Codec Mappings
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Codec Mappings
Codec Mapping
is a set of attributes to identify, name, and contextualize the format
and characteristics of encoded data that can be contained within Matroska Clusters.
Each TrackEntry used within Matroska
MUST
reference a defined
Codec Mapping
using the
Codec ID
to identify and describe the format of the encoded data in its associated Clusters.
This
Codec ID
is a unique registered identifier that represents the encoding stored within
the Track. Certain encodings
MAY
also require some form of codec initialization
in order to provide its decoder with context and technical metadata.
The intention behind this list is not to list all existing audio and video codecs,
but rather to list those codecs that are currently supported in Matroska and therefore
need a well defined
Codec ID
so that all developers supporting Matroska will use the
same
Codec ID
. If you feel we missed support for a very important codec, please tell
us on our development mailing list (cellar at ietf.org).
Defining Matroska Codec Support
Support for a codec is defined in Matroska with the following values.
Codec ID
Each codec supported for storage in Matroska
MUST
have a unique
Codec ID
Each
Codec ID
MUST
be prefixed with the string from the following table according to
the associated type of the codec. All characters of a
Codec ID Prefix
MUST
be
capital letters (A-Z) except for the last character of a
Codec ID Prefix
which
MUST
be
an underscore (“_”).
Codec Type
Codec ID Prefix
Video
“V_”
Audio
“A_”
Subtitle
“S_”
Button
“B_”
Each
Codec ID
MUST
include a
Major Codec ID
immediately following the
Codec ID Prefix
Major Codec ID
MAY
be followed by an
OPTIONAL
Codec ID Suffix
to communicate a refinement
of the
Major Codec ID
. If a
Codec ID Suffix
is used, then the
Codec ID
MUST
include a
forward slash (“/”) as a separator between the
Major Codec ID
and the
Codec ID Suffix
The
Major Codec ID
MUST
be composed of only capital letters (A-Z) and numbers (0-9).
The
Codec ID Suffix
MUST
be composed of only capital letters (A-Z), numbers (0-9),
underscore (“_”), and forward slash (“/”).
The following table provides examples of valid
Codec IDs
and their components:
Codec ID Prefix
Major Codec ID
Separator
Codec ID Suffix
Codec ID
A_
AAC
MPEG2/LC/SBR
A_AAC/MPEG2/LC/SBR
V_
MPEG4
ISO/ASP
V_MPEG4/ISO/ASP
V_
MPEG1
V_MPEG1
Codec Name
Each encoding supported for storage in Matroska
MUST
have a
Codec Name
The
Codec Name
provides a readable label for the encoding.
Description
An optional description for the encoding. This value is only intended for human consumption.
Initialization
Each encoding supported for storage in Matroska
MUST
have a defined Initialization.
The Initialization
MUST
describe the storage of data necessary to initialize the decoder,
which
MUST
be stored within the
CodecPrivate Element
. When the Initialization is updated
within a track, then that updated Initialization data
MUST
be written into the
CodecState Element
of the first
Cluster
to require it. If the encoding does not require any form of Initialization,
then
none
MUST
be used to define the Initialization and the
CodecPrivate Element
SHOULD NOT
be written and
MUST
be ignored. Data that is defined Initialization to be
stored in the
CodecPrivate Element
is known as
Private Data
Codec BlockAdditions
Additional data that contextualizes or supplements a
Block
can be stored within
the
BlockAdditional Element
of a
BlockMore Element
. This
BlockAdditional
data
MAY
be passed to the associated decoder along with the content of the
Block Element
Each
BlockAdditional
is coupled with a
BlockAddID
that identifies the kind of data
it contains. The following table defines the meanings of
BlockAddID
values.
BlockAddID Value
Definition
Invalid.
Indicates that the context of the
BlockAdditional
data is defined by the corresponding
Codec Mapping
2 or greater
BlockAddID
values of 2 and greater are mapped to the
BlockAddIDValue
of the
BlockAdditionMapping
of the associated Track.
The values of
BlockAddID
that are 2 of greater have no semantic meaning, but simply
associate the
BlockMore Element
with a
BlockAdditionMapping
of the associated Track.
See (#block-additional-mapping) on Block Additional Mappings for more information.
The following XML depicts the nested Elements of a
BlockGroup Element
with an example of BlockAdditions:
{Binary data of a VP9 video frame in YUV}
{alpha channel encoding to supplement the VP9 frame}
Citation
Documentation of the associated normative and informative references for the codec is
RECOMMENDED
Deprecation Date
A timestamp, expressed in [@!RFC3339] that notes when support for the
Codec Mapping
within Matroska was deprecated. If a
Codec Mapping
is defined with a
Deprecation Date
then it is
RECOMMENDED
that Matroska writers
SHOULD NOT
use the
Codec Mapping
after the
Deprecation Date
Superseded By
Codec Mapping
MAY
only be defined with a
Superseded By
value, if it has an
expressed
Deprecation Date
. If used, the
Superseded By
value
MUST
store
the
Codec ID
of another
Codec Mapping
that has superseded the
Codec Mapping
Recommendations for the Creation of New Codec Mappings
Creators of new
Codec Mappings
to be used in the context of Matroska:
SHOULD
assume that all
Codec Mappings
they create might become standardized, public,
commonly deployed, or usable across multiple implementations.
SHOULD
employ meaningful values for
Codec ID
and
Codec Name
that they have reason
to believe are currently unused.
SHOULD NOT
prefix their
Codec ID
with “X_” or similar constructs.
These recommendations are based upon Section 3 of [@!RFC6648].
Video Codec Mappings
V_MS/VFW/FOURCC
Codec ID:
V_MS/VFW/FOURCC
Codec Name: Microsoft (TM) Video Codec Manager (VCM)
Description: The private data contains the VCM structure BITMAPINFOHEADER including
the extra private bytes, as
defined by Microsoft
The data are stored in little-endian format (like on IA32 machines). Where is the Huffman table stored
in HuffYUV, not AVISTREAMINFO ??? And the FourCC, not in AVISTREAMINFO.fccHandler ???
Initialization:
Private Data
contains the VCM structure BITMAPINFOHEADER including the extra private bytes,
as defined by Microsoft in https://msdn.microsoft.com/en-us/library/windows/desktop/dd183376(v=vs.85).aspx.
Citation: https://msdn.microsoft.com/en-us/library/windows/desktop/dd183376(v=vs.85).aspx
V_UNCOMPRESSED
Codec ID: V_UNCOMPRESSED
Codec Name: Video, raw uncompressed video frames
Description: All details about the used color specs and bit depth are to be put/read from the
TrackEntry\Video\UncompressedFourCC
elements.
Initialization: none
V_MPEG4/ISO/SP
Codec ID: V_MPEG4/ISO/SP
Codec Name: MPEG4 ISO simple profile (DivX4)
Description: Stream was created via improved codec API (UCI) or even transmuxed from AVI (no b-frames in Simple Profile), frame order is coding order.
Initialization: none
V_MPEG4/ISO/ASP
Codec ID: V_MPEG4/ISO/ASP
Codec Name: MPEG4 ISO advanced simple profile (DivX5, XviD, FFMPEG)
Description: Stream was created via improved codec API (UCI) or transmuxed from MP4, not simply transmuxed from AVI.
Note there are differences how b-frames are handled in these native streams,
when being compared to a VfW created stream, as here there are
no
dummy frames inserted,
the frame order is exactly the same as the coding order, same as in MP4 streams.
Initialization: none
V_MPEG4/ISO/AP
Codec ID: V_MPEG4/ISO/AP
Codec Name: MPEG4 ISO advanced profile
Description: Stream was created via improved codec API (UCI) or transmuxed from MP4, not simply transmuxed from AVI.
Note there are differences how b-frames are handled in these native streams,
when being compared to a VfW created stream, as here there are
no
dummy frames inserted,
the frame order is exactly the same as the coding order, same as in MP4 streams.
Initialization: none
V_MPEG4/MS/V3
Codec ID: V_MPEG4/MS/V3
Codec Name: Microsoft (TM) MPEG4 V3
Description: Microsoft (TM) MPEG4 V3 and derivates, means DivX3, Angelpotion, SMR, etc.; stream was created using
VfW codec or transmuxed from AVI; note that V1/V2 are covered in VfW compatibility mode.
Initialization: none
V_MPEG1
Codec ID: V_MPEG1
Codec Name: MPEG 1
Description: The Matroska video stream will contain a demuxed Elementary Stream (ES), where block boundaries are still to be defined.
Its
RECOMMENDED
to use MPEG2MKV.exe for creating those files, and to compare
the results with self-made implementations
Initialization: none
V_MPEG2
Codec ID: V_MPEG2
Codec Name: MPEG 2
Description: The Matroska video stream will contain a demuxed Elementary Stream (ES), where block boundaries are still to be defined.
Its
RECOMMENDED
to use MPEG2MKV.exe for creating those files, and to compare
the results with self-made implementations
Initialization: none
V_MPEG4/ISO/AVC
Codec ID: V_MPEG4/ISO/AVC
Codec Name: AVC/H.264
Description: Individual pictures (which could be a frame, a field, or 2 fields having the same timestamp) of AVC/H.264 stored as described in [@!ISO.14496-15].
Initialization: The
Private Data
contains a
AVCDecoderConfigurationRecord
structure, as defined in [@!ISO.14496-15].
For legacy reasons, because Block Addition Mappings are preferred, see (#block-addition-mappings),
the
AVCDecoderConfigurationRecord
structure
MAY
be followed by an extension block beginning
with a 4-byte extension block size field in big-endian byte order which is the size of the extension block
minus 4 (excluding the size of the extension block size field) and a 4-byte field corresponding
to a
BlockAddIDType
of “mvcC” followed by a content corresponding to the content of
BlockAddIDExtraData
for
mvcC
; see (#mvcc).
V_MPEGH/ISO/HEVC
Codec ID: V_MPEGH/ISO/HEVC
Codec Name: HEVC/H.265
Description: Individual pictures (which could be a frame, a field, or 2 fields having the same timestamp) of HEVC/H.265 stored as described in [@!ISO.14496-15].
Initialization: The
Private Data
contains a
HEVCDecoderConfigurationRecord
structure, as defined in [@!ISO.14496-15].
V_AVS2
Codec ID: V_AVS2
Codec Name: AVS2-P2/IEEE.1857.4
Description: Individual pictures of AVS2-P2 stored as described in the second part of [@!IEEE.1857-4].
Initialization: none.
V_AVS3
Codec ID: V_AVS3
Codec Name: AVS3-P2/IEEE.1857.10
Description: Individual pictures of AVS3-P2 stored as described in the second part of [@!IEEE.1857-10].
Initialization: none.
V_REAL/RV10
Codec ID: V_REAL/RV10
Codec Name: RealVideo 1.0 aka RealVideo 5
Description: Individual slices from the Real container are combined into a single frame.
Initialization: The
Private Data
contains a
real_video_props_t
structure in big-endian byte order as found in
librmff
V_REAL/RV20
Codec ID: V_REAL/RV20
Codec Name: RealVideo G2 and RealVideo G2+SVT
Description: Individual slices from the Real container are combined into a single frame.
Initialization: The
Private Data
contains a
real_video_props_t
structure in big-endian byte order as found in
librmff
V_REAL/RV30
Codec ID: V_REAL/RV30
Codec Name: RealVideo 8
Description: Individual slices from the Real container are combined into a single frame.
Initialization: The
Private Data
contains a
real_video_props_t
structure in big-endian byte order as found in
librmff
V_REAL/RV40
Codec ID: V_REAL/RV40
Codec Name: rv40 : RealVideo 9
Description: Individual slices from the Real container are combined into a single frame.
Initialization: The
Private Data
contains a
real_video_props_t
structure in big-endian byte order as found in
librmff
V_QUICKTIME
Codec ID: V_QUICKTIME
Codec Name: Video taken from QuickTime(TM) files
Description: Several codecs as stored in QuickTime, e.g., Sorenson or Cinepak.
Initialization: The
Private Data
contains all additional data that is stored in the ‘stsd’ (sample description) atom
in the QuickTime file
after
the mandatory video descriptor structure
(starting with the size and FourCC fields). For an explanation of the QuickTime file format read
QuickTime File Format Specification
V_THEORA
Codec ID: V_THEORA
Codec Name: Theora
Initialization: The
Private Data
contains the first three Theora packets in order. The lengths of the packets precedes them. The actual layout is:
Byte 1: number of distinct packets
#p
minus one inside the CodecPrivate block. This
MUST
be “2” for current (as of 2016-07-08) Theora headers.
Bytes 2..n: lengths of the first
#p
packets, coded in Xiph-style lacing. The length of the last packet is the length of the CodecPrivate block minus the lengths coded in these bytes minus one.
Bytes n+1..: The Theora identification header, followed by the commend header followed by the codec setup header. Those are described in the
Theora specs
V_PRORES
Codec ID: V_PRORES
Codec Name: Apple ProRes
Initialization: The
Private Data
contains the FourCC as found in MP4 movies:
ap4x: ProRes 4444 XQ
ap4h: ProRes 4444
apch: ProRes 422 High Quality
apcn: ProRes 422 Standard Definition
apcs: ProRes 422 LT
apco: ProRes 422 Proxy
aprh: ProRes RAW High Quality
aprn: ProRes RAW Standard Definition
this page for more technical details on ProRes
V_VP8
Codec ID: V_VP8
Codec Name: VP8 Codec format
Description: VP8 is an open and royalty free video compression format developed by Google and created by On2 Technologies as a successor to VP7. [@!RFC6386]
Codec BlockAdditions: A single-channel encoding of an alpha channel
MAY
be stored in
BlockAdditions
. The
BlockAddId
of the
BlockMore
containing these data
MUST
be 1.
Initialization: none
V_VP9
Codec ID: V_VP9
Codec Name: VP9 Codec format
Description: VP9 is an open and royalty free video compression format developed by Google as a successor to VP8.
Draft VP9 Bitstream and Decoding Process Specification
Codec BlockAdditions: A single-channel encoding of an alpha channel
MAY
be stored in
BlockAdditions
. The
BlockAddId
of the
BlockMore
containing these data
MUST
be 1.
Initialization: none
V_FFV1
Codec ID: V_FFV1
Codec Name: FF Video Codec 1
Description: FFV1 is a lossless intra-frame video encoding format designed to efficiently compress video data in a variety of pixel formats.
Compared to uncompressed video, FFV1 offers storage compression, frame fixity, and self-description,
which makes FFV1 useful as a preservation or intermediate video format.
Draft FFV1 Specification
Initialization: For FFV1 versions 0 or 1,
Private Data
SHOULD NOT
be written. For FFV1 version 3 or greater, the
Private Data
MUST
contain the FFV1 Configuration Record structure, as defined in https://tools.ietf.org/html/draft-ietf-cellar-ffv1-04#section-4.2, and no other data.
Audio Codec Mappings
A_MPEG/L3
Codec ID: A_MPEG/L3
Codec Name: MPEG Audio 1, 2, 2.5 Layer III
Description: The data contain everything needed for playback in the MPEG Audio header of each frame. Corresponding ACM wFormatTag : 0x0055
Initialization: none
A_MPEG/L2
Codec ID: A_MPEG/L2
Codec Name: MPEG Audio 1, 2 Layer II
Description: The data contain everything needed for playback in the MPEG Audio header of each frame. Corresponding ACM wFormatTag : 0x0050
Initialization: none
A_MPEG/L1
Codec ID: A_MPEG/L1
Codec Name: MPEG Audio 1, 2 Layer I
Description: The data contain everything needed for playback in the MPEG Audio header of each frame. Corresponding ACM wFormatTag : 0x0050
Initialization: none
A_PCM/INT/BIG
Codec ID: A_PCM/INT/BIG
Codec Name: PCM Integer Big Endian
Description: The audio bit depth
MUST
be read and set from the
BitDepth Element
. Audio samples
MUST
be considered as signed values,
except if the audio bit depth is 8 which
MUST
be interpreted as unsigned values. Corresponding ACM wFormatTag : ???
Initialization: none
A_PCM/INT/LIT
Codec ID: A_PCM/INT/LIT
Codec Name: PCM Integer Little Endian
Description: The audio bit depth
MUST
be read and set from the
BitDepth Element
. Audio samples
MUST
be considered as signed values,
except if the audio bit depth is 8 which
MUST
be interpreted as unsigned values. Corresponding ACM wFormatTag : 0x0001
Initialization: none
A_PCM/FLOAT/IEEE
Codec ID: A_PCM/FLOAT/IEEE
Codec Name: Floating Point, IEEE compatible
Description: The audio bit depth
MUST
be read and set from the
BitDepth Element
(32 bit in most cases).
The floats are stored as defined in [@!IEEE.754] and in little-endian order. Corresponding ACM wFormatTag : 0x0003
Initialization: none
A_MPC
Codec ID: A_MPC
Codec Name: MPC (musepack) SV8
Description: The main developer for musepack has requested that we wait until the SV8 framing has been fully defined
for musepack before defining how to store it in Matroska.
A_AC3
Codec ID: A_AC3
Codec Name: (Dolby™) AC3
Description: BSID <= 8 !! The private data is void ??? Corresponding ACM wFormatTag : 0x2000 ; channel number have
to be read from the corresponding audio element
A_AC3/BSID9
Codec ID: A_AC3/BSID9
Codec Name: (Dolby™) AC3
Description: The ac3 frame header has, similar to the mpeg-audio header a version field. Normal ac3 is defined as bitstream id 8 (5 Bits, numbers are 0-15).
Everything below 8 is still compatible with all decoders that handle 8 correctly.
Everything higher are additions that break decoder compatibility.
For the samplerates 24kHz (00); 22,05kHz (01) and 16kHz (10) the BSID is 9
For the samplerates 12kHz (00); 11,025kHz (01) and 8kHz (10) the BSID is 10
Initialization: none
A_AC3/BSID10
Codec ID: A_AC3/BSID10
Codec Name: (Dolby™) AC3
Description: The ac3 frame header has, similar to the mpeg-audio header a version field. Normal ac3 is defined as bitstream id 8 (5 Bits, numbers are 0-15).
Everything below 8 is still compatible with all decoders that handle 8 correctly.
Everything higher are additions that break decoder compatibility.
For the samplerates 24kHz (00); 22,05kHz (01) and 16kHz (10) the BSID is 9
For the samplerates 12kHz (00); 11,025kHz (01) and 8kHz (10) the BSID is 10
Initialization: none
A_ALAC
Codec ID: A_ALAC
Codec Name: ALAC (Apple Lossless Audio Codec)
Initialization: The
Private Data
contains ALAC’s magic cookie (both the codec specific configuration as well as the optional channel layout information).
Its format is described in
ALAC’s official source code
A_DTS
Codec ID: A_DTS
Codec Name: Digital Theatre System
Description: Supports DTS, DTS-ES, DTS-96/26, DTS-HD High Resolution Audio and DTS-HD Master Audio.
The private data is void. Corresponding ACM wFormatTag : 0x2001
Initialization: none
A_DTS/EXPRESS
Codec ID: A_DTS/EXPRESS
Codec Name: Digital Theatre System Express
Description: DTS Express (a.k.a. LBR) audio streams. The private data is void. Corresponding ACM wFormatTag : 0x2001
Initialization: none
A_DTS/LOSSLESS
Codec ID: A_DTS/LOSSLESS
Codec Name: Digital Theatre System Lossless
Description: DTS Lossless audio that does not have a core substream. The private data is void. Corresponding ACM wFormatTag : 0x2001
Initialization: none
A_VORBIS
Codec ID: A_VORBIS
Codec Name: Vorbis
Initialization: The
Private Data
contains the first three Vorbis packet in order. The lengths of the packets precedes them. The actual layout is:
Byte 1: number of distinct packets
#p
minus one inside the CodecPrivate block.
This
MUST
be “2” for current (as of 2016-07-08) Vorbis headers.
Bytes 2..n: lengths of the first
#p
packets, coded in Xiph-style lacing.
The length of the last packet is the length of the CodecPrivate block minus the lengths coded in these bytes minus one.
Bytes n+1..: The
Vorbis identification header
followed by the
Vorbis comment header
followed by the
codec setup header
A_FLAC
Codec ID: A_FLAC
Codec Name:
FLAC (Free Lossless Audio Codec)
Initialization: The
Private Data
contains all the header/metadata packets before the first data packet.
These include the first header packet containing only the word
fLaC
as well as all metadata packets.
A_REAL/14_4
Codec ID: A_REAL/14_4
Codec Name: Real Audio 1
Initialization: The
Private Data
contains either the “real_audio_v4_props_t” or the “real_audio_v5_props_t” structure
(differentiated by their “version” field; big-endian byte order) as found in
librmff
A_REAL/28_8
Codec ID: A_REAL/28_8
Codec Name: Real Audio 2
Initialization: The
Private Data
contains either the “real_audio_v4_props_t” or the “real_audio_v5_props_t” structure
(differentiated by their “version” field; big-endian byte order) as found in
librmff
A_REAL/COOK
Codec ID: A_REAL/COOK
Codec Name: Real Audio Cook Codec (codename: Gecko)
Initialization: The
Private Data
contains either the “real_audio_v4_props_t” or the “real_audio_v5_props_t” structure
(differentiated by their “version” field; big-endian byte order) as found in
librmff
A_REAL/SIPR
Codec ID: A_REAL/SIPR
Codec Name: Sipro Voice Codec
Initialization: The
Private Data
contains either the “real_audio_v4_props_t” or the “real_audio_v5_props_t” structure
(differentiated by their “version” field; big-endian byte order) as found in
librmff
A_REAL/RALF
Codec ID: A_REAL/RALF
Codec Name: Real Audio Lossless Format
Initialization: The
Private Data
contains either the “real_audio_v4_props_t” or the “real_audio_v5_props_t” structure
(differentiated by their “version” field; big-endian byte order) as found in
librmff
A_REAL/ATRC
Codec ID: A_REAL/ATRC
Codec Name: Sony Atrac3 Codec
Initialization: The
Private Data
contains either the “real_audio_v4_props_t” or the “real_audio_v5_props_t” structure
(differentiated by their “version” field; big-endian byte order) as found in
librmff
A_MS/ACM
Codec ID: A_MS/ACM
Codec Name: Microsoft(TM) Audio Codec Manager (ACM)
Description: The data are stored in little-endian format (like on IA32 machines).
Initialization: The
Private Data
contains the [@!WAVEFORMATEX] structure including the extra format information bytes.
The structure is stored without packing or padding bytes.
WORD
corresponds to a signed 2 octets integer,
DWORD
corresponds to a signed 4 octets integer.
The extra format information are appended after the WAVEFORMATEX octets.
A_AAC/MPEG2/MAIN
Codec ID: A_AAC/MPEG2/MAIN
Codec Name: MPEG2 Main Profile
Description: Channel number and sample rate have to be read from the corresponding audio element. Audio stream is stripped
from ADTS headers and normal Matroska frame based muxing scheme is applied.
AAC audio always uses wFormatTag 0xFF.
Initialization: none
A_AAC/MPEG2/LC
Codec ID: A_AAC/MPEG2/LC
Codec Name: Low Complexity
Description: Channel number and sample rate have to be read from the corresponding audio element. Audio stream is stripped
from ADTS headers and normal Matroska frame based muxing scheme is applied.
AAC audio always uses wFormatTag 0xFF.
Initialization: none
A_AAC/MPEG2/LC/SBR
Codec ID: A_AAC/MPEG2/LC/SBR
Codec Name: Low Complexity with Spectral Band Replication
Description: Channel number and sample rate have to be read from the corresponding audio element. Audio stream is stripped
from ADTS headers and normal Matroska frame based muxing scheme is applied.
AAC audio always uses wFormatTag 0xFF.
Initialization: none
A_AAC/MPEG2/SSR
Codec ID: A_AAC/MPEG2/SSR
Codec Name: Scalable Sampling Rate
Description: Channel number and sample rate have to be read from the corresponding audio element. Audio stream is stripped
from ADTS headers and normal Matroska frame based muxing scheme is applied.
AAC audio always uses wFormatTag 0xFF.
Initialization: none
A_AAC/MPEG4/MAIN
Codec ID: A_AAC/MPEG4/MAIN
Codec Name: MPEG4 Main Profile
Description: Channel number and sample rate have to be read from the corresponding audio element. Audio stream is stripped
from ADTS headers and normal Matroska frame based muxing scheme is applied.
AAC audio always uses wFormatTag 0xFF.
Initialization: none
A_AAC/MPEG4/LC
Codec ID: A_AAC/MPEG4/LC
Codec Name: Low Complexity
Description: Channel number and sample rate have to be read from the corresponding audio element. Audio stream is stripped
from ADTS headers and normal Matroska frame based muxing scheme is applied.
AAC audio always uses wFormatTag 0xFF.
Initialization: none
A_AAC/MPEG4/LC/SBR
Codec ID: A_AAC/MPEG4/LC/SBR
Codec Name: Low Complexity with Spectral Band Replication
Description: Channel number and sample rate have to be read from the corresponding audio element. Audio stream is stripped
from ADTS headers and normal Matroska frame based muxing scheme is applied.
AAC audio always uses wFormatTag 0xFF.
Initialization: none
A_AAC/MPEG4/SSR
Codec ID: A_AAC/MPEG4/SSR
Codec Name: Scalable Sampling Rate
Description: Channel number and sample rate have to be read from the corresponding audio element. Audio stream is stripped
from ADTS headers and normal Matroska frame based muxing scheme is applied.
AAC audio always uses wFormatTag 0xFF.
Initialization: none
A_AAC/MPEG4/LTP
Codec ID: A_AAC/MPEG4/LTP
Codec Name: Long Term Prediction
Description: Channel number and sample rate have to be read from the corresponding audio element. Audio stream is stripped
from ADTS headers and normal Matroska frame based muxing scheme is applied.
AAC audio always uses wFormatTag 0xFF.
Initialization: none
A_QUICKTIME
Codec ID: A_QUICKTIME
Codec Name: Audio taken from QuickTime(TM) files
Description: Several codecs as stored in QuickTime, e.g., QDesign Music v1 or v2.
Initialization: The
Private Data
contains all additional data that is stored in the ‘stsd’ (sample description) atom
in the QuickTime file
after
the mandatory sound descriptor structure (starting with the size and FourCC fields).
For an explanation of the QuickTime file format read
QuickTime File Format Specification
A_QUICKTIME/QDMC
Codec ID: A_QUICKTIME/QDMC
Codec Name: QDesign Music
Description:
Initialization: The
Private Data
contains all additional data that is stored in the ‘stsd’ (sample description) atom
in the QuickTime file
after
the mandatory sound descriptor structure (starting with the size and FourCC fields).
For an explanation of the QuickTime file format read
QuickTime File Format Specification
Superseded By: A_QUICKTIME
A_QUICKTIME/QDM2
Codec ID: A_QUICKTIME/QDM2
Codec Name: QDesign Music v2
Description:
Initialization: The
Private Data
contains all additional data that is stored in the ‘stsd’ (sample description) atom
in the QuickTime file
after
the mandatory sound descriptor structure (starting with the size and FourCC fields).
For an explanation of the QuickTime file format read
QuickTime File Format Specification
Superseded By: A_QUICKTIME
A_TTA1
Codec ID: A_TTA1
Codec Name:
The True Audio
lossless audio compressor
Description:
TTA format description
Each frame is kept intact, including the CRC32. The header and seektable are dropped. SamplingFrequency, Channels and BitDepth are used in the TrackEntry. wFormatTag = 0x77A1
Initialization: none
A_WAVPACK4
Codec ID: A_WAVPACK4
Codec Name:
WavPack
lossless audio compressor
Description: The Wavpack packets consist of a stripped header followed by the frame data. For multi-track (> 2 tracks) a frame consists
of many packets. For more details, check the
WavPack muxing description
Codec BlockAdditions: For hybrid
A_WAVPACK4
encodings (that include a lossy encoding with a supplemental correction
to produce a lossless encoding), the correction part is stored in BlockAdditional.
The
BlockAddId
of the
BlockMore
containing these data
MUST
be 1.
Initialization: none
A_ATRAC/AT1
Codec ID: A_ATRAC/AT1
Codec Name: Sony ATRAC1 Codec
Description: The original ATRAC codec by Sony, mainly used in MiniDisc platforms. The core technical details on ATRAC1 can be found in [@?AtracAES]. An example encoder/decoder can be found at [@?atracdenc].
Initialization: None
Subtitle Codec Mappings
S_TEXT/UTF8
Codec ID: S_TEXT/UTF8
Codec Name: UTF-8 Plain Text
Description: Basic text subtitles. For more information, see (#subtitles) on Subtitles.
S_TEXT/SSA
Codec ID: S_TEXT/SSA
Codec Name: Subtitles Format
Description: The [Script Info] and [V4 Styles] sections are stored in the codecprivate. Each event is stored in its own Block.
For more information, see (#ssa-ass-subtitles) on SSA/ASS.
S_TEXT/ASS
Codec ID: S_TEXT/ASS
Codec Name: Advanced Subtitles Format
Description: The [Script Info] and [V4 Styles] sections are stored in the codecprivate. Each event is stored in its own Block.
For more information, see (#ssa-ass-subtitles) on SSA/ASS.
S_TEXT/WEBVTT
Codec ID: S_TEXT/WEBVTT
Codec Name: Web Video Text Tracks Format (WebVTT)
Description: Advanced text subtitles. For more information, see (#webvtt) on WebVTT.
S_IMAGE/BMP
Codec ID: S_IMAGE/BMP
Codec Name: Bitmap
Description: Basic image based subtitle format; The subtitles are stored as images, like in the DVD [@?DVD-Video].
The timestamp in the block header of Matroska indicates the start display time,
the duration is set with the Duration element. The full data for the subtitle bitmap
is stored in the Block’s data section.
S_DVBSUB
Codec ID: S_DVBSUB
Codec Name: Digital Video Broadcasting (DVB) subtitles
Description: This is the graphical subtitle format used in the Digital Video Broadcasting standard.
For more information, see (#digital-video-broadcasting-dvb-subtitles) on Digital Video Broadcasting (DVB).
S_VOBSUB
Codec ID: S_VOBSUB
Codec Name: VobSub subtitles
Description: The same subtitle format used on DVDs [@?DVD-Video]. Supported is only format version 7 and newer.
VobSubs consist of two files, the .idx containing information, and the .sub, containing the actual data.
The .idx file is stripped of all empty lines, of all comments and of lines beginning with
alt:
or
langidx:
The line beginning with
id:
SHOULD
be transformed into the appropriate Matroska track language element
and is discarded. All remaining lines but the ones containing timestamps and file positions
are put into the
CodecPrivate
element.
For each line containing the timestamp and file position data is read from the appropriate
position in the .sub file. This data consists of a MPEG program stream which in turn
contains SPU packets. The MPEG program stream data is discarded, and each SPU packet
is put into one Matroska frame.
S_HDMV/PGS
Codec ID: S_HDMV/PGS
Codec Name: HDMV presentation graphics subtitles (PGS)
Description: This is the graphical subtitle format used on Blu-rays. For more information,
see (#hdmv-text-subtitles) on HDMV text presentation.
S_HDMV/TEXTST
Codec ID: S_HDMV/TEXTST
Codec Name: HDMV text subtitles
Description: This is the textual subtitle format used on Blu-rays. For more information,
see (#hdmv-presentation-graphics-subtitles) on HDMV graphics presentation.
S_KATE
Codec ID: S_KATE
Codec Name: Karaoke And Text Encapsulation
Description: A subtitle format developed for ogg. The mapping for Matroska is described
on the
Xiph wiki
As for Theora and Vorbis, Kate headers are stored in the private data as xiph-laced packets.
S_ARIBSUB
Codec ID: S_ARIBSUB
Codec Name: ARIB STD-B24 subtitles
Description: This is the textual subtitle format used in the ISDB/ARIB broadcasting standard.
For more information, see (#arib-isdb-subtitles) on ARIB (ISDB) subtitles.
Button Codec Mappings
B_VOBBTN
Codec ID: B_VOBBTN
Codec Name: VobBtn Buttons
Description: Based on
MPEG/VOB PCI packets
The file contains a header consisting of the string “butonDVD” followed by the width and height
in pixels (16 bits integer each) and 4 reserved bytes. The rest is full
PCI packets
Block Addition Mappings
Registered
BlockAddIDType
are:
Use BlockAddIDValue
Block type identifier: 0
Block type name: Use BlockAddIDValue
Description: This value indicates that the actual type is stored in
BlockAddIDValue
instead.
This value is expected to be used when it is important to have a strong compatibility
with players or derived formats not supporting
BlockAdditionMapping
but using
BlockAdditions
with an unknown
BlockAddIDValue
, and
SHOULD NOT
be used if it is possible to use another value.
Opaque data
Block type identifier: 1
Block type name: Opaque data
Description: the
BlockAdditional
data is interpreted as opaque additional data passed to the codec
with the Block data.
BlockAddIDValue
MUST
be 1.
ITU T.35 metadata
Block type identifier: 4
Block type name: ITU T.35 metadata
Description: the
BlockAdditional
data is interpreted as ITU T.35 metadata, as defined by ITU-T T.35
terminal codes.
BlockAddIDValue
MUST
be 4.
avcE
Block type identifier: 0x61766345
Block type name: Dolby Vision enhancement-layer AVC configuration
Description: the
BlockAddIDExtraData
data is interpreted as the Dolby Vision enhancement-layer AVC
configuration box as described in [@!DolbyVisionWithinIso]. This extension
MUST NOT
be used if
Codec ID
is not
V_MPEG4/ISO/AVC
dvcC
Block type identifier: 0x64766343
Block type name: Dolby Vision configuration
Description: the
BlockAddIDExtraData
data is interpreted as
DOVIDecoderConfigurationRecord
structure, as defined in [@!DolbyVisionWithinIso],
for Dolby Vision profiles less than and equal to 7.
dvvC
Block type identifier: 0x64767643
Block type name: Dolby Vision configuration
Description: the
BlockAddIDExtraData
data is interpreted as
DOVIDecoderConfigurationRecord
structure, as defined in [@!DolbyVisionWithinIso],
for Dolby Vision profiles greater than 7.
hvcE
Block type identifier: 0x68766345
Block type name: Dolby Vision enhancement-layer HEVC configuration
Description: the
BlockAddIDExtraData
data is interpreted as the Dolby Vision enhancement-layer HEVC configuration as described in [@!DolbyVisionWithinIso].
This extension
MUST NOT
be used if
Codec ID
is not
V_MPEGH/ISO/HEVC
mvcC
Block type identifier: 0x6D766343
Block type name: MVC configuration
Description: the
BlockAddIDExtraData
data is interpreted as
MVCDecoderConfigurationRecord
structure, as defined in [@!ISO.14496-15].
This extension
MUST NOT
be used if
Codec ID
is not
V_MPEG4/ISO/AVC
Matroska Codec - WavPack
WavPack
stores each data in variable length frames. That means each frame can have a different number of samples.
For multi-track files (more than 2 tracks, like for 5.1). A frame consists of many blocks. The first one having the flag
WV_INITIAL_BLOCK
and the last one
WV_FINAL_BLOCK
. For a mono or stereo files, both flags are set in each block.
Each block starts with a header saved in little-endian with the following format :
typedef
struct
PACKED_STRUCTURE
char
ck_id
];
// "wvpk"
uint32_t
ck_size
// size of entire frame (minus 8, of course)
uint16_t
version
// major & minor version; only supported major version is 4; minor varies with the features used
uint8_t
track_no
// track number (0 if not used, like now)
uint8_t
index_no
// remember these? (0 if not used, like now)
uint32_t
total_samples
// for entire file (-1 if unknown)
uint32_t
block_index
// index of first sample in block (to file begin)
uint32_t
block_samples
// # samples in this block
uint32_t
flags
// various flags for id and decoding
uint32_t
crc
// crc for actual decoded data
wavpack_header_t
WavPack has an hybrid mode. That means the data are encoded in 2 files. The first one has a lossy part and the second file has the correction file that olds the missing data to reconstruct the original file losslessly. Each block in the correction file corresponds to a block in the lossy file with the same number of samples, that’s also true for a multi-track file. That means if a frame is made of 4 blocks, the correction file will have 4 blocks in the corresponding frame. The header of the correction block is exactly the same as in the lossy block, except for the crc. In Matroska we store the correction part as an additional data available to the Block (see BlockAdditions)
To save space and avoid redundant information in Matroska we remove data from the header, when saved in Matroska. All the data are kept in little-endian.
Lossless & lossy mono/stereo file
CodecPrivate
uint16_t
version
// major & minor version; only supported major version is 4; minor varies with the features used
Block
uint32_t
block_samples
// # samples in this block
uint32_t
flags
// various flags for id and decoding
uint32_t
crc
// crc for actual decoded data
block
data
Hybrid mono/stereo files
CodecPrivate
uint16_t
version
// major & minor version; only supported major version is 4; minor varies with the features used
Block
uint32_t
block_samples
// # samples in this block
uint32_t
flags
// various flags for id and decoding
uint32_t
crc
// crc for actual decoded data
block
data
BlockAdditional (level 1)
uint32_t
crc
// crc for actual decoded data
correction
block
data
Lossless & lossy multi-track file
CodecPrivate
uint16_t
version
// major & minor version; only supported major version is 4; minor varies with the features used
Block
uint32_t
block_samples
// # samples in this block
uint32_t
flags
// various flags for id and decoding
uint32_t
crc
// crc for actual decoded data
uint32_t
blocksize
// size of the data to follow
block
data
uint32_t
flags
// various flags for id and decoding
uint32_t
crc
// crc for actual decoded data
uint32_t
blocksize
// size of the data to follow
block
data
uint32_t
flags
// various flags for id and decoding
uint32_t
crc
// crc for actual decoded data
uint32_t
blocksize
// size of the data to follow
block
data
...
Hybrid multi-track files
CodecPrivate
uint16_t
version
// major & minor version; only supported major version is 4; minor varies with the features used
Block
uint32_t
block_samples
// # samples in this block
uint32_t
flags
// various flags for id and decoding
uint32_t
crc
// crc for actual decoded data
uint32_t
blocksize
// size of the data to follow
block
data
uint32_t
flags
// various flags for id and decoding
uint32_t
crc
// crc for actual decoded data
uint32_t
blocksize
// size of the data to follow
block
data
uint32_t
flags
// various flags for id and decoding
uint32_t
crc
// crc for actual decoded data
uint32_t
blocksize
// size of the data to follow
block
data
...
BlockAdditional (level 1)
uint32_t
crc
// crc for actual decoded data
uint32_t
blocksize
// size of the data to follow
correction
block
data
uint32_t
crc
// crc for actual decoded data
uint32_t
blocksize
// size of the data to follow
correction
block
data
uint32_t
crc
// crc for actual decoded data
uint32_t
blocksize
// size of the data to follow
correction
block
data
...
US