[MPlayer-users] advantages of xmga vs XV

[Stephen Mollett]

Hi,

On Tuesday 06 Jul 2004 21:17, Malte Gell wrote:
> Do I see it right that the advantage of xmga is that it has more
> advanced buffering compared to xv? Are there more or other advantages,
> like lower CPU consumption?

It does offer lower CPU usage: with xv, the frames are decompressed into a 
buffer which is then copied (by the X server) into the video card's memory, 
whereas with (x)mga, the video can be rendered directly into video RAM - a 
bit like DGA but in its native colourspace rather than in RGB.

(Aside: surely such direct access functionality could be implemented in the X 
server as an extension to the existing architecture, either as a YUV variant 
of DGA or as a direct-access variant of XVideo...? This would allow higher 
performance rendering on many more chipsets than are supported by the current 
batch of special drivers.)

> Does xmga have any disadvantages or should a Matrox user always prefer xmga
> over xv? 

I'm not sure on that one, but I would imagine that, because the mga_vid driver 
does things "behind the back" of the X server, there could be the potential 
for problems in some cases.

Having said that, I've been using xmga for a long time with my G400 and have 
never had any problems.

Regards,
Stephen