Computer music programs route audio by connecting unit generators in a signal processing graph

A unit generator (UGen) is a self-contained signal processing module: oscillator, filter, envelope generator, reverb, etc. Computer music environments like Max/MSP, Pd, SuperCollider, and Csound represent audio programs as directed graphs of connected UGens. The signal flow graph is a modular patching metaphor borrowed from analog synthesizers. Code-based systems specify the same graph programmatically rather than visually. UGens compute one block of samples at a time. The graph structure determines the signal chain: audio from an oscillator passes to a filter, passes to an amplitude envelope, passes to the output. This abstraction allows complex signal processing to be assembled from simple primitives.

Examples

In SuperCollider: {Saw.ar(440) * EnvGen.kr(Env.adsr)}.play. In Pd/Max: osc~ 440 connected to vcf~ connected to dac~. In Glicol: synth >> filter >> out.

Assessment

What is a unit generator? Sketch a signal graph for subtractive synthesis consisting of an oscillator, low-pass filter, and amplitude envelope.