CC Filter

cc filter plugin

One-pole low-pass filter whose cutoff is steered by an incoming MIDI CC (default CC74, the standard "brightness" controller).

Source: examples/truce-example-cc-filter/.

#What it demonstrates

  • Audio effect that consumes MIDI (midi_input = true in truce.toml; on AU this registers the component as an aumf MusicEffect so hosts actually route MIDI to it)
  • Handling EventBody::ControlChange events in process() to steer DSP state
  • Declarative host MIDI mapping via midi_cc = 74 on a #[param(...)] attribute
  • Logarithmic parameter range (range = "log(20, 20000)") with exponential smoothing (smooth = "exp(10)")
  • f64 DSP state (per-channel one-pole z1) cast to f32 only at the output boundary

#Parameters

Name Range Unit Description
Cutoff 20 to 20000 (log) Hz Cutoff used before any CC arrives; incoming CC overrides it
CC 0 to 127 -- CC number that steers the cutoff