sw-synth/dist/index.js

Lightweight sound synthesizer designed for real-time user interaction using the Web Audio API

"use strict";
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    if (k2 === undefined) k2 = k;
    var desc = Object.getOwnPropertyDescriptor(m, k);
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      desc = { enumerable: true, get: function() { return m[k]; } };
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    if (k2 === undefined) k2 = k;
    o[k2] = m[k];
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var __exportStar = (this && this.__exportStar) || function(m, exports) {
    for (var p in m) if (p !== "default" && !Object.prototype.hasOwnProperty.call(exports, p)) __createBinding(exports, m, p);
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.BufferSynth = exports.AperiodicSynth = exports.UnisonSynth = exports.Synth = void 0;
const oscillator_1 = require("./voice/oscillator");
const buffer_1 = require("./voice/buffer");
__exportStar(require("./voice"), exports);
// Tracking numbers for voice stealing
// Technically we could run out of note identifiers,
// but who is going to play 9007199254740991 notes in one session?
let NOTE_ID = 1;
/**
 * Simple web audio synth of finite polyphony.
 */
class Synth {
    constructor(audioContext, destination, log) {
        this.audioContext = audioContext;
        this.destination = destination;
        if (log === undefined) {
            // eslint-disable-next-line @typescript-eslint/no-unused-vars
            this.log = (msg) => { };
        }
        else {
            this.log = log;
        }
        this.voices = [];
    }
    _newVoice() {
        return new oscillator_1.OscillatorVoice(this.audioContext, this.destination, this.log);
    }
    setPolyphony(maxPolyphony) {
        if (maxPolyphony < 0 || maxPolyphony === Infinity || isNaN(maxPolyphony)) {
            throw new Error('Invalid max polyphony');
        }
        while (this.voices.length > maxPolyphony) {
            this.voices.pop().dispose();
        }
        while (this.voices.length < maxPolyphony) {
            this.voices.push(this._newVoice());
        }
    }
    get maxPolyphony() {
        return this.voices.length;
    }
    set maxPolyphony(value) {
        this.setPolyphony(value);
    }
    _allocateVoice() {
        // Allocate voices based on age.
        // Boils down to:
        // a) Pick the oldest released voice.
        // b) If there are no released voices, replace the oldest currently playing voice.
        let oldestVoice;
        for (const voice of this.voices) {
            voice.age++;
            if (oldestVoice === undefined || voice.age > oldestVoice.age) {
                oldestVoice = voice;
            }
        }
        return oldestVoice;
    }
    /**
     * Start playing a note at the specified frequency and velocity.
     * @param frequency Frequency in Hertz.
     * @param velocity Voice amplitude. Recomended range from 0 to 1.
     * @returns A callback that stops playing the note.
     */
    noteOn(frequency, velocity) {
        const oldestVoice = this._allocateVoice();
        if (oldestVoice === undefined) {
            return () => { };
        }
        if (this.voiceParams === undefined) {
            throw new Error('Synth.voiceParams must be set before calling Synth.noteOn');
        }
        return oldestVoice.noteOn(frequency, velocity, NOTE_ID++, this.voiceParams);
    }
    /**
     * Trigger panic and release all notes.
     */
    allNotesOff() {
        for (const voice of this.voices) {
            if (voice.lastNoteOff !== undefined) {
                voice.lastNoteOff();
            }
        }
    }
}
exports.Synth = Synth;
/**
 * Web audio synth of finite polyphony where the voices are stacked in unison.
 */
class UnisonSynth extends Synth {
    _newVoice() {
        return new oscillator_1.UnisonVoice(this.audioContext, this.destination, this.log);
    }
}
exports.UnisonSynth = UnisonSynth;
/**
 * Web audio synth of finite polyphony that supports inharmonic timbres.
 */
class AperiodicSynth extends Synth {
    _newVoice() {
        return new oscillator_1.AperiodicVoice(this.audioContext, this.destination, this.log);
    }
}
exports.AperiodicSynth = AperiodicSynth;
/**
 * Web audio synth of finite polyphony with user-provided audio buffers.
 */
class BufferSynth extends Synth {
    _newVoice() {
        return new buffer_1.BufferVoice(this.audioContext, this.destination, this.log);
    }
}
exports.BufferSynth = BufferSynth;
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