webrtc-samples
Version:
Project checking for WebRTC GitHub samples repo
52 lines (47 loc) • 1.59 kB
JavaScript
/*
* Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree.
*/
'use strict';
// Meter class that generates a number correlated to audio volume.
// The meter class itself displays nothing, but it makes the
// instantaneous and time-decaying volumes available for inspection.
// It also reports on the fraction of samples that were at or near
// the top of the measurement range.
function SoundMeter(context) {
this.context = context;
this.instant = 0.0;
this.slow = 0.0;
this.clip = 0.0;
this.script = context.createScriptProcessor(2048, 1, 1);
var that = this;
this.script.onaudioprocess = function(event) {
var input = event.inputBuffer.getChannelData(0);
var i;
var sum = 0.0;
var clipcount = 0;
for (i = 0; i < input.length; ++i) {
sum += input[i] * input[i];
if (Math.abs(input[i]) > 0.99) {
clipcount += 1;
}
}
that.instant = Math.sqrt(sum / input.length);
that.slow = 0.95 * that.slow + 0.05 * that.instant;
that.clip = clipcount / input.length;
};
}
SoundMeter.prototype.connectToSource = function(stream) {
console.log('SoundMeter connecting');
this.mic = this.context.createMediaStreamSource(stream);
this.mic.connect(this.script);
// necessary to make sample run, but should not be.
this.script.connect(this.context.destination);
};
SoundMeter.prototype.stop = function() {
this.mic.disconnect();
this.script.disconnect();
};