On Tue, Jul 30, 2024 at 03:11:47PM +0200, Giovanni Mascellani wrote: > I came across some H.264 files in the wild whose SAR is set to > 20480/0. The files are provided by the Ubisoft game OddBallers, and > are seemingly accepted and played properly when the game is played on > Windows (thus using the Microsoft Media Foundations > implementation). > > When running the game with Wine the files are ultimately decoded by > libavcodec (via GStreamer), and playback is broken. It seems that only > a frame each second or so (maybe the key frames? I didn't check) is > decoded and presented, the others are discarded. After dumping the > video, I ran it with ffplay and it has the same problem, and the > following message is emitted many times: > > [h264 @ 0x7fd7301ef440] ignoring invalid SAR: 20480/1 > > Interestingly the invalid SAR is dumped as 20480/1 (which would be > strange, but in princple legal), while the file has 20480/0 (which > doesn't make sense at all). Equally interestingly, the frames that are > presented are indeed presented with SAR 1/1, like they are on Windows. > > The H.264 standard says that "When aspect_ratio_idc is equal to 0 or > sar_width is equal to 0 or sar_height is equal to 0, the sample aspect > ratio shall be considered unspecified by this Recommendation | > International Standard". Given the behavior on Windows it seems that > the de facto standard way to solve the missing specification is to > assume that SAR is 1/1, which is what my patches seek to do.
Why does playback fail ? 1/1 and unspecified are different things, 0/0 would be unspecified where does 20480/0 turn into 20480/1 ? or did i misunderstand this? thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB In fact, the RIAA has been known to suggest that students drop out of college or go to community college in order to be able to afford settlements. -- The RIAA
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