Clean #processBuffer a bit and rely on Goertzel#eachDownsample for do…

…wnsampling.

compile.sh

@@ -2,4 +2,5 @@
 
 coffee -o build -c -b src/goertzel.coffee 
 coffee -o build -c -b src/dtmf.coffee
-coffee -c -b spec/goertzel.spec.coffee
+coffee -c -b spec/goertzel.spec.coffee
+coffee -c -b spec/dtmf.spec.coffee

src/dtmf.coffee

@@ -64,33 +64,26 @@ class DTMF
 
   processBuffer: (buffer) ->
     value = ''
-    intSample = undefined
-    register = undefined
-    windowedSample = undefined
-    energy = undefined
     highEnergies = []
     lowEnergies = []
-    frequency = undefined
     result = []
     # Downsample by choosing every Nth sample.
+    Goertzel.Utilities.eachDownsample buffer, @downsampleRate, (sample,i,downSampledBufferLength)=>
+      windowedSample = Goertzel.Utilities.exactBlackman(sample, i, downSampledBufferLength)
+      @goertzel.processSample(windowedSample)
+      value = @energyProfileToCharacter(@goertzel)
     i = 0
-    while i < buffer.length
-      intSample = buffer[i]
-      windowedSample = Goertzel.Utilities.exactBlackman(intSample, i, buffer.length / @downsampleRate)
-      register = @goertzel.processSample(windowedSample)
-      value = @energyProfileToCharacter(register)
-      i += @downsampleRate
     # END DOWNSAMPLE 
     # Run peak test to throw out samples with too many energy spectrum peaks or where the difference between energies is not great enough.
     highEnergies = []
     while i < @highFrequencies.length
       f = @highFrequencies[i]
-      highEnergies.push register.energies[f]
+      highEnergies.push @goertzel.energies[f]
       i++
     lowEnergies = []
     while i < @lowFrequencies.length
       freq = @lowFrequencies[i]
-      lowEnergies.push register.energies[freq]
+      lowEnergies.push @goertzel.energies[freq]
       i++
     badPeaks = Goertzel.Utilities.doublePeakFilter(highEnergies, lowEnergies, @peakFilterSensitivity)
     if badPeaks == false

src/goertzel.coffee

@@ -56,23 +56,27 @@ class Goertzel
       Math.round intSample
 
     downsampleBuffer: (buffer, downsampleRate, mapSample) ->
-      downsampledBuffer = []
+      bufferLength = buffer.length
+      # Prefer Uint8ClampedArray for performance
+      downsampledBuffer = new (Uint8ClampedArray or Array)(bufferLength / downsampleRate)
       i = 0
-      while i < buffer.length
+      while i < bufferLength
         sample = buffer[i]
         if mapSample
-          downsampledBuffer.push mapSample(sample, i, buffer.length, downsampleRate)
+          downsampledBuffer[i] = mapSample(sample, i, buffer.length, downsampleRate)
         else
-          downsampledBuffer.push sample
+          downsampledBuffer[i] = sample
         i += downsampleRate
       downsampledBuffer
 
-    eachDownsample: (buffer, downsampleRate, fn) ->
+    eachDownsample: (buffer, downSampleRate, fn) ->
       i = 0
-      while i < buffer.length
+      bufferLength = buffer.length
+      downSampledBufferLength = bufferLength / downSampleRate
+      while i < bufferLength
         sample = buffer[i]
-        fn?(sample, i, buffer.length, downsampleRate)
-        i += downsampleRate
+        fn?(sample, i, downSampledBufferLength)
+        i += downSampleRate
 
     hamming: (sample, sampleIndex, bufferSize) ->
       sample * (0.54 - 0.46 * Math.cos(2 * Math.PI * sampleIndex / bufferSize))