Bug#698503: tearing with Radeon HD 6970

Marc Dequènes (duck) duck at duckcorp.org
Fri Feb 1 14:37:09 PST 2013

reassign 698503 unagi

On 2013-01-20 15:55, Alex Deucher wrote:

> What are you using to render the videos (Xv, GL)?  Did you also 
> change
> your desktop environment?  Note that if you are using a compositing
> manager (compiz, gnome shell, kwm, etc.), the compositing manager is
> responsible for preventing tearing by syncing screen updates to 
> vsync.
>  If you are using Xv, the driver's anti-tearing Xv features only work
> when rendering directly to the display buffer.  If you are using a
> composting manager, the driver renders to an offscreen buffer and the
> compositor is responsible for updating the display buffer with the 
> new
> Xv data.

Thanks for your explanation. I did a few tests and clearly Unagi 
(compositing manager) is not behaving properly.

Without Unagi running, using vlc with Xv or GL backends seems to work 
without tearing, even if not always perfectly smooth (which may be due 
to the video itself). Unfortunately, a few apps like flashplugin-nonfree 
surely use X11 directly…

So I'm reassigning to the main problematic application and will try to 
spot other apps using bad renderers.


Marc Dequènes

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