[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 richardssam):

 I think I understand where the gamma 1.98 value is coming from. In
 quicktime and mp4 containers the rec709 ETOF definition is for the "Camera
 rec709" value, not bt1886.
 There is not any explicit setting (particularly in mp4's) which allow you
 to set bt1886.

 Both camera-rec709 (~1.98) and sRGB (~2.2) are approximations, which
 cannot be correctly represented by a single gamma value, so its somewhat
 scary for this to be applied automatically.

 I dont know what the right answer here is, although we should at least
 have the ability to override what it uses (particularly if we know the
 resulting image is bt1886 and does have a proper gamma of 2.4).
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/10000#comment:7>
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