Intel - XVideo

[Eric Anholt]

On Wed, 2007-06-13 at 18:56 +0200, Lukas Hejtmanek wrote: 
> Hello,
> 
> XV legacy overlay has begun to work again for me on i915GM. Good job! 
> 
> Anyway, I have a question about the textured videos. It seems that Planar
> videos are converted into packed before displaying even when there is a code
> in the i915_video.c to display planar format directly. Is the code planned to
> be removed?

I'd forgotten about that code.  It was quite broken, so I had gone with
planar to packed conversion to just get something working.  I've fixed
up the planar path now, which should help with XV performance issues on
this hardware.

> Is it technically possible to change brightness and contrast on textured
> videos (preferably independently of the rest of the screen)?

Since we're doing the entire YUV -> RGB conversion in our pixel shader,
we certainly could.  Nobody has bothered yet.

The other remaining issue I see with the 915 textured video path is
avoiding tearing.  Currently, there may be tearing by drawing while
scanout is happening to the area, and tearing from uploading to the
texture buffer while drawing from it.  My plan is to
1) drop a fence after each frame, and wait for that fence to pass before
uploading data to the same buffer
2) wait for vblank before starting our draw, if the destination is being
scanned out from.

1) requires the DRI to avoid spinning, so we'll just have tearing if you
can't do DRI.
2) requires i830, i855, or 915+ to do it from the command stream.  To
fix that, we might be able to use the scanline window wait, or I guess
use the DRM to wait for a vblank synchronously before emitting our draw.

My work in progress patch for this is at
git://people.freedesktop.org/~anholt/xf86-video-intel in the t-v-vblank
branch.  Right now it crashes the 945GM I've been testing on.  If
someone wanted to track this down, it would be great.

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

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