55 lines
1.7 KiB
JavaScript
55 lines
1.7 KiB
JavaScript
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"use strict";
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function VisualizerCore(mediaSource, fftSize = 1024) {
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this._stream = mediaSource;
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this._analyzing = false;
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this._updateListeners = [];
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this._audioCtx = new window.AudioContext();
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this._source = null; // Prepare for either a MediaStream or a MediaElement.
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try {
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this.source = this._audioCtx.createMediaStreamSource(this._stream);
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} catch (e) {
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this._source = this._audioCtx.createMediaElementSource(this._stream);
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}
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this._analyzer = this._audioCtx.createAnalyser();
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this._analyzer.fftSize = fftSize;
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this._source.connect(this._analyzer);
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this._analyzer.connect(this._audioCtx.destination);
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this._buffer = new Uint8Array(this._analyzer.frequencyBinCount);
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this.lastUpdate = null;
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this.analyze = function () {
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if (this._analyzing) {
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return;
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}
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this._analyzing = true;
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requestAnimationFrame(this.update);
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};
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let vcore = this; // since calling from requestAnimationFrame means "this" is no longer set to produced object.
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this.update = function (timestamp) {
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if (!vcore._analyzing) return;
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requestAnimationFrame(vcore.update);
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if (!vcore.lastUpdate) {
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vcore.lastUpdate = timestamp;
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}
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let delta = timestamp - vcore.lastUpdate;
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vcore._analyzer.getByteFrequencyData(vcore._buffer);
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vcore._updateListeners.forEach(listener => {
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listener(delta, vcore._buffer);
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});
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};
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this.stop = function () {
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this._analyzing = false;
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};
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this.addUpdateListener = function (listener) {
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this._updateListeners.push(listener);
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};
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this.getNumberOfBins = function () {
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return this._buffer.length;
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};
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}
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