System Audio Filter

A tool to manipulate your system audio.

What does it do?

This programm takes an audio source as input and puts the audio back to an output device while filtering chosen frequencies. Currently, the combination of a LowPass and a HighPass filter by biquad is being used to accomplish the desired effects.

While running, the filters' frequencies can be modified by commands in the terminal:

l<Enter> --> reset the lowpass cutoff to 20khz
l200<Enter> --> set the lowpass cutoff to 200hz
l+400<Enter> --> increase the lowpass cutoff by 400hz
l-150<Enter> --> decrease the lowpass cutoff by 150hz

All those commands work for the HighPass cutoff analogously for h as prefix.

The program can be quit by entering q<Enter> or using Ctrl+C.

Setup / Usage

Windows

Generally,

cargo run

should suffice if you just want to use a microphone as input. If you want to pipe all your system's sound to the program, you might want to install a virtual audio device such as the Virtual Audio Cable. After installing such a device, you need to set the standard audio output of Windows to that device, so that the sys-audio-filter can modify it.

After starting the program, you are first queried to enter the index (provided by a list) of an input device and an output device. Afterwards, the audio will be forwarded from input to output, changed by the filter.

Dependencies

Linux

The usage of rodio and cpal requires the ALSA development files. You can install these with e.g.

sudo apt install libasound2-dev

You also need to redirect the sound from applications you want the filter to work on onto the PulseAudio null-sink (which is automatically created by our program). You can do this using pactl or pavucontrol for example.

Windows

Optionally, install the virtual audio cable mentioned above.

TODO:

• Locate fitting crate to access sound
• Send simple audio (e.g. sine wave) to output
• Receive system audio and send it back to output
• Suppress system audio to prevent double output
• Access system audio on multiple platforms
• Manipulate stream's master volume
• Manipulate chosen frequencies
• Command Line interface
  • Enumerate all available devices and let the user choose input and output (not on linux)
  • Record into file (skipped feature)