[mythtv-users] VIA M10000 stuttering video playback

[Quintesse]

Just wanted to know if anybody is using MythTV on a system based on the
VIA M10000 motherboard with good video playback.
Because if so I would really like to know how the system was set up.

Currently I use this system in combination with a PVR250 and if I set it
to full PAL resolution and leave the bitrates as they are by default I
can do "mplayer -vo fbdev /dev/video0" from a shell without any
problems, it looks good, no jittering, sound is in sync etc. First doing
a "cat /dev/video0 > test.mpg" and playing it later with mplayer gives
the same results. CPU load according to top is about 60% in both cases.

If I start X (recompiled latest source tar ball with VIA support) and
try to use mplayer to play live TV using the same settings for the
PVR250 but using XV as output it just isn't doable, sounds starts to
stutter and video slows down a lot.

I tried going to lower resolutions, but going to any other vertical
resolution but 288 (half of full PAL resolution of 576) just looks
horrible and with 288 you lose SO much vertical detail that texts (we
use subtitles, so there's almost always text on the screen) are hardly
readable. But even so going down to 288 doesn't solve the problem, it
gets a lot better but sound will stutter once in a while. But anyway the
loss in quality made this a non-option for me.

So then I tried turning down the bit rates. I have to go down to
something like 4000000/500000 before mplayer will again start playing
live TV or prerecorded files without any problems. CPU load is now 100%
evenly divided between mplayer and X! (both taking 48% or so). The loss
of quality is noticable (especially in fast chaning scenes) but I could
definitely live with it.

So having found the bitrates that would let mplayer play live TV and
such I fired op MythTV to see how it would fare, but alas: slow video
and stuttering sound. :-/

So I exited MythTv again and started turning down the bitrates some more
to find the spot where MythTv would start workinig okay. I found the
spot.... but unfortunately it's too low to be of any use! I had to go
down to something like 1500000/2000000 before live TV would play without
any hitches. Problem is of course that with such a low bitrate only
still images are recognizable, the rest just breaks down in a flurry of
colored squares.

It seems that the VIA driver is taking up a lot of CPU time which
probably results in the poor overall result. Which is strange because I
would expect it to perform better than a frame buffer.

Output is done on a monitor at 800x600 for now, the idea is to move to a
TV when everything works.

So having told all this I'm wondering if people are using a similar
setup but with good results and would like to know what they did to get
there because I'm running out of (my limited) options.

I can think if two possible solutions:

a) I did something wrong while configuring X/VIA and am wasting CPU
cycles
b) there is a way to make MythTV use a frame buffer (no scaling I know,
but full PAL is close enough to 800x600 for me)

Any ideas anyone?

Thanks,
 -Tako