[Intel-gfx] Updated 965 textured video code

[Keith Packard]

On Thu, 2008-04-10 at 19:01 -0600, Chad wrote:
> On Wed, Apr 9, 2008 at 3:35 PM, Keith Packard <keithp at keithp.com> wrote:
> > I've rewritten the 965 textured video code to improve performance for
> >  packed video formats and add support for planar formats. I'd love to
> >  hear about people's experiences with this new code, especially if there
> >  are specific videos which aren't working now.
> >  --
> >  keith.packard at intel.com
> 
> What might "packed video" and "planar" formats be?  I did a bit of
> google-ing and really didn't find much beyond a pantent which
> interestingly was for Intel :)

There are two common YUV video formats; one where the Y, U and V pixels
are 'packed' together so that each scanline looks like:

YUYVYUYVYUYV...
YUYVYUYVYUYV...
...

In this format, the U and V values are duplicated on two successive
scanlines, wasting quite a bit of memory (and memory bandwidth).

The other (more) common format uses three separate buffers, one for Y,
one for U and a third for V.  This saves space and can go faster.

> While I'm exposing myself as an idiot, if I'm interested in displaying
> recordings from MythTV on an HDTV (preferably through DVI, HDMI or
> Component if available), am I interested in textured video or video
> overlay?

Either will work; textured video integrates with other applications and
compiz, overlay video can provide better quality when using large scale
factors.

And, until I fixed the 965 driver, overlay video used less CPU as it
didn't need to reformat the data from planar to packed formats.

>   The only discussion I could quickly find on that was from
> Keith a while back that seems probably above my level of current
> understanding:
> http://lists.freedesktop.org/archives/xorg/2007-March/022627.html
> (Which also seems to suggest the 965 doesn't have an overlay, which
> leads me to wonder if th G35 does...)

Yeah, well, we had a mis-communication with the hardware group which led
us to believe that the 965 and G35 didn't have an overlay, but it
actually does.

-- 
keith.packard at intel.com
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