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var WildEmitter = require('wildemitter');
function getMaxVolume (analyser, fftBins) {
var maxVolume = -Infinity;
analyser.getFloatFrequencyData(fftBins);
for(var i=4, ii=fftBins.length; i < ii; i++) {
if (fftBins[i] > maxVolume && fftBins[i] < 0) {
maxVolume = fftBins[i];
}
};
return maxVolume;
}
var audioContextType;
if (typeof window !== 'undefined') {
audioContextType = window.AudioContext || window.webkitAudioContext;
}
// use a single audio context due to hardware limits
var audioContext = null;
module.exports = function(stream, options) {
var harker = new WildEmitter();
// make it not break in non-supported browsers
if (!audioContextType) return harker;
//Config
var options = options || {},
smoothing = (options.smoothing || 0.1),
interval = (options.interval || 50),
threshold = options.threshold,
play = options.play,
history = options.history || 10,
running = true;
// Ensure that just a single AudioContext is internally created
audioContext = options.audioContext || audioContext || new audioContextType();
var sourceNode, fftBins, analyser;
analyser = audioContext.createAnalyser();
analyser.fftSize = 512;
analyser.smoothingTimeConstant = smoothing;
fftBins = new Float32Array(analyser.frequencyBinCount);
if (stream.jquery) stream = stream[0];
if (stream instanceof HTMLAudioElement || stream instanceof HTMLVideoElement) {
//Audio Tag
sourceNode = audioContext.createMediaElementSource(stream);
if (typeof play === 'undefined') play = true;
threshold = threshold || -50;
} else {
//WebRTC Stream
sourceNode = audioContext.createMediaStreamSource(stream);
threshold = threshold || -50;
}
sourceNode.connect(analyser);
if (play) analyser.connect(audioContext.destination);
harker.speaking = false;
harker.suspend = function() {
return audioContext.suspend();
}
harker.resume = function() {
return audioContext.resume();
}
Object.defineProperty(harker, 'state', { get: function() {
return audioContext.state;
}});
audioContext.onstatechange = function() {
harker.emit('state_change', audioContext.state);
}
harker.setThreshold = function(t) {
threshold = t;
};
harker.setInterval = function(i) {
interval = i;
};
harker.stop = function() {
running = false;
harker.emit('volume_change', -100, threshold);
if (harker.speaking) {
harker.speaking = false;
harker.emit('stopped_speaking');
}
analyser.disconnect();
sourceNode.disconnect();
};
harker.speakingHistory = [];
for (var i = 0; i < history; i++) {
harker.speakingHistory.push(0);
}
// Poll the analyser node to determine if speaking
// and emit events if changed
var looper = function() {
setTimeout(function() {
//check if stop has been called
if(!running) {
return;
}
var currentVolume = getMaxVolume(analyser, fftBins);
harker.emit('volume_change', currentVolume, threshold);
var history = 0;
if (currentVolume > threshold && !harker.speaking) {
// trigger quickly, short history
for (var i = harker.speakingHistory.length - 3; i < harker.speakingHistory.length; i++) {
history += harker.speakingHistory[i];
}
if (history >= 2) {
harker.speaking = true;
harker.emit('speaking');
}
} else if (currentVolume < threshold && harker.speaking) {
for (var i = 0; i < harker.speakingHistory.length; i++) {
history += harker.speakingHistory[i];
}
if (history == 0) {
harker.speaking = false;
harker.emit('stopped_speaking');
}
}
harker.speakingHistory.shift();
harker.speakingHistory.push(0 + (currentVolume > threshold));
looper();
}, interval);
};
looper();
return harker;
}