Alternative linux way to create two (or more) ALSA virtual soundcards , loopbacks

– 6may2023,afrt

Addition: It worked for a while but later on, my Ubuntu 24 went haywire. So maybe not do this. Linux audio is a daunting subject.

How to create two or more new virtual loopbacks in linux ALSA, .
that will be created at linux startup/boot. tested on Ubuntu24, with Fldigi, Wfview

  1. Edit the snd-aloop.service file

sudo nano /etc/systemd/system/snd-aloop.service

  1. Put the next lines into the file:

Description=Creates snd-aloop devices for audio routing

ExecStart=/sbin/modprobe snd-aloop enable=1,1 index=10,11


  1. Reboot your linux. If all in order you will have 4 stereo channels for audio

  2. (optional:)Check if the new loopbacks are present, look for lines
    with: “card 10 (2X) ,card11 (2X)”.

    #to show a list of devices (cards) , run:
    aplay -l

  3. In Wfview go:

    Settings>Radio Access>Audio Output, select : Loopback:PCM (hw:10,0)

Settings>Radio Access>Audio Input, select : Loopback:PCM (hw:11,0)

  1. In case Fldigi is used, go:

Configure>Conf dialog>Soundcard>vPortaudio>Capture: “Loopback: PCM (hw:10,1)”
Configure>Conf dialog>Soundcard>vPortaudio>Capture: “Loopback: PCM (hw:11,1)”

n.b. Fldigi can be unforgiving if it can’t find a matching device , no default fold-back. brace yourself.

Now Should be able to connect Fldigi or other app audiowize with WFview, bidirectionally.

  1. Listening to it by e.g. a loudspeaker. I do not know (yet) , … PulseAudio? sudo modprobe snd_pcm_oss …something .

Maybe doubled with something somewhere else, i looked. Gemini helped considerably
cheers, ko

Alternatively, look in the extensive wfview manual Audio Configuration | wfview