this repo has no description
Add ADSR node
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index.html
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index.html
src/Oscillator.ts
src/Oscillator.ts
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src/main.ts
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src/main.ts
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import { AdsrNode } from "./nodes/AdsrNode";
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import "./style.css";
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let audioCtx: AudioContext;
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let osc1: OscillatorNode;
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function start() {
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const startButton = document.getElementById("start");
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if (!startButton) {
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return;
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}
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const triggerButton = document.getElementById("trigger");
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if (!triggerButton) {
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return;
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}
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audioCtx = new AudioContext();
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const freq = 261.625565; // Middle C
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osc1 = new OscillatorNode(audioCtx, {
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frequency: freq,
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type: "sawtooth",
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});
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const adsr1 = new AdsrNode(audioCtx, {
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attack: 0.01,
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decay: 0.11,
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sustain: 0.0,
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release: 0.1,
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});
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adsr1.start();
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const vca1 = new GainNode(audioCtx);
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vca1.gain.value = 0.0;
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const vol = new GainNode(audioCtx);
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vol.gain.value = 1.0;
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adsr1.connect(vca1.gain);
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osc1.connect(vca1).connect(vol).connect(audioCtx.destination);
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osc1.start();
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const play = () => {
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console.log("Starting");
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if (audioCtx.state === "suspended") {
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console.log("Starting");
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audioCtx.resume();
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startButton.innerText = "Click to pause";
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} else if (audioCtx.state == "running") {
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console.log("Pausing");
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startButton.innerText = "Click to start";
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audioCtx.suspend();
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}
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};
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startButton.addEventListener("click", play);
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const trigger = () => {
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const noteTime = 0.5; // Quarter note at 120bpm
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const gateOnTime = noteTime / 2;
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adsr1.trigger(gateOnTime);
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};
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triggerButton.addEventListener("click", trigger);
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}
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start();
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src/nodes/AdsrNode.ts
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src/nodes/AdsrNode.ts
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export type AdsrNodeOptions = {
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attack?: number;
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decay?: number;
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sustain?: number;
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release?: number;
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};
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export class AdsrNode extends ConstantSourceNode {
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attack = 0;
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decay = 0;
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sustain = 0;
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release = 0;
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constructor(ctx: AudioContext, options?: AdsrNodeOptions) {
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super(ctx, { offset: 0 });
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const { attack = 0, decay = 0, sustain = 0, release = 0 } = options ?? {};
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this.attack = attack;
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this.decay = decay;
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this.sustain = sustain;
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this.release = release;
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}
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trigger(length: number) {
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this.offset.cancelScheduledValues(this.context.currentTime);
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this.offset.setValueAtTime(0.0, this.context.currentTime);
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// Attack
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this.offset.linearRampToValueAtTime(
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1.0,
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this.context.currentTime + this.attack,
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);
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// Sustain
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this.offset.linearRampToValueAtTime(
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this.sustain,
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this.context.currentTime + this.attack + this.decay,
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);
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this.offset.cancelAndHoldAtTime(this.context.currentTime + length);
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this.offset.setValueAtTime(this.sustain, this.context.currentTime + length);
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// Release
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this.offset.linearRampToValueAtTime(
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0.0,
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this.context.currentTime + length + this.release,
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);
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}
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}