vo_gpu: undeprecate --gamma-factor and --gamma-auto

[Akemi]

alternative to #14369

[github-actions]

Download the artifacts for this pull request:

Windows

• mpv-i686-w64-mingw32
• mpv-x86_64-w64-mingw32
• mpv-x86_64-windows-msvc

macOS

• mpv-macos-12-intel
• mpv-macos-13-intel
• mpv-macos-14-arm

[guidocella]

It was unclear to me too why these were deprecated. These will have to be added to gpu-next if undeprecated.

[Dudemanguy]

--gamma-factor is trivial. not sure about --gamma-auto

[kasper93]

These will have to be added to gpu-next if undeprecated.

/cc @haasn

[Akemi]

maybe it would be better to make 'ambient lux' an observable property which can be changed by the backend, and whoever wants to do something with that value can do it with a script? the old assumption was this after all and is hardcoded:

1.0
    Pitch black or dimly lit room (default)
1.1
    Moderately lit room, home
1.2
    Brightly illuminated room, office

NOTE: This is based around the assumptions of typical movie content, which
contains an implicit end-to-end of about 0.8 from scene to display. For
bright environments it can be useful to cancel that out.

with an observable property the behaviour could be changed by the user to whatever they like.

[Dudemanguy]

I think this is fine as is. I'll leave it up to you if you want to do anything more with --gamma-auto since it only works on macOS anyway.