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

[Dominique Michel]

Le Sat, 21 Oct 2006 11:59:14 -0400,
Lee Revell <rlrevell at joe-job.com> a écrit :

> 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
> 
I have a nvidia card in my box. If I use the nvidia driver, I get it
in /proc/interrupts, but if I use the nv driver, the card don't use an IRQ.
I am not a gamer, and for me, the nv driver is just better because I can use
this IRQ for another hardware and get a better IRQ setup with my rt kernel and
that already at the PIC level.

If compatibility is a concern, I think at it will be better to use a mechanism
provided by X that will exist on every single linux box, as to rely on a
hardware mechanism that will not be found on every system.

-- 
Dominique Michel