Synth

This is a simple modular-like command line synthesizer for Linux 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 [email protected]:iljarotar/synth.git

3. Install

cd synth
make build
cp bin/synth <SOMEWHERE_IN_YOUR_PATH>

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

To listen to an example run

synth examples/sequence.yaml

Run synth -h to see all configuration options.

Writing a patch file

Here is a simple example. Playing the following file outputs a 440 Hz sine wave.

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

In examples/template.yaml you can find templates for all available modules.

API Reference

Envelope
Field	Type	Description
attack	Input	attack time in seconds [0,10000]
decay	Input	decay time in seconds [0,10000]
sustain	Input	sustain time in seconds [0,10000]
release	Input	release time in seconds [0,10000]
peak	Input	peak amplitude [0,1]
sustain-level	Input	sustain amplitude [0,1]
bpm	Input	triggers per minute [0,600000]
delay	Float	initial delay

Filter
Field	Type	Description
low-cutoff	Float	cutoff frequency of the highpass filter in range [1,20000]
high-cutoff	Float	cutoff frequency of the lowpass filter in range [1,20000]

If both low-cutoff and high-cutoff are omitted, the filter is disabled. If low-cutoff is omitted, the filter is a lowpass filter transitioning at the high-cutoff frequency. If high-cutoff is omitted, the filter is a highpass filter transitioning at the low-cutoff frequency. If both cutoff frequencies are defined, it becomes a bandpass filter.

Input
Field	Type	Description
val	Float	initial value of the respective parameter
mod	String[0..*]	names of modulating modules (oscillators, samplers, wavetables, noises)
mod-amp	Float	amplitude of the modulation in range [0,1]

Noise
Field	Type	Description
name	String	should be unique in the scope of the file
amp	Input	amplitude in range [0,2]
pan	Input	stereo balance in range [-1,1]
filters	String[0..*]	names of the filters to apply
envelope	Envelope	envelope to apply; if omitted, noise will constantly sound

Oscillator
Field	Type	Description
name	String	should be unique in the scope of the file
type	OscillatorType	wave form
freq	Input	frequency in range [0,20000]
amp	Input	amplitude in range [0,2]
phase	Float	phase in range [-1,1]
pan	Input	stereo balance in range [-1,1]
filters	String[0..*]	names of the filters to apply
envelope	Envelope	envelope to apply; if omitted, oscillator will constantly sound

OscillatorType
Sine
Triangle
Square
Sawtooth
ReverseSawtooth

Sampler
Field	Type	Description
name	String	should be unique in the scope of the file
amp	Input	amplitude in range [0,2]
pan	Input	stereo balance in range [-1,1]
freq	Input	frequency in range [0,SAMPLE_RATE (default 44100)]
filters	String[0..*]	names of the filters to apply
inputs	String[0..*]	names of the modules that will be sampled
envelope	Envelope	envelope to apply; if omitted, sampler will constantly sound

A sampler periodically samples the output values of the given inputs and outputs their sum.

Sequence
Field	Type	Description
name	String	should be unique in the scope of the file
amp	Input	amplitude in range [0,2]
pan	Input	stereo balance in range [-1,1]
type	OscillatorType	wave form
sequence	String[0..*]	a sequence of notes
randomize	Boolean	if true, the notes of the sequence will be played in random order
pitch	Float	standard pitch in hz [400,500]
transpose	Input	transposition in semitones [-24,24]
filters	String[0..*]	names of the filters to apply
envelope	Envelope	envelope to apply; if omitted, first note of sequence will constantly sound

The sequence module takes a sequence of notes and plays them in a loop applying the provided envelope to each note. If randomize: true is given, the sequence will be played in random order. Notes are written in scientific pitch notation, i.e. c_4 is the middle C. The syntax for writing notes is the following:

• a note starts with a lower case letter out of a, b, c, d, e, f or g
• an accidental (# or b) can be added to make a note sharp or flat, e.g. f# is F sharp, bb is B flat, etc.
• double accidentals are not allowed; use enharmonic equivalence instead
• a note is followed by an underscore and a number denoting the octave
• the lowest possible octave is 0, the highest is 10

Some examples of syntactically valid notes: eb_5, c#_2, d_7, b#_4, fb_3, etc.

Synth
Field	Type	Description
vol	Float	main volume in range [0,2]
out	String[0..*]	names of all modules whose outputs will be audible
time	Float	initial time shift in seconds [0,7200]
oscillators	Oscillator[0..*]	all oscillators
noises	Noise[0..*]	all noise generators
wavetables	Wavetables[0..*]	all wavetables
samplers	Sampler[0..*]	all samplers
sequences	Sequence[0..*]	all sequences

Wavetable
Field	Type	Description
name	String	should be unique in the scope of the file
amp	Input	amplitude in range [0,2]
pan	Input	stereo balance in range [-1,1]
freq	Input	periods per second [0,20000]
table	Float[0..*]	output values
filters	String[0..*]	names of the filters to apply
envelope	Envelope	envelope to apply; if omitted, wavetable will constantly sound