[Xorg] Re: Damage/Composite + direct rendering clients

[Alex Deucher]

--- Eric Anholt <eta at lclark.edu> wrote:
> On Mon, 2004-05-17 at 11:02, Alex Deucher wrote:
> > --- Keith Packard <keithp at keithp.com> wrote:
> > > 
> > > Around 9 o'clock on May 17, Alex Deucher wrote:
> > > 
> > > > Many video overlays support alpha blending with the graphics
> layer,
> > > > it's just that support was never implemented since xfree86
> never
> > > > supported it.
> > > 
> > > Composite doesn't really expose things in a way that would make
> this 
> > > hardware capability usable.
> > > 
> > > Instead, it expects the video to be painted into the window
> pixmap so
> > > that 
> > > those pixels can be composed to form the screen image.
> > 
> > Sorry for my composite ignorance.  Couldn't we just have Xv ignore
> > composite and just use the video engine's native blending abilities
> to
> > blend video with the graphics layer?  or add composite "support" to
> Xv
> > by just passing it the required gamma value and letting the
> hardware
> > take care of the rest?
> 
> With composite you really want to be able to get at the pixels to be
> displayed so that transformations can be applied to them before
> displaying them, rather than just putting them up as the last
> transformation to be applied to the screen before display, as the
> overlay scaler would do.  I've found that the 3d hardware solves the
> XV
> problem pretty well in Xati (and gives you as many XV ports as you
> want), though it lacks the controls typically associated with YUV
> conversion using the overlay scaler, like brightness/saturation.
> 

that's probably the way to go since I suspect graphics HW may
eventually 
do away with the overlay all together in favor of YUV textures.  if it
doesn't already, I'd imagine the 3d hardware will eventually allow you
to adjust the brightness or gamma of the textures.

Alex

> -- 
> Eric Anholt                                eta at lclark.edu          
> http://people.freebsd.org/~anholt/         anholt at FreeBSD.org
> 
> 


	
		
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