I noticed this on DVD playback a few times and now just noticed it in my first imported videos (the SkyOne-sourced BSG avi files): I get horizontal tearing on my system. Most of the time, about halfway down the screen, you can see the top of the screen and the bottom of the screen aren't completely in sync and there's a borderline right across the middle. In action scenes or when the camera is moving it can be pretty jarring when it gets bad. In static scenes even when it happens it's almost unnoticable.

From what I can tell, by default under KnoppMyth, both DVD playback and playback of these avi files are done under mplayer.

My system is R5A12 on an athlon64 3400+ (2200MHz). Video is via an Nvidia FX5200 configured in XGA mode and the nvidia drivers packaged with R5A12 are installed (6629?). FWIW, XvMC is *not* installed.

The problem doesn't happen often enough to fully ruin the experience, but often enough to be annoying, esp. projected across the room to ~100" screen size.

Any suggestions on how to address? mplayer, X, mythtv configuration flags/options? Switch to P4? Post to a different forum?

-brendan

Searching had me chasing various X config and OpenGL config ghosts, but finally brought me back to the site and this post:

http://mysettopbox.tv/phpBB2/viewtopic.php?t=4178

Ah, right. Have to enable the vblank-related settings (plural) in nvidia-settings. Then add script to automatically load them from the config file upon starting up the mythtv user's X session (via fluxbox).

-brendan

Hmm, that seems to have reduced, but not eliminated the problem. I can still see if if I watch for it, but it's not too bad.

I wonder if perhaps I'm assuming incorrectly that the problem can be gotten rid of altogether?

Things tried so far:

1) Nvidia-settings
a. Changing nvidia-settings so that both vblank settings are enabled.
b. Verified with glxgears that frame rate was dropped to ~monitor refresh rate.
c. copied new /home/mythtv/.nvidia-settings-rc to /root/.nvidia-settings-rc (just for completeness).
d. created /home/mythtv/startup.sh and modified /home/mythtv/.fluxbox/apps as per previous link to force load of .nvidia-settings-rc when logging in via xwindows.

This seems to cut the problem down somewhat.

2) Having read that in some cases, multiple double bufferings can work against eachother, I tested X server with and without the double-buffering-extention ('Load "dbe"'). Returned it to original 'enabled' status in the end.

3) Explicitly turned off Twinview in XF86Config-4, just in case it was defaulting on.

4) Explicitly turned on the RenderAccel option in XF86Config-4.

5) Turned on fast writes via creation of /etc/modprobe.d/nvidia file containing: "options nvidia NVreg_EnableAGPSBA=1 NVreg_EnableAGPFW=1"

6) Added 'export __GL_SYNC_TO_VBLANK="1"' to /etc/profile, ~/.bashrc, ~/shartup.sh.

7) Added 'export XV_SYNC_TO_VBLANK="1"' to /etc/profile, ~/.bashrc, ~/shartup.sh, though I think this is superflous to the nvidia-settings up at #1.

Having read that (at some time in the past) xv wasn't able to use vertical blanking, I tried running mplayer with -vo gl2 instead of -vo xv, but that was worse. I suppose that's probably old info anyway.

In anycase, after the changes from #1, none of the above seemed to really make a difference.

-brendan

Next thing to try: reducing the bit depth of the X server.

-brendan

I've also seen mention this might be an issue cleared up in more recent nvidia X drivers. That's my next step.