Matroska Media Container Format Specifications
draft-ietf-cellar-matroska-12
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Active".
|
|
|---|---|---|---|
| Authors | Steve Lhomme, Moritz Bunkus, Dave Rice | ||
| Last updated | 2022-08-28 | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Reviews |
GENART Last Call review
(of
-15)
by Elwyn Davies
Almost ready
|
||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Consensus: Waiting for Write-Up | |
| Associated WG milestones |
|
||
| Document shepherd | Michael Richardson | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | mcr+ietf@sandelman.ca |
draft-ietf-cellar-matroska-12
Internet-Draft Matroska Format August 2022
definition: Specifies the language of the tag specified, in the
Matroska languages form; see Section 12 on language codes. This
Element MUST be ignored if the TagLanguageBCP47 Element is used
within the same SimpleTag Element.
5.1.8.1.2.3. TagLanguageBCP47 Element
name / type / id: TagLanguageBCP47 / string / 0x447B
path: \Segment\Tags\Tag\+SimpleTag\TagLanguageBCP47
maxOccurs: 1
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.
5.1.8.1.2.4. TagDefault Element
name / type / id: TagDefault / uinteger / 0x4484
path: \Segment\Tags\Tag\+SimpleTag\TagDefault
minOccurs - maxOccurs: 1 - 1
range: 0-1
default: 1
definition: A boolean value to indicate if this is the default/
original language to use for the given tag.
5.1.8.1.2.5. TagString Element
name / type / id: TagString / utf-8 / 0x4487
path: \Segment\Tags\Tag\+SimpleTag\TagString
maxOccurs: 1
definition: The value of the Tag.
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5.1.8.1.2.6. TagBinary Element
name / type / id: TagBinary / binary / 0x4485
path: \Segment\Tags\Tag\+SimpleTag\TagBinary
maxOccurs: 1
definition: The values of the Tag, if it is binary. Note that this
cannot be used in the same SimpleTag as TagString.
6. Matroska Element Ordering
Except for the EBML Header and the CRC-32 Element, the EBML
specification does not require any particular storage order for
Elements. This specification however defines mandates and
recommendations for ordering certain Elements in order to facilitate
better playback, seeking, and editing efficiency. This section
describes and offers rationale for ordering requirements and
recommendations for Matroska.
6.1. Top-Level Elements
The Info Element is the only REQUIRED Top-Level Element in a Matroska
file. To be playable, Matroska MUST also contain at least one Tracks
Element and Cluster Element. The first Info Element and the first
Tracks Element MUST either be stored before the first Cluster Element
or both SHALL be referenced by a SeekHead Element occurring before
the first Cluster Element.
When using Medium Linking, chapters are used to reference other
Segments to play in a given order Section 16.2. In that case the
Segment containing in these Chapters do no required a Track Element
or a Cluster Element.
It is possible to edit a Matroska file after it has been created.
For example, chapters, tags, or attachments can be added. When new
Top-Level Elements are added to a Matroska file, the SeekHead
Element(s) MUST be updated so that the SeekHead Element(s) itemize
the identity and position of all Top-Level Elements.
Editing, removing, or adding Elements to a Matroska file often
requires that some existing Elements be voided or extended.
Transforming the existing Elements into Void Elements as padding can
be used as a method to avoid moving large amounts of data around.
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6.2. CRC-32
As noted by the EBML specification, if a CRC-32 Element is used, then
the CRC-32 Element MUST be the first ordered Element within its
Parent Element.
In Matroska all Top-Level Elements of an EBML Document SHOULD include
a CRC-32 Element as a their first Child Element. The Segment
Element, which is the Root Element, SHOULD NOT have a CRC-32 Element.
6.3. SeekHead
If used, the first SeekHead Element MUST be the first non-CRC-32
Child Element of the Segment Element. If a second SeekHead Element
is used, then the first SeekHead Element MUST reference the identity
and position of the second SeekHead.
Additionally, the second SeekHead Element MUST only reference Cluster
Elements and not any other Top-Level Element already contained within
the first SeekHead Element.
The second SeekHead Element MAY be stored in any order relative to
the other Top-Level Elements. Whether one or two SeekHead Element(s)
are used, the SeekHead Element(s) MUST collectively reference the
identity and position of all Top-Level Elements except for the first
SeekHead Element.
6.4. Cues (index)
The Cues Element is RECOMMENDED to optimize seeking access in
Matroska. It is programmatically simpler to add the Cues Element
after all Cluster Elements have been written because this does not
require a prediction of how much space to reserve before writing the
Cluster Elements. However, storing the Cues Element before the
Cluster Elements can provide some seeking advantages. If the Cues
Element is present, then it SHOULD either be stored before the first
Cluster Element or be referenced by a SeekHead Element.
6.5. Info
The first Info Element SHOULD occur before the first Tracks Element
and first Cluster Element except when referenced by a SeekHead
Element.
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6.6. Chapters Element
The Chapters Element SHOULD be placed before the Cluster Element(s).
The Chapters Element can be used during playback even if the user
does not need to seek. It immediately gives the user information
about what section is being read and what other sections are
available. In the case of Ordered Chapters it is RECOMMENDED to
evaluate the logical linking even before playing. The Chapters
Element SHOULD be placed before the first Tracks Element and after
the first Info Element.
6.7. Attachments
The Attachments Element is not intended to be used by default when
playing the file, but could contain information relevant to the
content, such as cover art or fonts. Cover art is useful even before
the file is played and fonts could be needed before playback starts
for initialization of subtitles. The Attachments Element MAY be
placed before the first Cluster Element; however if the Attachments
Element is likely to be edited, then it SHOULD be placed after the
last Cluster Element.
6.8. Tags
The Tags Element is most subject to changes after the file was
originally created. For easier editing, the Tags Element 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.
7. Matroska versioning
Matroska is based upon the principle that a reading application does
not have to support 100% of the specifications in order to be able to
play the file. A Matroska file therefore contains version indicators
that tell a reading application what to expect.
It is possible and valid to have the version fields indicate that the
file contains Matroska Elements from a higher specification version
number while signaling that a reading application MUST only support a
lower version number properly in order to play it back (possibly with
a reduced feature set).
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The EBML Header of each Matroska document informs the reading
application on what version of Matroska to expect. The Elements
within EBML Header with jurisdiction over this information are
DocTypeVersion and DocTypeReadVersion.
DocTypeVersion MUST be equal to or greater than the highest Matroska
version number of any Element present in the Matroska file. For
example, a file using the SimpleBlock Element (Section 5.1.3.3) MUST
have a DocTypeVersion equal to or greater than 2. A file containing
CueRelativePosition Elements (Section 5.1.5.1.2.3) MUST have a
DocTypeVersion equal to or greater than 4.
The DocTypeReadVersion MUST contain the minimum version number that a
reading application can minimally support in order to play the file
back -- optionally with a reduced feature set. For example, if a
file contains only Elements of version 2 or lower except for
CueRelativePosition (which is a version 4 Matroska Element), then
DocTypeReadVersion SHOULD still be set to 2 and not 4 because
evaluating CueRelativePosition is not necessary for standard playback
-- it makes seeking more precise if used.
A reading application supporting Matroska version V MUST NOT refuse
to read an application with DocReadTypeVersion equal to or lower than
V even if DocTypeVersion is greater than V.
A reading application supporting at least Matroska version V reading
a file whose DocTypeReadVersion field is equal to or lower than V
MUST skip Matroska/EBML Elements it encounters but does not know
about if that unknown element fits into the size constraints set by
the current Parent Element.
8. Stream Copy
It is sometimes necessary to create a Matroska file from another
Matroska file, for example to add subtitles in a language or to edit
out a portion of the content. Some values from the original Matroska
file needs to be kept the same in the destination file. For example
the SamplingFrequency of an audio track wouldn't change between the
two files. Some other values may change between the two files, for
example the TrackNumber of an audio track when another track has been
added.
Elements are marked with a property: stream copy: True when the
values need to be kept between the source and destination file. If
that property is not set, elements may or may not keep the same value
between the source and destination.
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9. DefaultDecodedFieldDuration
The DefaultDecodedFieldDuration Element can signal to the displaying
application how often fields of a video sequence will be available
for displaying. It can be used for both interlaced and progressive
content. If the video sequence is signaled as interlaced, 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")
10. 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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10.1. 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 36: Block Header base parts
10.2. 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 37: Block Header flags part
10.3. SimpleBlock Structure
The SimpleBlock is inspired by the Block structure; see Section 10.
The main differences are the added Keyframe flag and Discardable
flag. Otherwise everything is the same.
Bit 0 is the most significant bit.
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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.
10.3.1. 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 38: SimpleBlock Header base parts
10.3.2. 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 |
+--------+-----+--------+------------------------------------------+
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Table 39: SimpleBlock Header flags part
10.4. Block Lacing
Lacing is a mechanism to save space when storing data. It is
typically used for small blocks of data (referred to as frames in
Matroska). It packs multiple frames into a single Block or
SimpleBlock.
Lacing MUST NOT be used to store a single frame in a Block or
SimpleBlock.
There are 3 types of lacing:
1. Xiph, inspired by what is found in the Ogg container [RFC3533]
2. EBML, which is the same with sizes coded differently
3. fixed-size, where the size is not coded
When lacing is not used, i.e. to store a single frame, the lacing
bits 5 and 6 of the Block or SimpleBlock MUST be set to zero.
For example, a user wants to store 3 frames of the same track. The
first frame is 800 octets long, the second is 500 octets long and the
third is 1000 octets long. As these data are small, they can be
stored in a lace to save space.
It is possible not to use lacing at all and just store a single frame
without any extra data. When the FlagLacing -- Section 5.1.4.1.12 --
is set to "0" all blocks of that track MUST NOT use lacing.
10.4.1. No lacing
When no lacing is used, the number of frames in the lace is ommitted
and only one frame can be stored in the Block. The bits 5-6 of the
Block Header flags are set to 00.
The Block for a 800 octets frame is as follows:
+==============+=========+===================+
| Block Octets | Value | Description |
+==============+=========+===================+
| 4-803 | <frame> | Single frame data |
+--------------+---------+-------------------+
Table 40: No lacing
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When a Block contains a single frame, it MUST use this No lacing
mode.
10.4.2. Xiph lacing
The Xiph lacing uses the same coding of size as found in the Ogg
container [RFC3533]. The bits 5-6 of the Block Header flags are set
to 01.
The Block data with laced frames is stored as follows:
* Lacing Head on 1 Octet: Number of frames in the lace minus 1.
* Lacing size of each frame except the last one.
* Binary data of each frame consecutively.
The lacing size is split into 255 values, stored as unsigned octets
-- for example, 500 is coded 255;245 or [0xFF 0xF5]. A frame with a
size multiple of 255 is coded with a 0 at the end of the size -- for
example, 765 is coded 255;255;255;0 or [0xFF 0xFF 0xFF 0x00].
The size of the last frame is deduced from the size remaining in the
Block after the other frames.
Because large sizes result in large coding of the sizes, it is
RECOMMENDED to use Xiph lacing only with small frames.
In our example, the 800, 500 and 1000 frames are stored with Xiph
lacing in a Block as follows:
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+=============+=====================+==========================+
| Block Octet | Value | Description |
+=============+=====================+==========================+
| 4 | 0x02 | Number of frames minus 1 |
+-------------+---------------------+--------------------------+
| 5-8 | 0xFF 0xFF 0xFF 0x23 | Size of the first frame |
| | | (255;255;255;35) |
+-------------+---------------------+--------------------------+
| 9-10 | 0xFF 0xF5 | Size of the second frame |
| | | (255;245) |
+-------------+---------------------+--------------------------+
| 11-810 | | First frame data |
+-------------+---------------------+--------------------------+
| 811-1310 | | Second frame data |
+-------------+---------------------+--------------------------+
| 1311-2310 | | Third frame data |
+-------------+---------------------+--------------------------+
Table 41: Xiph lacing example
The Block is 2311 octets large and the last frame starts at 1311, so
we can deduce the size of the last frame is 2311 - 1311 = 1000.
10.4.3. EBML lacing
The EBML lacing encodes the frame size with an EBML-like encoding
[RFC8794]. The bits 5-6 of the Block Header flags are set to 11.
The Block data with laced frames is stored as follows:
* Lacing Head on 1 Octet: Number of frames in the lace minus 1.
* Lacing size of each frame except the last one.
* Binary data of each frame consecutively.
The first frame size is encoded as an EBML Unsigned Integer Element
value. The other frame sizes are encoded as a difference with the
previous frame size as EBML Signed Integer Element values. That
corresponds to an EBML Data Size Values with two's complement
notation with the leftmost bit being the sign bit as found in
[RFC8794], giving this range of values:
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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 2^20-1 |
| xxxx | |
+--------------------------+---------------------------------------+
| 0001 xxxx xxxx xxxx xxxx | value -(2^27-1) to 2^27-1 |
| xxxx xxxx xxxx | |
+--------------------------+---------------------------------------+
| 0000 1xxx xxxx xxxx xxxx | value -(2^34-1) to 2^34-1 |
| xxxx xxxx xxxx xxxx xxxx | |
+--------------------------+---------------------------------------+
| 0000 01xx xxxx xxxx xxxx | value -(2^41-1) to 2^41-1 |
| xxxx xxxx xxxx xxxx xxxx | |
| xxxx xxxx | |
+--------------------------+---------------------------------------+
| 0000 001x xxxx xxxx xxxx | value -(2^48-1) to 2^48-1 |
| xxxx xxxx xxxx xxxx xxxx | |
| xxxx xxxx xxxx xxxx | |
+--------------------------+---------------------------------------+
Table 42: EBML Lacing bits usage
In our example, the 800, 500 and 1000 frames are stored with EBML
lacing in a Block as follows:
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+==============+===========+=====================================+
| Block Octets | Value | Description |
+==============+===========+=====================================+
| 4 | 0x02 | Number of frames minus 1 |
+--------------+-----------+-------------------------------------+
| 5-6 | 0x43 0x20 | Size of the first frame (800 = |
| | | 0x320 + 0x4000) |
+--------------+-----------+-------------------------------------+
| 7-8 | 0x5E 0xD3 | Size of the second frame (500 - 800 |
| | | = -300 = - 0x12C + 0x1FFF + 0x4000) |
+--------------+-----------+-------------------------------------+
| 8-807 | <frame1> | First frame data |
+--------------+-----------+-------------------------------------+
| 808-1307 | <frame2> | Second frame data |
+--------------+-----------+-------------------------------------+
| 1308-2307 | <frame3> | Third frame data |
+--------------+-----------+-------------------------------------+
Table 43: EBML lacing example
The Block is 2308 octets large and the last frame starts at 1308, so
we can deduce the size of the last frame is 2308 - 1308 = 1000.
10.4.4. Fixed-size lacing
The Fixed-size lacing doesn't store the frame size, only the number
of frames in the lace. Each frame MUST have the same size. The
frame size of each frame is deduced from the total size of the Block.
The bits 5-6 of the Block Header flags are set to 10.
The Block data with laced frames is stored as follows:
* Lacing Head on 1 Octet: Number of frames in the lace minus 1.
* Binary data of each frame consecutively.
For example, for 3 frames of 800 octets each:
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+==============+==========+==========================+
| Block Octets | Value | Description |
+==============+==========+==========================+
| 4 | 0x02 | Number of frames minus 1 |
+--------------+----------+--------------------------+
| 5-804 | <frame1> | First frame data |
+--------------+----------+--------------------------+
| 805-1604 | <frame2> | Second frame data |
+--------------+----------+--------------------------+
| 1605-2404 | <frame3> | Third frame data |
+--------------+----------+--------------------------+
Table 44: Fixed-size lacing example
This gives a Block of 2405 octets. When reading the Block we find
that there are 3 frames (Octet 4). The data start at Octet 5, so the
size of each frame is (2405 - 5) / 3 = 800.
10.4.5. Laced Frames Timestamp
A Block only contains a single timestamp value. But when lacing is
used, it contains more than one frame. Each frame originally has its
own timestamp, or Presentation Timestamp (PTS). That timestamp
applies to the first frame in the lace.
In the lace, each frame after the first one has an underdetermined
timestamp. But each of these frames MUST be contiguous -- i.e. the
decoded data MUST NOT contain any gap between them. If there is a
gap in the stream, the frames around the gap MUST NOT be in the same
Block.
Lacing is only useful for small contiguous data to save space. This
is usually the case for audio tracks and not the case for video --
which use a lot of data -- or subtitle tracks -- which have long
gaps. For audio, there is usually a fixed output sampling frequency
for the whole track. So the decoder should be able to recover the
timestamp of each sample, knowing each output sample is contiguous
with a fixed frequency. For subtitles this is usually not the case
so lacing SHOULD NOT be used.
10.5. Random Access Points
Random Access Points (RAP) are positions where the parser can seek to
and start playback without decoding of what was before. In Matroska
BlockGroups and SimpleBlocks can be RAPs. To seek to these elements
it is still necessary to seek to the Cluster containing them, read
the Cluster Timestamp and start playback from the BlockGroup or
SimpleBlock that is a RAP.
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Because a Matroska File is usually composed of multiple tracks
playing at the same time -- video, audio and subtitles -- to seek
properly to a RAP, each selected track must be taken in account.
Usually all audio and subtitle BlockGroup or SimpleBlock are RAP.
They are independent of each other and can be played randomly.
Video tracks on the other hand often use references to previous and
future frames for better coding efficiency. Frames with such
reference MUST either contain one or more ReferenceBlock Elements in
their BlockGroup or MUST be marked as non-keyframe in a SimpleBlock;
see Section 10.3.2.
* BlockGroup with a frame that references another frame, with the
EBML tree shown as XML:
<Cluster>
<Timestamp>123456</Timestamp>
<BlockGroup>
<!-- References a Block 40 Track Ticks before this one -->
<ReferenceBlock>-40</ReferenceBlock>
<Block/>
</BlockGroup>
...
</Cluster>
* SimpleBlock with a frame that references another frame, with the
EBML tree shown as XML:
<Cluster>
<Timestamp>123456</Timestamp>
<SimpleBlock/> (octet 3 bit 0 not set)
...
</Cluster>
Frames that are RAP -- i.e. they don't depend on other frames -- MUST
set the keyframe flag if they are in a SimpleBlock or their parent
BlockGroup MUST NOT contain a ReferenceBlock.
* BlockGroup with a frame that references no other frame, with the
EBML tree shown as XML:
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<Cluster>
<Timestamp>123456</Timestamp>
<BlockGroup>
<!-- No ReferenceBlock allowed in this BlockGroup -->
<Block/>
</BlockGroup>
...
</Cluster>
* SimpleBlock with a frame that references no other frame, with the
EBML tree shown as XML:
<Cluster>
<Timestamp>123456</Timestamp>
<SimpleBlock/> (octet 3 bit 0 set)
...
</Cluster>
There may be cases where the use of BlockGroup is necessary, as the
frame may need a BlockDuration, BlockAdditions, CodecState or a
DiscardPadding element. For thoses cases a SimpleBlock MUST NOT be
used, the reference information SHOULD be recovered for non-RAP
frames.
* SimpleBlock with a frame that references another frame, with the
EBML tree shown as XML:
<Cluster>
<Timestamp>123456</Timestamp>
<SimpleBlock/> (octet 3 bit 0 not set)
...
</Cluster>
* Same frame that references another frame put inside a BlockGroup
to add BlockDuration, with the EBML tree shown as XML:
<Cluster>
<Timestamp>123456</Timestamp>
<BlockGroup>
<!-- ReferenceBlock value recovered based on the codec -->
<ReferenceBlock>-40</ReferenceBlock>
<BlockDuration>20<BlockDuration>
<Block/>
</BlockGroup>
...
</Cluster>
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When a frame in a BlockGroup is not a RAP, all references SHOULD be
listed as a ReferenceBlock, at least some of them, even if not
accurate, or one ReferenceBlock with the value "0" corresponding to a
self or unknown reference. The lack of ReferenceBlock would mean
such a frame is a RAP and seeking on that frame that actually depends
on other frames MAY create bogus output or even crash.
* Same frame that references another frame put inside a BlockGroup
but the reference could not be recovered, with the EBML tree shown
as XML:
<Cluster>
<Timestamp>123456</Timestamp>
<BlockGroup>
<!-- ReferenceBlock value not recovered from the codec -->
<ReferenceBlock>0</ReferenceBlock>
<BlockDuration>20<BlockDuration>
<Block/>
</BlockGroup>
...
</Cluster>
* BlockGroup with a frame that references two other frames, with the
EBML tree shown as XML:
<Cluster>
<Timestamp>123456</Timestamp>
<BlockGroup>
<!-- References a Block 80 Track Ticks before this one -->
<ReferenceBlock>-80</ReferenceBlock>
<!-- References a Block 40 Track Ticks after this one -->
<ReferenceBlock>40</ReferenceBlock>
<Block/>
</BlockGroup>
...
</Cluster>
Intra-only video frames, such as the ones found in AV1 or VP9, can be
decoded without any other frame, but they don't reset the codec
state. So seeking to these frames is not possible as the next frames
may need frames that are not known from this seeking point. Such
intra-only frames MUST NOT be considered as keyframes so the keyframe
flag MUST NOT be set in the SimpleBlock or a ReferenceBlock MUST be
used to signify the frame is not a RAP. The timestamp value of the
ReferenceBlock MUST be "0", meaning it's referencing itself.
* Intra-only frame not an RAP, with the EBML tree shown as XML:
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<Cluster>
<Timestamp>123456</Timestamp>
<BlockGroup>
<!-- References itself to mark it should not be used as RAP -->
<ReferenceBlock>0</ReferenceBlock>
<Block/>
</BlockGroup>
...
</Cluster>
Because a video SimpleBlock has less references information than a
video BlockGroup, it is possible to remux a video track using
BlockGroup into a SimpleBlock, as long as it doesn't use any other
BlockGroup features than ReferenceBlock.
11. Timestamps
Historically timestamps in Matroska were mistakenly called timecodes.
The Timestamp Element was called Timecode, the TimestampScale Element
was called TimecodeScale, the TrackTimestampScale Element was called
TrackTimecodeScale and the ReferenceTimestamp Element was called
ReferenceTimeCode.
11.1. Timestamp Ticks
All timestamp values in Matroska are expressed in multiples of a
tick. They are usually stored as integers. There are three types of
ticks possible:
11.1.1. Matroska Ticks
For such elements, the timestamp value is stored directly in
nanoseconds.
The elements storing values in Matroska Ticks/nanoseconds are:
* TrackEntry\DefaultDuration; defined in Section 5.1.4.1.15
* TrackEntry\DefaultDecodedFieldDuration; defined in
Section 5.1.4.1.16
* TrackEntry\SeekPreRoll; defined in Section 5.1.4.1.29
* TrackEntry\CodecDelay; defined in Section 5.1.4.1.28
* BlockGroup\DiscardPadding; defined in Section 5.1.3.4.7
* ChapterAtom\ChapterTimeStart; defined in Section 5.1.7.1.4.3
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* ChapterAtom\ChapterTimeEnd; defined in Section 5.1.7.1.4.4
* CuePoint\CueTime; defined in Section 5.1.5.1.1
* CueReference\CueRefTime; defined in Section 5.1.5.1.1
11.1.2. Segment Ticks
Elements in Segment Ticks involve the use of the TimestampScale
Element of the Segment to get the timestamp in nanoseconds of the
element, with the following formula:
timestamp in nanosecond = element value * TimestampScale
This allows storing smaller integer values in the elements.
When using the default value of TimestampScale of "1,000,000", one
Segment Tick represents one millisecond.
The elements storing values in Segment Ticks are:
* Cluster\Timestamp; defined in Section 5.1.3.1
* Info\Duration is stored as a floating point but the same formula
applies; defined in Section 5.1.2.10
* CuePoint\CueTrackPositions\CueDuration; defined in
Section 5.1.5.1.2.4
11.1.3. Track Ticks
Elements in Track Ticks involve the use of the TimestampScale Element
of the Segment and the TrackTimestampScale Element of the Track to
get the timestamp in nanoseconds of the element, with the following
formula:
timestamp in nanoseconds =
element value * TrackTimestampScale * TimestampScale
This allows storing smaller integer values in the elements. The
resulting floating point values of the timestamps are still expressed
in nanoseconds.
When using the default values for TimestampScale and
TrackTimestampScale of "1,000,000" and of "1.0" respectively, one
Track Tick represents one millisecond.
The elements storing values in Track Ticks are:
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* Cluster\BlockGroup\Block and Cluster\SimpleBlock timestamps;
detailed in Section 11.2
* Cluster\BlockGroup\BlockDuration; defined in Section 5.1.3.4.3
* Cluster\BlockGroup\ReferenceBlock; defined in Section 5.1.3.4.5
When the TrackTimestampScale is interpreted as "1.0", Track Ticks are
equivalent to Segment Ticks and give an integer value in nanoseconds.
This is the most common case as TrackTimestampScale is usually
omitted.
A value of TrackTimestampScale other than "1.0" MAY be used to scale
the timestamps more in tune with each Track sampling frequency. For
historical reasons, a lot of Matroska readers don't take the
TrackTimestampScale value in account. So using a value other than
"1.0" MAY not work in many places.
11.2. Block Timestamps
A Block Element and SimpleBlock Element timestamp is the time when
the decoded data of the first frame in the Block/SimpleBlock MUST be
presented, if the track of that Block/SimpleBlock is selected for
playback. This is also known as the Presentation Timestamp (PTS).
The Block Element and SimpleBlock Element store their timestamps as
signed integers, relative to the Cluster\Timestamp value of the
Cluster they are stored in. To get the timestamp of a Block or
SimpleBlock in nanoseconds you have to use the following formula:
( Cluster\Timestamp + ( block timestamp * TrackTimestampScale ) ) *
TimestampScale
The Block Element and SimpleBlock Element store their timestamps as
16bit signed integers, allowing a range from "-32768" to "+32767"
Track Ticks. Although these values can be negative, when added to
the Cluster\Timestamp, the resulting frame timestamp SHOULD NOT be
negative.
When a CodecDelay Element is set, its value MUST be substracted from
each Block timestamp of that track. To get the timestamp in
nanoseconds of the first frame in a Block or SimpleBlock, the formula
becomes:
( ( Cluster\Timestamp + ( block timestamp * TrackTimestampScale ) ) *
TimestampScale ) - CodecDelay
The resulting frame timestamp SHOULD NOT be negative.
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During playback, when a frame has a negative timestamp, the content
MUST be decoded by the decoder but not played to the user.
11.3. TimestampScale Rounding
The default Track Tick duration is one millisecond.
The TimestampScale is a floating value, which is usually 1.0. But
when it's not, the multiplied Block Timestamp is a floating values in
nanoseconds. The Matroska Reader SHOULD use the nearest rounding
value in nanosecond to get the proper nanosecond timestamp of a
Block. This allows some clever TimestampScale values to have more
refined timestampt precision per frame.
12. Language Codes
Matroska from version 1 through 3 uses language codes that can be
either the 3 letters bibliographic ISO-639-2 form [ISO639-2] (like
"fre" for french), or such a language code followed by a dash and a
country code for specialities in languages (like "fre-ca" for
Canadian French). The ISO 639-2 Language Elements are "Language
Element", "TagLanguage Element", and "ChapLanguage Element".
Starting in Matroska version 4, either [ISO639-2] or [BCP47] MAY be
used, although BCP 47 is RECOMMENDED. The BCP 47 Language Elements
are "LanguageBCP47 Element", "TagLanguageBCP47 Element", and
"ChapLanguageBCP47 Element". If a BCP 47 Language Element and an ISO
639-2 Language Element are used within the same Parent Element, then
the ISO 639-2 Language Element MUST be ignored and precedence given
to the BCP 47 Language Element.
Country codes are the same 2 octets country-codes as in Internet
domains [IANADomains] based on [ISO3166-1] alpha-2 codes.
13. 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).
This document does not specify any kind of standard for encrypting
elements. The issue of key scheduling, authorisation, and
authentication are out of scope. External entities have used these
elements in proprietary ways.
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Because encryption occurs within the Block Element, it is possible to
manipulate encrypted streams without decrypting them. The streams
could potentially be copied, deleted, cut, appended, or any number of
other possible editing techniques without decryption. The data can
be used without having to expose it or go through the decrypting
process.
Encryption can also be layered within Matroska. This means that two
completely different types of encryption can be used, requiring two
separate keys to be able to decrypt a stream.
Encryption information is stored in the ContentEncodings Element
under the ContentEncryption Element.
For encryption systems sharing public/private keys, the creation of
the keys and the exchange of keys are not covered by this document.
They have to be handled by the system using Matroska.
The ContentEncodingScope Element gives an idea of which part of the
track are encrypted. But each ContentEncAlgo Element and its sub
elements like AESSettingsCipherMode really define how the encrypted
should be exactly interpreted.
The AES-CTR system, which corresponds to ContentEncAlgo = 5
(Section 5.1.4.1.34.9) and AESSettingsCipherMode = 1
(Section 5.1.4.1.34.12), is defined in the [WebM-Enc] document.
14. Image Presentation
14.1. 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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Cropping has to be performed before resizing and the display
dimensions given by DisplayWidth, DisplayHeight and DisplayUnit apply
to the already cropped image.
14.2. Rotation
The ProjectionPoseRoll Element (see Section 5.1.4.1.31.46) can be
used to indicate that the image from the associated video track
SHOULD be rotated for presentation. For instance, the following
representation of the Projection Element Section 5.1.4.1.31.41) and
the ProjectionPoseRoll Element represents a video track where the
image SHOULD be presented with a 90 degree counter-clockwise
rotation, with the EBML tree shown as XML :
<Projection>
<ProjectionPoseRoll>90</ProjectionPoseRoll>
</Projection>
Figure 11: Rotation example.
15. 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.
15.1. Segment Position Exception
Elements that are defined to store a Segment Position MAY define
reserved values to indicate a special meaning.
15.2. 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".
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0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
0 |1A|45|DF|A3|8B|42|82|88|6D|61|74|72|6F|73|6B|61|
^ EBML Header
0 | |18|53|80|67|
^ Segment ID
20 |93|
^ Segment Data Size
20 | |15|49|A9|66|8E|4D|80|84|69|65|74|66|57|41|84|69|65|74|66|
^ Start of Segment data
20 | |4D|80|84|69|65|74|66|57|41|84|69|65|74|66|
^ MuxingApp start
In the above example, the Element ID of the Segment Element is stored
at offset 16, the Element Data Size of the Segment Element is stored
at offset 20, and the Element Data of the Segment Element is stored
at offset 21.
The MuxingApp Element is stored at offset 26. Since the Segment
Position of an Element is calculated by subtracting the position of
the Element Data of the containing Segment Element from the position
of that Element, the Segment Position of MuxingApp Element in the
above example is '26 - 21' or '5'.
16. Linked Segments
Matroska provides several methods to link two or more Segment
Elements together to create a Linked Segment. A Linked Segment is a
set of multiple Segments linked together into a single presentation
by using Hard Linking or Medium Linking.
All Segments within a Linked Segment MUST have a SegmentUUID.
All Segments within a Linked Segment SHOULD be stored within the same
directory or be accessible quickly based on their SegmentUUID in
order to have seamless transition between segments.
All Segments within a Linked Segment MAY set a SegmentFamily with a
common value to make it easier for a Matroska Player to know which
Segments are meant to be played together.
The SegmentFilename, PrevFilename and NextFilename elements MAY also
give hints on the original filenames that were used when the Segment
links were created, in case some SegmentUUID are damaged.
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16.1. Hard Linking
Hard Linking, also called splitting, is the process of creating a
Linked Segment by linking multiple Segment Elements using the
NextUUID and PrevUUID Elements.
All Segments within a Hard Linked Segment MUST use the same Tracks
list and TimestampScale.
Within a Linked Segment, the timestamps of Block and SimpleBlock MUST
follow consecutively the timestamps of Block and SimpleBlock from the
previous Segment in linking order.
With Hard Linking, the chapters of any Segment within the Linked
Segment MUST only reference the current Segment. The NextUUID and
PrevUUID reference the respective SegmentUUID values of the next and
previous Segments.
The first Segment of a Linked Segment MUST NOT have a PrevUUID
Element. The last Segment of a Linked Segment MUST NOT have a
NextUUID Element.
For each node of the chain of Segments of a Linked Segment at least
one Segment MUST reference the other Segment of the node.
In a chain of Segments of a Linked Segment the NextUUID always takes
precedence over the PrevUUID. So if SegmentA has a NextUUID to
SegmentB and SegmentB has a PrevUUID to SegmentC, the link to use is
NextUUID between SegmentA and SegmentB, SegmentC is not part of the
Linked Segment.
If SegmentB has a PrevUUID to SegmentA but SegmentA has no NextUUID,
then the Matroska Player MAY consider these two Segments linked as
SegmentA followed by SegmentB.
As an example, three Segments can be Hard Linked as a Linked Segment
through cross-referencing each other with SegmentUUID, PrevUUID, and
NextUUID, as in this table:
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+==========+==================+==================+==================+
|file name | SegmentUUID | PrevUUID | NextUUID |
+==========+==================+==================+==================+
|start.mkv | 71000c23cd310998 | Invalid | a77b3598941cb803 |
| | 53fbc94dd984a5dd | | eac0fcdafe44fac9 |
+----------+------------------+------------------+------------------+
|middle.mkv| a77b3598941cb803 | 71000c23cd310998 | 6c92285fa6d3e827 |
| | eac0fcdafe44fac9 | 53fbc94dd984a5dd | b198d120ea3ac674 |
+----------+------------------+------------------+------------------+
|end.mkv | 6c92285fa6d3e827 | a77b3598941cb803 | Invalid |
| | b198d120ea3ac674 | eac0fcdafe44fac9 | |
+----------+------------------+------------------+------------------+
Table 45: Usual Hard Linking UIDs
An other example where only the NextUUID Element is used:
+============+==================+==========+==================+
| file name | SegmentUUID | PrevUUID | NextUUID |
+============+==================+==========+==================+
| start.mkv | 71000c23cd310998 | Invalid | a77b3598941cb803 |
| | 53fbc94dd984a5dd | | eac0fcdafe44fac9 |
+------------+------------------+----------+------------------+
| middle.mkv | a77b3598941cb803 | n/a | 6c92285fa6d3e827 |
| | eac0fcdafe44fac9 | | b198d120ea3ac674 |
+------------+------------------+----------+------------------+
| end.mkv | 6c92285fa6d3e827 | n/a | Invalid |
| | b198d120ea3ac674 | | |
+------------+------------------+----------+------------------+
Table 46: Hard Linking without PrevUUID
An example where only the PrevUUID Element is used:
+============+==================+==================+==========+
| file name | SegmentUUID | PrevUUID | NextUUID |
+============+==================+==================+==========+
| start.mkv | 71000c23cd310998 | Invalid | n/a |
| | 53fbc94dd984a5dd | | |
+------------+------------------+------------------+----------+
| middle.mkv | a77b3598941cb803 | 71000c23cd310998 | n/a |
| | eac0fcdafe44fac9 | 53fbc94dd984a5dd | |
+------------+------------------+------------------+----------+
| end.mkv | 6c92285fa6d3e827 | a77b3598941cb803 | Invalid |
| | b198d120ea3ac674 | eac0fcdafe44fac9 | |
+------------+------------------+------------------+----------+
Table 47: Hard Linking without NextUUID
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In this example only the middle.mkv is using the PrevUUID and
NextUUID Elements:
+==========+==================+==================+==================+
|file name | SegmentUUID | PrevUUID | NextUUID |
+==========+==================+==================+==================+
|start.mkv | 71000c23cd310998 | Invalid | n/a |
| | 53fbc94dd984a5dd | | |
+----------+------------------+------------------+------------------+
|middle.mkv| a77b3598941cb803 | 71000c23cd310998 | 6c92285fa6d3e827 |
| | eac0fcdafe44fac9 | 53fbc94dd984a5dd | b198d120ea3ac674 |
+----------+------------------+------------------+------------------+
|end.mkv | 6c92285fa6d3e827 | n/a | Invalid |
| | b198d120ea3ac674 | | |
+----------+------------------+------------------+------------------+
Table 48: Hard Linking with mixed UID links
16.2. Medium Linking
Medium Linking creates relationships between Segments using Ordered
Chapters (Section 19.1.3) and the ChapterSegmentUUID Element. A
Chapter Edition with Ordered Chapters MAY contain Chapter elements
that reference timestamp ranges from other Segments. The Segment
referenced by the Ordered Chapter via the ChapterSegmentUUID Element
SHOULD be played as part of a Linked Segment.
The timestamps of Segment content referenced by Ordered Chapters MUST
be adjusted according to the cumulative duration of the the previous
Ordered Chapters.
As an example a file named intro.mkv could have a SegmentUUID of
"0xb16a58609fc7e60653a60c984fc11ead". Another file called
program.mkv could use a Chapter Edition that contains two Ordered
Chapters. The first chapter references the Segment of intro.mkv with
the use of a ChapterSegmentUUID, ChapterSegmentEditionUID,
ChapterTimeStart, and optionally a ChapterTimeEnd element. The
second chapter references content within the Segment of program.mkv.
A Matroska Player SHOULD recognize the Linked Segment created by the
use of ChapterSegmentUUID in an enabled Edition and present the
reference content of the two Segments as a single presentation.
The ChapterSegmentUUID represents the Segment that holds the content
to play in place of the Linked Chapter. The ChapterSegmentUUID MUST
NOT be the SegmentUUID of its own Segment.
There are 2 ways to use a chapter link: * Linked-Duration linking, *
Linked-Edition linking
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16.2.1. Linked-Duration
A Matroska Player MUST play the content of the linked Segment from
the ChapterTimeStart until ChapterTimeEnd timestamp in place of the
Linked Chapter.
ChapterTimeStart and ChapterTimeEnd represent timestamps in the
Linked Segment matching the value of ChapterSegmentUUID. Their
values MUST be in the range of the linked Segment duration.
The ChapterTimeEnd value MUST be set when using linked-duration
chapter linking. ChapterSegmentEditionUID MUST NOT be set.
16.2.2. Linked-Edition
A Matroska Player MUST play the whole linked Edition of the linked
Segment in place of the Linked Chapter.
ChapterSegmentEditionUID represents a valid Edition from the Linked
Segment matching the value of ChapterSegmentUUID.
When using linked-edition chapter linking. ChapterTimeEnd is
OPTIONAL.
17. Track Flags
17.1. 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.
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17.2. 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.
17.3. 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.
17.4. 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.
17.5. 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.
17.6. 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.
17.7. Commentary flag
The "commentary" flag tells the Matroska Player that this track
contains commentary on the content.
17.8. 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.
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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.
17.9. 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.
17.10. Multi-planar and 3D videos
There are two different ways to compress 3D videos: have each eye
track in a separate track and have one track have both eyes combined
inside (which is more efficient, compression-wise). Matroska
supports both ways.
For the single track variant, there is the StereoMode Element, which
defines how planes are assembled in the track (mono or left-right
combined). Odd values of StereoMode means the left plane comes first
for more convenient reading. The pixel count of the track
(PixelWidth/PixelHeight) is the raw amount of pixels, for example
3840x1080 for full HD side by side, and the DisplayWidth/
DisplayHeight in pixels is the amount of pixels for one plane
(1920x1080 for that full HD stream). Old stereo 3D were displayed
using anaglyph (cyan and red colors separated). For compatibility
with such movies, there is a value of the StereoMode that corresponds
to AnaGlyph.
There is also a "packed" mode (values 13 and 14) which consists of
packing two frames together in a Block using lacing. The first frame
is the left eye and the other frame is the right eye (or vice versa).
The frames SHOULD be decoded in that order and are possibly dependent
on each other (P and B frames).
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For separate tracks, Matroska needs to define exactly which track
does what. TrackOperation with TrackCombinePlanes do that. For more
details look at Section 17.8 on how TrackOperation works.
The 3D support is still in infancy and may evolve to support more
features.
The StereoMode used to be part of Matroska v2 but it didn't meet the
requirement for multiple tracks. There was also a bug in libmatroska
prior to 0.9.0 that would save/read it as 0x53B9 instead of 0x53B8;
see OldStereoMode (Section 5.1.4.1.31.5). Matroska Readers may
support these legacy files by checking Matroska v2 or 0x53B9. The
older values of StereoMode were 0: mono, 1: right eye, 2: left eye,
3: both eyes, the only values that can be found in OldStereoMode.
They are not compatible with the StereoMode values found in Matroska
v3 and above.
18. 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.
18.1. Audio Selection
Example track set:
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+===+=====+====+======+========+=======+================+===========+
|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 49: Audio Tracks for default selection
Here we have a file with 7 audio tracks, of which 5 are in English
and 2 are in Spanish.
The English tracks all have the Original flag, indicating that
English is the original content language.
Generally the player will first consider the track languages: if the
player has an option to prefer original-language audio and the user
has enabled it, then it should prefer one of the Original-flagged
tracks. If configured to specifically prefer audio tracks in English
or Spanish, the player should select one of the tracks in the
corresponding language. The player may also wish to prefer an
Original-flagged track if no tracks matching any of the user's
explicitly-preferred languages are available.
Two of the tracks have the Visual-impaired flag. If the player has
been configured to prefer such tracks, it should select one;
otherwise, it should avoid them if possible.
If selecting an English track, when other settings have left multiple
possible options, it may be useful to exclude the tracks that lack
the Default flag: here, one provides descriptive service for the
visually impaired (which has its own flag and may be automatically
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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.
18.2. 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 50: Subtitle Tracks for default selection
Here we have 2 audio tracks and 5 subtitle tracks. As we can see,
French is the original language.
We'll start by discussing the case where the user prefers French (or
Original-language) audio (or has explicitly selected the French audio
track), and also prefers French subtitles.
In this case, if the player isn't configured to display captions when
the audio matches their preferred subtitle languages, the player
doesn't need to select a subtitle track at all.
If the user _has_ indicated that they want captions to be displayed,
the selection simply comes down to whether Hearing-impaired subtitles
are preferred.
The situation for a user who prefers Portuguese subtitles starts out
somewhat analogous. If they select the original French audio (either
by explicit audio language preference, preference for Original-
language tracks, or by explicitly selecting that track), then the
selection once again comes down to the hearing-impaired preference.
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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.
19. Chapters
The Matroska Chapters system can have multiple Editions and each
Edition can consist of Simple Chapters where a chapter start time is
used as marker in the timeline only. An Edition can be more complex
with Ordered Chapters where a chapter end time stamp is additionally
used or much more complex with Linked Chapters. The Matroska
Chapters system can also have a menu structure, borrowed from the DVD
menu system [DVD-Video], or have it's own Native Matroska menu
structure.
19.1. 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.
19.1.1. EditionFlagDefault
Only one Edition SHOULD have an EditionFlagDefault flag set to true.
19.1.2. 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.
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+===========+=============+=================+
| Edition | FlagDefault | Default Edition |
+===========+=============+=================+
| Edition 1 | true | X |
+-----------+-------------+-----------------+
| Edition 2 | true | |
+-----------+-------------+-----------------+
| Edition 3 | true | |
+-----------+-------------+-----------------+
Table 51: Default edition, all default
+===========+=============+=================+
| Edition | FlagDefault | Default Edition |
+===========+=============+=================+
| Edition 1 | false | X |
+-----------+-------------+-----------------+
| Edition 2 | false | |
+-----------+-------------+-----------------+
| Edition 3 | false | |
+-----------+-------------+-----------------+
Table 52: Default edition, no default
+===========+=============+=================+
| Edition | FlagDefault | Default Edition |
+===========+=============+=================+
| Edition 1 | false | |
+-----------+-------------+-----------------+
| Edition 2 | true | X |
+-----------+-------------+-----------------+
| Edition 3 | false | |
+-----------+-------------+-----------------+
Table 53: Default edition, with default
19.1.3. 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
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visual information excluded. If an Edition of Ordered Chapters is
enabled, then the Matroska Player MUST play those Chapters in their
stored order from the timestamp marked in the ChapterTimeStart
Element to the timestamp marked in to ChapterTimeEnd Element.
If the EditionFlagOrdered Flag evaluates to "0", Simple Chapters are
used and only the ChapterTimeStart of a Chapter is used as chapter
mark to jump to the predefined point in the timeline. With Simple
Chapters, a Matroska Player MUST ignore certain Chapter Elements. In
that case these elements are informational only.
The following list shows the different Chapter elements only found in
Ordered Chapters.
+======================================+
| Ordered Chapter elements |
+======================================+
| ChapterAtom/ChapterSegmentUUID |
+--------------------------------------+
| ChapterAtom/ChapterSegmentEditionUID |
+--------------------------------------+
| ChapterAtom/ChapterTrack |
+--------------------------------------+
| ChapterAtom/ChapProcess |
+--------------------------------------+
| Info/ChapterTranslate |
+--------------------------------------+
| TrackEntry/TrackTranslate |
+--------------------------------------+
Table 54: elements only found in
ordered chapters
Furthermore there are other EBML Elements which could be used if the
EditionFlagOrdered evaluates to "1".
19.1.3.1. Ordered-Edition and Matroska Segment-Linking
* Hard Linking: Ordered-Chapters supersedes the Hard Linking.
* Medium Linking: Ordered Chapters are used in a normal way and can
be combined with the ChapterSegmentUUID element which establishes
a link to another Segment.
See Section 16 on the Linked Segments for more information about Hard
Linking and Medium Linking.
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19.2. ChapterAtom
The ChapterAtom is also called a Chapter.
19.2.1. ChapterTimeStart
The timestamp of the start of Chapter with nanosecond accuracy, not
scaled by TimestampScale. For Simple Chapters this is the position
of the chapter markers in the timeline.
19.2.2. ChapterTimeEnd
The timestamp of the end of Chapter with nanosecond accuracy, not
scaled by TimestampScale. The timestamp defined by the
ChapterTimeEnd is not part of the Chapter. A Matroska Player
calculates the duration of this Chapter using the difference between
the ChapterTimeEnd and ChapterTimeStart. The end timestamp MUST be
greater than or equal to the start timestamp.
When the ChapterTimeEnd timestamp is equal to the ChapterTimeStart
timestamp, the timestamps is included in the Chapter. It can be
useful to put markers in a file or add chapter commands with ordered
chapter commands without having to play anything; see
Section 5.1.7.1.4.14.
+===========+=================+===============+===============+
| Chapter | Start timestamp | End timestamp | Duration |
+===========+=================+===============+===============+
| Chapter 1 | 0 | 1000000000 | 1000000000 |
+-----------+-----------------+---------------+---------------+
| Chapter 2 | 1000000000 | 5000000000 | 4000000000 |
+-----------+-----------------+---------------+---------------+
| Chapter 3 | 6000000000 | 6000000000 | 0 |
+-----------+-----------------+---------------+---------------+
| Chapter 4 | 9000000000 | 8000000000 | Invalid |
| | | | (-1000000000) |
+-----------+-----------------+---------------+---------------+
Table 55: ChapterTimeEnd usage possibilities
19.2.3. Nested Chapters
A ChapterAtom element can contain other ChapterAtom elements. That
element is a Parent Chapter and the ChapterAtom elements it contains
are Nested Chapters.
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Nested Chapters can be useful to tag small parts of a Segment that
already have tags or add Chapter Codec commands on smaller parts of a
Segment that already have Chapter Codec commands.
The ChapterTimeStart of a Nested Chapter MUST be greater than or
equal to the ChapterTimeStart its Parent Chapter.
If the Parent Chapter of a Nested Chapter has a ChapterTimeEnd, the
ChapterTimeStart of that Nested Chapter MUST be smaller than or equal
to the ChapterTimeEnd of the Parent Chapter.
19.2.4. Nested Chapters in Ordered Chapters
The ChapterTimeEnd of the lowest level of Nested Chapters MUST be set
for Ordered Chapters.
When used with Ordered Chapters, the ChapterTimeEnd value of a Parent
Chapter is useless for playback as the proper playback sections are
described in its Nested Chapters. The ChapterTimeEnd SHOULD NOT be
set in Parent Chapters and MUST be ignored for playback.
19.2.5. ChapterFlagHidden
Each Chapter ChapterFlagHidden flag works independently from parent
chapters. A Nested Chapter with a ChapterFlagHidden that evaluates
to "0" remains visible in the user interface even if the Parent
Chapter ChapterFlagHidden flag is set to "1".
+==========================+===================+=========+
| Chapter + Nested Chapter | ChapterFlagHidden | visible |
+==========================+===================+=========+
| Chapter 1 | 0 | yes |
+--------------------------+-------------------+---------+
| Nested Chapter 1.1 | 0 | yes |
+--------------------------+-------------------+---------+
| Nested Chapter 1.2 | 1 | no |
+--------------------------+-------------------+---------+
| Chapter 2 | 1 | no |
+--------------------------+-------------------+---------+
| Nested Chapter 2.1 | 0 | yes |
+--------------------------+-------------------+---------+
| Nested Chapter 2.2 | 1 | no |
+--------------------------+-------------------+---------+
Table 56: ChapterFlagHidden nested visibility
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19.3. Menu features
The menu features are handled like a chapter codec. That means each
codec has a type, some private data and some data in the chapters.
The type of the menu system is defined by the ChapProcessCodecID
parameter. For now, only 2 values are supported : 0 matroska script,
1 menu borrowed from the DVD [DVD-Video]. The private data depend on
the type of menu system (stored in ChapProcessPrivate), idem for the
data in the chapters (stored in ChapProcessData).
The menu system, as well as Chapter Codecs in general, can do actions
on the Matroska Player like jumping to another Chapter or Edition,
selecting different tracks and possibly more. The scope of all the
possibilities of Chapter Codecs is not covered in this document as it
depends on the Chapter Codec features and its integration in a
Matroska Player.
19.4. 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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+=======+=======================+=============+=====================+
| Value | Audio | Video | Comment |
+=======+=======================+=============+=====================+
| 70 | SET / PACKAGE | SET / | the collection of |
| | | PACKAGE | different media |
+-------+-----------------------+-------------+---------------------+
| 60 | CD / 12" / 10" / 7" / | DVD / VHS | the physical medium |
| | TAPE / MINIDISC / DAT | / | like a CD or a DVD |
| | | LASERDISC | |
+-------+-----------------------+-------------+---------------------+
| 50 | SIDE | SIDE | when the original |
| | | | medium (LP/DVD) has |
| | | | different sides |
+-------+-----------------------+-------------+---------------------+
| 40 | - | LAYER | another physical |
| | | | level on DVDs |
+-------+-----------------------+-------------+---------------------+
| 30 | SESSION | SESSION | as found on CDs and |
| | | | DVDs |
+-------+-----------------------+-------------+---------------------+
| 20 | TRACK | - | as found on audio |
| | | | CDs |
+-------+-----------------------+-------------+---------------------+
| 10 | INDEX | - | the first logical |
| | | | level of the side/ |
| | | | medium |
+-------+-----------------------+-------------+---------------------+
Table 57: ChapterPhysicalEquiv meaning per track type
19.5. Chapter Examples
19.5.1. Example 1 : basic chaptering
In this example a movie is split in different chapters. It could
also just be an audio file (album) on which each track corresponds to
a chapter.
* 00000ms - 05000ms : Intro
* 05000ms - 25000ms : Before the crime
* 25000ms - 27500ms : The crime
* 27500ms - 38000ms : The killer arrested
* 38000ms - 43000ms : Credits
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This would translate in the following matroska form, with the EBML
tree shown as XML :
<Chapters>
<EditionEntry>
<EditionUID>16603393396715046047</EditionUID>
<ChapterAtom>
<ChapterUID>1193046</ChapterUID>
<ChapterTimeStart>0</ChapterTimeStart>
<ChapterTimeEnd>5000000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Intro</ChapString>
</ChapterDisplay>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>2311527</ChapterUID>
<ChapterTimeStart>5000000000</ChapterTimeStart>
<ChapterTimeEnd>25000000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Before the crime</ChapString>
</ChapterDisplay>
<ChapterDisplay>
<ChapString>Avant le crime</ChapString>
<ChapLanguage>fra</ChapLanguage>
</ChapterDisplay>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>3430008</ChapterUID>
<ChapterTimeStart>25000000000</ChapterTimeStart>
<ChapterTimeEnd>27500000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>The crime</ChapString>
</ChapterDisplay>
<ChapterDisplay>
<ChapString>Le crime</ChapString>
<ChapLanguage>fra</ChapLanguage>
</ChapterDisplay>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>4548489</ChapterUID>
<ChapterTimeStart>27500000000</ChapterTimeStart>
<ChapterTimeEnd>38000000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>After the crime</ChapString>
</ChapterDisplay>
<ChapterDisplay>
<ChapString>Apres le crime</ChapString>
<ChapLanguage>fra</ChapLanguage>
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</ChapterDisplay>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>5666960</ChapterUID>
<ChapterTimeStart>38000000000</ChapterTimeStart>
<ChapterTimeEnd>43000000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Credits</ChapString>
</ChapterDisplay>
<ChapterDisplay>
<ChapString>Generique</ChapString>
<ChapLanguage>fra</ChapLanguage>
</ChapterDisplay>
</ChapterAtom>
</EditionEntry>
</Chapters>
Figure 12: Basic Chapters Example.
19.5.2. Example 2 : nested chapters
In this example an (existing) album is split into different chapters,
and one of them contain another splitting.
19.5.2.1. The Micronauts "Bleep To Bleep"
* 00:00 - 12:28 : Baby Wants To Bleep/Rock
- 00:00 - 04:38 : Baby wants to bleep (pt.1)
- 04:38 - 07:12 : Baby wants to rock
- 07:12 - 10:33 : Baby wants to bleep (pt.2)
- 10:33 - 12:28 : Baby wants to bleep (pt.3)
* 12:30 - 19:38 : Bleeper_O+2
* 19:40 - 22:20 : Baby wants to bleep (pt.4)
* 22:22 - 25:18 : Bleep to bleep
* 25:20 - 33:35 : Baby wants to bleep (k)
* 33:37 - 44:28 : Bleeper
This would translate in the following matroska form, with the EBML
tree shown as XML :
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<Chapters>
<EditionEntry>
<EditionUID>1281690858003401414</EditionUID>
<ChapterAtom>
<ChapterUID>1</ChapterUID>
<ChapterTimeStart>0</ChapterTimeStart>
<ChapterTimeEnd>748000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Baby wants to Bleep/Rock</ChapString>
</ChapterDisplay>
<ChapterAtom>
<ChapterUID>2</ChapterUID>
<ChapterTimeStart>0</ChapterTimeStart>
<ChapterTimeEnd>278000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Baby wants to bleep (pt.1)</ChapString>
</ChapterDisplay>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>3</ChapterUID>
<ChapterTimeStart>278000000</ChapterTimeStart>
<ChapterTimeEnd>432000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Baby wants to rock</ChapString>
</ChapterDisplay>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>4</ChapterUID>
<ChapterTimeStart>432000000</ChapterTimeStart>
<ChapterTimeEnd>633000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Baby wants to bleep (pt.2)</ChapString>
</ChapterDisplay>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>5</ChapterUID>
<ChapterTimeStart>633000000</ChapterTimeStart>
<ChapterTimeEnd>748000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Baby wants to bleep (pt.3)</ChapString>
</ChapterDisplay>
</ChapterAtom>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>6</ChapterUID>
<ChapterTimeStart>750000000</ChapterTimeStart>
<ChapterTimeEnd>1178500000</ChapterTimeEnd>
<ChapterDisplay>
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<ChapString>Bleeper_O+2</ChapString>
</ChapterDisplay>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>7</ChapterUID>
<ChapterTimeStart>1180500000</ChapterTimeStart>
<ChapterTimeEnd>1340000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Baby wants to bleep (pt.4)</ChapString>
</ChapterDisplay>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>8</ChapterUID>
<ChapterTimeStart>1342000000</ChapterTimeStart>
<ChapterTimeEnd>1518000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Bleep to bleep</ChapString>
</ChapterDisplay>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>9</ChapterUID>
<ChapterTimeStart>1520000000</ChapterTimeStart>
<ChapterTimeEnd>2015000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Baby wants to bleep (k)</ChapString>
</ChapterDisplay>
</ChapterAtom>
<ChapterAtom>
<ChapterUID>10</ChapterUID>
<ChapterTimeStart>2017000000</ChapterTimeStart>
<ChapterTimeEnd>2668000000</ChapterTimeEnd>
<ChapterDisplay>
<ChapString>Bleeper</ChapString>
</ChapterDisplay>
</ChapterAtom>
</EditionEntry>
</Chapters>
Figure 13: Nested Chapters Example.
20. 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.
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Matroska Readers MUST NOT execute files stored as Attachment
Elements.
20.1. 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 58: Cover Art Filenames
20.2. Font files
Font files MAY be added to a Matroska file as Attachments so that the
font file may be used to display an associated subtitle track. This
allows the presentation of a Matroska file to be consistent in
various environments where the needed fonts might not be available on
the local system.
Depending on the font format in question, each font file can contain
multiple font variants. Each font variant has a name which will be
referred to as Font Name from now on. This Font Name can be
different than the Attachment's FileName, even when disregarding the
extension. In order to select a font for display, a Matroska player
SHOULD consider both the Font Name and the base name of the
Attachment's FileName, preferring the former when there are multiple
matches.
Subtitle codecs, such as SubStation Alpha (SSA/ASS), usually refer to
a font by its Font Name, not by its filename. If none of the
Attachments are a match for the Font Name, the Matroska player SHOULD
attempt to find a system font whose Font Name matches the one used in
the subtitle track.
Since loading fonts temporarily can take a while, a Matroska player
usually loads or installs all the fonts found in attachments so they
are ready to be used during playback. Failure to use the font
attachment might result in incorrect rendering of the subtitles.
If a selected subtitle track has some AttachmentLink elements, the
player MAY use only these fonts.
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A Matroska player SHOULD handle the official font media types from
[RFC8081] when the system can handle the type: * font/sfnt: Generic
SFNT Font Type, * font/ttf: TTF Font Type, * font/otf: OpenType
Layout (OTF) Font Type, * font/collection: Collection Font Type, *
font/woff: WOFF 1.0, * font/woff2: WOFF 2.0.
Fonts in Matroska existed long before [RFC8081]. A few unofficial
media types for fonts were used in existing files. Therefore it is
RECOMMENDED for a Matroska player to support the following legacy
media types for font attachments:
* application/x-truetype-font: Truetype fonts, equivalent to font/
ttf and sometimes font/otf,
* application/x-font-ttf: TTF fonts, equivalent to font/ttf,
* application/vnd.ms-opentype: OpenType Layout fonts, equivalent to
font/otf
* application/font-sfnt: Generic SFNT Font Type, equivalent to font/
sfnt
* application/font-woff: WOFF 1.0, equivalent to font/woff
There may also be some font attachments with the application/octet-
stream media type. In that case the Matroska player MAY try to guess
the font type by checking the file extension of the
AttachedFile\FileName string. Common file extensions for fonts are:
* .ttf for Truetype fonts, equivalent to font/ttf, * .otf for
OpenType Layout fonts, equivalent to font/otf, * .ttc for Collection
fonts, equivalent to font/collection The file extension check MUST be
case insensitive.
Matroska writers SHOULD use a valid font media type from [RFC8081] in
the AttachedFile\FileMediaType of the font attachment. They MAY use
the media types found in older files when compatibility with older
players is necessary.
21. 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
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Matroska Reader with additional information to use in the
optimization of seeking performance.
21.1. Recommendations
The following recommendations are provided to optimize Matroska
performance.
* Unless Matroska is used as a live stream, it SHOULD contain a Cues
Element.
* For each video track, each keyframe SHOULD be referenced by a
CuePoint Element.
* It is RECOMMENDED to not reference non-keyframes of video tracks
in Cues unless it references a Cluster Element which contains a
CodecState Element but no keyframes.
* For each subtitle track present, each subtitle frame SHOULD be
referenced by a CuePoint Element with a CueDuration Element.
* References to audio tracks MAY be skipped in CuePoint Elements if
a video track is present. When included the CuePoint Elements
SHOULD reference audio keyframes at most once every 500
milliseconds.
* If the referenced frame is not stored within the first
SimpleBlock, or first BlockGroup within its Cluster Element, then
the CueRelativePosition Element SHOULD be written to reference
where in the Cluster the reference frame is stored.
* If a CuePoint Element references Cluster Element that includes a
CodecState Element, then that CuePoint Element MUST use a
CueCodecState Element.
* CuePoint Elements SHOULD be numerically sorted in storage order by
the value of the CueTime Element.
22. Matroska Streaming
In Matroska, there are two kinds of streaming: file access and
livestreaming.
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22.1. 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.
22.2. 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
SeekHead, Cues, Chapters, and Attachments, MUST NOT be used.
It is possible for a Matroska Player to detect that a stream is not
seekable. If the stream has neither a SeekHead list 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.
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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.
23. Tags Precedence
Tags allow tagging all kinds of Matroska parts with very detailed
metadata in multiple languages.
Some Matroska elements also contain their own string value like the
Track Name (Section 5.1.4.1.20) or the Chapter String
(Section 5.1.7.1.4.10).
The following Matroska elements can also be defined with tags:
* The Track Name Element (Section 5.1.4.1.20) corresponds to a tag
with the TagTrackUID (Section 5.1.8.1.1.3) set to the given track,
a TagName of TITLE (Section 5.1.8.1.2.1) and a TagLanguage
(Section 5.1.8.1.2.2) or TagLanguageBCP47 (Section 5.1.8.1.2.3) of
"und".
* The Chapter String Element (Section 5.1.7.1.4.10) corresponds to a
tag with the TagChapterUID (Section 5.1.8.1.1.5) set to the same
chapter UID, a TagName of TITLE (Section 5.1.8.1.2.1) and a
TagLanguage (Section 5.1.8.1.2.2) or TagLanguageBCP47
(Section 5.1.8.1.2.3) matching the ChapLanguage
(Section 5.1.7.1.4.11) or ChapLanguageBCP47 (Section 5.1.7.1.4.12)
respectively.
* The FileDescription Element (Section 5.1.6.1.1) of an attachment
corresponds to a tag with the TagAttachmentUID
(Section 5.1.8.1.1.6) set to the given attachment, a TagName of
TITLE (Section 5.1.8.1.2.1) and a TagLanguage
(Section 5.1.8.1.2.2) or TagLanguageBCP47 (Section 5.1.8.1.2.3) of
"und".
When both values exist in the file, the value found in Tags takes
precedence over the value found in original location of the element.
For example if you have a TrackEntry\Name element and Tag TITLE for
that track in a Matroska Segment, the Tag string SHOULD be used and
not the TrackEntry\Name string to identify the track.
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As the Tag element is optional, a lot of Matroska Readers do not
handle it and will not use the tags value when it's found. So for
maximum compatibility, it's usually better to put the strings in the
TrackEntry, ChapterAtom and Attachment and keep the tags matching
these values if tags are also used.
See [MatroskaTags] for more details on how to use tags.
24. Implementation Recommendations
24.1. Cluster
It is RECOMMENDED that the size of each individual Cluster Element be
limited to store no more than 5 seconds or 5 megabytes.
24.2. SeekHead
It is RECOMMENDED that the first SeekHead Element be followed by a
Void Element to allow for the SeekHead Element to be expanded to
cover new Top-Level Elements that could be added to the Matroska
file, such as Tags, Chapters, and Attachments Elements.
The size of this Void Element should be adjusted depending whether
the Matroska file already has Tags, Chapters, and Attachments
Elements.
24.3. Cues
For video files, it is RECOMMENDED to index at least the keyframes of
the video track.
24.4. Optimum Layouts
While there can be Top-Level Elements in any order, some ordering of
Elements are better than others. Here are few optimum layouts for
different use case:
24.4.1. Optimum layout for a muxer
This is the basic layout muxers should be using for an efficient
playback experience.
* SeekHead
* Info
* Tracks
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* Chapters
* Attachments
* Tags
* Clusters
* Cues
24.4.2. Optimum layout after editing tags
When tags from the previous layout need to be extended, they are
moved to the end with the extra information. The location where the
old tags were located is voided.
* SeekHead
* Info
* Tracks
* Chapters
* Attachments
* Void
* Clusters
* Cues
* Tags
24.4.3. Optimum layout with Cues at the front
Cues are usually a big chunk of data referencing a lot of locations
in the file. For a player that want to seek in the file they need to
seek to the end of the file to have these locations. It is often
better if they are placed early in the file. On the other hand that
means players that don't intend to seek will have to read/skip these
data no matter what.
Because the Cues reference locations further in the file, it's often
complicated to allocate the proper space for that element before all
the locations are known. Therefore shis layout is rarely used.
* SeekHead
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* Info
* Tracks
* Chapters
* Attachments
* Tags
* Cues
* Clusters
24.4.4. Optimum layout for livestreaming
In Livestreaming (Section 22.2) only a few elements make sense.
SeekHead and Cues are useless for example. All elements other than
the Clusters MUST be placed before the Clusters.
* Info
* Tracks
* Attachments (rare)
* Tags
* Clusters
25. Security Considerations
Matroska inherits security considerations from EBML.
Attacks on a Matroska Reader could include:
* Storage of a arbitrary and potentially executable data within an
Attachment Element. Matroska Readers that extract or use data
from Matroska Attachments SHOULD check that the data adheres to
expectations.
* A Matroska Attachment with an inaccurate mime-type.
* Damage to the Encryption and Compression fields (Section 13) that
would result in bogus binary data interpreted by the decoder.
26. IANA Considerations
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26.1. Matroska Element IDs Registry
This document creates a new IANA registry called the "Matroska
Element IDs" registry.
To register a new Element ID in this registry, one needs an Element
ID, a Change Controller (IESG or email of registrant) and an optional
Reference to a document describing the Element ID.
Element IDs are described in Section 5 of [RFC8794]. Element IDs are
encoded using the VINT mechanism described in Section 4 of [RFC8794]
and can be between one and five octets long. Five-octet-long Element
IDs are possible only if declared in the EBML header.
One-octet Element IDs MUST be between 0x80 and 0xFE. These items are
valuable because they are short, and they need to be used for
commonly repeated elements. Element IDs are to be allocated within
this range according to the "RFC Required" policy [RFC8126].
The following one-octet Element ID is RESERVED: 0xFF.
Values in the one-octet range of 0x00 to 0x7F are not valid for use
as an Element ID.
Two-octet Element IDs MUST be between 0x407F and 0x7FFE. Element IDs
are to be allocated within this range according to the "Specification
Required" policy [RFC8126].
The following two-octet Element ID is RESERVED: 0x7FFF.
Values in the two-octet ranges of 0x0000 to 0x4000 and 0x8000 to
0xFFFF are not valid for use as an Element ID.
Three-octet Element IDs MUST be between 0x203FFF and 0x3FFFFE.
Element IDs are to be allocated within this range according to the
"First Come First Served" policy [RFC8126].
The following three-octet Element ID is RESERVED: 0x3FFFFF.
Values in the three-octet ranges of 0x000000 to 0x200000 and 0x400000
to 0xFFFFFF are not valid for use as an Element ID.
Four-octet Element IDs MUST be between 0x101FFFFF and 0x1FFFFFFE.
Four-octet Element IDs are somewhat special in that they are useful
for resynchronizing to major structures in the event of data
corruption or loss. As such, four-octet Element IDs are split into
two categories. Four-octet Element IDs whose lower three octets (as
encoded) would make printable 7-bit ASCII values (0x20 to 0x7E,
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inclusive) MUST be allocated by the "Specification Required" policy.
Sequential allocation of values is not required: specifications
SHOULD include a specific request and are encouraged to do early
allocations.
To be clear about the above category: four-octet Element IDs always
start with hex 0x10 to 0x1F, and that octet may be chosen so that the
entire VINT has some desirable property, such as a specific CRC. The
other three octets, when ALL having values between 0x20 (32, ASCII
Space) and 0x7E (126, ASCII "~"), fall into this category.
Other four-octet Element IDs may be allocated by the "First Come
First Served" policy.
The following four-octet Element ID is RESERVED: 0x1FFFFFFF.
Values in the four-octet ranges of 0x00000000 to 0x10000000 and
0x20000000 to 0xFFFFFFFF are not valid for use as an Element ID.
Five-octet Element IDs (values from 0x080FFFFFFF to 0x0FFFFFFFFE) are
RESERVED according to the "Experimental Use" policy [RFC8126]: they
may be used by anyone at any time, but there is no coordination.
EBML IDs defined for the EBML Header -- as defined in Section 17.1 of
[RFC8794] -- MUST NOT be used as Matroska Element IDs.
Matroska Element IDs Values found in this document are assigned as
initial values as follows:
+============+=============================+======================+
| Element ID | Element Name | Reference |
+============+=============================+======================+
| 0xFD | ReferenceVirtual | Described in |
| | | Section 27.5 |
+------------+-----------------------------+----------------------+
| 0xFB | ReferenceBlock | Described in |
| | | Section 5.1.3.4.5 |
+------------+-----------------------------+----------------------+
| 0xFA | ReferencePriority | Described in |
| | | Section 5.1.3.4.4 |
+------------+-----------------------------+----------------------+
| 0xF7 | CueTrack | Described in |
| | | Section 5.1.5.1.2.1 |
+------------+-----------------------------+----------------------+
| 0xF1 | CueClusterPosition | Described in |
| | | Section 5.1.5.1.2.2 |
+------------+-----------------------------+----------------------+
| 0xF0 | CueRelativePosition | Described in |
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| | | Section 5.1.5.1.2.3 |
+------------+-----------------------------+----------------------+
| 0xEE | BlockAddID | Described in |
| | | Section 5.1.3.4.2.3 |
+------------+-----------------------------+----------------------+
| 0xED | TrackJoinUID | Described in |
| | | Section 5.1.4.1.33.6 |
+------------+-----------------------------+----------------------+
| 0xEB | CueRefCodecState | Described in |
| | | Section 27.37 |
+------------+-----------------------------+----------------------+
| 0xEA | CueCodecState | Described in |
| | | Section 5.1.5.1.2.6 |
+------------+-----------------------------+----------------------+
| 0xE9 | TrackJoinBlocks | Described in |
| | | Section 5.1.4.1.33.5 |
+------------+-----------------------------+----------------------+
| 0xE8 | TimeSlice | Described in |
| | | Section 27.7 |
+------------+-----------------------------+----------------------+
| 0xE7 | Timestamp | Described in |
| | | Section 5.1.3.1 |
+------------+-----------------------------+----------------------+
| 0xE6 | TrackPlaneType | Described in |
| | | Section 5.1.4.1.33.4 |
+------------+-----------------------------+----------------------+
| 0xE5 | TrackPlaneUID | Described in |
| | | Section 5.1.4.1.33.3 |
+------------+-----------------------------+----------------------+
| 0xE4 | TrackPlane | Described in |
| | | Section 5.1.4.1.33.2 |
+------------+-----------------------------+----------------------+
| 0xE3 | TrackCombinePlanes | Described in |
| | | Section 5.1.4.1.33.1 |
+------------+-----------------------------+----------------------+
| 0xE2 | TrackOperation | Described in |
| | | Section 5.1.4.1.33 |
+------------+-----------------------------+----------------------+
| 0xE1 | Audio | Described in |
| | | Section 5.1.4.1.32 |
+------------+-----------------------------+----------------------+
| 0xE0 | Video | Described in |
| | | Section 5.1.4.1.31 |
+------------+-----------------------------+----------------------+
| 0xDB | CueReference | Described in |
| | | Section 5.1.5.1.2.7 |
+------------+-----------------------------+----------------------+
| 0xD7 | TrackNumber | Described in |
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| | | Section 5.1.4.1.1 |
+------------+-----------------------------+----------------------+
| 0xCF | SliceDuration | Described in |
| | | Section 27.12 |
+------------+-----------------------------+----------------------+
| 0xCE | Delay | Described in |
| | | Section 27.11 |
+------------+-----------------------------+----------------------+
| 0xCD | FrameNumber | Described in |
| | | Section 27.9 |
+------------+-----------------------------+----------------------+
| 0xCC | LaceNumber | Described in |
| | | Section 27.8 |
+------------+-----------------------------+----------------------+
| 0xCB | BlockAdditionID | Described in |
| | | Section 27.10 |
+------------+-----------------------------+----------------------+
| 0xCA | ReferenceTimestamp | Described in |
| | | Section 27.15 |
+------------+-----------------------------+----------------------+
| 0xC9 | ReferenceOffset | Described in |
| | | Section 27.14 |
+------------+-----------------------------+----------------------+
| 0xC8 | ReferenceFrame | Described in |
| | | Section 27.13 |
+------------+-----------------------------+----------------------+
| 0xC7 | TrickMasterTrackUID | Described in |
| | | Section 27.29 |
+------------+-----------------------------+----------------------+
| 0xC6 | TrickTrackFlag | Described in |
| | | Section 27.28 |
+------------+-----------------------------+----------------------+
| 0xC4 | TrickMasterTrackSegmentUID | Described in |
| | | Section 27.30 |
+------------+-----------------------------+----------------------+
| 0xC1 | TrickTrackSegmentUID | Described in |
| | | Section 27.27 |
+------------+-----------------------------+----------------------+
| 0xC0 | TrickTrackUID | Described in |
| | | Section 27.26 |
+------------+-----------------------------+----------------------+
| 0xBB | CuePoint | Described in |
| | | Section 5.1.5.1 |
+------------+-----------------------------+----------------------+
| 0xBA | PixelHeight | Described in |
| | | Section 5.1.4.1.31.7 |
+------------+-----------------------------+----------------------+
| 0xB9 | FlagEnabled | Described in |
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| | | Section 5.1.4.1.4 |
+------------+-----------------------------+----------------------+
| 0xB7 | CueTrackPositions | Described in |
| | | Section 5.1.5.1.2 |
+------------+-----------------------------+----------------------+
| 0xB6 | ChapterAtom | Described in |
| | | Section 5.1.7.1.4 |
+------------+-----------------------------+----------------------+
| 0xB5 | SamplingFrequency | Described in |
| | | Section 5.1.4.1.32.1 |
+------------+-----------------------------+----------------------+
| 0xB3 | CueTime | Described in |
| | | Section 5.1.5.1.1 |
+------------+-----------------------------+----------------------+
| 0xB2 | CueDuration | Described in |
| | | Section 5.1.5.1.2.4 |
+------------+-----------------------------+----------------------+
| 0xB0 | PixelWidth | Described in |
| | | Section 5.1.4.1.31.6 |
+------------+-----------------------------+----------------------+
| 0xAF | EncryptedBlock | Described in |
| | | Section 27.16 |
+------------+-----------------------------+----------------------+
| 0xAE | TrackEntry | Described in |
| | | Section 5.1.4.1 |
+------------+-----------------------------+----------------------+
| 0xAB | PrevSize | Described in |
| | | Section 5.1.3.2 |
+------------+-----------------------------+----------------------+
| 0xAA | CodecDecodeAll | Described in |
| | | Section 27.21 |
+------------+-----------------------------+----------------------+
| 0xA7 | Position | Described in |
| | | Section 27.3 |
+------------+-----------------------------+----------------------+
| 0xA6 | BlockMore | Described in |
| | | Section 5.1.3.4.2.1 |
+------------+-----------------------------+----------------------+
| 0xA5 | BlockAdditional | Described in |
| | | Section 5.1.3.4.2.2 |
+------------+-----------------------------+----------------------+
| 0xA4 | CodecState | Described in |
| | | Section 5.1.3.4.6 |
+------------+-----------------------------+----------------------+
| 0xA3 | SimpleBlock | Described in |
| | | Section 5.1.3.3 |
+------------+-----------------------------+----------------------+
| 0xA2 | BlockVirtual | Described in |
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| | | Section 27.4 |
+------------+-----------------------------+----------------------+
| 0xA1 | Block | Described in |
| | | Section 5.1.3.4.1 |
+------------+-----------------------------+----------------------+
| 0xA0 | BlockGroup | Described in |
| | | Section 5.1.3.4 |
+------------+-----------------------------+----------------------+
| 0x9F | Channels | Described in |
| | | Section 5.1.4.1.32.3 |
+------------+-----------------------------+----------------------+
| 0x9D | FieldOrder | Described in |
| | | Section 5.1.4.1.31.2 |
+------------+-----------------------------+----------------------+
| 0x9C | FlagLacing | Described in |
| | | Section 5.1.4.1.12 |
+------------+-----------------------------+----------------------+
| 0x9B | BlockDuration | Described in |
| | | Section 5.1.3.4.3 |
+------------+-----------------------------+----------------------+
| 0x9A | FlagInterlaced | Described in |
| | | Section 5.1.4.1.31.1 |
+------------+-----------------------------+----------------------+
| 0x98 | ChapterFlagHidden | Described in |
| | | Section 5.1.7.1.4.5 |
+------------+-----------------------------+----------------------+
| 0x97 | CueRefCluster | Described in |
| | | Section 27.35 |
+------------+-----------------------------+----------------------+
| 0x96 | CueRefTime | Described in |
| | | Section 5.1.5.1.2.8 |
+------------+-----------------------------+----------------------+
| 0x92 | ChapterTimeEnd | Described in |
| | | Section 5.1.7.1.4.4 |
+------------+-----------------------------+----------------------+
| 0x91 | ChapterTimeStart | Described in |
| | | Section 5.1.7.1.4.3 |
+------------+-----------------------------+----------------------+
| 0x8E | Slices | Described in |
| | | Section 27.6 |
+------------+-----------------------------+----------------------+
| 0x88 | FlagDefault | Described in |
| | | Section 5.1.4.1.5 |
+------------+-----------------------------+----------------------+
| 0x86 | CodecID | Described in |
| | | Section 5.1.4.1.23 |
+------------+-----------------------------+----------------------+
| 0x85 | ChapString | Described in |
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| | | Section 5.1.7.1.4.10 |
+------------+-----------------------------+----------------------+
| 0x83 | TrackType | Described in |
| | | Section 5.1.4.1.3 |
+------------+-----------------------------+----------------------+
| 0x80 | ChapterDisplay | Described in |
| | | Section 5.1.7.1.4.9 |
+------------+-----------------------------+----------------------+
| 0x7D7B | ChannelPositions | Described in |
| | | Section 27.25 |
+------------+-----------------------------+----------------------+
| 0x7BA9 | Title | Described in |
| | | Section 5.1.2.12 |
+------------+-----------------------------+----------------------+
| 0x78B5 | OutputSamplingFrequency | Described in |
| | | Section 5.1.4.1.32.2 |
+------------+-----------------------------+----------------------+
| 0x7675 | ProjectionPoseRoll | Described in Section |
| | | 5.1.4.1.31.46 |
+------------+-----------------------------+----------------------+
| 0x7674 | ProjectionPosePitch | Described in Section |
| | | 5.1.4.1.31.45 |
+------------+-----------------------------+----------------------+
| 0x7673 | ProjectionPoseYaw | Described in Section |
| | | 5.1.4.1.31.44 |
+------------+-----------------------------+----------------------+
| 0x7672 | ProjectionPrivate | Described in Section |
| | | 5.1.4.1.31.43 |
+------------+-----------------------------+----------------------+
| 0x7671 | ProjectionType | Described in Section |
| | | 5.1.4.1.31.42 |
+------------+-----------------------------+----------------------+
| 0x7670 | Projection | Described in Section |
| | | 5.1.4.1.31.41 |
+------------+-----------------------------+----------------------+
| 0x75A2 | DiscardPadding | Described in |
| | | Section 5.1.3.4.7 |
+------------+-----------------------------+----------------------+
| 0x75A1 | BlockAdditions | Described in |
| | | Section 5.1.3.4.2 |
+------------+-----------------------------+----------------------+
| 0x7446 | AttachmentLink | Described in |
| | | Section 5.1.4.1.26 |
+------------+-----------------------------+----------------------+
| 0x73C5 | TrackUID | Described in |
| | | Section 5.1.4.1.2 |
+------------+-----------------------------+----------------------+
| 0x73C4 | ChapterUID | Described in |
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| | | Section 5.1.7.1.4.1 |
+------------+-----------------------------+----------------------+
| 0x73A4 | SegmentUUID | Described in |
| | | Section 5.1.2.1 |
+------------+-----------------------------+----------------------+
| 0x7384 | SegmentFilename | Described in |
| | | Section 5.1.2.2 |
+------------+-----------------------------+----------------------+
| 0x7373 | Tag | Described in |
| | | Section 5.1.8.1 |
+------------+-----------------------------+----------------------+
| 0x6FAB | TrackOverlay | Described in |
| | | Section 5.1.4.1.27 |
+------------+-----------------------------+----------------------+
| 0x6EBC | ChapterSegmentEditionUID | Described in |
| | | Section 5.1.7.1.4.7 |
+------------+-----------------------------+----------------------+
| 0x6E67 | ChapterSegmentUUID | Described in |
| | | Section 5.1.7.1.4.6 |
+------------+-----------------------------+----------------------+
| 0x6DF8 | MaxCache | Described in |
| | | Section 5.1.4.1.14 |
+------------+-----------------------------+----------------------+
| 0x6DE7 | MinCache | Described in |
| | | Section 5.1.4.1.13 |
+------------+-----------------------------+----------------------+
| 0x6D80 | ContentEncodings | Described in |
| | | Section 5.1.4.1.34 |
+------------+-----------------------------+----------------------+
| 0x69FC | ChapterTranslateEditionUID | Described in |
| | | Section 5.1.2.8.3 |
+------------+-----------------------------+----------------------+
| 0x69BF | ChapterTranslateCodec | Described in |
| | | Section 5.1.2.8.2 |
+------------+-----------------------------+----------------------+
| 0x69A5 | ChapterTranslateID | Described in |
| | | Section 5.1.2.8.1 |
+------------+-----------------------------+----------------------+
| 0x6955 | ChapProcessCodecID | Described in |
| | | Section 5.1.7.1.4.15 |
+------------+-----------------------------+----------------------+
| 0x6944 | ChapProcess | Described in |
| | | Section 5.1.7.1.4.14 |
+------------+-----------------------------+----------------------+
| 0x6933 | ChapProcessData | Described in |
| | | Section 5.1.7.1.4.19 |
+------------+-----------------------------+----------------------+
| 0x6924 | ChapterTranslate | Described in |
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| | | Section 5.1.2.8 |
+------------+-----------------------------+----------------------+
| 0x6922 | ChapProcessTime | Described in |
| | | Section 5.1.7.1.4.18 |
+------------+-----------------------------+----------------------+
| 0x6911 | ChapProcessCommand | Described in |
| | | Section 5.1.7.1.4.17 |
+------------+-----------------------------+----------------------+
| 0x68CA | TargetTypeValue | Described in |
| | | Section 5.1.8.1.1.1 |
+------------+-----------------------------+----------------------+
| 0x67C8 | SimpleTag | Described in |
| | | Section 5.1.8.1.2 |
+------------+-----------------------------+----------------------+
| 0x66FC | TrackTranslateEditionUID | Described in |
| | | Section 5.1.4.1.30.3 |
+------------+-----------------------------+----------------------+
| 0x66BF | TrackTranslateCodec | Described in |
| | | Section 5.1.4.1.30.2 |
+------------+-----------------------------+----------------------+
| 0x66A5 | TrackTranslateTrackID | Described in |
| | | Section 5.1.4.1.30.1 |
+------------+-----------------------------+----------------------+
| 0x6624 | TrackTranslate | Described in |
| | | Section 5.1.4.1.30 |
+------------+-----------------------------+----------------------+
| 0x63CA | TargetType | Described in |
| | | Section 5.1.8.1.1.2 |
+------------+-----------------------------+----------------------+
| 0x63C9 | TagEditionUID | Described in |
| | | Section 5.1.8.1.1.4 |
+------------+-----------------------------+----------------------+
| 0x63C6 | TagAttachmentUID | Described in |
| | | Section 5.1.8.1.1.6 |
+------------+-----------------------------+----------------------+
| 0x63C5 | TagTrackUID | Described in |
| | | Section 5.1.8.1.1.3 |
+------------+-----------------------------+----------------------+
| 0x63C4 | TagChapterUID | Described in |
| | | Section 5.1.8.1.1.5 |
+------------+-----------------------------+----------------------+
| 0x63C3 | ChapterPhysicalEquiv | Described in |
| | | Section 5.1.7.1.4.8 |
+------------+-----------------------------+----------------------+
| 0x63C0 | Targets | Described in |
| | | Section 5.1.8.1.1 |
+------------+-----------------------------+----------------------+
| 0x63A2 | CodecPrivate | Described in |
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| | | Section 5.1.4.1.24 |
+------------+-----------------------------+----------------------+
| 0x6264 | BitDepth | Described in |
| | | Section 5.1.4.1.32.4 |
+------------+-----------------------------+----------------------+
| 0x6240 | ContentEncoding | Described in |
| | | Section 5.1.4.1.34.1 |
+------------+-----------------------------+----------------------+
| 0x61A7 | AttachedFile | Described in |
| | | Section 5.1.6.1 |
+------------+-----------------------------+----------------------+
| 0x58D7 | SilentTrackNumber | Described in |
| | | Section 27.2 |
+------------+-----------------------------+----------------------+
| 0x5854 | SilentTracks | Described in |
| | | Section 27.1 |
+------------+-----------------------------+----------------------+
| 0x5741 | WritingApp | Described in |
| | | Section 5.1.2.14 |
+------------+-----------------------------+----------------------+
| 0x56BB | SeekPreRoll | Described in |
| | | Section 5.1.4.1.29 |
+------------+-----------------------------+----------------------+
| 0x56AA | CodecDelay | Described in |
| | | Section 5.1.4.1.28 |
+------------+-----------------------------+----------------------+
| 0x5654 | ChapterStringUID | Described in |
| | | Section 5.1.7.1.4.2 |
+------------+-----------------------------+----------------------+
| 0x55EE | MaxBlockAdditionID | Described in |
| | | Section 5.1.4.1.18 |
+------------+-----------------------------+----------------------+
| 0x55DA | LuminanceMin | Described in Section |
| | | 5.1.4.1.31.40 |
+------------+-----------------------------+----------------------+
| 0x55D9 | LuminanceMax | Described in Section |
| | | 5.1.4.1.31.39 |
+------------+-----------------------------+----------------------+
| 0x55D8 | WhitePointChromaticityY | Described in Section |
| | | 5.1.4.1.31.38 |
+------------+-----------------------------+----------------------+
| 0x55D7 | WhitePointChromaticityX | Described in Section |
| | | 5.1.4.1.31.37 |
+------------+-----------------------------+----------------------+
| 0x55D6 | PrimaryBChromaticityY | Described in Section |
| | | 5.1.4.1.31.36 |
+------------+-----------------------------+----------------------+
| 0x55D5 | PrimaryBChromaticityX | Described in Section |
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| | | 5.1.4.1.31.35 |
+------------+-----------------------------+----------------------+
| 0x55D4 | PrimaryGChromaticityY | Described in Section |
| | | 5.1.4.1.31.34 |
+------------+-----------------------------+----------------------+
| 0x55D3 | PrimaryGChromaticityX | Described in Section |
| | | 5.1.4.1.31.33 |
+------------+-----------------------------+----------------------+
| 0x55D2 | PrimaryRChromaticityY | Described in Section |
| | | 5.1.4.1.31.32 |
+------------+-----------------------------+----------------------+
| 0x55D1 | PrimaryRChromaticityX | Described in Section |
| | | 5.1.4.1.31.31 |
+------------+-----------------------------+----------------------+
| 0x55D0 | MasteringMetadata | Described in Section |
| | | 5.1.4.1.31.30 |
+------------+-----------------------------+----------------------+
| 0x55BD | MaxFALL | Described in Section |
| | | 5.1.4.1.31.29 |
+------------+-----------------------------+----------------------+
| 0x55BC | MaxCLL | Described in Section |
| | | 5.1.4.1.31.28 |
+------------+-----------------------------+----------------------+
| 0x55BB | Primaries | Described in Section |
| | | 5.1.4.1.31.27 |
+------------+-----------------------------+----------------------+
| 0x55BA | TransferCharacteristics | Described in Section |
| | | 5.1.4.1.31.26 |
+------------+-----------------------------+----------------------+
| 0x55B9 | Range | Described in Section |
| | | 5.1.4.1.31.25 |
+------------+-----------------------------+----------------------+
| 0x55B8 | ChromaSitingVert | Described in Section |
| | | 5.1.4.1.31.24 |
+------------+-----------------------------+----------------------+
| 0x55B7 | ChromaSitingHorz | Described in Section |
| | | 5.1.4.1.31.23 |
+------------+-----------------------------+----------------------+
| 0x55B6 | CbSubsamplingVert | Described in Section |
| | | 5.1.4.1.31.22 |
+------------+-----------------------------+----------------------+
| 0x55B5 | CbSubsamplingHorz | Described in Section |
| | | 5.1.4.1.31.21 |
+------------+-----------------------------+----------------------+
| 0x55B4 | ChromaSubsamplingVert | Described in Section |
| | | 5.1.4.1.31.20 |
+------------+-----------------------------+----------------------+
| 0x55B3 | ChromaSubsamplingHorz | Described in Section |
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| | | 5.1.4.1.31.19 |
+------------+-----------------------------+----------------------+
| 0x55B2 | BitsPerChannel | Described in Section |
| | | 5.1.4.1.31.18 |
+------------+-----------------------------+----------------------+
| 0x55B1 | MatrixCoefficients | Described in Section |
| | | 5.1.4.1.31.17 |
+------------+-----------------------------+----------------------+
| 0x55B0 | Colour | Described in Section |
| | | 5.1.4.1.31.16 |
+------------+-----------------------------+----------------------+
| 0x55AF | FlagCommentary | Described in |
| | | Section 5.1.4.1.11 |
+------------+-----------------------------+----------------------+
| 0x55AE | FlagOriginal | Described in |
| | | Section 5.1.4.1.10 |
+------------+-----------------------------+----------------------+
| 0x55AD | FlagTextDescriptions | Described in |
| | | Section 5.1.4.1.9 |
+------------+-----------------------------+----------------------+
| 0x55AC | FlagVisualImpaired | Described in |
| | | Section 5.1.4.1.8 |
+------------+-----------------------------+----------------------+
| 0x55AB | FlagHearingImpaired | Described in |
| | | Section 5.1.4.1.7 |
+------------+-----------------------------+----------------------+
| 0x55AA | FlagForced | Described in |
| | | Section 5.1.4.1.6 |
+------------+-----------------------------+----------------------+
| 0x54DD | PixelCropRight | Described in Section |
| | | 5.1.4.1.31.11 |
+------------+-----------------------------+----------------------+
| 0x54CC | PixelCropLeft | Described in Section |
| | | 5.1.4.1.31.10 |
+------------+-----------------------------+----------------------+
| 0x54BB | PixelCropTop | Described in |
| | | Section 5.1.4.1.31.9 |
+------------+-----------------------------+----------------------+
| 0x54BA | DisplayHeight | Described in Section |
| | | 5.1.4.1.31.13 |
+------------+-----------------------------+----------------------+
| 0x54B3 | AspectRatioType | Described in |
| | | Section 27.22 |
+------------+-----------------------------+----------------------+
| 0x54B2 | DisplayUnit | Described in Section |
| | | 5.1.4.1.31.14 |
+------------+-----------------------------+----------------------+
| 0x54B0 | DisplayWidth | Described in Section |
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| | | 5.1.4.1.31.12 |
+------------+-----------------------------+----------------------+
| 0x54AA | PixelCropBottom | Described in |
| | | Section 5.1.4.1.31.8 |
+------------+-----------------------------+----------------------+
| 0x53C0 | AlphaMode | Described in |
| | | Section 5.1.4.1.31.4 |
+------------+-----------------------------+----------------------+
| 0x53B9 | OldStereoMode | Described in |
| | | Section 5.1.4.1.31.5 |
+------------+-----------------------------+----------------------+
| 0x53B8 | StereoMode | Described in |
| | | Section 5.1.4.1.31.3 |
+------------+-----------------------------+----------------------+
| 0x53AC | SeekPosition | Described in |
| | | Section 5.1.1.1.2 |
+------------+-----------------------------+----------------------+
| 0x53AB | SeekID | Described in |
| | | Section 5.1.1.1.1 |
+------------+-----------------------------+----------------------+
| 0x537F | TrackOffset | Described in |
| | | Section 27.17 |
+------------+-----------------------------+----------------------+
| 0x5378 | CueBlockNumber | Described in |
| | | Section 5.1.5.1.2.5 |
+------------+-----------------------------+----------------------+
| 0x536E | Name | Described in |
| | | Section 5.1.4.1.20 |
+------------+-----------------------------+----------------------+
| 0x535F | CueRefNumber | Described in |
| | | Section 27.36 |
+------------+-----------------------------+----------------------+
| 0x5035 | ContentEncryption | Described in |
| | | Section 5.1.4.1.34.8 |
+------------+-----------------------------+----------------------+
| 0x5034 | ContentCompression | Described in |
| | | Section 5.1.4.1.34.5 |
+------------+-----------------------------+----------------------+
| 0x5033 | ContentEncodingType | Described in |
| | | Section 5.1.4.1.34.4 |
+------------+-----------------------------+----------------------+
| 0x5032 | ContentEncodingScope | Described in |
| | | Section 5.1.4.1.34.3 |
+------------+-----------------------------+----------------------+
| 0x5031 | ContentEncodingOrder | Described in |
| | | Section 5.1.4.1.34.2 |
+------------+-----------------------------+----------------------+
| 0x4DBB | Seek | Described in |
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| | | Section 5.1.1.1 |
+------------+-----------------------------+----------------------+
| 0x4D80 | MuxingApp | Described in |
| | | Section 5.1.2.13 |
+------------+-----------------------------+----------------------+
| 0x47E8 | AESSettingsCipherMode | Described in Section |
| | | 5.1.4.1.34.12 |
+------------+-----------------------------+----------------------+
| 0x47E7 | ContentEncAESSettings | Described in Section |
| | | 5.1.4.1.34.11 |
+------------+-----------------------------+----------------------+
| 0x47E6 | ContentSigHashAlgo | Described in |
| | | Section 27.34 |
+------------+-----------------------------+----------------------+
| 0x47E5 | ContentSigAlgo | Described in |
| | | Section 27.33 |
+------------+-----------------------------+----------------------+
| 0x47E4 | ContentSigKeyID | Described in |
| | | Section 27.32 |
+------------+-----------------------------+----------------------+
| 0x47E3 | ContentSignature | Described in |
| | | Section 27.31 |
+------------+-----------------------------+----------------------+
| 0x47E2 | ContentEncKeyID | Described in Section |
| | | 5.1.4.1.34.10 |
+------------+-----------------------------+----------------------+
| 0x47E1 | ContentEncAlgo | Described in |
| | | Section 5.1.4.1.34.9 |
+------------+-----------------------------+----------------------+
| 0x46AE | FileUID | Described in |
| | | Section 5.1.6.1.5 |
+------------+-----------------------------+----------------------+
| 0x467E | FileDescription | Described in |
| | | Section 5.1.6.1.1 |
+------------+-----------------------------+----------------------+
| 0x4675 | FileReferral | Described in |
| | | Section 27.38 |
+------------+-----------------------------+----------------------+
| 0x466E | FileName | Described in |
| | | Section 5.1.6.1.2 |
+------------+-----------------------------+----------------------+
| 0x4662 | FileUsedEndTime | Described in |
| | | Section 27.40 |
+------------+-----------------------------+----------------------+
| 0x4661 | FileUsedStartTime | Described in |
| | | Section 27.39 |
+------------+-----------------------------+----------------------+
| 0x4660 | FileMediaType | Described in |
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| | | Section 5.1.6.1.3 |
+------------+-----------------------------+----------------------+
| 0x465C | FileData | Described in |
| | | Section 5.1.6.1.4 |
+------------+-----------------------------+----------------------+
| 0x45DD | EditionFlagOrdered | Described in |
| | | Section 5.1.7.1.3 |
+------------+-----------------------------+----------------------+
| 0x45DB | EditionFlagDefault | Described in |
| | | Section 5.1.7.1.2 |
+------------+-----------------------------+----------------------+
| 0x45BC | EditionUID | Described in |
| | | Section 5.1.7.1.1 |
+------------+-----------------------------+----------------------+
| 0x45B9 | EditionEntry | Described in |
| | | Section 5.1.7.1 |
+------------+-----------------------------+----------------------+
| 0x45A3 | TagName | Described in |
| | | Section 5.1.8.1.2.1 |
+------------+-----------------------------+----------------------+
| 0x450D | ChapProcessPrivate | Described in |
| | | Section 5.1.7.1.4.16 |
+------------+-----------------------------+----------------------+
| 0x44B4 | TagDefaultBogus | Described in |
| | | Section 27.41 |
+------------+-----------------------------+----------------------+
| 0x4489 | Duration | Described in |
| | | Section 5.1.2.10 |
+------------+-----------------------------+----------------------+
| 0x4487 | TagString | Described in |
| | | Section 5.1.8.1.2.5 |
+------------+-----------------------------+----------------------+
| 0x4485 | TagBinary | Described in |
| | | Section 5.1.8.1.2.6 |
+------------+-----------------------------+----------------------+
| 0x4484 | TagDefault | Described in |
| | | Section 5.1.8.1.2.4 |
+------------+-----------------------------+----------------------+
| 0x447B | TagLanguageBCP47 | Described in |
| | | Section 5.1.8.1.2.3 |
+------------+-----------------------------+----------------------+
| 0x447A | TagLanguage | Described in |
| | | Section 5.1.8.1.2.2 |
+------------+-----------------------------+----------------------+
| 0x4461 | DateUTC | Described in |
| | | Section 5.1.2.11 |
+------------+-----------------------------+----------------------+
| 0x4444 | SegmentFamily | Described in |
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| | | Section 5.1.2.7 |
+------------+-----------------------------+----------------------+
| 0x437E | ChapCountry | Described in |
| | | Section 5.1.7.1.4.13 |
+------------+-----------------------------+----------------------+
| 0x437D | ChapLanguageBCP47 | Described in |
| | | Section 5.1.7.1.4.12 |
+------------+-----------------------------+----------------------+
| 0x437C | ChapLanguage | Described in |
| | | Section 5.1.7.1.4.11 |
+------------+-----------------------------+----------------------+
| 0x4255 | ContentCompSettings | Described in |
| | | Section 5.1.4.1.34.7 |
+------------+-----------------------------+----------------------+
| 0x4254 | ContentCompAlgo | Described in |
| | | Section 5.1.4.1.34.6 |
+------------+-----------------------------+----------------------+
| 0x41F0 | BlockAddIDValue | Described in |
| | | Section 5.1.4.1.19.1 |
+------------+-----------------------------+----------------------+
| 0x41ED | BlockAddIDExtraData | Described in |
| | | Section 5.1.4.1.19.4 |
+------------+-----------------------------+----------------------+
| 0x41E7 | BlockAddIDType | Described in |
| | | Section 5.1.4.1.19.3 |
+------------+-----------------------------+----------------------+
| 0x41E4 | BlockAdditionMapping | Described in |
| | | Section 5.1.4.1.19 |
+------------+-----------------------------+----------------------+
| 0x41A4 | BlockAddIDName | Described in |
| | | Section 5.1.4.1.19.2 |
+------------+-----------------------------+----------------------+
| 0x3EB923 | NextUUID | Described in |
| | | Section 5.1.2.5 |
+------------+-----------------------------+----------------------+
| 0x3E83BB | NextFilename | Described in |
| | | Section 5.1.2.6 |
+------------+-----------------------------+----------------------+
| 0x3CB923 | PrevUUID | Described in |
| | | Section 5.1.2.3 |
+------------+-----------------------------+----------------------+
| 0x3C83AB | PrevFilename | Described in |
| | | Section 5.1.2.4 |
+------------+-----------------------------+----------------------+
| 0x3B4040 | CodecInfoURL | Described in |
| | | Section 27.19 |
+------------+-----------------------------+----------------------+
| 0x3A9697 | CodecSettings | Described in |
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| | | Section 27.18 |
+------------+-----------------------------+----------------------+
| 0x2FB523 | GammaValue | Described in |
| | | Section 27.23 |
+------------+-----------------------------+----------------------+
| 0x2EB524 | UncompressedFourCC | Described in Section |
| | | 5.1.4.1.31.15 |
+------------+-----------------------------+----------------------+
| 0x2AD7B1 | TimestampScale | Described in |
| | | Section 5.1.2.9 |
+------------+-----------------------------+----------------------+
| 0x26B240 | CodecDownloadURL | Described in |
| | | Section 27.20 |
+------------+-----------------------------+----------------------+
| 0x258688 | CodecName | Described in |
| | | Section 5.1.4.1.25 |
+------------+-----------------------------+----------------------+
| 0x23E383 | DefaultDuration | Described in |
| | | Section 5.1.4.1.15 |
+------------+-----------------------------+----------------------+
| 0x2383E3 | FrameRate | Described in |
| | | Section 27.24 |
+------------+-----------------------------+----------------------+
| 0x234E7A | DefaultDecodedFieldDuration | Described in |
| | | Section 5.1.4.1.16 |
+------------+-----------------------------+----------------------+
| 0x23314F | TrackTimestampScale | Described in |
| | | Section 5.1.4.1.17 |
+------------+-----------------------------+----------------------+
| 0x22B59D | LanguageBCP47 | Described in |
| | | Section 5.1.4.1.22 |
+------------+-----------------------------+----------------------+
| 0x22B59C | Language | Described in |
| | | Section 5.1.4.1.21 |
+------------+-----------------------------+----------------------+
| 0x1F43B675 | Cluster | Described in |
| | | Section 5.1.3 |
+------------+-----------------------------+----------------------+
| 0x1C53BB6B | Cues | Described in |
| | | Section 5.1.5 |
+------------+-----------------------------+----------------------+
| 0x1941A469 | Attachments | Described in |
| | | Section 5.1.6 |
+------------+-----------------------------+----------------------+
| 0x18538067 | Segment | Described in |
| | | Section 5.1 |
+------------+-----------------------------+----------------------+
| 0x1654AE6B | Tracks | Described in |
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| | | Section 5.1.4 |
+------------+-----------------------------+----------------------+
| 0x1549A966 | Info | Described in |
| | | Section 5.1.2 |
+------------+-----------------------------+----------------------+
| 0x1254C367 | Tags | Described in |
| | | Section 5.1.8 |
+------------+-----------------------------+----------------------+
| 0x114D9B74 | SeekHead | Described in |
| | | Section 5.1.1 |
+------------+-----------------------------+----------------------+
| 0x1043A770 | Chapters | Described in |
| | | Section 5.1.7 |
+------------+-----------------------------+----------------------+
Table 59: IDs and Names for Matroska Element IDs assigned by
this document
26.2. Chapter Codec IDs Registry
This document creates a new IANA registry called the "Matroska
Chapter Codec IDs" registry. The values correspond to the
ChapProcessCodecID value described in Section 5.1.7.1.4.15.
ChapProcessCodecID values of "0" and "1" are RESERVED to the IETF for
future use.
26.3. Media Types
Matroska files and streams are found in three main forms: audio-video
files, audio-only and occasionally with stereoscopic video tracks.
Historically Matroska files and streams have used the following media
types with a "x-" prefix. For better compatibility a system SHOULD
be able to handle both formats. Newer systems SHOULD NOT use the
historic format and use the format that follows the [RFC6838] format
instead.
Please register three media types, the [RFC6838] templates are below:
26.3.1. For files containing video tracks
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Type name: video
Subtype name: matroska
Required parameters: none
Optional parameters: none
Encoding considerations: as per this document and RFC8794
Security considerations: See Section 25.
Interoperability considerations: The format is designed to be broadly interoperable.
Published specification: THISRFC
Applications that use this media type: ffmpeg, vlc, ...
Fragment identifier considerations: none
Additional information:
Deprecated alias names for this type: video/x-matroska
Magic number(s): not sure
File extension(s): mkv
Macintosh file type code(s): none
Person & email address to contact for further information: IETF CELLAR WG
Intended usage: COMMON
Restrictions on usage: N/A
Author: IETF CELLAR WG
Change controller: IESG
Provisional registration? (standards tree only): NO
26.3.2. For files containing audio tracks with no video tracks
Type name: audio
Subtype name: matroska
Required parameters: none
Optional parameters: none
Encoding considerations: as per this document and RFC8794
Security considerations: See Section 25.
Interoperability considerations: The format is designed to be broadly interoperable.
Published specification: THISRFC
Applications that use this media type: ffmpeg, vlc, ...
Fragment identifier considerations: none
Additional information:
Deprecated alias names for this type: audio/x-matroska
Magic number(s): not sure
File extension(s): mka
Macintosh file type code(s): none
Person & email address to contact for further information: IETF CELLAR WG
Intended usage: COMMON
Restrictions on usage: N/A
Author: IETF CELLAR WG
Change controller: IESG
Provisional registration? (standards tree only): NO
26.3.3. For files containing audio tracks with no video tracks
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Type name: video
Subtype name: matroska-3d
Required parameters: none
Optional parameters: none
Encoding considerations: as per this document and RFC8794
Security considerations: See Section 25.
Interoperability considerations: The format is designed to be broadly interoperable.
Published specification: THISRFC
Applications that use this media type: ffmpeg, vlc, ...
Fragment identifier considerations: none
Additional information:
Deprecated alias names for this type: video/matroska-3d
Magic number(s): not sure
File extension(s): mk3d
Macintosh file type code(s): none
Person & email address to contact for further information: IETF CELLAR WG
Intended usage: COMMON
Restrictions on usage: N/A
Author: IETF CELLAR WG
Change controller: IESG
Provisional registration? (standards tree only): NO
27. Annex A: Historic Deprecated Elements
As Matroska evolved since 2002 many parts that were considered for
use in the format were never used and often incorrectly designed.
Many of the elements that were then defined are not found in any
known files but were part of public specs. DivX also had a few
custom elements that were designed for custom features.
We list these elements that have a known ID that SHOULD NOT be reused
to avoid colliding with existing files.
27.1. SilentTracks Element
type / id: master / 0x5854
path: \Segment\Cluster\SilentTracks
documentation: 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.
27.2. SilentTrackNumber Element
type / id: uinteger / 0x58D7
path: \Segment\Cluster\SilentTracks\SilentTrackNumber
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documentation: One of the track number that are not used from now on
in the stream. It could change later if not specified as silent
in a further Cluster.
27.3. Position Element
type / id: uinteger / 0xA7
path: \Segment\Cluster\Position
documentation: The Segment Position of the Cluster in the Segment (0
in live streams). It might help to resynchronise offset on
damaged streams.
27.4. BlockVirtual Element
type / id: binary / 0xA2
path: \Segment\Cluster\BlockGroup\BlockVirtual
documentation: A Block with no data. It MUST be stored in the
stream at the place the real Block would be in display order.
27.5. ReferenceVirtual Element
type / id: integer / 0xFD
path: \Segment\Cluster\BlockGroup\ReferenceVirtual
documentation: The Segment Position of the data that would otherwise
be in position of the virtual block.
27.6. Slices Element
type / id: master / 0x8E
path: \Segment\Cluster\BlockGroup\Slices
documentation: Contains slices description.
27.7. TimeSlice Element
type / id: master / 0xE8
path: \Segment\Cluster\BlockGroup\Slices\TimeSlice
documentation: Contains extra time information about the data
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contained in the Block. Being able to interpret this Element is
not REQUIRED for playback.
27.8. LaceNumber Element
type / id: uinteger / 0xCC
path: \Segment\Cluster\BlockGroup\Slices\TimeSlice\LaceNumber
documentation: The reverse number of the frame in the lace (0 is the
last frame, 1 is the next to last, etc). Being able to interpret
this Element is not REQUIRED for playback.
27.9. FrameNumber Element
type / id: uinteger / 0xCD
path: \Segment\Cluster\BlockGroup\Slices\TimeSlice\FrameNumber
documentation: The number of the frame to generate from this lace
with this delay (allow you to generate many frames from the same
Block/Frame).
27.10. BlockAdditionID Element
type / id: uinteger / 0xCB
path: \Segment\Cluster\BlockGroup\Slices\TimeSlice\BlockAdditionID
documentation: The ID of the BlockAdditional Element (0 is the main
Block).
27.11. Delay Element
type / id: uinteger / 0xCE
path: \Segment\Cluster\BlockGroup\Slices\TimeSlice\Delay
documentation: The delay to apply to the Element, expressed in Track
Ticks; see Section 11.1.
27.12. SliceDuration Element
type / id: uinteger / 0xCF
path: \Segment\Cluster\BlockGroup\Slices\TimeSlice\SliceDuration
documentation: The duration to apply to the Element, expressed in
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Track Ticks; see Section 11.1.
27.13. ReferenceFrame Element
type / id: master / 0xC8
path: \Segment\Cluster\BlockGroup\ReferenceFrame
documentation: Contains information about the last reference frame.
See [DivXTrickTrack].
27.14. ReferenceOffset Element
type / id: uinteger / 0xC9
path: \Segment\Cluster\BlockGroup\ReferenceFrame\ReferenceOffset
documentation: The relative offset, in bytes, from the previous
BlockGroup element for this Smooth FF/RW video track to the
containing BlockGroup element. See [DivXTrickTrack].
27.15. ReferenceTimestamp Element
type / id: uinteger / 0xCA
path: \Segment\Cluster\BlockGroup\ReferenceFrame\ReferenceTimestamp
documentation: The timestamp of the BlockGroup pointed to by
ReferenceOffset, expressed in Track Ticks; see Section 11.1. See
[DivXTrickTrack].
27.16. EncryptedBlock Element
type / id: binary / 0xAF
path: \Segment\Cluster\EncryptedBlock
documentation: Similar to SimpleBlock, see Section 10.3, but the
data inside the Block are Transformed (encrypt and/or signed).
27.17. TrackOffset Element
type / id: integer / 0x537F
path: \Segment\Tracks\TrackEntry\TrackOffset
documentation: A value to add to the Block's Timestamp, expressed in
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Matroska Ticks -- ie in nanoseconds; see Section 11.1. This can
be used to adjust the playback offset of a track.
27.18. CodecSettings Element
type / id: utf-8 / 0x3A9697
path: \Segment\Tracks\TrackEntry\CodecSettings
documentation: A string describing the encoding setting used.
27.19. CodecInfoURL Element
type / id: string / 0x3B4040
path: \Segment\Tracks\TrackEntry\CodecInfoURL
documentation: A URL to find information about the codec used.
27.20. CodecDownloadURL Element
type / id: string / 0x26B240
path: \Segment\Tracks\TrackEntry\CodecDownloadURL
documentation: A URL to download about the codec used.
27.21. CodecDecodeAll Element
type / id: uinteger / 0xAA
path: \Segment\Tracks\TrackEntry\CodecDecodeAll
documentation: Set to 1 if the codec can decode potentially damaged
data.
27.22. AspectRatioType Element
type / id: uinteger / 0x54B3
path: \Segment\Tracks\TrackEntry\Video\AspectRatioType
documentation: Specify the possible modifications to the aspect
ratio.
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27.23. GammaValue Element
type / id: float / 0x2FB523
path: \Segment\Tracks\TrackEntry\Video\GammaValue
documentation: Gamma Value.
27.24. FrameRate Element
type / id: float / 0x2383E3
path: \Segment\Tracks\TrackEntry\Video\FrameRate
documentation: Number of frames per second. This value is
Informational only. It is intended for constant frame rate
streams, and SHOULD NOT be used for a variable frame rate
TrackEntry.
27.25. ChannelPositions Element
type / id: binary / 0x7D7B
path: \Segment\Tracks\TrackEntry\Audio\ChannelPositions
documentation: Table of horizontal angles for each successive
channel.
27.26. TrickTrackUID Element
type / id: uinteger / 0xC0
path: \Segment\Tracks\TrackEntry\TrickTrackUID
documentation: The TrackUID of the Smooth FF/RW video in the paired
EBML structure corresponding to this video track. See
[DivXTrickTrack].
27.27. TrickTrackSegmentUID Element
type / id: binary / 0xC1
path: \Segment\Tracks\TrackEntry\TrickTrackSegmentUID
documentation: The SegmentUID of the Segment containing the track
identified by TrickTrackUID. See [DivXTrickTrack].
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27.28. TrickTrackFlag Element
type / id: uinteger / 0xC6
path: \Segment\Tracks\TrackEntry\TrickTrackFlag
documentation: Set to 1 if this video track is a Smooth FF/RW track.
If set to 1, MasterTrackUID and MasterTrackSegUID should 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].
27.29. TrickMasterTrackUID Element
type / id: uinteger / 0xC7
path: \Segment\Tracks\TrackEntry\TrickMasterTrackUID
documentation: The TrackUID of the video track in the paired EBML
structure that corresponds to this Smooth FF/RW track. See
[DivXTrickTrack].
27.30. TrickMasterTrackSegmentUID Element
type / id: binary / 0xC4
path: \Segment\Tracks\TrackEntry\TrickMasterTrackSegmentUID
documentation: The SegmentUID of the Segment containing the track
identified by MasterTrackUID. See [DivXTrickTrack].
27.31. ContentSignature Element
type / id: binary / 0x47E3
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentEncryption\ContentSignature
documentation: A cryptographic signature of the contents.
27.32. ContentSigKeyID Element
type / id: binary / 0x47E4
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentEncryption\ContentSigKeyID
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documentation: This is the ID of the private key the data was signed
with.
27.33. ContentSigAlgo Element
type / id: uinteger / 0x47E5
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentEncryption\ContentSigAlgo
documentation: The algorithm used for the signature.
27.34. ContentSigHashAlgo Element
type / id: uinteger / 0x47E6
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentEncryption\ContentSigHashAlgo
documentation: The hash algorithm used for the signature.
27.35. CueRefCluster Element
type / id: uinteger / 0x97
path: \Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefCl
uster
documentation: The Segment Position of the Cluster containing the
referenced Block.
27.36. CueRefNumber Element
type / id: uinteger / 0x535F
path: \Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefNu
mber
documentation: Number of the referenced Block of Track X in the
specified Cluster.
27.37. CueRefCodecState Element
type / id: uinteger / 0xEB
path: \Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefCo
decState
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documentation: The Segment Position of the Codec State corresponding
to this referenced Element. 0 means that the data is taken from
the initial Track Entry.
27.38. FileReferral Element
type / id: binary / 0x4675
path: \Segment\Attachments\AttachedFile\FileReferral
documentation: A binary value that a track/codec can refer to when
the attachment is needed.
27.39. FileUsedStartTime Element
type / id: uinteger / 0x4661
path: \Segment\Attachments\AttachedFile\FileUsedStartTime
documentation: The timestamp at which this optimized font attachment
comes into context, expressed in Segment Ticks which is based on
TimestampScale. See [DivXWorldFonts].
27.40. FileUsedEndTime Element
type / id: uinteger / 0x4662
path: \Segment\Attachments\AttachedFile\FileUsedEndTime
documentation: The timestamp at which this optimized font attachment
goes out of context, expressed in Segment Ticks which is based on
TimestampScale. See [DivXWorldFonts].
27.41. TagDefaultBogus Element
type / id: uinteger / 0x44B4
path: \Segment\Tags\Tag\+SimpleTag\TagDefaultBogus
documentation: A variant of the TagDefault element with a bogus
Element ID; see Section 5.1.8.1.2.4.
28. 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>.
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[Blowfish] Schneier, B., "The Blowfish Encryption Algorithm", 1993,
<https://www.schneier.com/academic/blowfish/>.
[BZIP2] Seward, J., "bzip2", 18 July 1996,
<https://sourceware.org/bzip2/>.
[CIE-1931] Commission Internationale de l'Eclairage, "CIE 1931
Standard Colorimetric System", 1931, <https://cie.co.at/>.
[FIPS.197] US National Institute of Standards and Technology,
"Advanced Encryption Standard (AES)",
DOI 10.6028/NIST.FIPS.197, 26 November 2001,
<https://csrc.nist.gov/publications/detail/fips/197/
final>.
[FIPS.46-3]
US National Institute of Standards and Technology, "Data
Encryption Standard (DES)", FIPS PUB 46, 25 October 1999,
<https://csrc.nist.gov/publications/detail/fips/46/3/
archive/1999-10-25>.
[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>.
[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>.
[LZO] Tarreau, W., Rodgman, R., and M. Oberhumer, "Lempel-Ziv-
Oberhumer compression", 30 October 2018,
<https://www.kernel.org/doc/Documentation/lzo.txt>.
[MatroskaCodec]
Lhomme, S., Bunkus, M., and D. Rice, "Media Container
Codec Specifications", Work in Progress, Internet-Draft,
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draft-ietf-cellar-codec-09, 12 April 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-cellar-
codec-09>.
[MatroskaTags]
Lhomme, S., Bunkus, M., and D. Rice, "Matroska Media
Container Tag Specifications", Work in Progress, Internet-
Draft, draft-ietf-cellar-tags-09, 12 April 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-cellar-
tags-09>.
[RFC1950] Deutsch, P. and J-L. Gailly, "ZLIB Compressed Data Format
Specification version 3.3", RFC 1950,
DOI 10.17487/RFC1950, May 1996,
<https://www.rfc-editor.org/info/rfc1950>.
[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>.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122,
DOI 10.17487/RFC4122, July 2005,
<https://www.rfc-editor.org/info/rfc4122>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
<https://www.rfc-editor.org/info/rfc6838>.
[RFC8081] Lilley, C., "The "font" Top-Level Media Type", RFC 8081,
DOI 10.17487/RFC8081, February 2017,
<https://www.rfc-editor.org/info/rfc8081>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[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>.
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[SP.800-38A]
US National Institute of Standards and Technology,
"Recommendation for Block Cipher Modes of Operation:
Methods and Techniques", DOI 10.6028/NIST.SP.800-38A, 1
December 2001,
<https://csrc.nist.gov/publications/detail/fips/197/
final>.
[SP.800-67]
US National Institute of Standards and Technology,
"Recommendation for the Triple Data Encryption Algorithm
(TDEA) Block Cipher",
DOI 10.6028/10.6028/NIST.SP.800-67r2, 1 November 2017,
<https://csrc.nist.gov/publications/detail/fips/197/
final>.
[Twofish] Schneier, B., Kelsey, J., Whiting, D., Wagner, D., Hall,
C., and N. Ferguson, "Twofish: A 128-Bit Block Cipher", 15
June 1998, <https://www.schneier.com/academic/twofish/>.
[WebM-Enc] Galligan, F., "WebM Encryption", 19 September 2016,
<https://www.webmproject.org/docs/webm-encryption/>.
[WebVTT] Pieters, S., Pfeiffer, S., Ed., Jaegenstedt, P., and I.
Hickson, "WebVTT Cue Identifier", 4 April 2019,
<https://www.w3.org/TR/webvtt1/#webvtt-cue-identifier>.
29. Informative References
[AVIFormat]
Microsoft, "AVI RIFF File Reference", 31 May 2018,
<https://docs.microsoft.com/en-
us/windows/win32/directshow/avi-riff-file-reference>.
[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>.
[DVD-Video]
DVD Forum, "DVD-Books: Part 3 DVD-Video Book", 1 November
1995, <http://www.dvdforum.org/>.
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[FourCC-RGB]
Silicon.dk ApS, "RGB Pixel Format FourCCs",
<https://www.fourcc.org/rgb.php>.
[FourCC-YUV]
Silicon.dk ApS, "YUV Pixel Format FourCCs",
<https://www.fourcc.org/yuv.php>.
[MCF] "Media Container Format", 17 July 2002,
<http://mukoli.free.fr/mcf/mcf.html>.
[RFC3533] Pfeiffer, S., "The Ogg Encapsulation Format Version 0",
RFC 3533, DOI 10.17487/RFC3533, May 2003,
<https://www.rfc-editor.org/info/rfc3533>.
[RFC5378] Bradner, S., Ed. and J. Contreras, Ed., "Rights
Contributors Provide to the IETF Trust", BCP 78, RFC 5378,
DOI 10.17487/RFC5378, November 2008,
<https://www.rfc-editor.org/info/rfc5378>.
[RFC8179] Bradner, S. and J. Contreras, "Intellectual Property
Rights in IETF Technology", BCP 79, RFC 8179,
DOI 10.17487/RFC8179, May 2017,
<https://www.rfc-editor.org/info/rfc8179>.
Authors' Addresses
Steve Lhomme
Email: slhomme@matroska.org
Moritz Bunkus
Email: moritz@bunkus.org
Dave Rice
Email: dave@dericed.com
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