[mythtv-users] ATI w/XvMC

Michelle Dupuis support at ocg.ca
Mon Jun 4 16:49:23 UTC 2007

My box is dedicated to Myth, I'm using the MythDora distro as a starting
point (but I've recompiled the OS and Myth since).

Do you mean that is I want to use ATI's proprietary driver I need to disable
Direct Rendering Management?  How did you come to that conclusion (or where
did you find reference to it)?  The xorg.0.log file shows DRI loaded and
running ok...

I thought about open source drivers but my X1600 isn't officially supported.
Based on messages, the open source drivers also didn't appear any better
than the proprietary ones (for stability & features)

The key seems to be in XvMC (motion compensation).  My display
flickers/stutters (shows a frame from 1/2 second back every second) which I
think is VxMC related.  Did disabling Direct Rendering Management in the
kernel help a similar problem for the proprietary driver ? (Or the open
source one)


-----Original Message-----
From: mythtv-users-bounces at mythtv.org
[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Cnudde, Paul
Sent: Monday, June 04, 2007 12:20 PM
To: mythtv-users at mythtv.org
Subject: Re: [mythtv-users] ATI w/XvMC

I'm not sure what card you are using, but in my experience I have had to
jump through several hoops to get an X800 pro (AGP) to work properly.  The
same applies for a 9500 pro.

Here's what worked for me:

In order to use the fglrx drivers Direct Rendering Management needs to be
removed from the kernel, otherwise the system will be subject to lockup and
various stability issues.  Other issues with the fglrx drivers include the
inability to display certain resolutions even when using custom modelines
and starnge aspect ratio problems.

Ditching the fglrx drivers I went with the open source radeon driver
provided with xorg.  There is also a stability problem with this driver but
was easily circumvented (after much research) by adding the following line
to my xorg.conf

Option "BusType" "PCI"

See http://www.die.net/doc/linux/man/man4/radeon.4.html for further

Also, I'm not sure if your system is a dedicated myth box, if it is, try to
go with as minimal an install of your distro as possible.  I have two
systems at home: one dedicated, the other with a full desktop environment
with asscoiated suites of progams. There is a considerable  performance
difference between the two.  The one with the minimal install gives me no
grief, the one with the full desktop environment will give me the old
"prebuffering pause" while watching live tv (both analog and digital).
Recorded content plays back fine on both though.

Michelle Dupuis wrote:
> After much playing, it appears to be XvMC related.  I'm running the 
> latest ati proprietary driver - still no help.
> Any ATI Radeon users have smooth playback (no frame
> jumpy/stutter/flashes) - and what settings are you using?
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