[mythtv] Re: Another data point for the new XvMC stuff

[Mark Frey]

> On Mon, 2005-05-02 at 23:24 -0700, Mark Frey wrote:
> > > Try the OGL VSync toggle first. If that prevents the tearing I can
> > > disable sync to vblank when VSync is being used, and put some help text
> > > along with XvMC suggesting the use of OGL VSync.
> > 
> > Hmmm, I am using OGL VSync. I don't have any tearing with plain Xv, but
> > definite tearing in the upper quarter of the screen with XvMC while
> > watching HD.
> The timing is different for those two display methods. Try toggling
> VSync, and tell me if that makes any difference in the amount of
> tearing.
> 
> -- Daniel

Okay, I pulled down the latest CVS rebuilt with OpenGL vsync off, and
here's a summary of all the cases:

OpenGL vsync compile flag off and:

1. No sync to vblank settings on through the nvidia driver: smooth
playback, even with the OSD up, no stuttering at all even coming out of
skip forward/back or ff/rw, but serious tearing of the image.

2. OpenGL sync to vblank through the nvidia-settings tool: relatively
smooth playback except some stutter when skip forward/back or ff/rw.
Moderate tearing of the image.

3. OpenGL sync to vblank, Video Texture sync to vblank, and Video
Blitter sync to vblank on through the nvidia settings tool: severe
stuttering, especially with the OSD up and coming out of skip
forward/back. Would seem to get into a mode where it would constantly
stutter, skipping back a couple of times would fix it such that the
stuttering was only occasional. No visible tearing of the image.

OpenGL vsync compile flag on and:

1. No sync to vblank settings on through the nvidia settings tool:
smooth playback except some small stuttering when coming out of skip
forward/back and when the OSD is up. Small to moderate tearing limited
to the top quarter of the screen.

2. OpenGL sync to vblank turned on through the nvidia-settings tool:
much as above, with slightly more stutter.

3. OpenGL sync to vblank, Video Texture sync to vblank, and Video
Blitter sync to vblank on through the nvidia settings tool: the worst
stuttering, especially with the OSD up and coming out of skip
forward/back. Would seem to get into a mode where it would constantly
stutter, skipping back a couple of times would fix it such that the
stuttering was only occasional. No visible tearing of the image.

In all cases the source material was recorded 720p HD on a pcHDTV 3000
using the DVB drivers. Processor use was about 50% in all cases (+/-
5%).

-Mark
-- 
  Mark Frey
  markfrey at fastmail.fm