[LAU] Output to 2 sound cards simultaneously

[drew Roberts]

First, let me say I am mostly ignorant here but I still may be able to help.

What do you want to play to the two cards? The same stereo stream? Two 
different stereo streams? 4 mono tracks of a single multi track recording?

I see that in the thread, someone mentioned not being able to keep the cards 
in sync. I have seen that problem mentioned before but also that if your 
cards do word clock that this can be overcome iirc.

I also see that someone mentioned jack and you seem to have always had trouble 
with it. Jack has alwasy been my friend. If I can find some time today ot 
tonight, I will try and run a jack test with two sound cards for you. One 
internal on my laptop and one usb.

If you want to try the jack route, I would be happy to help out some. Try and 
catch me as zloc or zotz in #rivendell on irc.freenode.net ...

all the best,

drew

On Thursday 27 September 2007 10:37 pm, Mark Constable wrote:
> I've read this a couple of times over the years but it still
> does not make much sense (to me)...
>
>  http://alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html
>
> As a baseline, say I started with this, where could I go
> from here to get an app (ie; Amarok) to play back out two
> soundcards at once ?
>
> # cat .asoundrc
> pcm.NVidia { type hw; card NVidia; }
> ctl.NVidia { type hw; card NVidia; }
>
> pcm.USX2Y  { type hw; card USX2Y; }
> ctl.USX2Y  { type hw; card USX2Y; }
>
> pcm.shared {
>   type dshare
>   ipc_key 321456  # any unique value
>   ipc_key_add_uid true
>   slave NVidia
>   slave USX2Y
>   bindings {
>     0 0
>     1 1
>   }
> }
>
> --markc
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