@tonaljs/voice-leading
v5.1.0
Published
Voice leading logic for transitions between voicings
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@tonaljs/voice-leading
Contains a collection functions to find optimal transitions between chord voicings. Used by @tonaljs/voicings.
Usage
ES6:
import { VoiceLeading } from "tonal";
Nodejs:
const { VoiceLeading } = require("tonal");
API
VoiceLeading
declare type VoiceLeadingFunction = (
voicings: string[][],
lastVoicing: string[]
) => string[];
A function that decides which of a set of voicings is picked as a follow up to lastVoicing.
Example:
const topNoteDiff: VoiceLeadingFunction = (voicings, lastVoicing) => {
if (!lastVoicing || !lastVoicing.length) {
// if no lastVoicing is given
return voicings[0];
}
const topNoteMidi = (voicing: string[]) =>
Note.midi(voicing[voicing.length - 1]) || 0;
const diff = (voicing: string[]) =>
Math.abs(topNoteMidi(lastVoicing) - topNoteMidi(voicing));
return voicings.sort((a, b) => diff(a) - diff(b))[0]; // return voicing with least diff
};
Usage
topNoteDiff(
[
["F3", "A3", "C4", "E4"], // top note = E4
["C4", "E4", "F4", "A4"], // top note = A4
],
["C4", "E4", "G4", "B4"] // top note = B4
);
// ['C4', 'E4', 'F4', 'A4'] // => A4 is closer to B4 than E4
show available voice leading functions.
See @tonaljs/voicings for usage examples.