[mythtv-users] OpenGL vsync broken on Xorg 7.1 or latest nVidia driver?

John P Poet jppoet at gmail.com
Wed Feb 14 02:09:44 UTC 2007

On 11/6/06, Doug Larrick <doug at parkercat.org> wrote:
> John P Poet wrote:
> > I have been using OpenGL vsync ever since Doug added it to Myth.
> >
> > I just did a fresh install of FC6 on my frontend machine.  Ever since
> > doing so, enabling OpenGL vsync causes a minor but consistant stutter
> > of HD playback.  It is basically like a micro-second pause every
> > second.  If I turn off OpenGL vsync, the problem goes away.
> >
> > Has anyone else noticed this?  If so, has anyone determine whether it
> > is a Xorg 7.1 or an nVidia driver problem?  I tried going back on
> > version of the nVidia driver, but that had no effect.  Unfortunately,
> > I don't remember exactly which version of the nVidia driver I was
> > running before.
> I'm running Xorg 7.1 (Debian) and nvidia 8776 on my main box with an
> FX5200; no issues.
> I'm running Xorg 7.1 and nvidia 9625 (beta) on my dev box with an MX440
> and have my choice between tearing (which I'd never seen from any nvidia
> driver ever before) or high CPU usage (too high to watch HD), depending
> on the sync-to-vblank settings in nvidia-settings.

I was not even doing a "nvidia-settings --load-config-only", so I kind
of discounted this, but you are right.

If I have "0/SyncToVBlank=0" it smooths-out the playback, and the
stuttering is gone -- but I end up with MAJOR tearing.

If I do not load the nvidia-settings at all, or have
"0/SyncToVBlank=1", then I do not get the tearing, but have the
stuttering problem.

My CPU usage does get high with HD material, but is low with SD
material.  I have the stuttering problem with SD material too.

This is with nVidia driver 9746 on a FX5700LE.

I guess I will try an older nVidia driver.

Thanks Doug.


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