[linux-audio-user] Multiple soundcard with Jack

[Paul Davis]

On Mon, 2005-08-08 at 12:32 +0200, Jody Noury wrote:
> Hi,
> 
> I'm discovering Demudi live, I have setup a box with two differents
> sound cards (pci), both are working.
> 
> I'm not familiar with jack, I believed that it could handle several
> sound output but can't see where to add the second card, It seems that I
> can switch between the two cards but not to have twice in jack patch bay.
> 
> Is someone could light my mind ? :)

JACK handles one and only one ALSA PCM device per "direction" (playback,
capture). Generally, it is run using the same PCM device for both
directions.

ALSA can be used to "merge" soundcards together but:

	1) there is rarely a good reason to do this, *especially* with
	   cheap audio interfaces. 

	2) if there is a good reason (such as when using multiple
	   high end interfaces with word clock sync), ALSA doesn't
	   seem to do a particular good job and its hellish to
	   handle the config file syntax for setting it up unless
           you are already a programmer or want to be.

--p