[mythtv-users] Adventures in HDTV - Notes from the trenches

Matt Mossholder matt at mossholder.com
Mon Dec 19 09:23:13 EST 2005

On Mon, 2005-12-19 at 07:53 -0500, Doug Larrick wrote:

> Matt Mossholder wrote:
> >     Here are a few links to other people experiencing the VBlank
> > problem. Basically, if I have VBlank enabled, and play back video
> > content with Xv, the system hangs. On further inspection it isn't
> > limited to DVI...
> > 
> > http://www.nvnews.net/vbulletin/showthread.php?t=56384
> > <http://www.nvnews.net/vbulletin/showthread.php?t=56384&highlight=xvideo+vblank>
> If I'm understanding correctly, if (in nvidia-settings) "X Server XVideo
> Settings -> Video Texture Adaptor -> Sync to VBlank" is checked, it
> hangs?  Then don't do that!  Instead, to avoid tearing, uncheck that
> setting, and make sure MythTV is using OpenGL vsync.  This is the *only*
> way to get tearing-free, stutter-free playback out of MythTV, because
> it's one of only two video timing methods (the other working only with
> ancient nVidia drivers, like 4xxx) that measures when the vertical
> retrace happens.
> -Doug

    Thanks for pointing out that I am an idiot ;) I had been assuming
that the reason that Myth wasn't using opengl-vsync, even though I had
compiled in the support,  was because of the Sync to Vblank settings in
nvidia-settings. Your prompting made me take another look, and realize
that the version of 0.18.1 that I have is missing the defines to enable
OpenGL VBlank syning. Compiling now... and crossing my fingers :)

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