tone
Version:
A Web Audio framework for making interactive music in the browser.
124 lines • 4.07 kB
JavaScript
import { ToneAudioNode, } from "../../core/context/ToneAudioNode.js";
import { optionsFromArguments } from "../../core/util/Defaults.js";
import { Split } from "../channel/Split.js";
import { Gain } from "../../core/context/Gain.js";
import { assert, assertRange } from "../../core/util/Debug.js";
/**
* Wrapper around the native Web Audio's [AnalyserNode](http://webaudio.github.io/web-audio-api/#idl-def-AnalyserNode).
* Extracts FFT or Waveform data from the incoming signal.
* @category Component
*/
export class Analyser extends ToneAudioNode {
constructor() {
const options = optionsFromArguments(Analyser.getDefaults(), arguments, ["type", "size"]);
super(options);
this.name = "Analyser";
/**
* The analyser node.
*/
this._analysers = [];
/**
* The buffer that the FFT data is written to
*/
this._buffers = [];
this.input =
this.output =
this._gain =
new Gain({ context: this.context });
this._split = new Split({
context: this.context,
channels: options.channels,
});
this.input.connect(this._split);
assertRange(options.channels, 1);
// create the analysers
for (let channel = 0; channel < options.channels; channel++) {
this._analysers[channel] = this.context.createAnalyser();
this._split.connect(this._analysers[channel], channel, 0);
}
// set the values initially
this.size = options.size;
this.type = options.type;
this.smoothing = options.smoothing;
}
static getDefaults() {
return Object.assign(ToneAudioNode.getDefaults(), {
size: 1024,
smoothing: 0.8,
type: "fft",
channels: 1,
});
}
/**
* Run the analysis given the current settings. If {@link channels} = 1,
* it will return a Float32Array. If {@link channels} > 1, it will
* return an array of Float32Arrays where each index in the array
* represents the analysis done on a channel.
*/
getValue() {
this._analysers.forEach((analyser, index) => {
const buffer = this._buffers[index];
if (this._type === "fft") {
analyser.getFloatFrequencyData(buffer);
}
else if (this._type === "waveform") {
analyser.getFloatTimeDomainData(buffer);
}
});
if (this.channels === 1) {
return this._buffers[0];
}
else {
return this._buffers;
}
}
/**
* The size of analysis. This must be a power of two in the range 16 to 16384.
*/
get size() {
return this._analysers[0].frequencyBinCount;
}
set size(size) {
this._analysers.forEach((analyser, index) => {
analyser.fftSize = size * 2;
this._buffers[index] = new Float32Array(size);
});
}
/**
* The number of channels the analyser does the analysis on. Channel
* separation is done using {@link Split}
*/
get channels() {
return this._analysers.length;
}
/**
* The analysis function returned by analyser.getValue(), either "fft" or "waveform".
*/
get type() {
return this._type;
}
set type(type) {
assert(type === "waveform" || type === "fft", `Analyser: invalid type: ${type}`);
this._type = type;
}
/**
* 0 represents no time averaging with the last analysis frame.
*/
get smoothing() {
return this._analysers[0].smoothingTimeConstant;
}
set smoothing(val) {
this._analysers.forEach((a) => (a.smoothingTimeConstant = val));
}
/**
* Clean up.
*/
dispose() {
super.dispose();
this._analysers.forEach((a) => a.disconnect());
this._split.dispose();
this._gain.dispose();
return this;
}
}
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