tone
Version:
A Web Audio framework for making interactive music in the browser.
106 lines • 4.28 kB
JavaScript
import { Gain } from "../../core/context/Gain.js";
import { connect, ToneAudioNode, } from "../../core/context/ToneAudioNode.js";
import { optionsFromArguments } from "../../core/util/Defaults.js";
import { readOnly } from "../../core/util/Interface.js";
import { GainToAudio } from "../../signal/GainToAudio.js";
import { Signal } from "../../signal/Signal.js";
/**
* Tone.Crossfade provides equal power fading between two inputs.
* More on crossfading technique [here](https://en.wikipedia.org/wiki/Fade_(audio_engineering)#Crossfading).
* ```
* +---------+
* +> input a +>--+
* +-----------+ +---------------------+ | | |
* | 1s signal +>--> stereoPannerNode L +>----> gain | |
* +-----------+ | | +---------+ |
* +-> pan R +>-+ | +--------+
* | +---------------------+ | +---> output +>
* +------+ | | +---------+ | +--------+
* | fade +>----+ | +> input b +>--+
* +------+ | | |
* +--> gain |
* +---------+
* ```
* @example
* const crossFade = new Tone.CrossFade().toDestination();
* // connect two inputs Tone.to a/b
* const inputA = new Tone.Oscillator(440, "square").connect(crossFade.a).start();
* const inputB = new Tone.Oscillator(440, "sine").connect(crossFade.b).start();
* // use the fade to control the mix between the two
* crossFade.fade.value = 0.5;
* @category Component
*/
export class CrossFade extends ToneAudioNode {
constructor() {
const options = optionsFromArguments(CrossFade.getDefaults(), arguments, ["fade"]);
super(options);
this.name = "CrossFade";
/**
* The crossfading is done by a StereoPannerNode
*/
this._panner = this.context.createStereoPanner();
/**
* Split the output of the panner node into two values used to control the gains.
*/
this._split = this.context.createChannelSplitter(2);
/**
* Convert the fade value into an audio range value so it can be connected
* to the panner.pan AudioParam
*/
this._g2a = new GainToAudio({ context: this.context });
/**
* The input which is at full level when fade = 0
*/
this.a = new Gain({
context: this.context,
gain: 0,
});
/**
* The input which is at full level when fade = 1
*/
this.b = new Gain({
context: this.context,
gain: 0,
});
/**
* The output is a mix between `a` and `b` at the ratio of `fade`
*/
this.output = new Gain({ context: this.context });
this._internalChannels = [this.a, this.b];
this.fade = new Signal({
context: this.context,
units: "normalRange",
value: options.fade,
});
readOnly(this, "fade");
this.context.getConstant(1).connect(this._panner);
this._panner.connect(this._split);
// this is necessary for standardized-audio-context
// doesn't make any difference for the native AudioContext
// https://github.com/chrisguttandin/standardized-audio-context/issues/647
this._panner.channelCount = 1;
this._panner.channelCountMode = "explicit";
connect(this._split, this.a.gain, 0);
connect(this._split, this.b.gain, 1);
this.fade.chain(this._g2a, this._panner.pan);
this.a.connect(this.output);
this.b.connect(this.output);
}
static getDefaults() {
return Object.assign(ToneAudioNode.getDefaults(), {
fade: 0.5,
});
}
dispose() {
super.dispose();
this.a.dispose();
this.b.dispose();
this.output.dispose();
this.fade.dispose();
this._g2a.dispose();
this._panner.disconnect();
this._split.disconnect();
return this;
}
}
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