Anton Khirnov: > Quoting James Almer (2020-03-18 17:05:38) >> On 3/13/2020 7:28 AM, Anton Khirnov wrote: >>> It represents the relationship between them more naturally and will be >>> useful in the following commits. >>> >>> Allows significantly more frames in fate-h264-attachment-631 to be >>> decoded. >> >> That sample is odd. It has an SPS/PPS pair in extradata that's wrong for >> the Buffering Period and Picture Timing SEI messages in-band, but >> seemingly correct to actually decode all these frames revealed by this >> patch. >> The SPS that makes the aforementioned SEI messages parseable, but the >> frames seemingly undecodeable, is in-band in the second RAP (Which fwiw >> reports a different bitstream level). So this patch prevents the >> extradata PPS from using the in-band SPS after it replaced the extradata >> one in sps_list. There's no PPS in-band. >> >> Is this really intended? Is the active PPS' sps_id meant to reference >> the SPS with that id that's currently "valid" and in sps_list, or the >> whichever one was valid at the time the PPS was first parsed?. If the >> latter, then why replace the SPS in-band but never the PPS? >> The in-band SPS is virtually unused after this change. > > My guess would be that someone (or some/thing/, dun dun dun) did some > botched/misunderstood processing on that sample, so trying to figure out > what was intended is futile. > > According to the spec, SPS contents must not change within a sequence > (they can change on sequence boundaries), so this sample is invalid.
While this sample is invalid, isn't it possible to have a sample as follows: First a SPS and a PPS referencing the SPS, then a coded video sequence for which these SPS and PPS are active, then another IDR access unit with a new SPS that overwrites the old one, but with no new PPS. This is valid if I am not mistaken. With your patch, the second SPS would never be used. - Andreas _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".