mirror of
https://github.com/Tonejs/Tone.js
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93 lines
2.1 KiB
TypeScript
93 lines
2.1 KiB
TypeScript
import { Time } from "../../core/type/Units.js";
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import {
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InputNode,
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OutputNode,
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ToneAudioNode,
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ToneAudioNodeOptions,
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} from "../../core/context/ToneAudioNode.js";
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import { optionsFromArguments } from "../../core/util/Defaults.js";
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import { OnePoleFilter } from "../filter/OnePoleFilter.js";
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import { Abs } from "../../signal/Abs.js";
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export interface FollowerOptions extends ToneAudioNodeOptions {
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smoothing: Time;
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}
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/**
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* Follower is a simple envelope follower.
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* It's implemented by applying a lowpass filter to the absolute value of the incoming signal.
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* ```
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* +-----+ +---------------+
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* Input +--> Abs +----> OnePoleFilter +--> Output
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* +-----+ +---------------+
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* ```
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* @category Component
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*/
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export class Follower extends ToneAudioNode<FollowerOptions> {
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readonly name: string = "Follower";
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readonly input: InputNode;
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readonly output: OutputNode;
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/**
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* Private reference to the smoothing parameter
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*/
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private _smoothing: Time;
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/**
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* The lowpass filter
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*/
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private _lowpass: OnePoleFilter;
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/**
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* The absolute value
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*/
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private _abs: Abs;
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/**
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* @param smoothing The rate of change of the follower.
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*/
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constructor(smoothing?: Time);
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constructor(options?: Partial<FollowerOptions>);
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constructor() {
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const options = optionsFromArguments(
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Follower.getDefaults(),
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arguments,
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["smoothing"]
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);
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super(options);
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this._abs = this.input = new Abs({ context: this.context });
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this._lowpass = this.output = new OnePoleFilter({
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context: this.context,
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frequency: 1 / this.toSeconds(options.smoothing),
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type: "lowpass",
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});
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this._abs.connect(this._lowpass);
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this._smoothing = options.smoothing;
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}
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static getDefaults(): FollowerOptions {
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return Object.assign(ToneAudioNode.getDefaults(), {
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smoothing: 0.05,
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});
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}
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/**
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* The amount of time it takes a value change to arrive at the updated value.
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*/
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get smoothing(): Time {
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return this._smoothing;
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}
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set smoothing(smoothing) {
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this._smoothing = smoothing;
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this._lowpass.frequency = 1 / this.toSeconds(this.smoothing);
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}
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dispose(): this {
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super.dispose();
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this._abs.dispose();
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this._lowpass.dispose();
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return this;
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}
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}
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