[linux-audio-dev] best option for audiovisual synchrony

[Lee Revell]

On Fri, 2006-10-20 at 16:53 -0400, Paul Davis wrote:
> On Fri, 2006-10-20 at 22:44 +0200, Tim Goetze wrote:
> > [Fons Adriaensen]
> > >Input the vertical video sync signal via the audio card and analyse
> > >its timing in terms of audio samples (e.g. using a DLL). This will
> > >enable you to predict where the next sync will be in the audio input.
> > 
> > Back in the 80s, the humble Commodore 64 could be readily programmed 
> > to fire an interrupt on vertical sync.  Have 20 years of progress 
> > really deprived us of this fine feature, or is it just missing from X?
> 
> it was missing from X until Xorg put it back in as an extension. its
> obviously not of much use in a general purpose X app, since the display
> may not be the host on which the app runs, making access to the vsync
> pulse pretty pointless.
> 

I think any Linux system with DRI can do this.  Check /proc/interrupts -
if your video card is listed, then you should have vsync interrupt
capability.

Lee