Pipewire, pro-audio, default sink/source

A bit of continuation for my previous post. As pro-audio mode skips creating mixers for inputs and outputs and there are no channels maps, a pulseaudio client like Chrome will just use stereo input for microphone. On my system this would be guitar DI in left ear and microphone on right ear :) So I created another loopback device for the microphone used mostly by pulseaudio clients like Chrome, Discord and games.

~/.config/pipewire/pipewire.conf.d/loopback.conf

context.modules = [
  { name = libpipewire-module-loopback
        args = {
            node.name = "ssl"
            capture.props = {
                media.class = "Audio/Sink"
                audio.position = [ FL FR ]
            }
            playback.props = {
                audio.position = [ FL FR ]
                stream.dont-remix = true
                node.passive = true
                node.autoconnect = false
            }
        }
    }
  { name = libpipewire-module-loopback
        args = {
            node.name = "mic"
            capture.props = {
                audio.position = [ AUX1 ]
                target.object = "alsa_input.usb-Solid_State_Logic_SSL_2_-00.pro-input-0"
                stream.dont-remix = true
                node.passive = true
            }
            playback.props = {
                media.class = "Audio/Source"
                audio.position = [ MONO ]
                # Prevent apps like Chromium/Chrome fiddling with the volume if clipping
                channelmix.lock-volumes = true   
            }
        }
    }
 ]

The target.object is the node.name shown with wpctl inspect <id> for input device and audio.position starts from [AUX0].

After pipewire restart, the loopback is visible on wpctl status with the given node.name. Setting default with wp-ctl set-default 39 and voila.

Audio
 ├─ Devices:
 │      58. SSL 2+                              [alsa]
 ├─ Sources:
 │  *   39. mic                                 [vol: 1.00]
 │      98. SSL 2+ Pro                          [vol: 1.00]

And in the bottom.

Settings
└─ Default Configured Node Names:
        0. Audio/Sink    input.ssl
        1. Audio/Source  output.mic

Also a script which toggles connections from the loopback stereo sink to either AUX0+AUX1 or AUX2+AUX3 or both.

#!/bin/bash

case "${1}" in
  aoff)
    pw-link -d output.ssl:output_FL alsa_output.usb-Solid_State_Logic_SSL_2_-00.pro-output-0:playback_AUX0 2> /dev/null
    pw-link -d output.ssl:output_FR alsa_output.usb-Solid_State_Logic_SSL_2_-00.pro-output-0:playback_AUX1 2> /dev/null

    pw-link -d output.ssl:output_FL alsa_output.usb-Solid_State_Logic_SSL_2_-00.pro-output-0:playback_AUX2 2> /dev/null
    pw-link -d output.ssl:output_FR alsa_output.usb-Solid_State_Logic_SSL_2_-00.pro-output-0:playback_AUX3 2> /dev/null
    ;;
  1on)
    pw-link output.ssl:output_FL alsa_output.usb-Solid_State_Logic_SSL_2_-00.pro-output-0:playback_AUX0 2> /dev/null
    pw-link output.ssl:output_FR alsa_output.usb-Solid_State_Logic_SSL_2_-00.pro-output-0:playback_AUX1 2> /dev/null
    ;;
  2on)
    pw-link output.ssl:output_FL alsa_output.usb-Solid_State_Logic_SSL_2_-00.pro-output-0:playback_AUX2 2> /dev/null
    pw-link output.ssl:output_FR alsa_output.usb-Solid_State_Logic_SSL_2_-00.pro-output-0:playback_AUX3 2> /dev/null
    ;;
   *)
    exit 0
    ;;
esac