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Add extended HE-AAC to the AAC WebCodecs Registration #930

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Merged
Djuffin merged 3 commits into from
Mar 19, 2026
Merged

Add extended HE-AAC to the AAC WebCodecs Registration #930

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7b6070f
Add Extended HE-AAC to AAC WebCodecs Registration
google-labs-jules[bot] Mar 10, 2026
aeb58fd
Address PR comments on AudioDecoderConfig description
google-labs-jules[bot] Mar 10, 2026
71f8e4a
Implement PR feedback for Extended HE-AAC
google-labs-jules[bot] Mar 10, 2026
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27 changes: 20 additions & 7 deletions aac_codec_registration.src.html
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Expand Up @@ -36,10 +36,22 @@
<pre class='biblio'>
{
"iso14496-3": {
"href": "https://www.iso.org/standard/53943.html",
"title": "ISO/IEC 14496-3:2009 - Information technology — Coding of audio-visual objects — Part 3: Audio",
"href": "https://www.iso.org/standard/76383.html",
"title": "ISO/IEC 14496-3:2019 - Information technology — Coding of audio-visual objects — Part 3: Audio",
"publisher": "ISO",
"date": "2009-09"
"date": "2019-12"
},
"iso23003-3": {
"href": "https://www.iso.org/standard/76385.html",
"title": "ISO/IEC 23003-3:2020 - Information technology — MPEG audio technologies — Part 3: Unified speech and audio coding",
"publisher": "ISO",
"date": "2020-06"
},
"iso23003-4": {
"href": "https://www.iso.org/standard/89036.html",
"title": "ISO/IEC 23003-4:2025 - Information technology — MPEG audio technologies — Part 4: Dynamic range control",
"publisher": "ISO",
"date": "2025-03"
}
}
</pre>
Expand All @@ -54,6 +66,7 @@
- `"mp4a.40.5"` — MPEG-4 HE-AAC v1 (AAC LC + SBR)
- `"mp4a.40.05"` — MPEG-4 HE-AAC v1 (AAC LC + SBR), leading 0 for Aud-OTI compatibility
- `"mp4a.40.29"` — MPEG-4 HE-AAC v2 (AAC LC + SBR + PS)
- `"mp4a.40.42"` — Extended HE-AAC (MPEG-D USAC + MPEG-D DRC) as defined in [[iso23003-3]] and [[iso23003-4]]
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@dalecurtis dalecurtis Mar 10, 2026

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I'd add (xHE-AAC) in parenthesis, but up to you.

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@Djuffin Djuffin Mar 10, 2026

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done

- `"mp4a.67"` — MPEG-2 AAC LC

EncodedAudioChunk data {#encodedaudiochunk-data}
Expand All @@ -66,14 +79,14 @@
If the bitstream is in {{AacBitstreamFormat/aac}} format, the
{{EncodedAudioChunk/[[internal data]]}} of {{EncodedAudioChunk}}s are expected
to be a raw AAC frame (syntax element `raw_data_block()`), as described in
section 4.4.2.1 of [[iso14496-3]].
section 4.4.2.1 of [[iso14496-3]]. Extended HE-AAC shall be in {{AacBitstreamFormat/aac}} format.
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@dalecurtis dalecurtis Mar 10, 2026

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I forget if we're supposed to use "must" now.

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@Djuffin Djuffin Mar 10, 2026 •
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indeed


AudioDecoderConfig description {#audiodecoderconfig-description}
================================================================

If {{AudioDecoderConfig/description}} is present, it is assumed to a
`AudioSpecificConfig` as defined in [[iso14496-3]] section 1.6.2.1, Table 1.15,
and the bitstream is assumed to be in {{AacBitstreamFormat/aac}}.
If {{AudioDecoderConfig/description}} is present, it is assumed to be an
`AudioSpecificConfig` as defined in [[iso14496-3]] section 1.6.2.1, Table 1.19,
and the bitstream is assumed to be in {{AacBitstreamFormat/aac}} format.

If the {{AudioDecoderConfig/description}} is not present, the bitstream is
assumed to be in {{AacBitstreamFormat/adts}} format.
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