It might be worthwhile revisiting this topic where the whole polyphonic thing was hashed out:
And then of course the terse language from the manual:
Polyphony ¶
If your module supports polyphonic inputs or has polyphonic outputs, then it can be considered a “polyphonic module”, so add the “Polyphonic” tag to the module’s manifest. It is recommended to support up to 16 channels, which is the maximum that Rack allows.
Typically each voice in your module can be abstracted into an “engine”. The number of active engines NN should be defined by the number of channels of the “primary” input (e.g. 1 V/oct input for VCOs, audio input for filters, gate input for envelope generators, etc). All other secondary inputs with MM channels should follow these rules:
- If monophonic (M = 1M=1), its voltage should be copied to all engines.
- If polyphonic with enough channels (M \geq NM≥N), each channel voltage should be used in its respective engine.
- If polyphonic but not enough channels (1 < M < N1<M<N), 0 V should be copied to out-of-bounds engines.
All of this behavior is provided by
Port::getPolyVoltage(c).Monophonic modules should handle polyphonic inputs gracefully:
- For inputs intended to be used solely for audio, sum the voltages of all channels (e.g. with
Port::getVoltageSum())- For inputs intended to be used for CV or hybrid audio/CV, use the first channel’s voltage (e.g. with
Port::getVoltage())