unit generator
{{Short description|Basic formal unit in MUSIC-N-style programming languages}}
Unit generators (or ugens) are the basic formal units in many MUSIC-N-style computer music programming languages.{{Cite web |title=ChucK - [Language Specification] |url=https://chuck.stanford.edu/doc/language/ugen.html |access-date=2024-11-03 |website=chuck.stanford.edu}} They are sometimes called opcodes (particularly in Csound),{{Cite journal |last=Lazzarini |first=Victor |date=2017 |title=Supporting an Object-Oriented Approach to Unit Generator Development: The Csound Plugin Opcode Framework |url=https://mural.maynoothuniversity.ie/11607/ |journal=Applied Sciences |language=en |volume=7 |issue=10 |pages=970 |issn=2076-3417 |doi=10.3390/app7100970|doi-access=free }} though this expression is not considered accurate in that these are not written directly as machine-level instructions.{{cn|date=November 2024|reason=It would be good to have verification here because this reads more like original research or synth, but I'm not familiar enough with the tech to definitively say.}}
Unit generators form the building blocks for designing synthesis and signal processing algorithms in software.{{Cite web |title=UGen {{!}} SuperCollider 3.13.0 Help |url=https://docs.supercollider.online/Classes/UGen.html |access-date=2024-11-03 |website=docs.supercollider.online}}
The unit generator theory of sound synthesis was first developed and implemented by Max Mathews{{Cite journal |last=Smith |first=Julius |date=2007 |title=Unit-generator architectures in computer music |url=https://www.researchgate.net/publication/252185943 |journal=Journal of the Acoustical Society of America |volume=122 |issue=5 |page=3080 |doi=10.1121/1.2943000}} and his colleagues at Bell Labs in the 1950s.{{Cite web |date=2000-04-07 |title=Bell Labs: Background: Bell Labs Text-to-Speech Synthesis: Then and Now |url=http://www.bell-labs.com/news/1997/march/5/2.html |archive-url=https://web.archive.org/web/20000407081031/http://www.bell-labs.com/news/1997/march/5/2.html |archive-date=2000-04-07 |access-date=2024-11-03 |website=bell-labs.com |url-status=dead}}
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{{Cite web |title=SinOsc {{!}} SuperCollider 3.13.0 Help |url=https://docs.supercollider.online/Classes/SinOsc.html |access-date=2024-11-03 |website=docs.supercollider.online}} inherits methods from an overarching unit generator class (UGen) that generates a sine wave. The example below makes a sine wave at frequency 440, phase 0, and amplitude 0.5.
:
SinOsc.ar(440, 0, 0.5);