mutemagic-rs - Linux userspace driver for USB HID mute buttons

MuteMagic is an open-source userspace daemon that monitors pipewire streams and uses that information to manage mute buttons.

Currently MuteMagic provides drivers for the MuteMe Original (although test reports for the MuteMe Mini would be very welcome). Extending mutemagic-rs so other similar products (or DIY button pads) should be very simple: there is far more code to manage pipewire than there is to manipulate the hardware!

Features

• Indicates when the microphones are active and inactive
• Preserves mute state through application relaunch, if supported by your pipewire session manager)
• Power efficient. MuteMagic does not use polling to track the button or hotplug state so, unless you press the button, there are zero wakeups per second.

How it works

MuteMagic monitors pipewire for capture streams. When a stream is created MuteMagic gets the current mute status and displays that using LEDs in the mute button.

By monitoring for active capture streams MuteMagic can show more than just the mute state! It is also able to show whether the microphone is in use or not. This works for applications that use pipewire, pulseaudio and jack libraries to communicate with pipewire. It also works for raw ALSA applications, providing those applications use the default ALSA configuration (rather than going direct to the hardware devices).

Additionally by muting capture streams rather then hardware sources, MuteMagic allows the Pipewire session manager to maintain a different mute states for different applications (e.g. for each application pipewire will remember the most recently used mute state and MuteMagic will show the correct mute state).

When using a MuteMe Original the different states are presented as shown below:

• Off -> No audio capture streams are running
• Green -> Unmuted, meaning that one or more audio capture streams are currently running and every stream is unmuted.
• Pulsing red -> Muted, meaning that one more audio capture streams are currently running and every stream is muted.
• Pulsing green -> Partially unmuted, meaning two or more audio capture streams are running, some of which are muted and some of which are unmuted.

Usage

To run in place try:

RUST_LOG=info cargo run

Set the log level to whatever is appropriate. debug shows basic activity whilst debug and trace will show, at different levels of detail, the data structures received from pipewire and what MuteMagic does with them. The debug mode logs are especially useful when debugging and extending the pipewire integration.

To install try:

git clone https://github.com/daniel-thompson/mutemagic-rs
cd mutemagic-rs
cargo install --path .

# If you do not install the appropriate udev rules then you will be
# forced to run MuteMagic as root...
sudo cp rules.d/60-mutemagic.rules /etc/udev/rules.d
sudo udevadm control --reload

# Now lets get it running automatically whenever we login
mkdir -p $HOME/.config/systemd/user
cp mutemagic.service $HOME/.config/systemd/user
systemctl --user enable --now mutemagic
systemctl --user status mutemagic

License

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose. See the GNU General Public License for more details.