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

[Doug Larrick]

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.

If I turn on something like Compiz things go to pot: I see maybe 10 fps
(that is, all the frames are displayed by Myth but only some of them
make it to the actual screen).  Not altogether surprising.

You might measure your CPU consumption; if it's too high you'll see the
behavior you're describing as the non-realtime threads get starved.

-Doug

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