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Microphone.js
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Microphone.js
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// Thanks to George Gally for this bit of code, which has been modified to suit our needs.
// https://hackernoon.com/creative-coding-using-the-microphone-to-make-sound-reactive-art-part1-164fd3d972f3
function Microphone(_fft) {
var FFT_SIZE = _fft || 2048;
this.spectrum = new Uint8Array(FFT_SIZE / 2);
this.data = [];
this.volume = this.vol = 0;
this.peak_volume = 0;
var self = this;
var audioContext = new AudioContext();
var SAMPLE_RATE = audioContext.sampleRate;
window.AudioContext = window.AudioContext || window.webkitAudioContext;
navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia;
window.addEventListener("load", init, false);
function init () {
try {
startMic(new AudioContext());
} catch (e) {
alert("Web Audio API is not supported in this browser");
}
}
function startMic(context) {
navigator.getUserMedia({ audio: true }, processSound, error);
function processSound(stream) {
// analyser extracts frequency, waveform, and other data
var analyser = context.createAnalyser();
analyser.smoothingTimeConstant = 0.2;
analyser.fftSize = FFT_SIZE;
var node = context.createScriptProcessor(FFT_SIZE * 2, 1, 1);
node.onaudioprocess = function () {
// getByteFrequencyData returns the amplitude for each frequency
analyser.getByteFrequencyData(self.spectrum);
self.data = adjustFreqData(self.spectrum);
self.vol = self.getRMS(self.spectrum);
if (self.vol > self.peak_volume) {
self.peak_volume = self.vol;
}
self.volume = self.vol;
};
var input = context.createMediaStreamSource(stream);
input.connect(analyser);
analyser.connect(node);
node.connect(context.destination);
}
function error() {
console.log(arguments);
}
}
this.getVol = function () {
// map total volume to 100 for convenience
self.volume = map(self.vol, 0, self.peak_volume, 0, 100);
return self.volume;
};
// A more accurate way to get overall volume
this.getRMS = function (spectrum) {
var rms = 0;
for (var i = 0; i < spectrum.length; i++) {
rms += spectrum[i] * spectrum[i];
}
rms /= spectrum.length;
rms = Math.sqrt(rms);
return rms;
};
// freq = n * SAMPLE_RATE / MY_FFT_SIZE
function mapFreq(i) {
return i * SAMPLE_RATE / FFT_SIZE;
}
// getMix function. Computes the current frequency with
// computeFreqFromFFT, then returns bass, mids and his
// sub bass : 0 > 100hz
// mid bass : 80 > 500hz
// mid range: 400 > 2000hz
// upper mid: 1000 > 6000hz
// high freq: 4000 > 12000hz
// Very high freq: 10000 > 20000hz and above
this.getMix = function () {
var highs = [];
var mids = [];
var bass = [];
for (var i = 0; i < self.spectrum.length; i++) {
var band = mapFreq(i);
var v = map(self.spectrum[i], 0, self.peak_volume, 0, 100);
if (band < 500) {
bass.push(v);
}
if (band > 400 && band < 6000) {
mids.push(v);
}
if (band > 4000) {
highs.push(v);
}
}
return {
bass: bass,
mids: mids,
highs: highs
};
};
this.getHighsVol = function (_min, _max) {
var min = _min || 0;
var max = _max || 100;
return map(this.getRMS(this.getMix().highs), 0, self.peak_volume, min, max);
};
this.getMidsVol = function (_min, _max) {
var min = _min || 0;
var max = _max || 100;
return map(this.getRMS(this.getMix().mids), 0, self.peak_volume, min, max);
};
this.getBassVol = function (_min, _max) {
var min = _min || 0;
var max = _max || 100;
return map(this.getRMS(this.getMix().bass), 0, self.peak_volume, min, max);
};
function adjustFreqData(frequencyData, ammt) {
frequencyData.slice(0, frequencyData.length / 2);
var new_length = ammt || 16;
var newFreqs = [], prevRangeStart = 0, prevItemCount = 0;
// looping for my new 16 items
for (let j = 1; j <= new_length; j++) {
var pow, itemCount, rangeStart;
if (j % 2 === 1) {
pow = (j - 1) / 2;
} else {
pow = j / 2;
}
itemCount = Math.pow(2, pow);
if (prevItemCount === 1) {
rangeStart = 0;
} else {
rangeStart = prevRangeStart + prevItemCount / 2;
}
// get average value, add to new array
var newValue = 0, total = 0;
for (var k = rangeStart; k < rangeStart + itemCount; k++) {
total += frequencyData[k];
newValue = total / itemCount;
}
newFreqs.push(newValue);
prevItemCount = itemCount;
prevRangeStart = rangeStart;
}
return newFreqs;
}
function map(value, min1, max1, min2, max2) {
return (value - min1) / (max1 - min1) * (max2 - min2) + min2;
}
this.soundValues = function () {
return {
vol: Math.round(this.getVol()),
bass: Math.round(self.getBassVol()),
mids: Math.round(self.getMidsVol()),
highs: Math.round(self.getHighsVol())
};
};
return this;
}