[FFmpeg-trac] #11182(swscale:closed): yuvtestsrc and yuv444p->rgba->yuv444p conversion result in huge difference

[FFmpeg]

#11182: yuvtestsrc and yuv444p->rgba->yuv444p conversion result in huge difference
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             Reporter:  Andrew-R     |                    Owner:  (none)
                 Type:  defect       |                   Status:  closed
             Priority:  normal       |                Component:  swscale
              Version:  unspecified  |               Resolution:  invalid
             Keywords:  colorspace   |               Blocked By:
  color_primaries                    |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by Balling):

 "Interesting technology, but probably not something ffmpeg can do (or
 expose to external use). "

 Yes, encoding negative RGB into alpha channel is insane. It does utilise
 it, as zscale support xvYCC, which is what those "illegal" YCbCr values
 are (at the time where Silicon graphics was Nvidia, lol, it may have been
 illegal, but even then BBC wrote some quides how to limit data in YCbCr).
 Paul fixed some code so some of the LUTs are also preserving these data.
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Ticket URL: <https://trac.ffmpeg.org/ticket/11182#comment:31>
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