[MPlayer-dev-eng] [PATCH] Improved DGA vertical retrace sync

[Stephen Davies]

On Tue, 24 Sep 2002, Arpi wrote:

> Steve Davies wrote:
> > Does the tdfxfb driver handle VSYNC?  I don't think so from looking at the
> > kernel tdfxfb.c and at vo_tdfxfb.c.  Or, have I missed something?
> > 
> 
> i don't think so, as the tdfxfb isn't really an overlay, but a bitmap scaler
> which support yuv format textures too.
> so, in case of tdfxfb, the scaled image is in the framebuffer, unlike mga
> where it's a ghost over the buffer not really rendered but scaled onthefly
> by DAC


Hi,

I'm way out of my depth, but...

I'm sure that you are right about the tdfxfb driver using textures, but
I've been looking at the XFree86 tdfx driver's XVideo code, and the
Voodoo3 docs, and the Voodoo3 seems to have overlay capability.

Overlay is used by the tdfx driver in X.  I added tracing and the overlay
codes is used when mplayer plays through -vo xv (via, presumably,
Xv[Shm]PutImage)  (Actually, the X driver has an XF86Config option to
instead use textures)

Perhaps this wasn't present on earlier 3dfx boards and that's why its not
used in tdfxfb?

X's tdfx driver doesn't double-buffer the images, but reading the chip
docs it should be possible to do that - the card can also flip the overlay
source buffer on VSYNC like the Matrox.

I'll have a go and see what happens.  It'd be nice to get rid of tearing
on my system.

Steve