xf86-video-intel: unexpected phenomenon on XV texture adapter with no scaling

[Jacques, Hugo]

Hi all,

I get a strange phenomenon using the XV texture adapter in YV12 format on my 945G hardware and a 2.7.0 xf86-video-intel driver.

I fill a rectangle with many 1 pixel-high horizontal lines. Odd lines are black and even lines are white.  I send this rectangle using XVShmPutImage to a window with the same size so that no scaling occurs.

I would expect to see the black/white horizontal lines pattern. But I get a uniformly grey rectangle! Same phenomenon appears on either VGA, DVI or CVBS-TV monitors: it doesn't seem to be monitor/video encoder issue-related.

I also saw that on much older drivers. Maybe it has always been this way.

Notes:
1) When the output window is one pixel higher(upscaling) or one pixel shorter(downscaling) than the source rectangle, I do see the expected pattern, but with some scaling distortion (as I expected). 

2) Opening a bitmap or .jpeg with the same pattern with an image viewer (GIMP), everything is fine. The phenomenon seems to be Xv-specific.

3) With the XV overlay adapter, if the pattern has the same size as the window, I do get all lines but with an unexpected scaling distortion.  If the pattern is one pixel higher than the window (downscaling case), I do get the same phenomenon as when the texture adapter is used with no scaling. There seems to be a skew of 1 pixel on the overlay adapter vs. the texture one.

Is this a known issue?  Should I enter this into Bugzilla?



Hugo Jacques
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