Xv performance and quality issues at 1920x1080/60 resolution

[Roland Scheidegger]

On 15.09.2008 19:53, Jason Keirstead wrote:
> Hi. Fist of all, I want to say that I sure am glad I have finally
> switched to the open source ATi driver. Afer days/weeks mf messing with
> fglrx and it's problems I finally decided to try the latest open source
> driver and have thus far been impressed - I can finally watch TV at
> 1920x1080 and have it mostly work!
> 
> But of course, there are some small issues :) Hopefully someone will
> have some ideas on config tweaks or something I could do to help my problem.
> 
> First my stats - I have an AMD 690G chipset with a Radeon X1250 onboard.
> My CPU is pretty beefy, an AMD X2 6400+. I am running at 1920x1080/60
> resolution. I use Xv scaling to scale video. I am running the latest
> git/subversion of all of DRI, MESA, and the Xorg radeon driver, as of
> last night.
> 
> Issue #1 - When I am playing video full screen, regardless of the source
> resolution of the video, there are these diagonal "jaggy lines" that
> appear in the video intermittently. It seems to happen most often when
> there is high-motion in the video.
I think what you're seeing are artifacts due to the video update not
being synced to vblank. This used to be much worse (because it tended to
be a full diagonal split, whereas now I only see this in small parts of
the screen).
Alex Deucher has done some initial work on this, though I'm not sure it
actually works currently.
http://cgit.freedesktop.org/~agd5f/xf86-video-ati/log/?h=vsync_accel

> 
> Issue #2 - When I am playing video full screen whose native resolution
> is 1920x1080/60 (1080i content) (as in it is not scaled) the update
> performance of the display is not very good. It can not even keep the
> display up to speed with the audio. When I look at 'top'  My xorg CPU
> useage is only at 23%, so that does not seem to be the bottleneck.
> 
> I am wondering if there are any configuration tweaks I could do in my
> xorg.conf to help my issues. RIght now I am running a pretty much
> "stock" configuration.
As long as dri gets enabled, I don't think there's much you can do.
Though if the bottleneck is the cpu, it might help if the driver could
do planar video instead of converting it to packed.
What content are you playing back? In particular, if this is some h.264
content coming from some DVB stream using xinelib to decode, xinelib (at
least released versions) might not be able to use both cpu cores to
decode, a X2 6400+ will likely indeed be too slow in this case. If that
isn't the problem, I'm not sure if the gpu could really be too slow -
sounds unlikely (though for maximum gpu performance you'd want to make
sure you're using dual channel memory).

Roland