[LAU] ALSA - JACK via loopback device

From: Sebastian Rose <s.rose@email-addr-hidden>
Date: Sun Sep 23 2012 - 14:08:04 EEST

Hello,

currently I have set up a ALSA <-> JACK connection with the loopback
device approach as described here:
http://www.penguinproducer.com/2011/11/jack-alsa-bridge-kit/

This works fine, except for one problem: Simultaneous playback of
multiple applications using the ALSA loopback device to channel the
audiostream to JACK fails with this error:
Device or resource busy

The setup in my asound.conf is quite simple:

# Audio _to_ JACK
pcm.jack_playback {
     type plug
     slave.pcm "hw:Loopback,0,0"
}
# Audio _from_ JACK
pcm.jack_capture {
     type plug
     slave.pcm "hw:Loopback,0,1"
}
pcm.playback_loop {
     type plug
     slave.pcm "hw:Loopback,1,0"
}
pcm.capture_loop {
     type plug
     slave.pcm "hw:Loopback,1,1"
}
pcm.jack_audio {
     type asym
     playback.pcm "jack_playback"
     capture.pcm "jack_capture"
}

I thought that "type plug" should autoconfigure the device in use
accordingly. I tried to make a manual configuration with dmix but it
didn't work and I'm not sure if it is necessary. The alsa documentation
states that dmix is used when the device has no hardware mixer and I'm
quite sure that a virtual loopback device has none.

best,
semkath
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Received on Sun Sep 23 16:15:01 2012

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