On 1/7/2026 10:25 AM, Christophe Gisquet via ffmpeg-devel wrote:
Hi,


Le dim. 28 déc. 2025, 19:46, Jun Zhao via ffmpeg-devel <
[email protected]> a écrit :

PR #21307 opened by Jun Zhao (mypopydev)
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21307
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21307.patch

This patch series V2 adds support for carrying AV1 video streams in MPEG-2
Transport Stream
containers, following the AOM "Carriage of AV1 in MPEG-2 TS" specification.

   Key Features

   - MPEG-TS Muxer: Converts AV1 from Section 5 (low overhead) format to
start code format,
   where each OBU is prefixed with a 0x000001 start code. Includes
Registration Descriptor ('AV01')
   and AV1 Video Descriptor (0x80) in PMT.
   - MPEG-TS Demuxer: Identifies AV1 streams by stream_type 0x06 (private
data) and
   Registration Descriptor. Outputs AV1 data in start code format.
   - av1_tstosection5 BSF: Converts AV1 from MPEG-TS start code format back
to Section 5
   format for compatibility with other containers and decoders.
Automatically inserted when
   remuxing to MP4, MKV, FLV, IVF, and raw OBU files.
   - Decoder Support: Both libdav1d and libaom decoders can directly decode
AV1 in start code format.


I haven't followed that AoM activity in a very long time, but from what I
remember, there was a big reason why it remained a draft, as there was no
consensus/decision possible for some of the features (maybe start code).

I think the previously mentioned wisdom that ffmpeg shouldn't generate
files that could end up not being spec-compliant, should be applied here as
well. Ie maybe delay merging this until there is clear indication the
implemented features are no longer subject to change.

Note that for RTP, it was more about being lost in limbo, with little
interop (ie between vendors) really possible, and with a global agreement
on all classical points. I don't think what was merged in ffmpeg ended up
non-spec compliant, but it could be argued it was out of luck.

Mostly my 2 cents,
Regards,
Christophe

Muxing was removed from the PR, so that should not be an issue. Supposedly, the existing draft is being used by some content deliver services, but I'm not sure how widespread is support for it out there.

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