[FFmpeg-trac] #8779(avfilter:new): Zscale transform to ST 2084 EOTF results in black video output

[FFmpeg]

#8779: Zscale transform to ST 2084 EOTF results in black video output
-------------------------------------+-------------------------------------
             Reporter:  zambelli     |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:  avfilter
              Version:  git-master   |               Resolution:
             Keywords:  zscale       |               Blocked By:
  regression                         |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Changes (by mawazi):

 * component:  undetermined => avfilter


Comment:

 This appears to be a problem in zimg, fixed with the following zimg
 commit: https://github.com/sekrit-
 twc/zimg/commit/fc7473db7e730b46fd8f05b3d9d15631c6aa79a1

 The npl parameter of zscale, which deals with peak luminance when
 converting between HDR and SDR, was not being dealt with properly when not
 explicitly set. This can also be worked around in current ffmpeg builds by
 setting npl=100 (which should be the default when not set) when using
 zscale to convert between HDR and SDR transfer functions (and vice-versa).

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Ticket URL: <https://trac.ffmpeg.org/ticket/8779#comment:4>
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