[FFmpeg-trac] #4829(swscale:open): Overflows (?) in xyz -> rgb conversion

[FFmpeg]

#4829: Overflows (?) in xyz -> rgb conversion
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             Reporter:  cehoyos     |                    Owner:
                 Type:  defect      |                   Status:  open
             Priority:  normal      |                Component:  swscale
              Version:  git-master  |               Resolution:
             Keywords:  xyz         |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
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Changes (by Balling):

 * status:  new => open


Comment:

 >in fact decoded fine (at least visually)

 Oh really? The only way to preserve the xyz12le stuff is rawvideo (see
 last comment in #1279) and it is not lossless compared to -c:v
 libopenjpeg. I.e. file produced by (-pixel_format xyz12le is needed for
 libopenjpeg before https://github.com/uclouvain/openjpeg/pull/1200 is
 applied):

 ffmpeg -pixel_format xyz12le -c:v libopenjpeg -i frm_000127.j2c -f
 rawvideo out

 is not the same as:

 ffmpeg -i frm_000127.j2c -f rawvideo out

 has off-by-one error somewhere that breaks every 32 byte if you compare in
 hex diff. It is kind of hard for me to say what decoder is correct.

 >a png with massive artefacts (posterization) in the top left

 So what? Of course, the artifacts can be in original xyz12le file.

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Ticket URL: <https://trac.ffmpeg.org/ticket/4829#comment:3>
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