Locate and position the current Audacity source code, and clear a variety of old junk out of the way into junk-branches

src/Spectrum.cpp

@@ -0,0 +1,164 @@
+/**********************************************************************
+
+  Audacity: A Digital Audio Editor
+
+  Spectrum.cpp
+
+  Dominic Mazzoni
+
+*******************************************************************//*!
+
+\file Spectrum.cpp
+\brief Functions for computing Spectra.
+
+*//*******************************************************************/
+
+#include <math.h>
+
+#include "Spectrum.h"
+#include "FFT.h"
+
+#if 1 //(UGLY_IEEE754_FLOAT32_HACK :-)
+
+static inline float todB_a(const float *x){
+  return (float)((*(wxInt32 *)x)&0x7fffffff) * 7.17711438e-7f -764.6161886f;
+}
+
+#else
+
+static inline float todB_a(const float *x){
+   return (*(x)==0?-400.f:log(*(x)**(x))*4.34294480f);
+}
+
+#endif
+
+
+bool ComputeSpectrum(float * data, int width,
+                     int windowSize,
+                     double rate, float *output,
+                     bool autocorrelation, int windowFunc)
+{
+   if (width < windowSize)
+      return false;
+
+   if (!data || !output)
+      return true;
+
+   float *processed = new float[windowSize];
+
+   int i;
+   for (i = 0; i < windowSize; i++)
+      processed[i] = float(0.0);
+   int half = windowSize / 2;
+
+   float *in = new float[windowSize];
+   float *out = new float[windowSize];
+   float *out2 = new float[windowSize];
+
+   int start = 0;
+   int windows = 0;
+   while (start + windowSize <= width) {
+      for (i = 0; i < windowSize; i++)
+         in[i] = data[start + i];
+
+      WindowFunc(windowFunc, windowSize, in);
+
+      if (autocorrelation) {
+         // Take FFT
+#ifdef EXPERIMENTAL_USE_REALFFTF
+         RealFFT(windowSize, in, out, out2);
+#else
+         FFT(windowSize, false, in, NULL, out, out2);
+#endif
+         // Compute power
+         for (i = 0; i < windowSize; i++)
+            in[i] = (out[i] * out[i]) + (out2[i] * out2[i]);
+
+         // Tolonen and Karjalainen recommend taking the cube root
+         // of the power, instead of the square root
+
+         for (i = 0; i < windowSize; i++)
+            in[i] = pow(in[i], 1.0f / 3.0f);
+
+         // Take FFT
+#ifdef EXPERIMENTAL_USE_REALFFTF
+         RealFFT(windowSize, in, out, out2);
+#else
+         FFT(windowSize, false, in, NULL, out, out2);
+#endif
+
+      }
+      else
+         PowerSpectrum(windowSize, in, out);
+
+      // Take real part of result
+      for (i = 0; i < half; i++)
+        processed[i] += out[i];
+
+      start += half;
+      windows++;
+   }
+
+   if (autocorrelation) {
+
+      // Peak Pruning as described by Tolonen and Karjalainen, 2000
+      /*
+       Combine most of the calculations in a single for loop.
+       It should be safe, as indexes refer only to current and previous elements,
+       that have already been clipped, etc...
+      */
+      for (i = 0; i < half; i++) {
+        // Clip at zero, copy to temp array
+        if (processed[i] < 0.0)
+            processed[i] = float(0.0);
+        out[i] = processed[i];
+        // Subtract a time-doubled signal (linearly interp.) from the original
+        // (clipped) signal
+        if ((i % 2) == 0)
+           processed[i] -= out[i / 2];
+        else
+           processed[i] -= ((out[i / 2] + out[i / 2 + 1]) / 2);
+
+        // Clip at zero again
+        if (processed[i] < 0.0)
+            processed[i] = float(0.0);
+      }
+
+      // Reverse and scale
+      for (i = 0; i < half; i++)
+         in[i] = processed[i] / (windowSize / 4);
+      for (i = 0; i < half; i++)
+         processed[half - 1 - i] = in[i];
+   } else {
+      // Convert to decibels
+      // But do it safely; -Inf is nobody's friend
+      for (i = 0; i < half; i++){
+         float temp=(processed[i] / windowSize / windows);
+         if (temp > 0.0)
+            processed[i] = 10*log10(temp);
+         else
+            processed[i] = 0;
+      }
+   }
+
+   for(i=0;i<half;i++)
+      output[i] = processed[i];
+   delete[]in;
+   delete[]out;
+   delete[]out2;
+   delete[]processed;
+
+   return true;
+}
+
+// Indentation settings for Vim and Emacs and unique identifier for Arch, a
+// version control system. Please do not modify past this point.
+//
+// Local Variables:
+// c-basic-offset: 3
+// indent-tabs-mode: nil
+// End:
+//
+// vim: et sts=3 sw=3
+// arch-tag: 29527ca5-00d0-442d-afde-d699aee29a31
+