[Alsa-user] Alsa virtual device

[Alan Bromborsky]

I am looking for a reference/example to do the following -

I have a program with audio output that cannot be redirected/piped to
another program from the command line. This program (Kodi) allows me to
select the alsa device the sound stream is directed to. I wish to to
split a stereo stream into six channels (three for the right and three
for the left channel) and apply dsp (probably using ecasound) processing
to each channel. Basically my left and right speakers each will have a
three way electronic dsp crossover. I have heard comments that this can
be done by defining a virtual (loopback?) alsa device. Is there any good
reference/example on how to do this. Specifically how does the output of
the virtual device get sent to the software? Thank you for any advice
you can give me.

[Clemens Ladisch]

Post by Alan Bromborsky
I have a program with audio output that cannot be redirected/piped to
another program from the command line. This program (Kodi) allows me
to select the alsa device the sound stream is directed to. I wish to
to split a stereo stream into six channels (three for the right and
three for the left channel) and apply dsp (probably using ecasound)
processing to each channel.

"Probably"? It's different if your DSP stuff wants ALSA devices or
is a Jack plugin.

Post by Alan Bromborsky
Basically my left and right speakers each will have a three way
electronic dsp crossover. I have heard comments that this can be
done by defining a virtual (loopback?) alsa device.

There are "filter" plugins that sit between the application and the
actual device.

But if your processing is done by an application that wants to capture
data, munge them, and play them back, you need a loopback device, or
the ALSA<->Jack plugin.


Regards,
Clemens