[mythtv] OpenGL vsync issues

Mark Kendall mark.kendall at gmail.com
Mon Jun 4 12:42:21 UTC 2007

On 6/4/07, Matt Doran <matt.doran at papercut.biz> wrote:
> What could cause the strange jerkyness and tearing only when the
> deinterlacing has been disabled because we're playing progressive video?!?


I'd suggest you first confirm whether opengl vsync is actually working
as expected for you.

In OpenGLVideoSync::WaitForFrame there are several calls to
glXWaitVideoSyncSGI. After those calls, frameNum is updated to the
number of the retrace count that the display synced to.

For your setup, you should see this incrementing smoothly - by 1 when
using bob and 2 otherwise.

If this is the case and you still have problems, as Doug says it may
be worthwhile adding some timing output to confirm that the gap
between syncs is correct. If not, that would suggest to me a driver



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