[Alsa-user] Loopback/Monitor ice1712 Re: Reading from an output stream

[andrew c. <an...@ac...>]

andrew cooke <andrew <at> acooke.org> writes:
> But I can't work out how to make a stream loop back so that it enters and 
> leaves on the same "side" of ALSA.  For example, if I have some software 
> playing music from a file, I can route that down to hardware OK.  But I 
> can't seem to route it back to software so that some other program can read 
> it from ALSA in the same way that program would read, say, data coming in 
> via a soundcard inputs.
> 
> This seems absolutely basic, so I think I am missing something really obvious.
> 
> One way of describing it would be an ALSA "loopback".

My card is an envy24/ice1712 MAudio Audiophile 2496 and so it seems I should be
able to access the hardware mixer.  So I ran envy24 control and made sure that
the mixer was used (HW out now uses digital mix; the LED bars on pcmout 1 and 2
and the hardware mix all move when sound is plyed).

Next I changed my asoundrc to the following:

pcm.!default {
   type plug
   slave.pcm "maudio"
}

pcm.monitor {
   type plug
   ttable.0.0 1 # (Out Left)
   ttable.0.1 1 # (Out Right)
   slave.pcm "maudio"
}

pcm.maudio {
   type hw
   card 0
   device 0
}

ctl.maudio {
   type hw
   card 0
   device 0
}

This works for playback, but when I try to record I get:
: arecord -D monitor foo.wav
arecord: main:550: audio open error: Device or resource busy

This is even when playing sound using:
: aplay /usr/share/sounds/alsa/test.wav

Can anyone correct me?  The asoundrc was based on
http://alsa.opensrc.org/1712_.asoundrc and
http://www.linuxquestions.org/hcl/showproduct.php/product/3126

Thanks,
Andrew