For an upcoming hack week I wanted to have some live jam sessions with colleagues on a video call. Mostly I wanted some background music we could listen to while we hacked together, occasionally discussing our work, etc. I don’t normally use Pulseaudio in anger but it seemed like the closest and potentially simplest solution.

The biggest thing I like about Pulseaudio is having independent mixer controls for every application. The pulsemixer tool sits in an open terminal all day to make it easier for me to move audio levels around.

One big requirement was that I wanted to be able to make the volume in my headphones louder than it was for other participants in the call.

Using pacctl I set out to solve this with:

  • Create two null sinks:
    • Music
    • Playback
  • Create three loopback devices:
    • Two from Music sink
    • Microphone
pactl load-module module-null-sink sink_name=Playback sink_properties=device.description=Stream
pactl load-module module-loopback source=Music.Monitor
pactl load-module module-loopback source=Music.monitor
pactl load-module module-combine-sink sink_name=Dualie slaves="Music,Playback" channels=2 channel_map=left,right

Then I:

  • assigned my music to the Music null sink.
  • Move “Music loopback” and “Microphone loopback” to the Playback sink
  • Move another Music loopback to my headphones.

Finally, I select “Monitor of Stream” as the input device in the video call.

With a rhythm driving in the background, the hacking can commence!