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Ravenstine · Apr 7, 2014 · 4707881 · 4707881
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diff --git a/LICENSE b/LICENSE
@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2014 Ravenstine
+Copyright (c) 2014 Benjamin Titcomb
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

diff --git a/README.md b/README.md
@@ -1,4 +1,4 @@
-goertzeljs
+goertzel.js
 ==========
 
 A pure JavaScript implementation of the Goertzel algorithm.
diff --git a/demo.html b/demo.html
@@ -0,0 +1,14 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <title>Goertzel.js DTMF Demo</title>
+<script data-turbolinks-track="true" src="/assets/goertzel.js?body=1"></script>
+<script data-turbolinks-track="true" src="/assets/dtmf.js?body=1"></script>
+<script data-turbolinks-track="true" src="/assets/demo.js?body=1"></script>
+</head>
+<body>
+
+<div id="output"></div>
+
+</body>
+</html>
diff --git a/demo.js b/demo.js
@@ -0,0 +1,35 @@
+if (!navigator.getUserMedia)
+        navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia ||
+                      navigator.mozGetUserMedia || navigator.msGetUserMedia
+
+if (navigator.getUserMedia){
+    navigator.getUserMedia({audio:true}, success, function(e) {
+    alert('Error capturing audio.')
+    })
+} else alert('getUserMedia not supported in this browser.')
+
+
+function success(e){
+    audioContext = window.AudioContext || window.webkitAudioContext
+    context = new audioContext()
+    volume = context.createGain()
+    audioInput = context.createMediaStreamSource(e)
+    audioInput.connect(volume)
+    var bufferSize = 2048
+    recorder = context.createJavaScriptNode(bufferSize, 1, 1)
+    var outputElement = document.querySelector('#output')
+    var dtmf = new DTMF(context.sampleRate,5,0)
+    dtmf.onDecode = function(value){
+      outputElement.innerHTML = outputElement.innerHTML + value
+    }
+    recorder.onaudioprocess = function(e){
+        var bin = e.inputBuffer.getChannelData (0)
+        dtmf.processBin(bin)
+        dtmf.refresh()
+    }
+
+    volume.connect (recorder)
+    recorder.connect (context.destination) 
+}
+
+
diff --git a/dtmf.js b/dtmf.js
@@ -0,0 +1,87 @@
+function DTMF(samplerate,decimation,threshold){
+  var self = this
+  var samplerate = samplerate / decimation
+  var decimation = decimation || 5
+  var threshold = threshold || 0.0002
+  var frequencyTable = {
+    697: {1209: "1", 1336: "2", 1477: "3", 1633: "A"}, 
+    770: {1209: "4", 1336: "5", 1477: "6", 1633: "B"},
+    852: {1209: "7", 1336: "8", 1477: "9", 1633: "C"},
+    941: {1209: "*", 1336: "0", 1477: "#", 1633: "D"}
+  }
+  var lowFrequencies = []
+  for(var key in frequencyTable) lowFrequencies.push(parseInt(key))
+  var highFrequencies = []
+  for (var key in frequencyTable[lowFrequencies[0]]) highFrequencies.push(parseInt(key))
+  var allFrequencies = lowFrequencies.concat(highFrequencies)
+  var frequencyData = {
+    frequencyTable: frequencyTable,
+    lowFrequencies: lowFrequencies,
+    highFrequencies: highFrequencies,
+    allFrequencies: allFrequencies
+  }
+
+  self.repeatCounter = 0
+  self.firstPreviousValue = ""
+  self.goertzel = new Goertzel(frequencyData,samplerate,threshold)
+
+  self.processBin = function(bin){
+    var value = ""
+    var register = self.generateFrequencyRegister()
+    // Downsample by decimation(choosing every Nth sample).
+    for ( var i=0; i< bin.length; i+=decimation ) {
+      floatSample = bin[i] * 32768 ;
+      if ( floatSample > 32767 ) { 
+        floatSample = 32767 
+      } else if (floatSample < -32786) {
+        floatSample = -32768;
+      }
+
+      intSample = Math.round(floatSample)
+      register.sample = intSample
+
+      register = self.goertzel.getEnergyFromSample(register)
+      value = self.goertzel.energyProfileToCharacter(register)
+    }
+      if (value == self.firstPreviousValue && value != undefined ){
+        self.repeatCounter+=1
+        if (self.repeatCounter == 4 && typeof this.onDecode === "function"){
+          // outputElement.innerHTML = outputElement.innerHTML + value
+          setTimeout(this.onDecode(value), 1);
+        }
+      } else {
+        self.repeatCounter = 0
+        self.firstPreviousValue = value
+      }
+
+  }
+
+  self.generateFrequencyRegister = function(){
+    var register = {
+      firstPrevious: {}, 
+      secondPrevious: {}, 
+      totalPower: {}, 
+      filterLength: {}, 
+      sample: 0, 
+      energies: {},
+      rememberSample: function(sample,frequency){
+        this.secondPrevious[frequency] = this.firstPrevious[frequency]
+        this.firstPrevious[frequency] = sample
+      }
+    }
+    for ( var i=0; i< allFrequencies.length; i++ ){
+      var frequency = allFrequencies[i]
+      register.firstPrevious[frequency] = 0.0
+      register.secondPrevious[frequency] = 0.0
+      register.totalPower[frequency] = 0.0
+      register.filterLength[frequency] = 0.0
+      register.energies[frequency] = 0.0
+    }
+    return register
+  }
+
+  self.refresh = function(){
+    self.goertzel.refresh()
+  }
+
+}
diff --git a/goertzel.js b/goertzel.js
@@ -0,0 +1,85 @@
+function Goertzel(frequencyData,samplerate,threshold){
+  var self = this
+  self.threshold = threshold
+  self.samplerate = samplerate
+  self.frequencyTable = frequencyData.frequencyTable
+  self.lowFrequencies = frequencyData.lowFrequencies
+  self.highFrequencies = frequencyData.highFrequencies
+  self.allFrequencies = frequencyData.allFrequencies
+  self.firstPrevious = {}
+  self.secondPrevious = {}
+  self.totalPower = {}
+  self.filterLength = {}
+  self.coefficient = {}
+
+  for ( var i=0; i< self.allFrequencies.length; i++ ){
+    var frequency = self.allFrequencies[i]
+    normalizedFrequency = frequency / self.samplerate
+    self.coefficient[frequency] = 2.0*Math.cos(2.0 * 3.14 * normalizedFrequency)
+  }
+
+  self.refresh = function(){
+    self.firstPrevious = {}
+    self.secondPrevious = {}
+    self.totalPower = {}
+    self.filterLength = {}
+
+    for ( var i=0; i< self.allFrequencies.length; i++ ){
+      var frequency = self.allFrequencies[i]
+      self.firstPrevious[frequency] = 0.0
+      self.secondPrevious[frequency] = 0.0
+      self.totalPower[frequency] = 0.0
+      self.filterLength[frequency] = 0.0
+    }
+  }
+
+  self.energyProfileToCharacter = function(register){
+    var energies = register.energies
+    var highFrequency = 0.0
+    var highFrequencyEngergy = 0.0
+
+    for (var i=0; i<self.highFrequencies.length; i++){
+      var f = self.highFrequencies[i]
+      if (energies[f] > highFrequencyEngergy && energies[f] > self.threshold){
+        highFrequencyEngergy = energies[f]
+        highFrequency = f
+      }
+    }
+
+    var lowFrequency = 0.0
+    var lowFrequencyEnergy = 0.0
+
+    for (var i=0; i<self.lowFrequencies.length; i++){
+      var f = self.lowFrequencies[i]
+      if (energies[f] > lowFrequencyEnergy && energies[f] > self.threshold){
+        lowFrequencyEnergy = energies[f]
+        lowFrequency = f
+      }
+    }
+    register = null
+    delete register
+    if (self.frequencyTable[lowFrequency] != undefined){
+      return self.frequencyTable[lowFrequency][highFrequency] || null
+    }
+
+  }
+
+  self.getEnergyFromSample = function(register){
+    for ( var i=0; i< self.allFrequencies.length; i++ ){
+        var frequency = self.allFrequencies[i]
+        sine = register.sample + (self.coefficient[frequency] * register.firstPrevious[frequency]) - register.secondPrevious[frequency]
+        register.rememberSample(sine,frequency)
+        register.filterLength[frequency]+=1
+        power = (register.secondPrevious[frequency]*register.secondPrevious[frequency]) + (register.firstPrevious[frequency]*register.firstPrevious[frequency]) - (self.coefficient[frequency]*register.firstPrevious[frequency]*register.secondPrevious[frequency])
+        register.totalPower[frequency]+=register.sample*register.sample
+        if(register.totalPower[frequency] == 0){
+            register.totalPower[frequency] = 1
+        }
+        register.energies[frequency] = power / register.totalPower[frequency] / register.filterLength[frequency]
+    }
+    return register
+  }
+
+  self.refresh()
+
+}