[mythtv-users] ATI w/XvMC

Jonathan Rogers jonner at teegra.net
Mon Jun 4 18:30:10 UTC 2007


On Mon, 2007-06-04 at 14:09 -0400, Cnudde, Paul wrote:
> I don't recall exactly where I read that, it was after much googling and it was probably over a year ago.  I came across a link saying that the fglrx drivers and DRM didn't play nice together and that and recompiling the kernel without it was the way to go.  After doing this I was able to play Doom3 and watch myth with the flgrx driver without any lockups whatsoever.
> If memory serves I beleve the proprietary drivers (fglrx) provide their own 3d acceleration mechanism.
> The specific problem I was having which was rectified by recompiling my kernel without DRM was that, using the fglrx driver, my machine would freeze after a couple minutes and nothing but a hard reset would bring it back.
> This might be completely moot though as I believe my problem was related to the fact that my video card is AGP whereas yours is pcie.
> Hope you get it worked out.

Both the free "radeon" and proprietary "fglrx" drivers use DRI,
including DRM in the kernel. However, there have been several versions
of DRM, some of which have been incompatible with fglrx.
<URL:http://wiki.x.org/wiki/ATIProprietaryDriver?highlight=%28ati%29>

> 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)

Currently, there is no way to use XvMC with ATI hardware, as no free or
proprietary driver supports it.
<URL:http://mythtv.org/wiki/index.php/XvMC#Drivers>

However, I'm skeptical about its value. I'm seeing similar HD playback
performance on my Athlon64 systems using either a Radeon 9600 with the
"radeon" free driver and an Nvidia 6600GT using the Nvidia proprietary
driver and either plain Xv or XvMC.

Clearly, some people are getting great performance out of Nvidia
proprietary drivers and XvMC, but my best experience for video playback
so far is the Radeon 9600 and the free driver. Ironically, the MythTV
GUI is extremely slow with that configuration, though video playback is
great. I think this is a MythTV bug, but I need to investigate it more.

I still haven't gotten perfect frame/field timing with any configuration
(except PVR-350, which is great for SD, but doesn't do HD), which means
that Bob deinterlacing often looks jumpy and kernel deinterlacing looks
pretty good, but still slightly jerky at times. Progressive video like
720p is less problematic, and usually looks nearly perfect.
-- 
Jonathan Rogers <jonner at teegra.net>
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