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Old 03-17-09, 04:25 PM   #1
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Join Date: Feb 2008
Posts: 19
Default Tearing on dual-head Twinview setup

Okay, I've tried everything*, and I am still at a loss.

* means:

(1) Xv vsync in nvidia-settings, which appears to do nothing in mythtv, mplayer, or xine
(2) OpenGL vsync in nvidia-settings, which appears to do nothing in mythtv, mplayer (-vo gl and -vo gl2), or xine, and makes playback not smooth at best, and unwatchably-bursty at worst
(3) OpenGL vsync in mythtv's configuration, which appears to do nothing
(4) XvMC, which just gives me a blank screen in mythtv and then forces me to quit X, unload the nvidia module, reload it, and restart X if I want to continue testing anything, obviously the result of something getting into a bad state
(5) Upping the rtc max-user-freq to 1024
(6) I do not use compiz: I use fvwm, which I am pretty sure makes no use of OpenGL or overlays
(7) I use the qt painter in mythtv, not OpenGL

The only thing I can think of at this point is adjusting the vertical refresh to be closer to a multiple of 24 fps (maybe 50Hz? The monitors are currently running at 60Hz), but I have my doubts that this is even possible given a half hour of tinkering with the Twinview mode settings.

Is there something else I haven't tried? For that matter, has anyone figured out this problem? I've done many google searches on this subject, referencing tearing, vsync, etc., and had no luck, having only found many references to "solutions" I've already tried.

Is my attempt to eliminate tearing with Twinview simply in vain? Can I then expect a better solution if and when nvidia supports true xrandr?

Running 180.11 on Ubuntu Intrepid with an 8600 GT.

FWIW, why did I not used to have this problem a few years ago? I recall mythtv used to use a different facility (/dev/nvidia0?) to time the vertical refresh, but that appears to have vanished. Was that responsible for good performance historically? If so, why did that facility suddenly disappear from the driver?
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