bark!

low latency multi-receiver synchronised audio streaming for local networks.

• Transmits uncompressed 48khz stereo audio over UDP multicast

• Requires precisely synchronised system clocks. Implementation recommendation is to run a chronyd server locally, it can achieve precision in the tens of microseconds over LANs

Running the server under Pipewire

Note: you must have pipewire-alsa installed for this to work.

• First create a virtual node for Bark to receive audio from. You will configure applications to send audio to this node.

  $ pactl load-module module-null-sink media.class=Audio/Duplex sink_name=Bark audio.position=FL,FR
  

• Then find the Pipewire node ID for the new virtual node you just created. You can use pactl and jq to do this programatically. The output on my machine looks something like:

  $ pactl --format=json list sources | jq 'map({ key: .name, value: .index }) | from_entries'
  {
    "alsa_output.usb-Focusrite_Scarlett_Solo_USB-00.analog-stereo.monitor": 75,
    "alsa_input.usb-Focusrite_Scarlett_Solo_USB-00.analog-stereo": 76,
    "alsa_input.usb-Logitech_Webcam_C930e-02.analog-stereo": 77,
    "Bark": 145
  }
  

• Run the Bark server passing the node ID in the PIPEWIRE_NODE environment variable:

  $ PIPEWIRE_NODE=145 bark stream --group 224.100.100.100 --port 1234
  

• Then run your audio source! You can use the same node ID to arrange for it to send its audio to the Bark node:

  $ PIPEWIRE_NODE=145 ffplay music.flac
  

Running the receiver

$ bark receive --group 224.100.100.100 --port 1234

Simple as