[FFmpeg-trac] #7037(avcodec:open): ffmpeg destroys HDR information when encoding

FFmpeg trac at avcodec.org
Mon Dec 16 15:08:29 EET 2019

#7037: ffmpeg destroys HDR information when encoding
             Reporter:  mario66      |                    Owner:  cehoyos
                 Type:  enhancement  |                   Status:  open
             Priority:  normal       |                Component:  avcodec
              Version:  git-master   |               Resolution:
             Keywords:  libx265 hdr  |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |

Comment (by mario66):

 Replying to [comment:36 Balling]:
 I appreciate your more technical clarification, but in a nutshell my
 explanation is correct and provides people who have never neared of HDR an
 intuitive introduction in this topic. Because in its core, the following
 mechanism is true: If you open up color space, i.e. you can now represent
 brighter values, you have to tell the TV that your distribution changed
 and that max brightness is now much higher. Basically with a TV you can
 only control the ''max'' brightness, although obviously you are interested
 in controlling the ''average'' brightness. Everything will orient itself
 around this max brightness. And depending on whether the content is
 equally distributed within the color space or if you have a long-tail
 distribution you need to set different ''max'' brightness values to
 archive the same ''average'' brightness. This effect is based on logic and
 cannot be wrong, although of course this is just a simplification and in
 reality they are more complex.

Ticket URL: <https://trac.ffmpeg.org/ticket/7037#comment:37>
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