Xv performance and quality issues at 1920x1080/60 resolution

[Michel Dänzer]

On Mon, 2008-09-15 at 19:08 -0300, Jason Keirstead wrote:
> On Mon, Sep 15, 2008 at 3:33 PM, Roland Scheidegger
> <sroland at tungstengraphics.com> wrote:
> > 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
> 
> I probably should have mentioned this before but this is a MythTV box.
> as such I do currently have the "Sync to VBlanK" option in myth
> enabled, though I am unsure if this works or does anything at all with
> the ATI driver.

It probably only applies to OpenGL rendering, not XVideo. Something like
Alex's changes above would be necessary to prevent tearing with textured
XVideo.


> > 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).
> 
> I do have dual channel memory ( 2x1 GB ). The content is over DVB but
> it is not H.264 - it is MPEG2 @ 1080i . The CPU is not th ebottleneck
> - if I pop in another video card the box can process the video no
> problem.

Option "DMAForXv" "off"

might make a difference (for better or worse :) for you here.


-- 
Earthling Michel Dänzer           |          http://tungstengraphics.com
Libre software enthusiast         |          Debian, X and DRI developer