Real-time Microphone Noise Cancellation on Linux

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Updated: 12–06–2021

Prerequisites:

• PipeWire
• Arch Linux or Fedora

What is Pipewire?

The PipeWire is a multimedia framework built from scratch for very low latency processing of audio/video.

One of the best features of Pipewire is that it provides a real-time capable plugin structure. The PipeWire daemon was built using this framework and is compatible with PulseAudio, JACK, ALSA and GStreamer-based applications.

Is PipeWire a requirement?

No. You can configure this with PulseAudio. However, I have not tested it and verified .

By default, Fedora comes with PipeWire, and most other distributions include the PulseAudio.

This article will focus on configuring the Noise cancelling plugin with PipeWire and creating a Virtual Source to use as an input for any application, even web-based applications like Google Meet and Microsoft teams.

The RNNoise — a noise suppression library based on a recurrent neural network is the foundation of the Noice cancelling plugin.

Follow this link if you are interested in learning how RNNoise library works: https://jmvalin.ca/demo/rnnoise/

The Danylo Piliaiev develops and maintains the plugin, and it eliminates a wide range of noise origins like an aeroplane, construction, office/crowd and computer fans.

1. Plugin Installation

Arch Linux:

To install the plugin on Arch Linux, you must use the noise-suppression-for-voice AUR package.

Read more: AUR — Arch User Repository

Execute the following command to install the package using `yay` an AUR helper.

$ yay -S noise-suppression-for-voice

or you can install without an AUR helper with the following commands:

$ sudo pacman -S git

$ git clone https://aur.archlinux.org/noise-suppression-for-voice.git
$ cd noise-suppression-for-voice
$ makepkg -si

Fedora:

The plugin can be installed on Fedora using the COPR repository. To configure this repository, enter the following command:

$ sudo dnf copr enable ycollet/linuxmao

To install the latest package, enter the following command:

$ sudo dnf install ladspa-noise-suppression-for-voice

Complete the above tasks to install the plugin binary into the location “/usr/lib/ladspa/librnnoise_ladspa.so”.

2. Create Filter chain for PipeWire

A filter chain provides the capability to insert an arbitrary graph of LADSPA (Linux Audio Developer’s Simple Plugin API) and built-in plugins in front of a sink or a source to create a new Virtual filtered sink/source.

2.1 Create a configuration directory to store filter chain configuration files.

$ mkdir -p ~/.config/pipewire/

2.2 Create a filter chain file with the name “input-filter-chain.conf”.

You can use any name you prefer, but make sure to use it throughout the configuration.

$ vim ~/.config/pipewire/input-filter-chain.conf

You can use this to create a configuration file for a PipeWire filter chain as below.

Notice the first filter graph node has a plugin property that points to the plugin location.

plugin = /usr/lib/ladspa/librnnoise_ladspa.so

Paste the following content to the above file.

3. Persist the configuration

To load this filter chain to the PipeWire, we need to create a systemd service. The service we will be making as a systemd user instance and it will start at the first login.
The systemd user instance is a per-user process and not per-session.

3.1 Create the systemd user configuration directory if it does not exist.

$ mkdir -p ~/.config/systemd/user/

3.2 Create a new systemd unit file.

$ vim ~/.config/systemd/user/pipewire-input-filter-chain.service

Make sure to:

• Replace the file name if you have used a different name for the filter chain configuration file.
• Replace the <username> with your account username.

3.3 Reload systemd user unit files.

$ systemctl --user daemon-reload

3.4 Enable the created systemd service.

$ systemctl --user enable pipewire-input-filter-chain.service

Log out and log back in and check the sound control panel on your DE and you will see a new input source with the name “Noise cancelling source”.

If you do not see the new Virtual Source device, please check the systemd service’s status and rectify any errors in the configuration if the service fails to start.

$ systemctl --user status pipewire-input-filter-chain.service

4. Finally select the new audio source on applications.

Google Meet

Google meet provides a Noise cancellation option but I have deactivated it as the PipeWire plugin provided better voice quality compared to Google Meet built-in method.

Slack

For other applications, the configuration would be similar.

Now you can make your meetings more effective and enjoy your podcasts and game streams without worrying about the background noise.

References:

• Real-time Noise Suppression Plugin: https://github.com/werman/noise-suppression-for-voice
• AUR repository: https://aur.archlinux.org/packages/noise-suppression-for-voice/
• Photo by Sandra Tenschert on Unsplash