On 7/19/2018 12:16 PM, James Almer wrote: > On 7/19/2018 9:57 AM, Francois Cartegnie wrote: >> Hi, >> >> Sorry, can't reply to thread. >> >>> + if (version != 0) { >>> + av_log(c->fc, AV_LOG_WARNING, "Unknown AV1 Codec Configuration Box >>> version %d\n", version); >>> + return 0; >>> + } >>> + avio_skip(pb, 3); /* flags */ >>> + >>> + avio_skip(pb, 1); /* reserved, initial_presentation_delay_present, >>> initial_presentation_delay_minus_one */ >>> + >>> + ret = ff_get_extradata(c->fc, st->codecpar, pb, atom.size - 5); >> >> Seems to me that using OBU only as internal extradata, unlike h264 or >> hevc, will only cause issues. >> >> There's no version as a guarantee on which OBU should be found, and it >> implies parsing OBU just like with AnnexB. > > Unlike avcc and hvcc, the spec didn't define a custom encapsulation for > av1c, but it does state which types should be found: > > "The configOBUs field is expected to contain only OBU_SEQUENCE_HEADER > and OBU_METADATA when the metadata OBU is applicable to all the > associated samples" > > Matroska has the same requirements. > >> Parsing might also not be possible without accessing samples data when >> there's potentially zero OBU in DCR. > > Steve Lhomme opened a issue[1] about it. The spec states "zero or more > OBUs" in av1c, whereas In Matroska the Sequence Header is guaranteed to > be present as they say "one or more OBUs". > > Fwiw, in ffmpeg's case at least, libavformat will generate the internal > extradata on its own by extracting the first Sequence Header from the > bitstream if the demuxer didn't allocate it itself. This is what's done > for ivf and such containers. > >> >> I've raised the issue on the spec, as the DCR itself does not seems to >> contain enough extracted information, like profile for routing to a >> proper decoder. > > Like you said, you're clearly expected to parse the Sequence Header OBU > in configOBUs. Profile is the very first value in it after the OBU header. > > [1] https://github.com/AOMediaCodec/av1-isobmff/issues/46
I made a summary of all the comments/suggestions scattered across issues/PRs into https://github.com/AOMediaCodec/av1-isobmff/issues/50. Yours, and those by Steve Lhomme. We'll see what, if anything, comes out of it. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel