Sorting out Intel options

[Doug Larrick]

Jesse Barnes wrote:
> On Sunday, July 22, 2007 8:30:18 am Chad wrote:
>> The Intel 965 producing "tearing" (which I read as tear like rip a
>> phone book in half, not tear like I cried, can anyone confirm what
>> "tearing" means?) with the latest intel driver.
> 
> I think this is fixed in git (and maybe the latest released driver) for 965 
> textured video and was never a problem with the overlay video port, so you 
> should be ok with a 965.

Tearing is caused by writing to the video buffer at the same time it's
being output to the display device.  Hence you get the top part of one
frame, and the bottom part of another one.  It's as if you'd torn a page
in a flipbook and peeled part of it back.  The solution is
double-buffering in the driver, or waiting for vertical blanking.
MythTV implements waiting for vertical blanking before drawing, but it
seems that at high enough resolutions (480i/480p is fine; 720p/1080i is
not) the Intel driver takes long enough to paint the video image that
tearing occurs at a consistent vertical location in the frame.

I can verify that tearing with textured video on G965 with Intel driver
2.1.0 (Debian package) is not fixed.  And I don't see any commits in git
that would have fixed it.  I don't think 965 can use video overlay.  Do
you have more info on when/how this might have been fixed?

-Doug

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