/**   @file pitch.c   @brief Pitch analysis*//* Copyright (C) 2005   This library is free software; you can redistribute it and/or   modify it under the terms of the GNU Lesser General Public   License as published by the Free Software Foundation; either   version 2.1 of the License, or (at your option) any later version.   This library is distributed in the hope that it will be useful,   but WITHOUT ANY WARRANTY; without even the implied warranty of   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU   Lesser General Public License for more details.   You should have received a copy of the GNU Lesser General Public   License along with this library; if not, write to the Free Software   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA*/#include <stdio.h>#include <math.h>#include "fftwrap.h"#include "pitch.h"void find_spectral_pitch(void *fft, float *x, float *y, int lag, int len, int *pitch){   int n2 = lag/2;   float xx[lag];   float X[lag];   float Y[lag];   float curve[n2];   int i;      for (i=0;i<lag;i++)      xx[i] = 0;   for (i=0;i<len;i++)      xx[i] = x[i];      spx_fft(fft, xx, X);   spx_fft(fft, y, Y);   curve[0] = 1;   for (i=1;i<n2;i++)   {      curve[i] = sqrt((X[2*i-1]*X[2*i-1] + X[2*i  ]*X[2*i  ])*(Y[2*i-1]*Y[2*i-1] + Y[2*i  ]*Y[2*i  ]));      curve[i] = curve[i]+.7*curve[i];   }   for (i=n2-2;i>=0;i--)      curve[i] = curve[i] + .7*curve[i+1];      X[0] = 0;   for (i=1;i<lag/2;i++)   {      float n;      //n = 1.f/(1e1+sqrt(sqrt((X[2*i-1]*X[2*i-1] + X[2*i  ]*X[2*i  ])*(Y[2*i-1]*Y[2*i-1] + Y[2*i  ]*Y[2*i  ]))));      //n = 1;      n = 1.f/pow(1+curve[i],.8)/(i+60);      //if (i>lag/6)      //   n *= .5;      float tmp = X[2*i-1];      X[2*i-1] = (X[2*i-1]*Y[2*i-1] + X[2*i  ]*Y[2*i  ])*n;      X[2*i  ] = (- X[2*i  ]*Y[2*i-1] + tmp*Y[2*i  ])*n;   }   X[lag-1] = 0;   X[0] = X[lag-1] = 0;   spx_ifft(fft, X, xx);      float max_corr=-1e10;   //int pitch;   *pitch = 0;   for (i=0;i<lag-len;i++)   {      //printf ("%f ", xx[i]);      if (xx[i] > max_corr)      {         *pitch = i;         max_corr = xx[i];      }   }   //printf ("\n");   //printf ("%d %f\n", *pitch, max_corr);   //printf ("%d\n", *pitch);}