MPV: Severe tearing / lack of vsync

[realnc]

There is severe tearing going on when watching videos in fullscreen mode with MPV as backend and using an opengl renderer as video output (opengl-hq or opengl-old).

The problem does not exist when running mpv on its own, using the same command-line options that smplayer uses to run mpv (except for the slave options.)

It seems mpv does not vsync when run in slave mode? Forcing vsync in NVidia's control panel, or running with __GL_SYNC_TO_VBLANK=1 does not help.

(This is a problem with fullscreen-only simply because fullscreen is configured to disable desktop compositing in my KDE setup. If I disable compositing completely, the problem also appears in non-fullscreen mode.)

Using vdpau as backend does not have that problem, but it's unusable because vdpau crashes mpv or sometimes freezes the entire desktop when switching from non-composited fullscreen to composited windowed mode.

Enabling compositing for fullscreen windows is also not a good solution, because (a) it drops frames very often, making videos stutter from time to time, and (b) it makes video games completely unplayable due to insane input lag and introduces micro-stutter.