On 1/12/2026 1:31 PM, Nicolas Gaullier via ffmpeg-devel wrote:
On 12/28/25 19:45, Jun Zhao via ffmpeg-devel wrote: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.patchAdd functions to parse AV1 OBUs in MPEG-TS start code format (0x000001 prefix). This is needed for AV1 streams from MPEG-TS containers per AOM AV1 in MPEG-2 TS specification.I have some questions around aligned PES and start codes; please correct me if I am wrong.Start codes: it seems to me current PR autodetects start codes, which means if a stream miss them, it would still be successfully decoded. This is possible because, additionally, AV1 requires aligned PES (which
Where does the spec say that?
is unusual for h2645 typically). Being able to handle non-conformant files is nice until there are no downsides. The situation is maybe a little bit tricky here since this format is not widespread, you may want to be more carefull, check interoperability etc., and maybe you want to be warned that "this file may not be supported outside of ffmpeg" ? It
Why would we warn that? Demuxing has no need for any kind of warning like that. We're reading a file and trying to make sense of its contents. What other readers can or can't do is irrelevant.
seems there is no "issue" in the other way (a stream which is not pes- aligned would not be decodable since there is no "find_frame_end" in the parser to split the packets), but anyway maybe it could be
I already wrote an implementation for Temporal Unit assembly in av1_parser, but I'm waiting until all is said and done, and probably an actual sample is provided.
an interesting opportunity to introduce pes alignment support in mpegts ? If I understand correctly, it would allow disabling packet repacking in some use cases (j2k for example: I just had a quick look today since mpegts mandates pes alignment for it too).Nicolas _______________________________________________ ffmpeg-devel mailing list -- [email protected] To unsubscribe send an email to [email protected]
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