--icc-force-contrast does not work with --vo=gpu-next

[aufkrawall]

icc-profile-auto
icc-force-contrast=inf

--vo=gpu:

--icc-force-contrast=inf should turn BT.1886 gamma curve into pure power 2.4, but it doesn't with --vo=gpu-next:

--vf=format:gamma=gamma2.4 can be used as a workaround.

Log:
output.txt

latest mpv & libplacebo git-master as of today.
Tested on Linux Xorg.

I btw. still think that pure power gamma 2.4 would be a better default for rec709 content, as BT.1886 just looks too bright with most of the content on any display that doesn't have an extremely low black point.

[CrHasher]

Please remove label "os:linux", it applies also to windows. In addition "gamma-factor" doesn't work.

[OrangeColaJuice]

Is the "bt.1886" treated like something in-between sRGB and gamma2.2 because it has hard-coded 1000 contrast over the spec's formula? That's definitely how it feels to me after experimenting.

[haasn]

Is the "bt.1886" treated like something in-between sRGB and gamma2.2 because it has hard-coded 1000 contrast over the spec's formula? That's definitely how it feels to me after experimenting.

Yes and no. libplacebo assumes 1000:1 contrast by default for SDR displays with unknown contrast information. If you use an ICC profile, it will instead take the effective contrast of the ICC profile's LUTs. (Note that --icc-force-contrast is currently ignored by --vo=gpu-next, this is a known limitation.)

In theory BT.1886 can be tuned to any contrast point you want, but the mpv integration does not expose all options.