[Intel-gfx] Problem with flicker

Jesse Barnes jbarnes at virtuousgeek.org
Mon Nov 16 22:47:39 CET 2009

On Mon, 16 Nov 2009 21:39:03 +0800
Mike Wright <bodyjarrocks at gmail.com> wrote:

> Hi Intel Graphics Dev team,
> I have an really annoying flickering problem.  In MythTV or MPlayer,
> pressing skip ahead causes my screen to flicker for about 5-7 seconds
> after which time it settles back to a solid image.  This happens about
> 40% of the time I press skip ahead.  I have taken a video at 60fps of
> the problem with my Canon IXUS 50:
> http://members.iinet.net.au/~mikewright/TopGear_Flicker.avi    (about
> 13Mb)
> I'm pretty convinced that this has nothing to do with MythTV since
> MPlayer does it too.  I'm pretty sure it is not XV either since I'm
> think this happens using OpenGL renderer in both players.
> I am running:
> - Asus P5E-VM using HDMI connected to Pioneer 6th generation plasma
> TV.
> - Ubuntu Jaunty (xserver-xorg-video-intel v2.6.3)
> - MythTV 0.21-fixes using XV overlay.
> - 1280x720 at 50Hz
> - I'm using Yadif de-interlacer.
> My guess is that some burst of system load is generated when I skip
> video and that causes the Intel (G33) GFX to scan out from a black
> buffer every 3 or 4 frames.  Could I be using triple-buffering and be
> hitting a GFX Pipe starvation issue?
> How do I diagnose this issue???  I'm comfortable building the Intel
> drivers from source and have done in the past to chase other issues.
> If my assumption is correct then I need to be looking at how the
> driver sets up the buffer to scan out from.
> Any clues?  WAF is at stake here :-)

Doesn't look like a typical FIFO underrun; that usually causes the
screen to shift around a bit too.  Are you sure it happens the same way
with OpenGL outputs?  I can easily imagine an overlay related problem

Jesse Barnes, Intel Open Source Technology Center

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