File: AudioMaskerExample.cc-example.tex

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\hypertarget{AudioMaskerExample.cc-example}{
\section{AudioMaskerExample.cc}
}
This is an example of how to use the \hyperlink{classAudioMasker}{AudioMasker} class See the example file to work out how to use these Audio masking classes


\begin{DoxyCodeInclude}

/*
* 
* This example shows how to use Dr M.R. Flax's (2000) hybrid
* simultaneous audio masking class to find the masking threshold of a time domain
       signal.
* 
* The compilation of this file is demonstrated in Makefile.
* Run this file : ./AudioMaskerExample
* View the results of this file using www.octave.org by running the script view.m
      
* - simply type view once octave has started and you are in the suitable director
      y.
* 
* The input audio should be stored in the file INPUTFILENAME in text format - eac
      h sample seperated by a * white space.
* 
* ========================= HOWTO ===============================
* \code
*     // First find the masking threshold
*     AudioMasker masker(sampleFreq, count); // Create the audio masker class usi
      ng fs=sampleFreq and count filters
*     masker.excite(input, sampleCount); // find the mask for the array of input 
      data which has sampleCount time samples.
* 
*     // Now do something with the masking threshold ...
* 
*     // The frequency domain mask is now located here
*     for (int j=0; j<count;j++)
*         masker.mask[j]; // This is the mask at each of the count frequencies of
       interest
* 
*     // A more sophisticated example - find the threshold for each Fourier bin
*     double fact=(double)sampleFreq/((double)sampleCount-1.0); // convert from a
      n index to the equivalent * Fourier bin frequency
*     for (int j=0; j<halfSampleCount;j++){
*         cout<<"finding for freq "<<j*fact<<'\t'; // The frequency we are inspec
      ting
*         double threshold=masker.findThreshold(j*fact); // The masking threshold
      
*         20*log10(threshold); // The threshold in decibels (dB)
*     }
* 
* \endcode
*   // The following example calculates the spectral power and the masking thresh
      old for each Fourier bin of interest ...
*/

#include <math.h>
#include "AudioMasker.H"

#define INPUTFILENAME "audio.44100.txt" // input file - text written samples sepe
      rated by white spaces
#define POWFILENAME "fa.pow" // The power spectrum of the input signal
#define THRESHFILENAME "thresh.dat" // The masking threshold at each frequency of
       the input signal
#define TMASKFILENAME "fa.t.mask" // The masking threshold for each filter CF
#define EXCITEFILENAME "fa.excite" // The excitation
#include <fstream>

int main(void){

    // Setup many variables
    // The number of time domain samples
  int sampleCount=1024, halfSampleCount=(int)rint((double)sampleCount/2.0);
  // The filter bank count and sample frequency
  int count=50, sampleFreq=44100;
  // The number of time domain samples to skip before the sample of interest.
  int skip=8192-sampleCount-1;
  // The input array to hold the input time data
  double input[sampleCount];

  // open the input file
  ifstream inputF(INPUTFILENAME);

  // Skip the first 2*'skip' samples.
  int temp;
  for (int i=0; i<skip;i++)
    inputF >> temp >> input[0];

    // load sampleCount samples as the input to the algorithm
  for (int i=0; i<sampleCount;i++)
    inputF >> input[i];
  inputF.close();

  ofstream outputCF("cf.dat"); // central freq. output file
  ofstream outputT(TMASKFILENAME);
  ofstream outputP(POWFILENAME); // Input data Fourier power file

  // Get our masking function (class) ...
  AudioMasker masker(sampleFreq, count);
  //AudioMasker masker; // Can also be called like so with default filter banks a
      nd sampleFrequency

  masker.excite(input, sampleCount); // find the mask

  for (int j=0; j<count;j++){ // Output the central freq to file
    outputCF <<masker.pfb->cf[j]*((double)sampleCount/(double)sampleFreq)<<'\t';
    outputT  << 20*log10(masker.mask[j])<<'\t'; // output the mask for each filte
      r CF to file
  }
  outputCF<<endl;
  outputT<<endl;

  realFFTData fftData(sampleCount); // Find the fourier transform for the output 
      of the power to file
  realFFT fft(&fftData); // init the Fourier transform
  for (int j=0; j<sampleCount;j++) // load the time domain input to the Fourier t
      ransform
    fftData.in[j]=input[j];
  fft.fwdTransform(); // Perform the transformation of the time domain to the fre
      quency domain.
  fftData.compPowerSpec(); // Find the power spectrum
  for (int j=0; j<sampleCount/2;j++) // Output the power spectrum to file
    outputP<<20*log10(sqrt(fftData.power_spectrum[j]))<<'\t';
  outputP<<endl;

  outputCF.close();
  outputT.close();
  outputP.close();

  ofstream outputF(THRESHFILENAME); // Find and output the masking threshold for 
      each Fourier bin in the power spectrum
  double fact=(double)sampleFreq/((double)sampleCount-1.0); // convert from an in
      dex to the equivalent Fourier bin frequency
  for (int j=0; j<halfSampleCount;j++){
    //    cout<<"finding for freq "<<j*fact<<'\t';
    outputF<<20*log10(masker.findThreshold(j*fact))<<'\t';
  }
  outputF<<endl;
  outputF.close();
}


\end{DoxyCodeInclude}