Unit generator

Unit generators (or ugens) are the basic formal units in many MUSIC-N-style computer music programming languages.^[1] They are sometimes called opcodes (particularly in Csound),^[2] though this expression is not considered accurate in that these are not written directly as machine-level instructions.^{[citation needed]}

Unit generators form the building blocks for designing synthesis and signal processing algorithms in software.^[3] The unit generator theory of sound synthesis was first developed and implemented by Max Mathews^[4] and his colleagues at Bell Labs in the 1950s.^[5]

Examples

A simple unit generator called OSC could generate a sinusoidal waveform of a specific frequency (given as an input or argument to the function or class that represents the unit generator). ENV could be a unit generator that delineates a breakpoint function. Thus ENV could be used to drive the amplitude envelope of the oscillator OSC through the equation OSC*ENV. Unit generators often use predefined arrays of values for their functions (which are filled with waveforms or other shapes by calling a specific generator function).

In the SuperCollider language, the .ar method in the SinOsc class^[6] inherits methods from an overarching unit generator class (UGen)^[3] that generates a sine wave. The example below makes a sine wave at frequency 440, phase 0, and amplitude 0.5.