[vlc-devel] Another stutter issue

Rémi Denis-Courmont remi at remlab.net
Sat Mar 5 18:19:28 CET 2011

Le samedi 5 mars 2011 19:11:59 Juha Jeronen, vous avez écrit :
> a) Maybe the processing chain is not aligned to vsync? Framerate doubler
> = 60Hz, LCD display, also 60Hz. There should be exactly one output frame
> rendered at each vsync, and there is no room for any misses. This may
> set limits on acceptable times when the decoding of the next frame
> should begin (so that all output frames can be rendered in time for the
> next vsync).

I believe we cannot synchronize with the vertical refresh using plain X11. 
This issue is quite evident when resizing a video.

With XVideo, the driver will do it automatically... or not. You can check with 
'xvinfo' if XV_SYNC_TO_VBLANK is set to 1 (good), 0 (bad) or missing (probably 

With OpenGL, I think we have to do it by hand from the video output plugin, 
and I'm not sure we actually do.

Rémi Denis-Courmont

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