I'm using an old Mac mini (i7 26xx, 4 cores with integrated graphics, i915 driver) as a media player using Ubuntu 24.04 on wayland and MPV.
This setup is old but more than enough for 1080 and most 4k files.
However I have trouble decoding 1080p AV1 in 10bits HDR. The strange part is that the decoding is fine at first, and then after a few minutes I have dropped frames. It's not tied to a specific scene, but to a duration.
I tried all the available -vo, gpu is the best one. Gpu-next yields better performances but is buggy (in full screen luma is upside down while chroma is correct)
The Cpu monitor shows a usage under 50%. I can play twice the same file nearing 100% CPU and noticing the same performance. So the CPU is not the bottleneck here (or maybe if something is monothreaded)
I then tried to play the file with ffplay (without any parameters to handle correctly the HDR) and the file is playing fine without any lag and I have a ~30% CPU usage. But of course the colours are completely off.
I play again with zscale to handle the hdr. -vf "zscale=transfer=linear,tonemap=hable,zscale=transfer=bt709,format=gbrp"Then I have the same problem. Dropped frames and 50% cpu.
So the problem seems to be with the HDR color conversion. Is there a specific filter I can use in MPV to have better performances?