tone/Tone/component/filter/EQ3.ts

A Web Audio framework for making interactive music in the browser.

import { Gain } from "../../core/context/Gain.js";
import { Param } from "../../core/context/Param.js";
import {
	ToneAudioNode,
	ToneAudioNodeOptions,
} from "../../core/context/ToneAudioNode.js";
import { Decibels, Frequency } from "../../core/type/Units.js";
import { optionsFromArguments } from "../../core/util/Defaults.js";
import { readOnly, writable } from "../../core/util/Interface.js";
import { Signal } from "../../signal/Signal.js";
import { MultibandSplit } from "../channel/MultibandSplit.js";

interface EQ3Options extends ToneAudioNodeOptions {
	low: Decibels;
	mid: Decibels;
	high: Decibels;
	lowFrequency: Frequency;
	highFrequency: Frequency;
}

/**
 * EQ3 provides 3 equalizer bins: Low/Mid/High.
 * @category Component
 */
export class EQ3 extends ToneAudioNode<EQ3Options> {
	readonly name: string = "EQ3";

	/**
	 * the input
	 */
	readonly input: MultibandSplit;

	/**
	 * the output
	 */
	readonly output = new Gain({ context: this.context });

	/**
	 * Splits the input into three outputs
	 */
	private _multibandSplit: MultibandSplit;

	/**
	 * The gain for the lower signals
	 */
	private _lowGain: Gain<"decibels">;

	/**
	 * The gain for the mid signals
	 */
	private _midGain: Gain<"decibels">;

	/**
	 * The gain for the high signals
	 */
	private _highGain: Gain<"decibels">;

	/**
	 * The gain in decibels of the low part
	 */
	readonly low: Param<"decibels">;

	/**
	 * The gain in decibels of the mid part
	 */
	readonly mid: Param<"decibels">;

	/**
	 * The gain in decibels of the high part
	 */
	readonly high: Param<"decibels">;

	/**
	 * The Q value for all of the filters.
	 */
	readonly Q: Signal<"positive">;

	/**
	 * The low/mid crossover frequency.
	 */
	readonly lowFrequency: Signal<"frequency">;

	/**
	 * The mid/high crossover frequency.
	 */
	readonly highFrequency: Signal<"frequency">;

	protected _internalChannels: ToneAudioNode[] = [];

	constructor(lowLevel?: Decibels, midLevel?: Decibels, highLevel?: Decibels);
	constructor(options: Partial<EQ3Options>);
	constructor() {
		const options = optionsFromArguments(EQ3.getDefaults(), arguments, [
			"low",
			"mid",
			"high",
		]);
		super(options);

		this.input = this._multibandSplit = new MultibandSplit({
			context: this.context,
			highFrequency: options.highFrequency,
			lowFrequency: options.lowFrequency,
		});

		this._lowGain = new Gain({
			context: this.context,
			gain: options.low,
			units: "decibels",
		});

		this._midGain = new Gain({
			context: this.context,
			gain: options.mid,
			units: "decibels",
		});

		this._highGain = new Gain({
			context: this.context,
			gain: options.high,
			units: "decibels",
		});

		this.low = this._lowGain.gain;
		this.mid = this._midGain.gain;
		this.high = this._highGain.gain;
		this.Q = this._multibandSplit.Q;
		this.lowFrequency = this._multibandSplit.lowFrequency;
		this.highFrequency = this._multibandSplit.highFrequency;

		// the frequency bands
		this._multibandSplit.low.chain(this._lowGain, this.output);
		this._multibandSplit.mid.chain(this._midGain, this.output);
		this._multibandSplit.high.chain(this._highGain, this.output);

		readOnly(this, ["low", "mid", "high", "lowFrequency", "highFrequency"]);
		this._internalChannels = [this._multibandSplit];
	}

	static getDefaults(): EQ3Options {
		return Object.assign(ToneAudioNode.getDefaults(), {
			high: 0,
			highFrequency: 2500,
			low: 0,
			lowFrequency: 400,
			mid: 0,
		});
	}

	/**
	 * Clean up.
	 */
	dispose(): this {
		super.dispose();
		writable(this, ["low", "mid", "high", "lowFrequency", "highFrequency"]);
		this._multibandSplit.dispose();
		this.lowFrequency.dispose();
		this.highFrequency.dispose();
		this._lowGain.dispose();
		this._midGain.dispose();
		this._highGain.dispose();
		this.low.dispose();
		this.mid.dispose();
		this.high.dispose();
		this.Q.dispose();
		return this;
	}
}