Video tearing on Sandybridge

[Oliver Seitz <info@vtnd.de>]

Hello,

I'm running vaapi-mplayer on debian wheezy, which has fairly up-to-date 
intel drivers. (Right now i965-va-driver is outdated, so I use the sid 
package of that.)

I do not have any window manager, only X and an xterm. (Really, not even 
twm. It is only a test installation.)

Both output via OpenGL and VA-API play fine if there is only one active 
screen, or two screens which display the same picture (clone mode).

If, however, two screens are next to or on top of each other, playing 
video on one of the screens can show some tearing. It is not always seen 
with normal video, a special test pattern is helpful. Also, it does only 
tear in one out of ten tries, you can hit pause again and again, sooner 
or later the tearing will appear, and disappear again after the next 
pause/unpause cycle. While the tearing is there, it stays at about the 
same height of the video until the next pause/unpause cycle. Most times 
it is seen in the top third of the video. It does not matter if the 
video is fullscreen or not.

One screen is 1440x900 via DVI, the other is 1920x1080 via HDMI. Both 
screens run 60Hz, my test video is 30fps and full 1920x1080.

Is it likely that this is a bug, or am I doing something wrong?

Thank you all!

Greets,
Kiste