[Gta04-owner] Low latency audio routing

[NeilBrown]

On Tue, 17 Jan 2012 20:37:42 +0000 Bob Ham <rah at bash.sh> wrote:

> On Tue, 2012-01-17 at 21:27 +0000, Radek Polak wrote:
> 
> > I am 
> > going to continue with experiments, but any hints in mean time are highly 
> > appreciated.
> 
> Have you tried JACK?
> 
>   http://jackaudio.org/
> 
> I though I saw mention of it on the list before but I don't recall
> whether it was actually tried?
> 

jackd only works with a single sound-card.
We have 2 we want to route between.

There are two ways you can approach this in jackd.

1/ Tell ALSA to create a virtual sound card that slaves the two sound cards.
 This apparently will lead to clicks if the two cards don't have the same
 clock, and as the GSM module has its own clock, I suspect this will lead to
 clicks.  I haven't tried it.

2/ use the 'alsa_in' and 'alsa_out' jackd clients to feed data from one sound
  card into jack, which then directly controls the other sound card.
  This is supposed to handle differences in clocks correctly.
  I tried this but didn't get it working in any useful way.

pulseaudio should also be able to do it.  I haven't tried very hard, and
Radek tried but with no success yet.

If some early adopter has a gta04 that they are wondering what to do with,
then experimenting with audio routing would probably be a useful contribution.


NeilBrown
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