[FFmpeg-trac] #8509(avcodec:new): Converting 8 bit ARGB to Prores 4444 using prores_ks produces alpha channel that is not 100% opaque

FFmpeg trac at avcodec.org
Mon Feb 3 23:57:40 EET 2020


#8509: Converting 8 bit ARGB to Prores 4444 using prores_ks produces alpha channel
that is not 100% opaque
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             Reporter:  bford       |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  normal      |                Component:  avcodec
              Version:  git-master  |               Resolution:
             Keywords:  prores      |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
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Comment (by bford):

 I dont think so.  The alpha channel itself should not be undergoing any
 color space conversion.
 The RGB components would convert to YUV and back; but the Alpha should not
 be affected.
 It would however undergo an 8bit to 16bit conversion as I believe it is
 being stored as 16bit in the output file, and that could be where the
 issue comes from.

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Ticket URL: <https://trac.ffmpeg.org/ticket/8509#comment:3>
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