[plug] Dual Sound cards

[bk]

On Fri, Jul 16, 1999 at 03:23:06PM +0800, Brad Campbell wrote:
> G'day All....
> Heres a good one..
> I have an .mp3 system that I wrote for windows, for Ballroom dancing DJ
work.
> It has 2 independent .mp3 players, one for playing and one for cueing.

So two separate outputs? one to the amp/speakers, the other for
headphones?

> In windows, I could do this coz I have a dual soundcard. This is
unfortunately a 
> device with no linux driver. But I can make this work with 2 soundcards,
coz windows
> will allow 2 or more sound drivers..
> Has anyone ever done this with linux ?

I can play two mp3s at once (independent of each other) with my AudioPCI
64 + ALSA. First mpg123 uses /dev/adsp0 the second uses /dev/adsp1. Do you
mean like that?

I'm not sure if you can have it output sound to two different output jacks
with ALSA but should be possible.

> I can't see any reason it would not work, but have not got around to
trying it..
> maybe /dev/dsp and /dev/dsp1 ????
> I'm not sufficently familiar with the kernel driver model yet to know if
you can do it??
> 
> I'm porting this system to linux and X, and of course at the moment, I
am using one machine
> to control everything, and a second 'dumb' slave machine for the other
sound channel over NFS
> and a tcp/ip channel for control.
> I'd like to be able to eliminate this second machine and pop a second
card in the first machine...

One guy I know had 5 /dev/dsp's active on his machine, using 3 soundcards.

> 
> Thanks for any pointers...
> 
> As an aside, the car pc psu for the in-car mp3 player is being
difficult..
> We have blown up about $60 worth of Cap's and Fet's, plus wound numerous
> transofrmers.. Getting there slowly..
> Switchmode design is a lot harder than it looks :p)
> 
> The software is looking good, and the user interface is currently under
development.
> This is a 40x2 LCD with some custom buttons.. This allows to create
several playlists
> on a floppy and toggle between them in the car. With the usual
skip/search/stop/go
> buttons. Also an input from a car phone to pause the music when the
phone rings or a 
> call is made.
how about lowering the volume to 10-25%. This is what's done with my
stereo system in the car when I rpess the mute button.

> 
> When I say several playlists, they are small text files, and you can fit
a LOT of
> small text files on a 1.44 floppy :p)
> You can also fit a LOT of .mp3's on an 18GB Fireball Hard disk..
> Should be good for a couple of trips across the red centre :p)

What's with this wider-than-80-columns email editors? It's very annoying
not being able to read text which spans beyond 80cols over a remote
connection.

-David (bk at bofh.ns.ca).