify if the chapters can be defined multiple times
and the order to play them is enforced.
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9.7.1.4. ChapterAtom Element
name: ChapterAtom
path: "\Segment\Chapters\EditionEntry\+ChapterAtom"
id: 0xB6
minOccurs: 1
type: master
recursive: 1
definition: Contains the atom information to use as the chapter atom
(apply to all tracks).
9.7.1.4.1. ChapterUID Element
name: ChapterUID
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterUID"
id: 0x73C4
minOccurs: 1
maxOccurs: 1
range: not 0
type: uinteger
definition: A unique ID to identify the Chapter.
9.7.1.4.2. ChapterStringUID Element
name: ChapterStringUID
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterStringUID"
id: 0x5654
maxOccurs: 1
type: utf-8
minver: 3
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definition: A unique string ID to identify the Chapter. Use for
WebVTT cue identifier storage [WebVTT].
9.7.1.4.3. ChapterTimeStart Element
name: ChapterTimeStart
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterTimeStart"
id: 0x91
minOccurs: 1
maxOccurs: 1
type: uinteger
definition: Timestamp of the start of Chapter (not scaled).
9.7.1.4.4. ChapterTimeEnd Element
name: ChapterTimeEnd
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterTimeEnd"
id: 0x92
maxOccurs: 1
type: uinteger
definition: Timestamp of the end of Chapter (timestamp excluded, not
scaled). The value MUST be strictly greater than the
"ChapterTimeStart" of the same "ChapterAtom".
9.7.1.4.5. ChapterFlagHidden Element
name: ChapterFlagHidden
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterFlagHidden
"
id: 0x98
minOccurs: 1
maxOccurs: 1
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range: 0-1
default: 0
type: uinteger
definition: Set to 1 if a chapter is hidden. Hidden chapters it
SHOULD NOT be available to the user interface (but still to
Control Tracks; see Section 11.2.3 on Chapter flags).
9.7.1.4.6. ChapterSegmentUID Element
name: ChapterSegmentUID
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterSegmentUID
"
id: 0x6E67
minOccurs: see implementation notes
maxOccurs: 1
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 39
9.7.1.4.7. ChapterSegmentEditionUID Element
name: ChapterSegmentEditionUID
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterSegmentEdi
tionUID"
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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.
9.7.1.4.8. ChapterPhysicalEquiv Element
name: ChapterPhysicalEquiv
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterPhysicalEq
uiv"
id: 0x63C3
maxOccurs: 1
type: uinteger
definition: Specify the physical equivalent of this ChapterAtom like
"DVD" (60) or "SIDE" (50); see Section 6.2.2 for a complete list
of values.
9.7.1.4.9. ChapterDisplay Element
name: ChapterDisplay
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay"
id: 0x80
type: master
definition: Contains all possible strings to use for the chapter
display.
9.7.1.4.9.1. ChapString Element
name: ChapString
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay\Ch
apString"
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id: 0x85
minOccurs: 1
maxOccurs: 1
type: utf-8
definition: Contains the string to use as the chapter atom.
9.7.1.4.9.2. ChapLanguage Element
name: ChapLanguage
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay\Ch
apLanguage"
id: 0x437C
minOccurs: 1
default: eng
type: string
definition: The languages corresponding to the string, in the
bibliographic ISO-639-2 form [ISO639-2]. This Element MUST be
ignored if the ChapLanguageIETF Element is used within the same
ChapterDisplay Element.
9.7.1.4.9.3. ChapLanguageIETF Element
name: ChapLanguageIETF
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay\Ch
apLanguageIETF"
id: 0x437D
type: string
minver: 4
definition: Specifies the language used in the ChapString according
to [BCP47] and using the IANA Language Subtag Registry
[IANALangRegistry]. If this Element is used, then any
ChapLanguage Elements used in the same ChapterDisplay MUST be
ignored.
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9.7.1.4.9.4. ChapCountry Element
name: ChapCountry
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay\Ch
apCountry"
id: 0x437E
type: string
definition: The countries corresponding to the string, same 2 octets
country-codes as in Internet domains [IANADomains] based on
[ISO3166-1] alpha-2 codes. This Element MUST be ignored if the
ChapLanguageIETF Element is used within the same ChapterDisplay
Element.
9.7.1.4.10. ChapProcess Element
name: ChapProcess
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess"
id: 0x6944
type: master
definition: Contains all the commands associated to the Atom.
9.7.1.4.10.1. ChapProcessCodecID Element
name: ChapProcessCodecID
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapP
rocessCodecID"
id: 0x6955
minOccurs: 1
maxOccurs: 1
default: 0
type: uinteger
definition: Contains the type of the codec used for the processing.
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A value of 0 means native Matroska processing (to be defined), a
value of 1 means the DVD command set is used; see Section 11.3 on
DVD menus. More codec IDs can be added later.
9.7.1.4.10.2. ChapProcessPrivate Element
name: ChapProcessPrivate
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapP
rocessPrivate"
id: 0x450D
maxOccurs: 1
type: binary
definition: Some optional data attached to the ChapProcessCodecID
information. For ChapProcessCodecID = 1, it is the "DVD level"
equivalent; see Section 11.3 on DVD menus.
9.7.1.4.10.3. ChapProcessCommand Element
name: ChapProcessCommand
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapP
rocessCommand"
id: 0x6911
type: master
definition: Contains all the commands associated to the Atom.
9.7.1.4.10.4. ChapProcessTime Element
name: ChapProcessTime
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapP
rocessCommand\ChapProcessTime"
id: 0x6922
minOccurs: 1
maxOccurs: 1
type: uinteger
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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 40
9.7.1.4.10.5. ChapProcessData Element
name: ChapProcessData
path: "\Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapP
rocessCommand\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; see Section 11.3 on DVD menus.
9.8. Tags Element
name: Tags
path: "\Segment\Tags"
id: 0x1254C367
type: master
definition: Element containing metadata describing Tracks, Editions,
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Chapters, Attachments, or the Segment as a whole. A list of valid
tags can be found in [I-D.ietf-cellar-tags].
9.8.1. Tag Element
name: Tag
path: "\Segment\Tags\Tag"
id: 0x7373
minOccurs: 1
type: master
definition: A single metadata descriptor.
9.8.1.1. Targets Element
name: Targets
path: "\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.
9.8.1.1.1. TargetTypeValue Element
name: TargetTypeValue
path: "\Segment\Tags\Tag\Targets\TargetTypeValue"
id: 0x68CA
maxOccurs: 1
default: 50
type: uinteger
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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 41
9.8.1.1.2. TargetType Element
name: TargetType
path: "\Segment\Tags\Tag\Targets\TargetType"
id: 0x63CA
maxOccurs: 1
type: string
definition: An informational string that can be used to display the
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logical level of the target like "ALBUM", "TRACK", "MOVIE",
"CHAPTER", etc ; see Section 6.4 of [I-D.ietf-cellar-tags].
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 |
+------------+------------+
| TRACK | TRACK |
+------------+------------+
| SONG | SONG |
+------------+------------+
| CHAPTER | CHAPTER |
+------------+------------+
| SUBTRACK | SUBTRACK |
+------------+------------+
| PART | PART |
+------------+------------+
| MOVEMENT | MOVEMENT |
+------------+------------+
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| SCENE | SCENE |
+------------+------------+
| SHOT | SHOT |
+------------+------------+
Table 42
9.8.1.1.3. TagTrackUID Element
name: TagTrackUID
path: "\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.
9.8.1.1.4. TagEditionUID Element
name: TagEditionUID
path: "\Segment\Tags\Tag\Targets\TagEditionUID"
id: 0x63C9
default: 0
type: uinteger
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.
9.8.1.1.5. TagChapterUID Element
name: TagChapterUID
path: "\Segment\Tags\Tag\Targets\TagChapterUID"
id: 0x63C4
default: 0
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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.
9.8.1.1.6. TagAttachmentUID Element
name: TagAttachmentUID
path: "\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.
9.8.1.2. SimpleTag Element
name: SimpleTag
path: "\Segment\Tags\Tag\+SimpleTag"
id: 0x67C8
minOccurs: 1
type: master
recursive: 1
definition: Contains general information about the target.
9.8.1.2.1. TagName Element
name: TagName
path: "\Segment\Tags\Tag\+SimpleTag\TagName"
id: 0x45A3
minOccurs: 1
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maxOccurs: 1
type: utf-8
definition: The name of the Tag that is going to be stored.
9.8.1.2.2. TagLanguage Element
name: TagLanguage
path: "\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; see Section 6.2.1 on language codes.
This Element MUST be ignored if the TagLanguageIETF Element is
used within the same SimpleTag Element.
9.8.1.2.3. TagLanguageIETF Element
name: TagLanguageIETF
path: "\Segment\Tags\Tag\+SimpleTag\TagLanguageIETF"
id: 0x447B
maxOccurs: 1
type: string
minver: 4
definition: Specifies the language used in the TagString according
to [BCP47] and using the IANA Language Subtag Registry
[IANALangRegistry]. If this Element is used, then any TagLanguage
Elements used in the same SimpleTag MUST be ignored.
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9.8.1.2.4. TagDefault Element
name: TagDefault
path: "\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.
9.8.1.2.5. TagString Element
name: TagString
path: "\Segment\Tags\Tag\+SimpleTag\TagString"
id: 0x4487
maxOccurs: 1
type: utf-8
definition: The value of the Tag.
9.8.1.2.6. TagBinary Element
name: TagBinary
path: "\Segment\Tags\Tag\+SimpleTag\TagBinary"
id: 0x4485
maxOccurs: 1
type: binary
definition: The values of the Tag, if it is binary. Note that this
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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".
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".
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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".
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 is RECOMMENDED to
evaluate the logical linking even before playing. The "Chapters
Element" SHOULD be placed before the first "Tracks Element" and after
the first "Info Element".
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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
* Clusters
* Cues
10.10. Optimum layout after editing tags
* SeekHead
* Info
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* 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".
11. Chapters
The Matroska Chapters system can have multiple "Editions" and each
"Edition" can consist of "Simple Chapters" where a chapter start time
is used as marker in the timeline only. An "Edition" can be more
complex with "Ordered Chapters" where a chapter end time stamp is
additionally used or much more complex with "Linked Chapters". The
Matroska Chapters system can also have a menu structure, borrowed
from the DVD menu system, or have it's own Native Matroska menu
structure.
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11.1. EditionEntry
The "EditionEntry" is also called an "Edition". An "Edition"
contains a set of "Edition" flags and MUST contain at least one
"ChapterAtom Element". Chapters are always inside an "Edition" (or a
Chapter itself part of an "Edition"). Multiple Editions are allowed.
Some of these Editions MAY be ordered and others not.
11.1.1. EditionFlagDefault
Only one "Edition" SHOULD have an "EditionFlagDefault" flag set to
"true".
11.1.2. Default Edition
The "Default Edition" is the "Edition" that a "Matroska Player"
SHOULD use for playback by default.
The first "Edition" with the "EditionFlagDefault" flag set to "true"
is the "Default Edition".
When all "EditionFlagDefault" flags are set to "false", then the
first "Edition" is the "Default Edition".
+===========+=============+=================+
| Edition | FlagDefault | Default Edition |
+===========+=============+=================+
| Edition 1 | true | X |
+-----------+-------------+-----------------+
| Edition 2 | true | |
+-----------+-------------+-----------------+
| Edition 3 | true | |
+-----------+-------------+-----------------+
Table 43: Default edition, all default
+===========+=============+=================+
| Edition | FlagDefault | Default Edition |
+===========+=============+=================+
| Edition 1 | false | X |
+-----------+-------------+-----------------+
| Edition 2 | false | |
+-----------+-------------+-----------------+
| Edition 3 | false | |
+-----------+-------------+-----------------+
Table 44: Default edition, no default
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+===========+=============+=================+
| Edition | FlagDefault | Default Edition |
+===========+=============+=================+
| Edition 1 | false | |
+-----------+-------------+-----------------+
| Edition 2 | true | X |
+-----------+-------------+-----------------+
| Edition 3 | false | |
+-----------+-------------+-----------------+
Table 45: Default edition, with default
11.1.3. EditionFlagOrdered
The "EditionFlagOrdered Flag" is a significant feature as it enables
an "Edition" of "Ordered Chapters" which defines and arranges a
virtual timeline rather than simply labeling points within the
timeline. For example, with "Editions" of "Ordered Chapters" a
single "Matroska file" can present multiple edits of a film without
duplicating content. Alternatively, if a videotape is digitized in
full, one "Ordered Edition" could present the full content (including
colorbars, countdown, slate, a feature presentation, and black
frames), while another "Edition" of "Ordered Chapters" can use
"Chapters" that only mark the intended presentation with the
colorbars and other ancillary 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 Chapter elements only found in
"Ordered Chapters".
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+======================================+
| Ordered Chapter elements |
+======================================+
| ChapterAtom/ChapterSegmentUID |
+--------------------------------------+
| ChapterAtom/ChapterSegmentEditionUID |
+--------------------------------------+
| ChapterAtom/ChapterTrack |
+--------------------------------------+
| ChapterAtom/ChapProcess |
+--------------------------------------+
| Info/SegmentFamily |
+--------------------------------------+
| Info/ChapterTranslate |
+--------------------------------------+
| TrackEntry/TrackTranslate |
+--------------------------------------+
Table 46: elements only found in
ordered chapters
Furthermore there are other EBML "Elements" which could be used if
the "EditionFlagOrdered" flag is set to "true".
11.1.3.1. 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 Segment.
See Section 23 on the Linked Segments for more information about
"Hard Linking", "Soft Linking", and "Medium Linking".
11.1.4. ChapterSegmentUID
The "ChapterSegmentUID" is a binary value and the base element to set
up a "Linked Chapter" in 2 variations: the Linked-Duration linking
and the Linked-Edition linking. For both variations, the following 3
conditions MUST be met:
1. The "EditionFlagOrdered Flag" MUST be true.
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2. The "ChapterSegmentUID" MUST NOT be the "SegmentUID" of its own
"Segment".
3. The linked Segments MUST BE in the same folder.
11.1.4.1. Variation 1: Linked-Duration
Two more conditions MUST be met:
1. "ChapterTimeStart" and "ChapterTimeEnd" timestamps MUST be in the
range of the linked Segment duration.
2. "ChapterSegmentEditionUID" MUST be not set.
A "Matroska Player" MUST play the content of the linked Segment from
the "ChapterTimeStart" until "ChapterTimeEnd" timestamp.
11.1.4.2. Variation 2: Linked-Edition
When the "ChapterSegmentEditionUID" is set to a valid "EditionUID"
from the linked Segment. A "Matroska Player" MUST play these linked
"Edition".
11.2. ChapterAtom
The "ChapterAtom" is also called a "Chapter". A "Chapter" element
can be used recursively. Such a child "Chapter" is called "Nested
Chapter".
11.2.1. ChapterTimeStart
A not scaled timestamp of the start of "Chapter" with nanosecond
accuracy. For "Simple Chapters" this is the position of the chapter
markers in the timeline.
11.2.2. ChapterTimeEnd
A not scaled timestamp of the end of "Chapter" with nanosecond
accuracy. The end timestamp is used when the "EditionFlagOrdered"
flag of the "Edition" is set to "true". The timestamp defined by the
"ChapterTimeEnd" is not part of the "Chapter". A "Matroska Player"
calculates the duration of this "Chapter" using the difference
between the "ChapterTimeEnd" and "ChapterTimeStart". The end
timestamp MUST be greater than the start timestamp otherwise the
duration would be negative which is illegal. If the duration of a
"Chapter" is 0, this "Chapter" MUST be ignored.
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+===========+=================+===============+=============+
| Chapter | Start timestamp | End timestamp | Duration |
+===========+=================+===============+=============+
| Chapter 1 | 0 | 1000000000 | 1000000000 |
+-----------+-----------------+---------------+-------------+
| Chapter 2 | 1000000000 | 5000000000 | 4000000000 |
+-----------+-----------------+---------------+-------------+
| Chapter 3 | 6000000000 | 6000000000 | 0 (chapter |
| | | | not used) |
+-----------+-----------------+---------------+-------------+
| Chapter 4 | 9000000000 | 8000000000 | -1000000000 |
| | | | (illegal) |
+-----------+-----------------+---------------+-------------+
Table 47
11.2.3. ChapterFlagHidden
Each Chapter "ChapterFlagHidden" flag works independently from parent
chapters. A "Nested Chapter" with "ChapterFlagHidden" flag set to
"false" remains visible even if the "Parent Chapter"
"ChapterFlagHidden" flag is set to "true".
+==========================+===================+=========+
| Chapter + Nested Chapter | ChapterFlagHidden | visible |
+==========================+===================+=========+
| Chapter 1 | false | yes |
+--------------------------+-------------------+---------+
| Nested Chapter 1.1 | false | yes |
+--------------------------+-------------------+---------+
| Nested Chapter 1.2 | true | no |
+--------------------------+-------------------+---------+
| Chapter 2 | true | no |
+--------------------------+-------------------+---------+
| Nested Chapter 2.1 | false | yes |
+--------------------------+-------------------+---------+
| Nested Chapter 2.2 | true | no |
+--------------------------+-------------------+---------+
Table 48
11.3. Menu features
The menu features are handled like a "chapter codec". That means
each codec has a type, some private data and some data in the
chapters.
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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").
The menu system, as well a Chapter Codecs in general, can do actions
on the "Matroska Player" like jumping to another Chapter or Edition,
selecting different tracks and possibly more. The scope of all the
possibilities of Chapter Codecs is not covered in this document as it
depends on the Chapter Codec features and its integration in a
"Matroska Player".
11.4. Chapter Examples
11.4.1. Example 1 : basic chaptering
In this example a movie is split in different chapters. It could
also just be an audio file (album) on which each track corresponds to
a chapter.
* 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 :
<Chapters>
<EditionEntry>
<EditionUID>16603393396715046047</EditionUID>
<ChapterAtom>
<ChapterUID>1193046</ChapterUID>
<ChapterTimeStart>0</ChapterTimeStart>
<ChapterTimeEnd>5000000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Intro</ChapString>
<ChapLanguage>eng</ChapLanguage>
</ChapterDisplay>
<ChapterFlagHidden>0</ChapterFlagHidden>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>2311527</ChapterUID>
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<ChapterTimeStart>5000000000</ChapterTimeStart>
<ChapterTimeEnd>25000000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Before the crime</ChapString>
<ChapLanguage>eng</ChapLanguage>
</ChapterDisplay>
<ChapterDisplay>
<ChapString>Avant le crime</ChapString>
<ChapLanguage>fra</ChapLanguage>
</ChapterDisplay>
<ChapterFlagHidden>0</ChapterFlagHidden>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>3430008</ChapterUID>
<ChapterTimeStart>25000000000</ChapterTimeStart>
<ChapterTimeEnd>27500000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>The crime</ChapString>
<ChapLanguage>eng</ChapLanguage>
</ChapterDisplay>
<ChapterDisplay>
<ChapString>Le crime</ChapString>
<ChapLanguage>fra</ChapLanguage>
</ChapterDisplay>
<ChapterFlagHidden>0</ChapterFlagHidden>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>4548489</ChapterUID>
<ChapterTimeStart>27500000000</ChapterTimeStart>
<ChapterTimeEnd>38000000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>After the crime</ChapString>
<ChapLanguage>eng</ChapLanguage>
</ChapterDisplay>
<ChapterDisplay>
<ChapString>Après le crime</ChapString>
<ChapLanguage>fra</ChapLanguage>
</ChapterDisplay>
<ChapterFlagHidden>0</ChapterFlagHidden>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>5666960</ChapterUID>
<ChapterTimeStart>38000000000</ChapterTimeStart>
<ChapterTimeEnd>43000000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Credits</ChapString>
<ChapLanguage>eng</ChapLanguage>
</ChapterDisplay>
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<ChapterDisplay>
<ChapString>Générique</ChapString>
<ChapLanguage>fra</ChapLanguage>
</ChapterDisplay>
<ChapterFlagHidden>0</ChapterFlagHidden>
</ChapterAtom>
<EditionFlagDefault>0</EditionFlagDefault>
</EditionEntry>
</Chapters>
11.4.2. Example 2 : nested chapters
In this example an (existing) album is split into different chapters,
and one of them contain another splitting.
11.4.2.1. The Micronauts "Bleep To Bleep"
* 00:00 - 12:28 : Baby Wants To Bleep/Rock
- 00:00 - 04:38 : Baby wants to bleep (pt.1)
- 04:38 - 07:12 : Baby wants to rock
- 07:12 - 10:33 : Baby wants to bleep (pt.2)
- 10:33 - 12:28 : Baby wants to bleep (pt.3)
* 12:30 - 19:38 : Bleeper_O+2
* 19:40 - 22:20 : Baby wants to bleep (pt.4)
* 22:22 - 25:18 : Bleep to bleep
* 25:20 - 33:35 : Baby wants to bleep (k)
* 33:37 - 44:28 : Bleeper
<Chapters>
<EditionEntry>
<EditionUID>1281690858003401414</EditionUID>
<ChapterAtom>
<ChapterUID>1</ChapterUID>
<ChapterTimeStart>0</ChapterTimeStart>
<ChapterTimeEnd>748000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Baby wants to Bleep/Rock</ChapString>
<ChapLanguage>eng</ChapLanguage>
</ChapterDisplay>
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<ChapterAtom>
<ChapterUID>2</ChapterUID>
<ChapterTimeStart>0</ChapterTimeStart>
<ChapterTimeEnd>278000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Baby wants to bleep (pt.1)</ChapString>
<ChapLanguage>eng</ChapLanguage>
</ChapterDisplay>
<ChapterFlagHidden>0</ChapterFlagHidden>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>3</ChapterUID>
<ChapterTimeStart>278000000</ChapterTimeStart>
<ChapterTimeEnd>432000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Baby wants to rock</ChapString>
<ChapLanguage>eng</ChapLanguage>
</ChapterDisplay>
<ChapterFlagHidden>0</ChapterFlagHidden>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>4</ChapterUID>
<ChapterTimeStart>432000000</ChapterTimeStart>
<ChapterTimeEnd>633000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Baby wants to bleep (pt.2)</ChapString>
<ChapLanguage>eng</ChapLanguage>
</ChapterDisplay>
<ChapterFlagHidden>0</ChapterFlagHidden>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>5</ChapterUID>
<ChapterTimeStart>633000000</ChapterTimeStart>
<ChapterTimeEnd>748000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Baby wants to bleep (pt.3)</ChapString>
<ChapLanguage>eng</ChapLanguage>
</ChapterDisplay>
<ChapterFlagHidden>0</ChapterFlagHidden>
</ChapterAtom>
<ChapterFlagHidden>0</ChapterFlagHidden>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>6</ChapterUID>
<ChapterTimeStart>750000000</ChapterTimeStart>
<ChapterTimeEnd>1178500000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Bleeper_O+2</ChapString>
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<ChapLanguage>eng</ChapLanguage>
</ChapterDisplay>
<ChapterFlagHidden>0</ChapterFlagHidden>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>7</ChapterUID>
<ChapterTimeStart>1180500000</ChapterTimeStart>
<ChapterTimeEnd>1340000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Baby wants to bleep (pt.4)</ChapString>
<ChapLanguage>eng</ChapLanguage>
</ChapterDisplay>
<ChapterFlagHidden>0</ChapterFlagHidden>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>8</ChapterUID>
<ChapterTimeStart>1342000000</ChapterTimeStart>
<ChapterTimeEnd>1518000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Bleep to bleep</ChapString>
<ChapLanguage>eng</ChapLanguage>
</ChapterDisplay>
<ChapterFlagHidden>0</ChapterFlagHidden>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>9</ChapterUID>
<ChapterTimeStart>1520000000</ChapterTimeStart>
<ChapterTimeEnd>2015000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Baby wants to bleep (k)</ChapString>
<ChapLanguage>eng</ChapLanguage>
</ChapterDisplay>
<ChapterFlagHidden>0</ChapterFlagHidden>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>10</ChapterUID>
<ChapterTimeStart>2017000000</ChapterTimeStart>
<ChapterTimeEnd>2668000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Bleeper</ChapString>
<ChapLanguage>eng</ChapLanguage>
</ChapterDisplay>
<ChapterFlagHidden>0</ChapterFlagHidden>
</ChapterAtom>
<EditionFlagDefault>0</EditionFlagDefault>
</EditionEntry>
</Chapters>
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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).
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.
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+======================+===================+=================+
| FileName | Image Orientation | Pixel Length of |
| | | Smallest Side |
+======================+===================+=================+
| cover.jpg | Portrait or | 600 |
| | square | |
+----------------------+-------------------+-----------------+
| small_cover.png | Portrait or | 120 |
| | square | |
+----------------------+-------------------+-----------------+
| cover_land.png | Landscape | 600 |
+----------------------+-------------------+-----------------+
| small_cover_land.jpg | Landscape | 120 |
+----------------------+-------------------+-----------------+
Table 49
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".
* 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".
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* 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.
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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. 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
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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".
16. 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.
17. 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
* 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")
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18. 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".
19. Image Presentation
19.1. Cropping
The "PixelCrop Elements" ("PixelCropTop", "PixelCropBottom",
"PixelCropRight", and "PixelCropLeft") indicate when, and by how
much, encoded videos frames SHOULD be cropped for display. These
Elements allow edges of the frame that are not intended for display,
such as the sprockets of a full-frame film scan or the VANC area of a
digitized analog videotape, to be stored but hidden. "PixelCropTop"
and "PixelCropBottom" store an integer of how many rows of pixels
SHOULD be cropped from the top and bottom of the image
(respectively). "PixelCropLeft" and "PixelCropRight" store an
integer of how many columns of pixels SHOULD be cropped from the left
and right of the image (respectively). For example, a pillar-boxed
video that stores a 1440x1080 visual image within the center of a
padded 1920x1080 encoded image MAY set both "PixelCropLeft" and
"PixelCropRight" to "240", so that a "Matroska Player" SHOULD crop
off 240 columns of pixels from the left and right of the encoded
image to present the image with the pillar-boxes hidden.
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19.2. Rotation
The ProjectionPoseRoll Element (see Section 9.4.1.36.20.5) 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 9.4.1.36.20) and the
ProjectionPoseRoll Element represents a video track where the image
SHOULD be presentation with a 90 degree counter-clockwise rotation.
<Projection>
<ProjectionPoseRoll>90</ProjectionPoseRoll>
</Projection>
20. 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 in Section 15.
21. MIME Types
There is no IETF endorsed MIME type for Matroska files. These
definitions can be used:
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* .mka : Matroska audio "audio/x-matroska"
* .mkv : Matroska video "video/x-matroska"
* .mk3d : Matroska 3D video "video/x-matroska-3d"
22. 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".
22.1. Segment Position Exception
"Elements" that are defined to store a "Segment Position" MAY define
reserved values to indicate a special meaning.
22.2. 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.
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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'.
23. 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".
23.1. 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.
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+==========+==================+==================+==================+
|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 50
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 51
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 52
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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 53
23.2. 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.
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23.3. 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
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.
24. Track Flags
24.1. Default flag
The "default track" flag is a hint for a "Matroska Player" indicating
that a given track SHOULD be eligible to be automatically selected as
the default track for a given language. If no tracks in a given
language have the default track flag set, then all tracks in that
language are eligible for automatic selection. This can be used to
indicate that a track provides "regular service" suitable for users
with default settings, as opposed to specialized services, such as
commentary, hearing-impaired captions, or descriptive audio.
The "Matroska Player" MAY override the "default track" flag for any
reason, including user preferences to prefer tracks providing
accessibility services.
24.2. Forced flag
The "forced" flag tells the "Matroska Player" that it SHOULD display
this subtitle track, even if user preferences usually would not call
for any subtitles to be displayed alongside the current selected
audio track. This can be used to indicate that a track contains
translations of onscreen text, or of dialogue spoken in a different
language than the track's primary one.
24.3. Hearing-impaired flag
The "hearing impaired" flag tells the "Matroska Player" that it
SHOULD prefer this track when selecting a default track for a
hearing-impaired user, and that it MAY prefer to select a different
track when selecting a default track for a non-hearing-impaired user.
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24.4. Visual-impaired flag
The "visual impaired" flag tells the "Matroska Player" that it SHOULD
prefer this track when selecting a default track for a visually-
impaired user, and that it MAY prefer to select a different track
when selecting a default track for a non-visually-impaired user.
24.5. Descriptions flag
The "descriptions" flag tells the "Matroska Player" that this track
is suitable to play via a text-to-speech system for a visually-
impaired user, and that it SHOULD NOT automatically select this track
when selecting a default track for a non-visually-impaired user.
24.6. Original flag
The "original" flag tells the "Matroska Player" that this track is in
the original language, and that it SHOULD prefer it if configured to
prefer original-language tracks of this track's type.
24.7. Commentary flag
The "commentary" flag tells the "Matroska Player" that this track
contains commentary on the content.
24.8. Track Operation
"TrackOperation" allows combining multiple tracks to make a virtual
one. It uses two separate system to combine tracks. One to create a
3D "composition" (left/right/background planes) and one to simplify
join two tracks together to make a single track.
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
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.
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24.9. 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.
24.10. Multi-planar and 3D videos
There are two different ways to compress 3D videos: have each eye
track in a separate track and have one track have both eyes combined
inside (which is more efficient, compression-wise). Matroska
supports both ways.
For the single track variant, there is the "StereoMode Element",
which defines how planes are assembled in the track (mono or left-
right combined). Odd values of StereoMode means the left plane comes
first for more convenient reading. The pixel count of the track
("PixelWidth"/"PixelHeight") is the raw amount of pixels, for example
3840x1080 for full HD side by side, and the
"DisplayWidth"/"DisplayHeight" in pixels is the amount of pixels for
one plane (1920x1080 for that full HD stream). Old stereo 3D were
displayed using anaglyph (cyan and red 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 Section 24.8 on how TrackOperation works.
The 3D support is still in infancy and may evolve to support more
features.
The StereoMode used to be part of Matroska v2 but it didn't meet the
requirement for multiple tracks. There was also a bug in libmatroska
prior to 0.9.0 that would save/read it as 0x53B9 instead of 0x53B8.
"Matroska Readers" may support these legacy files by checking
Matroska v2 or 0x53B9. The older values were 0: mono, 1: right eye,
2: left eye, 3: both eyes.
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25. Default track selection
This section provides some example sets of Tracks and hypothetical
user settings, along with indications of which ones a similarly-
configured "Matroska Player" SHOULD automatically select for playback
by default in such a situation. A player MAY provide additional
settings with more detailed controls for more nuanced scenarios.
These examples are provided as guidelines to illustrate the intended
usages of the various supported Track flags, and their expected
behaviors.
Track names are shown in English for illustrative purposes; actual
files may have titles in the language of each track, or provide
titles in multiple languages.
25.1. Audio Selection
Example track set:
+===+=====+====+======+========+=======+================+===========+
|No.|Type |Lang|Layout|Original|Default|Other flags |Name |
+===+=====+====+======+========+=======+================+===========+
|1 |Video|und |N/A |N/A |N/A |None | |
+---+-----+----+------+--------+-------+----------------+-----------+
|2 |Audio|eng |5.1 |1 |1 |None | |
+---+-----+----+------+--------+-------+----------------+-----------+
|3 |Audio|eng |2.0 |1 |1 |None | |
+---+-----+----+------+--------+-------+----------------+-----------+
|4 |Audio|eng |2.0 |1 |0 |Visual-impaired |Descriptive|
| | | | | | | |audio |
+---+-----+----+------+--------+-------+----------------+-----------+
|5 |Audio|esp |5.1 |0 |1 |None | |
+---+-----+----+------+--------+-------+----------------+-----------+
|6 |Audio|esp |2.0 |0 |0 |Visual-impaired |Descriptive|
| | | | | | | |audio |
+---+-----+----+------+--------+-------+----------------+-----------+
|7 |Audio|eng |2.0 |1 |0 |Commentary |Director's |
| | | | | | | |Commentary |
+---+-----+----+------+--------+-------+----------------+-----------+
|8 |Audio|eng |2.0 |1 |0 |None |Karaoke |
+---+-----+----+------+--------+-------+----------------+-----------+
Table 54
Here we have a file with 7 audio tracks, of which 5 are in English
and 2 are in Spanish.
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The English tracks all have the Original flag, indicating that
English is the original content language.
Generally the player will first consider the track languages: if the
player has an option to prefer original-language audio and the user
has enabled it, then it should prefer one of the Original-flagged
tracks. If configured to specifically prefer audio tracks in English
or Spanish, the player should select one of the tracks in the
corresponding language. The player may also wish to prefer an
Original-flagged track if no tracks matching any of the user's
explicitly-preferred languages are available.
Two of the tracks have the Visual-impaired flag. If the player has
been configured to prefer such tracks, it should select one;
otherwise, it should avoid them if possible.
If selecting an English track, when other settings have left multiple
possible options, it may be useful to exclude the tracks that lack
the Default flag: here, one provides descriptive service for the
visually impaired (which has its own flag and may be automatically
selected by user configuration, but is unsuitable for users with
default-configured players), one is a commentary track (which has its
own flag, which the player may or may not have specialized handling
for), and the last contains karaoke versions of the music that plays
during the film, which is an unusual specialized audio service that
Matroska has no built-in support for indicating, so it's indicated in
the track name instead. By not setting the Default flag on these
specialized tracks, the file's author hints that they should not be
automatically selected by a default-configured player.
Having narrowed its choices down, our example player now may have to
select between tracks 2 and 3. The only difference between these
tracks is their channel layouts: 2 is 5.1 surround, while 3 is
stereo. If the player is aware that the output device is a pair of
headphones or stereo speakers, it may wish to prefer the stereo mix
automatically. On the other hand, if it knows that the device is a
surround system, it may wish to prefer the surround mix.
If the player finishes analyzing all of the available audio tracks
and finds that multiple seem equally and maximally preferable, it
SHOULD default to the first of the group.
25.2. Subtitle selection
Example track set:
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+===+===========+====+=========+=======+======+==========+==========+
|No.| Type |Lang|Original |Default|Forced| Other | Name |
| | | | | | | flags | |
+===+===========+====+=========+=======+======+==========+==========+
|1 | Video |und |N/A |N/A |N/A | None | |
+---+-----------+----+---------+-------+------+----------+----------+
|2 | Audio |fra |1 |1 |N/A | None | |
+---+-----------+----+---------+-------+------+----------+----------+
|3 | Audio |por |0 |1 |N/A | None | |
+---+-----------+----+---------+-------+------+----------+----------+
|4 | Subtitles |fra |1 |1 |0 | None | |
+---+-----------+----+---------+-------+------+----------+----------+
|5 | Subtitles |fra |1 |0 |0 | Hearing- | Captions |
| | | | | | | impaired | for the |
| | | | | | | | hearing- |
| | | | | | | | impaired |
+---+-----------+----+---------+-------+------+----------+----------+
|6 | Subtitles |por |0 |1 |0 | None | |
+---+-----------+----+---------+-------+------+----------+----------+
|7 | Subtitles |por |0 |0 |1 | None | Signs |
+---+-----------+----+---------+-------+------+----------+----------+
|8 | Subtitles |por |0 |0 |0 | Hearing- | SDH |
| | | | | | | impaired | |
+---+-----------+----+---------+-------+------+----------+----------+
Table 55
Here we have 2 audio tracks and 5 subtitle tracks. As we can see,
French is the original language.
We'll start by discussing the case where the user prefers French (or
Original-language) audio (or has explicitly selected the French audio
track), and also prefers French subtitles.
In this case, if the player isn't configured to display captions when
the audio matches their preferred subtitle languages, the player
doesn't need to select a subtitle track at all.
If the user _has_ indicated that they want captions to be displayed,
the selection simply comes down to whether Hearing-impaired subtitles
are preferred.
The situation for a user who prefers Portuguese subtitles starts out
somewhat analogous. If they select the original French audio (either
by explicit audio language preference, preference for Original-
language tracks, or by explicitly selecting that track), then the
selection once again comes down to the hearing-impaired preference.
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However, the case where the Portuguese audio track is selected has an
important catch: a Forced track in Portuguese is present. This may
contain translations of onscreen text from the video track, or of
portions of the audio that are not translated (music, for instance).
This means that even if the user's preferences wouldn't normally call
for captions here, the Forced track should be selected nonetheless,
rather than selecting no track at all. On the other hand, if the
user's preferences _do_ call for captions, the non-Forced tracks
should be preferred, as the Forced track will not contain captioning
for the dialogue.
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
Section 26.4 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.
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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".
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.
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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
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.
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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".
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
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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
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, see
Section 26.3, 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, see
Section 26.1, of 100 seconds would have a "Raw Timestamp" of
104.66666667 seconds, and so would be stored in that part of the
file.
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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.
27. Normative References
[BCP47] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying
Languages", DOI 10.17487/RFC5646, September 2009,
<https://www.rfc-editor.org/info/rfc5646>.
[I-D.ietf-cellar-codec]
Lhomme, S., Bunkus, M., and D. Rice, "Matroska Media
Container Codec Specifications", Work in Progress,
Internet-Draft, draft-ietf-cellar-codec-05, 19 October
2020,
<https://tools.ietf.org/html/draft-ietf-cellar-codec-05>.
[I-D.ietf-cellar-tags]
Lhomme, S., Bunkus, M., and D. Rice, "Matroska Media
Container Tag Specifications", Work in Progress, Internet-
Draft, draft-ietf-cellar-tags-05, 19 October 2020,
<https://tools.ietf.org/html/draft-ietf-cellar-tags-05>.
[IANADomains]
"IANA Root Zone Database",
<https://www.iana.org/domains/root/db>.
[IANALangRegistry]
"IANA Language Subtag Registry", 28 February 2013,
<https://www.iana.org/assignments/language-subtag-
registry/language-subtag-registry>.
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[ISO3166-1]
International Organization for Standardization, "Codes for
the representation of names of countries and their
subdivisions -- Part 1: Country code", ISO 3166-1:2020,
August 2020, <https://www.iso.org/standard/72482.html>.
[ISO639-2] United States Library Of Congress, "Codes for the
Representation of Names of Languages", ISO 639-2:1998, 21
December 2017, <https://www.loc.gov/standards/iso639-
2/php/code_list.php>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8794] Lhomme, S., Rice, D., and M. Bunkus, "Extensible Binary
Meta Language", RFC 8794, DOI 10.17487/RFC8794, July 2020,
<https://www.rfc-editor.org/info/rfc8794>.
[WebVTT] Pieters, S., Pfeiffer, S., Ed., Jägenstedt, P., and I.
Hickson, "WebVTT Cue Identifier", 4 April 2019,
<https://www.w3.org/TR/webvtt1/#webvtt-cue-identifier>.
28. Informative References
[DivXTrickTrack]
"DivX Trick Track Extensions", 14 December 2010,
<http://web.archive.org/web/20101222001148/
http://labs.divx.com/node/16601>.
[DivXWorldFonts]
"DivX World Fonts Extensions", 14 December 2010,
<http://web.archive.org/web/20110214132246/
http://labs.divx.com/node/16602>.
[MCF] "Media Container Format", 17 July 2002,
<http://mukoli.free.fr/mcf/mcf.html>.
Authors' Addresses
Steve Lhomme
Email: slhomme@matroska.org
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Moritz Bunkus
Email: moritz@bunkus.org
Dave Rice
Email: dave@dericed.com
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