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62 lines
1.8 KiB
62 lines
1.8 KiB
/*
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* Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree.
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*/
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'use strict';
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// Meter class that generates a number correlated to audio volume.
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// The meter class itself displays nothing, but it makes the
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// instantaneous and time-decaying volumes available for inspection.
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// It also reports on the fraction of samples that were at or near
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// the top of the measurement range.
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function SoundMeter(context) {
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this.context = context;
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this.instant = 0.0;
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this.slow = 0.0;
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this.clip = 0.0;
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this.script = context.createScriptProcessor(2048, 1, 1);
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const that = this;
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this.script.onaudioprocess = function(event) {
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const input = event.inputBuffer.getChannelData(0);
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let i;
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let sum = 0.0;
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let clipcount = 0;
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for (i = 0; i < input.length; ++i) {
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sum += input[i] * input[i];
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if (Math.abs(input[i]) > 0.99) {
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clipcount += 1;
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}
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}
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that.instant = Math.sqrt(sum / input.length);
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that.slow = 0.95 * that.slow + 0.05 * that.instant;
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that.clip = clipcount / input.length;
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};
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}
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SoundMeter.prototype.connectToSource = function(stream, callback) {
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console.log('SoundMeter connecting');
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try {
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this.mic = this.context.createMediaStreamSource(stream);
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this.mic.connect(this.script);
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// necessary to make sample run, but should not be.
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this.script.connect(this.context.destination);
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if (typeof callback !== 'undefined') {
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callback(null);
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}
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} catch (e) {
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console.error(e);
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if (typeof callback !== 'undefined') {
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callback(e);
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}
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}
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};
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SoundMeter.prototype.stop = function() {
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console.log('SoundMeter stopping');
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this.mic.disconnect();
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this.script.disconnect();
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};
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