[RFC] vo_gpu: remove deprecated options --gamma-factor and --gamma-auto

[Akemi]

--gamma-factor and --gamma-auto were deprecated in 0.35 (ac39661 and 2207236). the latter was only used on macOS.
the equivalent client API functionality wasn't officially deprecated.

what i would like to discuss:
do we want to remove those options already?
if yes, how do we want to remove them? since the client API equivalent wasn't deprecated, removal of the functionality can't be done immediately?
do we want to deprecate the client API functionality first in the next release and remove the functionality in one of the releases after the next one?
the client API deprecation change should probably be taken separately?

hope i found all the dependent code and removed it properly.

[kasper93]

This can be removed too, no? It is not public API.

[Akemi]

yeah, i wasn't sure how to handle this since we would get a 'hole' in that enum or would we want to renumber it?

[kasper93]

hole is fine, I think, to keep it simple. There are plenty of bits left for new values.

[Dudemanguy]

If something new is added later, we can always just fill the hole in too.

[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

[ruihe774]

FWIW I wonder what is the alternative of --gamma-factor? I am using --gamma-factor=1.2239 on macOS to match the color with QuickTime Player.

[hooke007]

what is the alternative

#10699 (comment) #11153
But it doesn't give the real answer.

[na-na-hi]

Note that after deprecating --gamma-factor, there is no longer a meaningful way to set gamma anymore. The value of --gamma is essentially a meaningless implementation detail:

mpv/video/csputils.c

Line 499 in 71d3f41

params->gamma = exp(log(8.0) * eq->values[MP_CSP_EQ_GAMMA] / 100.0);

I suggest to undeprecate --gamma-factor. Even though it was implemented as a part of something which no longer works, the option still has valid uses.

[Dudemanguy]

I'm not sure --gamma-auto has any use but I agree with @na-na-hi that --gamma-factor is worth keeping. It's just a simple multiplier anyway so it's not like there's great code complexity.

[Akemi]

why was this option deprecated in the first place?

[hooke007]

https://github.com/mpv-player/mpv/wiki/GPU-Next-vs-GPU

--gamma-factor and --gamma-auto: considered deprecated by design, the new BPC logic handles this much better

Not sure if it was related.

[Akemi]

from the commits and the PR i could only gather "outdated information" and "--gamma-auto not working". though both aren't really a reason to deprecate the options. for the former update the info, for the latter fix it or open an issue (without knowing what exactly is broken, hard to judge).

seems like the initial use case for --gamma-factor is gone, though it still has a more general use case of being the only way to adjust gamma at all (besides video filters via ffmpeg i guess?).

then i am also of the opinion to undeprecate both options.

[ruihe774]

https://github.com/mpv-player/mpv/wiki/GPU-Next-vs-GPU

--gamma-factor and --gamma-auto: considered deprecated by design, the new BPC logic handles this much better

Not sure if it was related.

I wonder what is "BPC"? I cannot find the word in any other places.

[Akemi]

black point compensation, is my guess. at least that's what i see when working with colour profiles and related.