Wayland Weston & Sway - vsync stutters in mpv on Intel graphics
Submitted by aufkrawall
Assigned to Intel GFX Bugs mailing list
Created attachment 146003
dmesg log of the test system
Originally reported here, but posting here in case it might be a kernel issue: mesa/mesa#2048 (moved)
The issue: Stutter free video playback is not possible on Gemini Lake with Wayland compositors.
To reproduce, run mpv 0.30 via
"mpv --no-config --video-sync=display-resample --hwdec=vaapi http://www.oc-burner.de/ftp/Videos/juddertest/juddertest_60.mp4"
on a ~60Hz display in a Weston or Sway Wayland session (mpv automatically uses native Wayland windowing, no xwayland involved). There is stutter each few seconds, thus mpv's statistics recognize vsync jitter spikes and in the wake mistimed or delayed frames (either watch mpv's terminal output or enable LUA stats via Shift + i).
There is no stutter with xf86-video-intel DDX on Xserver (also not in fullscreen with pageflipping triggered). There is also no stutter with AMD GPU on Wayland, so the root of the issue should not lie in mpv.
modesetting DDX on Xserver shows a very similar (if not exactly the same?) issue as Wayland with Intel graphics, if that's important. Though there probably is xf86-video-intel for a good reason, so perhaps the Wayland situation is more deserving of attention.
Issue also ocurs with --hwdec=vaapi-copy, which uses the same windowing context as software decoding.
Arch Linux / Manjaro 5.3.8
xorg 1.20.5-4 from Arch/Manjaro repo
recent sway-git/wlroots-git which supports correct vsync presentation feedback
Attaching a dmesg log of the test system.
Attachment 146003, "dmesg log of the test system":