synth

Synth

This is a simple modular-like command line synthesizer written in golang.

Installation

To run the synthesizer you might also need to install portaudio.

Install with Go

1. Install and setup Go
2. Clone the repository

git clone git@github.com:iljarotar/synth.git

1. Install

cd synth
go install

Usage

How it works

The synth is programmed by providing a patch file. A patch is a yaml file, that tells the synth, which oscillators, noise generators, etc. should be created and how they should be connected. When you tell the synth to load a file, if will start playing immediately. During playback a hot reload is possible, so if you change and save the patch file, it will be applied instantly.

Command line interface

Type synth and you should get an output like this

command line synthesizer

documentation and usage: https://github.com/iljarotar/synth

Usage:
  synth [flags]

Flags:
  -d, --duration string      duration in seconds excluding fade-in and fade-out. a negative duration will cause the synth to play until stopped manually (default "-1")
      --fade-in string       fade-in in seconds (default "1")
      --fade-out string      fade-out in seconds (default "1")
  -f, --file string          path to your patch file
  -h, --help                 print help
  -o, --out string           if provided, a .wav file with the given name will be recorded
  -s, --sample-rate string   sample rate (default "44100")

To listen to an example run

git clone git@github.com:iljarotar/synth.git
cd synth
synth -f examples/a-major.yaml

More examples can be found here.

Note: If you want to record the output, you must specify a non-negative duration. Otherwise you will get am empty .wav file.

Writing a patch file

Data types

If both low-cutoff and high-cutoff are 0, the filter is disabled. If low-cutoff is 0, the filter is a lowpass filter transitioning at the high-cutoff frequency. If high-cutoff is 0, the filter is a highpass filter transitioning at the low-cutoff frequency.

A higher order improves the filter's precision, but it also makes it more expensive in terms of computation. If the sound becomes glitchy, decreasing the filter order might be necessary.

Structure of a patch file

vol:
out:
noises:
  - name:
    amp:
      val:
      mod:
      mod-amp:
    pan:
      val:
      mod:
      mod-amp:
    filter:
      order:
      low-cutoff:
      high-cutoff:
      
oscillators:
  - name:
    type:
    freq:
      val:
      mod:
      mod-amp:
    amp:
      val:
      mod:
      mod-amp:
    pan:
      val:
      mod:
      mod-amp:
    phase:

custom-signals:
  - name:
    freq:
      val:
      mod:
      mod-amp:
    amp:
      val:
      mod:
      mod-amp:
    pan:
      val:
      mod:
      mod-amp:
    data: []

text-processors:
  - name:
    bpm:
      val:
      mod:
      mod-amp:
    pan:
      val:
      mod:
      mod-amp:
    amp:
      val:
      mod:
      mod-amp:
    text:

envelopes:
  - name:
    attack:
      val:
      mod:
      mod-amp:
    decay:
      val:
      mod:
      mod-amp:
    sustain:
      val:
      mod:
      mod-amp:
    release:
      val:
      mod:
      mod-amp:
    peak:
      val:
      mod:
      mod-amp:
    sustain-level:
      val:
      mod:
      mod-amp:
    threshold:
      val:
      mod:
      mod-amp:
    triggers: []
    negative:

Most of the fields are optional. A simple 440hz sine wave looks like this:

vol: 1
out: [osc]
oscillators:
  - name: osc
    type: Sine
    freq: {val: 440}
    amp: {val: 1}