Melody, key (or 'infer'), harmonic rhythm, reharmonization
strength, height-search flags, and seed.
The chosen transpose, key, chord path, and per-note roles.
import { harmonizeMelody, majorKey } from '@libraz/libcantus';
const result = harmonizeMelody({
melody: [
{ pitch: 60, startBeat: 0, durationBeat: 1 },
{ pitch: 64, startBeat: 1, durationBeat: 1 },
],
key: majorKey(0),
harmonicRhythm: 1,
reharmonize: 'diatonic',
placement: { transposeSearch: false, octaveSearch: false },
});
result.chords; // one ChordSpan per harmonic-rhythm segment
Harmonize a melody with a min-cost chord progression.
The melody is segmented by
harmonicRhythm; each segment is scored against diatonic (and, perreharmonize, secondary-dominant and borrowed) candidate chords by melody fit, and a Viterbi search picks the lowest-cost path using a functional-flow transition cost. Whenplacement.transposeSearch/octaveSearchis set, the whole melody is transposed across a range and the best(transpose, progression)pair is returned; a small tessitura cost breaks ties toward placements that keep the melody in a comfortable register.The
seeddrives a deterministic tie-break only: it perturbs candidates by a magnitude far below any real cost difference (see TIE_BREAK_JITTER), so it can decide between chords or paths of otherwise-equal cost but never overrides melody fit or functional flow. For a well-determined melody the result is identical across seeds; the same seed always yields the same result.