HOW IT WORKS.

CPAL captures guitar audio at 48kHz in 128-sample blocks, ring-buffered to the DSP thread. MIDI input from any controller also lands here.

let stream = cpal::default_host()
  .default_input_device()?
  .build_input_stream(&cfg, …)?;

McLeod autocorrelation + single-cycle refinement. Onset via spectral flux. Pitch voting smooths jitter. Sub-3ms per buffer.

let note = pitch_detection::
  mcleod_pitch(
    &buf, 48_000.0
  )?;

HarmonyEngine resolves the note against the current Scale and HarmonyMode. Stateful modes (Contrary, Strict CP) advance their internal history.

let line = engine
  .harmonize_note_on(note)?;

VoiceLeadingProcessor places each harmony pitch-class into Soprano / Alto / Tenor / Bass, cartesian-products the combinations, scores them, picks the best.

let chord = solver
  .revoice_chord(line, prev)?;

Jitter, velocity, swing, duration. A per-note record ties Note-Off to its Note-On so releases stay coherent.

let humanized = humanizer
  .humanize_note_on(note, vel);

Virtual MIDI (CoreMIDI / WinMM / ALSA) to your DAW, or straight into a CLAP plugin hosted inside Contrapunk via clack-host.

midi_out.send(NoteOn {
  ch, note, vel
})?;