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<pre class='metadata'>
Title: AVC (H.264) WebCodecs Registration
Repository: w3c/webcodecs
Status: NOTE-ED
Shortname: webcodecs-avc-codec-registration
Level: none
Group: mediawg
ED: https://w3c.github.io/webcodecs/avc_codec_registration.html
TR: https://www.w3.org/TR/webcodecs-avc-codec-registration/
Editor: Chris Cunningham, w3cid 114832, Google Inc. https://www.google.com/
Editor: Paul Adenot, w3cid 62410, Mozilla https://www.mozilla.org/
Editor: Bernard Aboba, w3cid 65611, Microsoft Corporation https://www.microsoft.com/
Abstract: This registration is entered into the [[webcodecs-codec-registry]].
It describes, for AVC (H.264), the (1) fully qualified codec strings,
(2) the codec-specific {{EncodedVideoChunk}}
[=EncodedVideoChunk/[[internal data]]=] bytes, (3) the
{{VideoDecoderConfig.description}} bytes, (4) the values of
{{EncodedVideoChunk}} [=EncodedVideoChunk/[[type]]=], and (5) the
codec-specific extensions to {{VideoEncoderConfig}}
The registration is not intended to include any information on whether a
codec format is encumbered by intellectual property claims. Implementers and
authors are advised to seek appropriate legal counsel in this matter if they
intend to implement or use a specific codec format. Implementers of
WebCodecs are not required to support the AVC / H.264 codec.
This registration is non-normative.
Markup Shorthands:css no, markdown yes, dfn yes
!Participate: <a href="https://github.com/w3c/webcodecs">Git Repository.</a>
!Participate: <a href="https://github.com/w3c/webcodecs/issues/new">File an issue.</a>
!Version History: <a href="https://github.com/w3c/webcodecs/commits">https://github.com/w3c/webcodecs/commits</a>
</pre>
<pre class='anchors'>
spec: WEBCODECS; urlPrefix: https://w3c.github.io/webcodecs/#
type: attribute
text: EncodedVideoChunkMetadata.decoderConfig; url: dom-encodedvideochunkmetadata-decoderconfig
for: EncodedVideoChunkType; text: key; url: dom-encodedvideochunktype-key
text: VideoDecoderConfig.description; url: dom-videodecoderconfig-description
type: dfn
for: EncodedVideoChunk; text: [[internal data]]; url: dom-encodedvideochunk-internal-data-slot
for: EncodedVideoChunk; text: [[type]]; url: dom-encodedvideochunk-type-slot
for: VideoEncoder; text: [[output callback]]; url: dom-videoencoder-output-callback-slot
type: interface
text: EncodedVideoChunk; url: encodedvideochunk
text: VideoEncoder; url: videoencoder
type: dictionary
text: VideoEncoderConfig; url: dictdef-videoencoderconfig
text: VideoDecoderConfig; url: dictdef-videodecoderconfig
</pre>
<pre class='biblio'>
{
"ITU-T-REC-H.264": {
"href": "https://www.itu.int/rec/T-REC-H.264",
"title": "H.264 : Advanced video coding for generic audiovisual services",
"publisher": "ITU",
"date": "June 2019"
},
"iso14496-15": {
"href": "https://www.iso.org/standard/74429.html",
"title": "ISO/IEC 14496-15:2019 Information technology — Coding of audio-visual objects — Part 15: Carriage of network abstraction layer (NAL) unit structured video in the ISO base media file format",
"publisher": "ISO",
"date": "September 2019"
}
}
</pre>
Fully qualified codec strings {#fully-qualified-codec-strings}
==============================================================
The codec string begins with the prefix "avc1." or "avc3.", with a suffix of 6
characters as described respectively in Section 3.4 of [[rfc6381]] and Section
5.4.1 of [[iso14496-15]].
EncodedVideoChunk data {#encodedvideochunk-data}
================================================
{{EncodedVideoChunk}} [=EncodedVideoChunk/[[internal data]]=] is expected to be
an access unit as defined in [[ITU-T-REC-H.264]] section 7.4.1.2.
NOTE: An access unit contains exactly one primary coded picture.
If the bitstream is in {{AvcBitstreamFormat/avc}} format,
[=EncodedVideoChunk/[[internal data]]=] is assumed to be in canonical format, as
defined in [[iso14496-15]] section 5.3.2.
If the bitstream is in {{AvcBitstreamFormat/annexb}} format,
[=EncodedVideoChunk/[[internal data]]=] is assumed to be in in Annex B format,
as defined in [[ITU-T-REC-H.264]] Annex B.
NOTE: Since [=EncodedVideoChunk/[[internal data]]=] is inherently byte-aligned,
implementations are not required to recover byte-alignment.
VideoDecoderConfig description {#videodecoderconfig-description}
================================================================
If the {{VideoDecoderConfig.description}} is present, it is assumed to be an
`AVCDecoderConfigurationRecord`, as defined by [[iso14496-15]], section
5.3.3.1, and the bitstream is assumed to be in {{AvcBitstreamFormat/avc}}
format.
NOTE: This format is commonly used in .MP4 files, where the player generally
has random access to the media data.
If the {{VideoDecoderConfig.description}} is not present, the bitstream is
assumed to be in {{AvcBitstreamFormat/annexb}} format.
NOTE: "annexb" format is described in greater detail by [[ITU-T-REC-H.264]],
Annex B. This format is commonly used in live-streaming applications, where
including the SPS and PPS data periodically allows users to easily start
from the middle of the stream.
EncodedVideoChunk type {#encodedvideochunk-type}
================================================
If an {{EncodedVideoChunk}}'s [=EncodedVideoChunk/[[type]]=] is
{{EncodedVideoChunkType/key}}, and the bitstream is in
{{AvcBitstreamFormat/avc}} format, then the {{EncodedVideoChunk}} is expected to
contain a primary coded picture that is an instantaneous decoding refresh (IDR)
picture.
NOTE: If the bitstream is in {{AvcBitstreamFormat/avc}} format, parameter sets
necessary for decoding are included in {{VideoDecoderConfig.description}}.
If an {{EncodedVideoChunk}}'s [=EncodedVideoChunk/[[type]]=] is
{{EncodedVideoChunkType/key}}, and the bitstream is in
{{AvcBitstreamFormat/annexb}} format, then the {{EncodedVideoChunk}} is expected
to contain both a primary coded picture that is an instantaneous decoding
refresh (IDR) picture, and all parameter sets necessary to decode all video data
NAL units in the {{EncodedVideoChunk}}.
VideoEncoderConfig extensions {#videoencoderconfig-extensions}
==============================================================
<pre class='idl'>
<xmp>
partial dictionary VideoEncoderConfig {
AvcEncoderConfig avc;
};
</xmp>
</pre>
<dl>
<dt><dfn dict-member for=VideoEncoderConfig>avc</dfn></dt>
<dd>
Contains codec specific configuration options for the AVC (H.264) codec.
</dd>
</dl>
AvcEncoderConfig {#avc-encoder-config}
--------------------------------------
<pre class='idl'>
<xmp>
dictionary AvcEncoderConfig {
AvcBitstreamFormat format = "avc";
};
</xmp>
</pre>
<dl>
<dt><dfn dict-member for=AvcEncoderConfig>format</dfn></dt>
<dd>
Configures the format of output {{EncodedVideoChunk}}s. See
{{AvcBitstreamFormat}}.
</dd>
</dl>
AvcBitstreamFormat {#avc-bitstream-format}
------------------------------------------
<pre class='idl'>
<xmp>
enum AvcBitstreamFormat {
"annexb",
"avc",
};
</xmp>
</pre>
The {{AvcBitstreamFormat}} determines the location of AVC parameter sets, and
mechanisms for packaging the bitstream.
<dl>
<dt><dfn enum-value for=AvcBitstreamFormat>annexb</dfn></dt>
<dd>
SPS and PPS data are included periodically throughout the bitstream.
NOTE: This format is described in greater detail by [[ITU-T-REC-H.264]],
Annex B. This format is commonly used in live-streaming applications,
where including the SPS and PPS data periodically allows users to easily
start from the middle of the stream.
</dd>
<dt><dfn enum-value for=AvcBitstreamFormat>avc</dfn></dt>
<dd>
SPS and PPS data are not included in the bitstream and are instead emitted
via the [=VideoEncoder/[[output callback]]=] as the
{{VideoDecoderConfig.description}} of the
{{EncodedVideoChunkMetadata.decoderConfig}}.
NOTE: This format is described in greater detail by [[iso14496-15]],
section 5.3. This format is commonly used in .MP4 files, where the
player generally has random access to the media data.
</dl>
Privacy Considerations {#privacy-considerations}
==========================================================================
Please refer to the section [[WEBCODECS#privacy-considerations|Privacy
Considerations]] in [[WEBCODECS]].
Security Considerations {#security-considerations}
==========================================================================
Please refer to the section [[WEBCODECS#security-considerations|Security
Considerations]] in [[WEBCODECS]].