ARGB off the off-screen

Daniel Stone daniel at
Tue Sep 25 03:32:41 PDT 2007

On Tue, Sep 25, 2007 at 09:55:02AM +0200, sshachar at wrote:
> Quoting Daniel Stone <daniel at>:
> > Sounds like you need to use wfb.
> Thank you, Daniel. What is this wfb? A Google search didn't lead me anywhere,
> neither did a wiki search or sifting through my R6.8/R7.1 code

wfb allows you to define custom access methods to read and write pixels,
so you can store anything with an arbitrary pixmap.

> BTW there must be a way for current video cards to achieve this, no? (otherwise
> they could for instance decode say video to an offscreen pixmap, potentially
> with an alpha channel or a color key, and have the accelerator copy the decoded
> frames or damaged regions of the window containing the frame into onscreen. but
> now consider HD video at 60 or even higher frame rates - this is adds a huge
> amount of seemingly unecessary work when their decoder could simply deploy
> frames directly to the screen with the same alpha map or color key. The same is
> true for 3D rendered frame buffers)

Current videos either have an overlay that is scanned out straight from
the buffer, or as a 3D texture.
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