i915, Textured Video, and Compositing?

Eric Anholt eric at anholt.net
Fri Nov 10 13:12:44 PST 2006

On Thu, 2006-11-02 at 15:28 -0700, Jeffrey K. wrote:
> http://www.intellinuxgraphics.org/documentation.html says the following:
> "To better support the Composite extension, the Intel graphics driver
> supports --for i915 and later-- textured video which uses the 3D
> hardware to paint the video directly to the frame buffer instead of
> using an overlay. This means there's no funny 'blue' image caused by
> the color key, and it means you can capture video frames with normal X
> tools."
> I have an i915, and when using compositing with the 1.7.2 driver, I'm
> still getting that funny blue image on areas of a video where, for
> example, a shadow of some other window overlaps, whereas the rest of
> the video looks fine.  According to Xorg.0.log, textured video *is*
> being enabled correctly, but this doesn't seem like the correct
> behavior.  Am I misunderstanding the Website's assessment of the
> current driver's functionality, or are there extra steps that must be
> taken before compositing and Xv will work as expected, or is this not
> yet fully implemented in the driver?

Actually, the website is incorrect.  While textured video is the basic
code necessary to do video scaling correctly in a composited
environment, with XAA we don't have a way (that I've found) to force
pixmaps into video memory, so we can't actually paint to the backing
store.  That means we end up with screenshot ability, but continued
wrong composite behavior.  When EXA is done, we should be able to fix
this correctly.

However, the presence of blue when blended does indicate that you're
using the overlay scaler and not textured video, anyway.

Eric Anholt                             anholt at FreeBSD.org
eric at anholt.net                         eric.anholt at intel.com
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