README.md

Rust audio shenanigans

This repo contains my adventures in using Rust for audio synthesis and processing.

Try it

If you want to try this, go ahead and get some midi files. You can start the application with cargo run, or optionally cargo run -- song.mid to specify a song to play. You will see a simple gui with a file picker, start and stop buttons.

The midi file you want to play will be performed using a simple polyphonic square wave based instrument.

What is this about?

I wanted to write a synthesizer in Rust. One that makes easy to create any sound you want, by additive or substractive synthesis, or even frequency modulation.

Some examples:

constant(440) >> square(); // A 440hz square wave

// A 800hz square wave that wobbles slightly at 2hz
(constant(800) + (constant(2) >> sine())) >> (square() * 0.5)

A simple instrument made up of 8 voices. This one is not complete, it needs an input.

let wave = triangle();
let wave2 = ((pass() * 2) >> square()) * 0.5;
let wave3 = ((pass() * 3) >> square()) * 0.25;
let wave4 = ((pass() * 4) >> square()) * 0.125;
let wave5 = ((pass() * 5) >> square()) * 0.0625;
let wave6 = ((pass() * 6) >> square()) * 0.03125;
let wave7 = ((pass() * 7) >> square()) * 0.015625;
let wave8 = ((pass() * 8) >> square()) * 0.0078125;

((wave + wave2 + wave3 + wave4 + wave5 + wave6 + wave7 + wave8) * 0.2) >> lowpass(5000.0, 1.0)

Waves can be combined using operators like * for multiplication, + for addition, >> for chaining (lhs determines the frequency of lhs).

The PolyInstrument struct takes a wave that needs an input and uses that to play it with any source pitch, enabling usage like a midi synthesizer.

To play around different sounds, you can edit src/player.rs. At the top of the file resides the definition for the sound that the program uses to play a file.