[FFmpeg-trac] #8735(avcodec:new): videotoolbox causes chroma artifacts in comparison to sw decoding
FFmpeg
trac at avcodec.org
Mon Jun 15 01:57:19 EEST 2020
#8735: videotoolbox causes chroma artifacts in comparison to sw decoding
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Reporter: der_richter | Owner:
Type: defect | Status: new
Priority: normal | Component: avcodec
Version: git-master | Resolution:
Keywords: videotoolbox | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Comment (by der_richter):
the first and last few frames are probably bit-exact because they are
complete black frames and whatever transformation videotoolbox does
internally translates black to black (0 > 0 (full), or 16 > 16 (limited 8
bit), or 64 > 64 (limited 10bit)).
mentioning a transformation because there was a similar problem before
with full range videos.
https://github.com/FFmpeg/FFmpeg/commit/2a9d461abcc88ab74f2143aada1e366a0961830c
#diff-c16efb3d450eaaeb30bd45f817966fc6
in that case videotoolbox internally converted the full range video stream
to limited, but it was still treated as full range. leading to washed out
output.
anyway, it's possible that videotoolbox does something unexpected because
it doesn't get the appropriate information it needs to decode the stream
properly. so basically it could be an inappropriate or wrong usage of the
videotoolbox API.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/8735#comment:7>
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