convolve2.cpp

#include <fftw3.h>
#include <cmath>

#include <iostream>
#include "Buffer.h"

#include "types.h"
#include "libs/config_parser.h"
#include "wav.h"
#include "gnuplot_ipp/gnuplot_ipp.h"
#include "filters.h"
#include "extra.h"

#include <string.h> // memcpy

#include <limits.h>

#include "libs/timer.h"


using std::cout;
using std::endl;

#include <complex>

real complex_norm(real re, real im)
{
  return sqrt(re*re + im*im);
}

/// @warn Might not behave well for n=odd!

/* READ!!: http://www.fftw.org/doc/The-Halfcomplex_002dformat-DFT.html */
void HC2magnitude(int N, real *hc, real *magnitude)
{
  magnitude[0] = hc[0];
  for (idx i=1; i < N/2; ++i)
    magnitude[i] = complex_norm(hc[i], hc[N-i]); // Not true for odd N!!!
}


/**
   Z = Z1*Z2
   @param[in] re1 - Re{Z1}
   @param[in] im1 - Im{Z1}
   @param[in] re2 - Re{Z2}
   @param[in] im2 - Im{Z2}
   @param[out] re - Re{Z}
   @param[out] im - Im{Z}

*/
inline void complex_multiply(real re1, real im1, real re2, real im2, real *re, real *im)
{
  *re = re1*re2 - im1*im2;
  *im = re1*im2 + im1*re2;
}

/**
   HalfComplex representation multiply
   @param[in] z1 - Input  HC array
   @param[in] z2 - Input  HC array
   @param[out] z - Output HC array
   @param[in] size - Size of the HC array

   @warn: ONLY FOR EVEN TRANSFORMATIONS!!!
*/
void hc_multiply (real *z1, real *z2, real *z, idx size)
{
  z[0] = z1[0]*z2[0];

  idx max_i = size/2;
  for (idx i=1; i < max_i; ++i)
    complex_multiply(z1[i], z1[size-i],
		     z2[i], z2[size-i],
		     &z[i], &z[size-i]);
}



int main(int argc, char **argv)
{
  /* Name convention throughout this file:
  	
     i - input
     o - output
     m - magnitude

     and capital letters for the frequency domain
  */	
  Gnuplot  pwav, pi, po, pM, ph, p;

	
  fftw_plan forward_plan, backwards_plan, h_forward_plan;

  Guarantee(argc == 4, "Missing program options:\n \tconvolver <input_wav> <impulse_response_wav> <output_wav>");


  SndfileHandle input_wav(argv[1]);
  SndfileHandle input_h(argv[2]);

  uint sample_rate_Hz = input_wav.samplerate();

  Guarantee(input_wav.samplerate() == input_h.samplerate(), "Sample rates must match.");

  Guarantee(wav::ok(input_wav) && wav::ok(input_h), "File doesn't exist.");

  Guarantee(wav::mono(input_wav) && wav::mono(input_h), "Inputs must be mono.");

  size_t FFT_N = input_wav.frames();
  FFT_N += (FFT_N%2);

  // g = wav, h = impulse response, g*h = convolution (output)
  Buffer<real> g(FFT_N, 0, fftw_malloc, fftw_free), h(g), G(g), H(g), M(g), gh(g), GH(g), f(g), t(g);

  input_wav.read(g(), input_wav.frames());
  input_h.read(h(), input_h.frames());

  real FFT_df = sample_rate_Hz / (real) FFT_N;
  real T_sampling = 1/(real)sample_rate_Hz;

  int FFT_flags = FFTW_ESTIMATE; // Use wisdom + FFTW_EXHAUSTIVE later!

  forward_plan   = fftw_plan_r2r_1d(FFT_N, g() , G() , FFTW_R2HC, FFT_flags); 
  h_forward_plan = fftw_plan_r2r_1d(FFT_N, h() , H() , FFTW_R2HC, FFT_flags); 
  backwards_plan = fftw_plan_r2r_1d(FFT_N, GH(), gh(), FFTW_HC2R, FFT_flags); 


  // Fill plot x-axis buffers
  for (idx i=0; i < FFT_N; ++i)
    {
      t[i] = i * T_sampling;
      f[i] = i * FFT_df;      
    }


  fftw_execute(forward_plan);
  fftw_execute(h_forward_plan);
  ph.set_labels("t (s)", "Amplitude");
  ph.plot_xy(t(), h(), h.size(), "h(t)");
  pM.set_labels("f (Hz)", "Magnitude");
  pM.cmd("set logscale y");
  HC2magnitude(FFT_N, H(), M());
  pM.plot_xy(&f[1], &M[1], FFT_N/2-1, "|H(f)| AC");


  Timer convolution_timer;
  convolution_timer.start();

  hc_multiply(G(), H(), GH(), FFT_N);		
  fftw_execute(backwards_plan);
  gh /= (real) FFT_N;

  convolution_timer.stop();

  printf("Convolution execution time: %lf (s)\n", convolution_timer.getElapsedTimeInSec());

  // Normalize
  gh /= array_ops::max_abs(gh(), FFT_N);

  p.set_labels("t (s)", "Amplitude");
  p.plot_xy(t(), gh(), FFT_N, "g*h");

  wav::write_mono (argv[3], gh(), FFT_N, sample_rate_Hz);

  wait();
  fftw_destroy_plan(forward_plan); 
  fftw_destroy_plan(h_forward_plan);
  fftw_destroy_plan(backwards_plan);
  puts("\nSuccess!");
  return 0;
}