PipeWire Orchestrator

PipeWire Orchestrator is a background daemon that performs several audio and MIDI-related tasks on Linux. Some of the features include (but are not limited to):

• MIDI processing and mapping based on configuration rules
  • Map MIDI buttons to arbitrary shell commands
  • Separate short press, long press, and shift press actions
  • Remapping individual MIDI inputs to other channels or controllers
  • Remapping entire MIDI devices to appear as other devices
  • Sending analog inputs through a continuous function (sqrt, square, etc) before sending to system MIDI
  • Changing the perceived min and max range of an analog input (1/2 or 1/3rd range, etc)
  • Controlling LED colors of MIDI devices
• PipeWire connection graph monitoring
  • Connecting and disconnecting nodes automatically based on configuration rules
  • Assigning application outputs to volume mixer channels in a round-robin fashion
  • Running arbitrary commands when nodes are added and removed from the connection graph
• JACK LV2 plugin host
  • Basic support for running LV2 plugins with JACK and controlling them with aforementioned MIDI processing.
• Provide configuration as either JSON or YAML with automatic runtime validation

Here are some examples of things you can do with PipeWire Orchestrator and a cheap USB MIDI controller:

• Per-application volume control with physical dials, including buttons to mute or activate "quiet mode"
• Play sound effects through your microphone with the push of a button
• Load system-wide parametric EQ profiles with buttons
• Trigger home automation events with buttons or dials (turn on/off or dim lights with MIDI)
• Globally mute audio sources regardless of which applications are using them
• Control system media Play/Pause Next/Previous with hardware buttons
• Toggle direct monitoring of any audio source with a button or dial (hear your microphone through your headset, for example)

Essentially the point of this program is to allow MIDI controllers to be used as general purpose input devices instead of just for musical performances.

TODO

• Hot reloading config file
• Save and restore MIDI state between restarts
• Gracefully handle unplugging MIDI device
• Improve and extend LV2 plugin host capabilities
• Improve LED control in config file
• Batch hex requests to amidi
• Layers
• Shift key to turn dials without sending input
• Mute controls for dials
• Guitar amp selection with buttons
• Microphone mute button
• EQ selection with buttons
• Auto-connect gain controllers with pw-dump watcher
• Auto-connect virtual midi devices with aconnect
• Add TCP RPC
• Combine MIDI and Pipewire watch modes
• Use shift/other modifier key to open popup dialog for assigning dial to application
• Add long press/momentary push functionality
• Request parameter dump from midi device on startup (not supported on current hardware)
• Better error handling besides "it's wrong"
• Round robin mixer channel assignment

Development

Regenerating the config file JSON schema

If you make a change to the Config type in config.ts you need to regenerate the config file JSON schema. Use the following command:

yarn typegen

Enable Virtual MIDI in Linux

sudo modprobe snd_virmidi
echo "snd_virmidi" | sudo tee /etc/modules-load.d/snd-virmidi.conf