SpecPowerMeter.cpp

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/**********************************************************************
 
  Audacity: A Digital Audio Editor
 
  SpecPowerCalculation.cpp
 
  Philipp Sibler
 
******************************************************************//*******************************************************************/
 
#include "SpecPowerMeter.h"
 
#include <cmath>
#include <cstdlib>
#include <wx/defs.h>
 
#include "FFT.h"
 
SpecPowerCalculation::SpecPowerCalculation(size_t sigLen)
  : mSigLen(sigLen)
  , mSigI{ sigLen, true }
  , mSigFR{ sigLen }
  , mSigFI{ sigLen }
{
}
 
SpecPowerCalculation::~SpecPowerCalculation()
{
}
 
float SpecPowerCalculation::CalcPower(float* sig, float fc, float bw)
{
   float pwr;
   int loBin, hiBin;
   
   // Given the bandwidth bw, get the boundary bin numbers
   loBin = Freq2Bin(fc - (bw / 2.0f));
   hiBin = Freq2Bin(fc + (bw / 2.0f));
   if (loBin == hiBin)
   {
      hiBin = loBin + 1;
   }
   
   // Calc the FFT
   FFT(mSigLen, 0, sig, mSigI.get(), mSigFR.get(), mSigFI.get());
   
   // Calc the in-band power
   pwr = CalcBinPower(mSigFR.get(), mSigFI.get(), loBin, hiBin);
   
   return pwr;     
}
 
float SpecPowerCalculation::CalcBinPower(float* sig_f_r, float* sig_f_i, int loBin, int hiBin)
{
   float pwr = 0.0f;
   
   for (int n = loBin; n < hiBin; n++)
   {
      pwr += ((sig_f_r[n]*sig_f_r[n])+(sig_f_i[n]*sig_f_i[n]));
   }
   
   return pwr;
}
 
int SpecPowerCalculation::Freq2Bin(float fc)
{
   int bin;
   
   // There is no round() in (older) MSVSs ...
   bin = floor((double)fc * mSigLen);
   bin %= (int)mSigLen;
   
   return bin;   
}