[FFmpeg-trac] #3785(swscale:closed): SWSCALE: in_range, in_color_matrix, out_range, out_color_matrix incorrect

[FFmpeg]

#3785: SWSCALE: in_range, in_color_matrix, out_range, out_color_matrix incorrect
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             Reporter:  troy_s      |                    Owner:  (none)
                 Type:  defect      |                   Status:  closed
             Priority:  normal      |                Component:  swscale
              Version:  git-master  |               Resolution:  invalid
             Keywords:  range       |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
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Comment (by pdr0):

 Replying to [comment:28 Balling]:
 > >The following, despite being 601 coefficients, should yield perfect 1:1
 with RGB values (RGB being a relative color space) but quantization issues
 again result.
 >
 > No, it should not. FFplay does not really support some BT.601 stuff,
 because it uses SDL library for decoding (very dumb, I know). If you want
 correct output use mpv. See #8862


 Yes , but because of incomplete syntax. FFplay supports "BT.601 stuff"
 with vf scale as he was using. But for ffplay, when using -vf scale
 arguments - you just add the format=gbrp to the end after -vf scale
 arguments (rgb24 works as well) to get the expected "almost" correct +/-3
 colors.

 -vf scale=in_range=full:in_color_matrix=bt601,format=gbrp

 "almost" correct because that is an 8bit pipeline. You'd get psnr inf when
 using 10bit444 for the RGB => 10bit YCbCr => RGB round trip




 Yes, there are other issues with ffplay reading flags automatically and
 adjusting. But it's the same workaround for #8862 until a proper "auto"
 fix is implemented

 ffplay -i vokoscreenNG.x264_q0_high.mkv -vf
 scale=in_color_matrix=bt601,format=gbrp

 (But on the other hand, sometimes files are flagged improperly. You can
 make a case for not autoadjusting the rgb conversion)
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/3785#comment:29>
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