[FFmpeg-trac] #10000(undetermined:open): PNG produced from BT.709 video should be tagged as gAMA 2.4

[FFmpeg]

#10000: PNG produced from BT.709 video should be tagged as gAMA 2.4
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             Reporter:  Balling      |                    Owner:  (none)
                 Type:  defect       |                   Status:  open
             Priority:  normal       |                Component:
                                     |  undetermined
              Version:  git-master   |               Resolution:
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by Balling):

 From https://github.com/mpv-player/mpv/issues/13438


 >The PNG specification recommends that PNG writers write gAMA chunks even
 if it writes other color chunks that override it as fallback metadata to
 poorly color managed PNG viewers. The actual file is tagged correctly with
 cICP chunk, which overrides the fallback gAMA chunk.

 NO, the PNG SPEC v3 does not specify any such chunk for BT.709. So this is
 an open issue with a standard. Also, Mac does not use 1.9 gamma for EOTF,
 it also use close to 2.4.
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Ticket URL: <https://trac.ffmpeg.org/ticket/10000#comment:9>
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