[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
             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             |

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.
 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

 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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