raedwulf / glitch

Minimal algorithmic music composer and synthesizer

Glitch

Glitch is a minimal environment for creating algorithmic music and live coding.

It uses arithmetic expressions to synthesize instruments or make music patterns.

Try it online: http://naivesound.com/glitch

Download for Mac, Windows or Linux: https://github.com/naivesound/glitch/releases

Read more about Glitch on Medium: https://medium.com/@naive_sound

Build

On linux: make alsa=1 or make alsa=1 pulse=1. If you want to use JACK: make jack=1.

On windows: make windows=1.

On MacOS: make macos=1.

Reference

Glitch syntax is arithmetic expressions, most likely you still remember it from the math class.

Arithmetics: + - * / % (modulo) ** (power)

Bitwise: & | ^ (xor or bitwise not) << >>

Compare: == != < <= > >= (return 1 or 0)

Grouping: ( ) , (separates expressions or function arguments)

Conditional: && || (short-circuit operators)

Assignment: = (left side must be a variable)

Instruments:

Function	Description	Example
sin(freq)	sine wave at given frequency	sin(440)
tri(freq)	triangular wave at given frequency	tri(440)
saw(freq)	saw-tooth wave at given frequency	saw(440)
sqr(freq, [pwm=0.5])	square wave at given frequency and (optionally) pwm	sqr(440)
fm(freq, [m1, v1, m2, v2, m3, v3])	FM-synthesizer with 3 operators, vN is operator strength, mN is operator multiplier, operators 1 and 2 are sequential, operator 3 is parallel to operator 1	fm(440, 0.5, 0.5)
tr808(drum, [vol=1])	plays TR808 drum sample at given volume. the following drum IDs may be used: BD (bass drum), SD (snare drum), MT (middle tom), MA (maracas), RS (rimshot), CP (clap), CB (cowbell), OH (open hat), HH (hi-hat)	tr808(BD, 1)

Oscillators (sin, tri, saw, sqr) change the frequency seamlessly, there is no "clicks" when the frequency changes.

FM synthesizer change the frequency when the signal crosses zero level, so the "click" effect is minimized.

FM synthesizer and TR808 sampler are reset if any of the parameters is NAN. All instruments return NAN if the input is NAN.

Sequencers:

Function	Description	Example
a(i, ...)	array element by its index, most primitive sequencer	sin(a(t>>10, 440, 466, 493))
seq(tempo, ...)	switches elements at given tempo	sin(loop(120, 400, 466, 493))
loop(tempo, ...)	switches elements at given tempo, unlike seq() it evaluates each argument for each time frame which makes it possible to nest loops	sin(loop(60, seq(240,400,466,493), seq(480, 400,493)))

Tempo can be a single number (beats per minute) or a pair (offset, bpm), where offset is number of beats to skip before starting the sequence.

Seq and loop values can be pairs, too. Then the first value is a relative beat duration and the second is the actual returned value: seq(120, (3/4, 1), (1/4, 1)) returns the value of "1", but the first value lasts 3 times longer than the second value.

If seq takes more values, they will be sliding from one another, e.g. seq(120, (1, 0, 4, 2), (1, 2, 4, 0)) slides the values like 0->4->2->2->4->0. The first value in a group is still a relative beat duration.

Seq and loop return NAN every then the value is changed.

Utils:

Function	Description	Example
r(max)	random number in the range [0..max), it sounds like white noise, good for synthesizing drums or making randomized music patterns	r(100)
s(phase)	sine wave amplitude at the given phase, unline sin() you must provide phase in the range [0..255], not frequency	s(t*14)
l(x)	binary logarith, useful to convert frequencies to note values	note=l(440)*12
hz(note)	note frequency of the given note index, index 0 is note A of 4th octave, you may also use helper variables like A#4, C2, Db3	sin(hz(A4))
scale(pos, mode)	return note index at given position in given scale, scale 0 is major scale, scale 6 is minor	sin(hz(scale(t>>11&7)))
env(signal, (dt, level)...)	Creates an ADSR envelope for the signal, envelope is reset if signal is NAN, if first part has non-zero level - the initial level starts from 1, otherwise from 0; if last argument is not zero - the release section is inserted automatically	env(v, (0.1, 0.2))
mix(...)	mixes voices together, each parameter is a signal or a pair of (volume, signal). Signals are clipped if overflow the volume range (0..255).	mix(sin(220), sin(440), tri(880))
lpf(voice, cutoff)	applies low-pass filter to the voice at given cutoff frequency	lpf(v, 200)
hpf(voice, cutoff)	applies high-pass filter to the voice at given cutoff frequency	hpf(v, 400)
delay(voice, time, level, feedback)	delays signal by given time, delay level can be controlled as well as the amount of delay feedback, which affect the number of delay repetitions	delay(v, 0.1, 0.5, 0.2)

Special variables:

t is time variable that increases at rate 8000/second. x and y in the web version are mouse cursor position, normalized to (0..1) range. bpm is a tempo, user input is synchronized with the playback at this rate, so you might want to use bpm=120/4 to synchronize user input every 4 beats.