libghost/pitch.c

   1 /**
   2    @file pitch.c
   3    @brief Pitch analysis
   4 */
   5
   6 /* Copyright (C) 2005
   7
   8    This library is free software; you can redistribute it and/or
   9    modify it under the terms of the GNU Lesser General Public
  10    License as published by the Free Software Foundation; either
  11    version 2.1 of the License, or (at your option) any later version.
  12
  13    This library is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16    Lesser General Public License for more details.
  17
  18    You should have received a copy of the GNU Lesser General Public
  19    License along with this library; if not, write to the Free Software
  20    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  21 */
  22
  23
  24 #include <stdio.h>
  25 #include <math.h>
  26 #include "fftwrap.h"
  27
  28 float inner_prod(float *x, float *y, int len)
  29 {
  30    float sum=0;
  31    int i;
  32    for (i=0;i<len;i++)
  33    {
  34       sum += x[i]*y[i];
  35    }
  36    return sum;
  37 }
  38
  39 void find_pitch(float *x, float *gain, float *pitch, int start, int end, int len)
  40 {
  41    int i;
  42    float max_score = -1;
  43    float sc[end+1];
  44    int p=0;
  45    for (i=start;i<=end;i++)
  46    {
  47       float corr, score, E;
  48       corr = inner_prod(x,x-i,len);
  49       E = inner_prod(x-i,x-i,len);
  50       //E = inner_prod(x,x,len);
  51       //printf ("%f ", E);
  52       score = corr*fabs(corr)/(1e4+E);
  53       sc[i] = score;
  54       if (score > max_score || i==start)
  55       {
  56          p = i;
  57          max_score = score;
  58          *gain = corr/(1+E);
  59       }
  60    }
  61    if (p == start || p == end)
  62    {
  63       *pitch = p;
  64    } else {
  65       *pitch = p+.5*(sc[p+1]-sc[p-1])/(2*sc[p]-sc[p-1]-sc[p+1]);
  66    }
  67 }
  68
  69
  70 void find_spectral_pitch(float *x, float *y, int lag, int len, int *pitch, float *curve)
  71 {
  72    //FIXME: Yuck!!!
  73    static void *fft;
  74
  75    if (!fft)
  76       fft = spx_fft_init(lag);
  77
  78    float xx[lag];
  79    float X[lag];
  80    float Y[lag];
  81    int i;
  82
  83    for (i=0;i<lag;i++)
  84       xx[i] = 0;
  85    for (i=0;i<len;i++)
  86       xx[i] = x[i];
  87
  88    spx_fft(fft, xx, X);
  89    spx_fft(fft, y, Y);
  90    X[0] = X[0]*Y[0];
  91    for (i=1;i<lag/2;i++)
  92    {
  93       float n = 1.f/(1e1+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  ])));
  94       //n = 1;
  95       n = 1.f/(1+curve[i]);
  96       /*if (i>10)
  97          n *= .5;
  98       if (i>20)
  99          n *= .5;*/
 100       float tmp = X[2*i-1];
 101       X[2*i-1] = (X[2*i-1]*Y[2*i-1] + X[2*i  ]*Y[2*i  ])*n;
 102       X[2*i  ] = (- X[2*i  ]*Y[2*i-1] + tmp*Y[2*i  ])*n;
 103    }
 104    X[len-1] = 0;
 105    X[0] = X[len-1] = 0;
 106    spx_ifft(fft, X, xx);
 107
 108    float max_corr=-1;
 109    //int pitch;
 110    *pitch = -1;
 111    for (i=0;i<lag-len;i++)
 112    {
 113       //printf ("%f ", xx[i]);
 114       if (xx[i] > max_corr)
 115       {
 116          *pitch = i;
 117          max_corr = xx[i];
 118       }
 119    }
 120    //printf ("%d\n", *pitch);
 121 }