Subj : alsa, dmix and dsnoop
To   : comp.os.linux
From : Alberto Hernando
Date : Sun Oct 24 2004 02:44 pm

Hi.

I'm using alsa in my debian testing box. Recently, I was able to configura
alsa with dmix to share the sound card (output) amongst many applications
at once. But now I want to do the same with the input. I think that this is
used via the dsnoop plugin. Searching in google, I found an old article
with a config file. This is what I am using now:

-------------------------------
pcm.dmixer {
ipc_key 1024
type dmix
slave {
    pcm "hw:1"
    rate 44100
}

}

#handles software mixing of capture
pcm.dsnooper {
ipc_key 2048
type dsnoop
slave.pcm "hw:1"
}

#fuses input and output mixing into a duplex device
pcm.duplex {
type asym
playback.pcm "dmixer"
capture.pcm "dsnooper"
}

#this has something to do with sample rate conversion
pcm.!default {
type plug
slave.pcm "duplex"
}

#control device
ctl.!default {
type hw
card 1
}

#aoss emulation stuff:
#pcm.dsp0 {
#type plug
#slave.pcm "duplex"
#}
-----------------------------------------------

The last part is commentated out because it gave some problems. Well, with
this, dmix works. It seems that dsnoop should be configured, and a full
duplex device is created, but this doesn't seem to make any change. Trying
with jackd, it says that it can't work full duplex with alsa. arts
complains about this too, and other sound tests, like the one coming with
gnomemeeting doesn't work either. In this case, I see the dmixed output,
but not the dsnooped input.and last thing: before adding dsnoop, if I
enable the mic output in the mixer, I can hear my voice in the speakers.
Now I can't. I guess it means that something is happening, but probably not
what I want. Can anybody help me?

Thanks in advance, and sorry for my English.

 Alberto

.