[FFmpeg-trac] #10839(swscale:reopened): incorrect YCoCg to RGB conversion in swscale

[FFmpeg]

#10839: incorrect YCoCg to RGB conversion in swscale
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             Reporter:  Connor       |                    Owner:  (none)
  Worley                             |
                 Type:  defect       |                   Status:  reopened
             Priority:  wish         |                Component:  swscale
              Version:  unspecified  |               Resolution:
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by Connor Worley):

 Summarizing what I believe is wrong:

 * In ffplay, going through vf_scale should cause an error after 45e09a3041
 (vf_scale: use colorspace negotiation API), but ffplay does not set the
 colorspace parameter on the buffersrc filter so some default conversion is
 chosen.
 * In ffplay, automatic conversion can erroneously happen without going
 through vf_scale because the buffersink filter accepts YCoCg as a
 mergeable colorspace.
 * swscale silently returns nonsense coefficients for YCoCg

 I would like for these things to work, but if they can't, I would much
 rather they error than produce incorrect output.
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/10839#comment:13>
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