[MPlayer-dev-eng] Brightness broken

[Reimar Döffinger]

> On 23 May 2022, at 14:15, Nicolas George <george at nsup.org> wrote:
> 
> Reimar Döffinger (12022-05-21):
>>> ffmpeg -lavfi testsrc2=s=1280x720:d=2 -c:v libx265 \
>>>   -pix_fmt yuv420p10 -crf 18 -y /tmp/test.mkv
> 
>> Unfortunately I can't reproduce.
>> This change makes no difference, in all cases, the behaviour is:
>> - brightness works with -vo gl
>> - works but looks different with -vo gl:yuv=0
>> - does not work with -vo corevideo
>> 
>> I guess it could be specific to Linux/graphics driver/support texture formats?
> 
> Did you test with the generated test video I suggested? The -pix_fmt
> yuv420p10 is necessary to reproduce the issue, I should have insisted
> more about it.

I copy-pasted the command exactly as-is. But I do suspect something goes different with my versions of FFmpeg and x265, I suspect the result is not 10 bit video. Not sure how, maybe a libx265 without 10 bit support?

> I suspect the problem lies in the 10 bits → 8 bits
> conversion.

Except - that should not involve swscale.
-vo gl can natively support 420p10.
I tried adding -vf format=420p10, and brightness still works. Also vo gl displays it directly:
VO: [gl_nosw] 1280x720 => 1280x720 Planar 420P 10-bit little-endian 
Suspect that there are multiple things different between our systems...