source: src/filter.c @ 961c39c3

/*
   Copyright (C) 2003 Paul Brossier

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/


/* Requires lsmp_t to be long or double. float will NOT give reliable 
 * results */

#include "aubio_priv.h"
#include "sample.h"
#include "mathutils.h"
#include "filter.h"

struct _aubio_filter_t {
  uint_t order;
  lsmp_t * a;
  lsmp_t * b;
  lsmp_t * y;
  lsmp_t * x;
};

/* bug: mono only */
void aubio_filter_do(aubio_filter_t * f, fvec_t * in) {
  uint_t i,j,l, order = f->order;
  lsmp_t *x = f->x;
  lsmp_t *y = f->y;
  lsmp_t *a = f->a;
  lsmp_t *b = f->b;
  i=0;//for (i=0;i<in->channels;i++) {
  for (j = 0; j < in->length; j++) {
    /* new input */
    //AUBIO_DBG("befor %f\t", in->data[i][j]);
    x[0] = in->data[i][j];
    y[0] = b[0] * x[0];
    for (l=1;l<order; l++) {
      y[0] += b[l] * x[l];
      y[0] -= a[l] * y[l];
    } /* + 1e-37; for denormal ? */
    /* new output */
    in->data[i][j] = y[0];
    //AUBIO_DBG("after %f\n", in->data[i][j]);
    /* store states for next sample */
    for (l=order-1; l>0; l--){
      x[l] = x[l-1];
      y[l] = y[l-1];
    }
  }
  /* store states for next buffer */
  f->x = x;
  f->y = y;
  //}   
}

void aubio_filter_do_outplace(aubio_filter_t * f, fvec_t * in, fvec_t * out) {
  uint_t i,j,l, order = f->order;
  lsmp_t *x = f->x;
  lsmp_t *y = f->y;
  lsmp_t *a = f->a;
  lsmp_t *b = f->b;

  i=0; // works in mono only !!!
  //for (i=0;i<in->channels;i++) {
  for (j = 0; j < in->length; j++) {
    /* new input */
    x[0] = in->data[i][j];
    y[0] = b[0] * x[0];
    for (l=1;l<order; l++) {
      y[0] += b[l] * x[l];
      y[0] -= a[l] * y[l];
    }
    // + 1e-37;
    /* new output */
    out->data[i][j] = y[0];
    /* store for next sample */
    for (l=order-1; l>0; l--){
      x[l] = x[l-1];
      y[l] = y[l-1];
    }
  }
  /* store for next run */
  f->x = x;
  f->y = y;
  //}
}

/*  
 *
 * despite mirroring, end effects destroy both phse and amplitude. the longer
 * the buffer, the less affected they are.
 *
 * replacing with zeros clicks.
 *
 * seems broken for order > 4 (see biquad_do_filtfilt for audible one) 
 */
void aubio_filter_do_filtfilt(aubio_filter_t * f, fvec_t * in, fvec_t * tmp) {
  uint_t j,i=0;
  uint_t length = in->length;
  //uint_t order = f->order;
  //lsmp_t mir;
  /* mirroring */
  //mir = 2*in->data[i][0];
  //for (j=1;j<order;j++)
  //f->x[j] = 0.;//mir - in->data[i][order-j];
  /* apply filtering */
  aubio_filter_do(f,in);
  /* invert */
  for (j = 0; j < length; j++)
    tmp->data[i][length-j-1] = in->data[i][j];
  /* mirror inverted */
  //mir = 2*tmp->data[i][0];
  //for (j=1;j<order;j++)
  //f->x[j] = 0.;//mir - tmp->data[i][order-j];
  /* apply filtering on inverted */
  aubio_filter_do(f,tmp);
  /* invert back */
  for (j = 0; j < length; j++)
    in->data[i][j] = tmp->data[i][length-j-1];
}


aubio_filter_t * new_aubio_adsgn_filter(uint_t samplerate) {
  aubio_filter_t * f = new_aubio_filter(samplerate, 7);
  lsmp_t * a = f->a;
  lsmp_t * b = f->b;
  /* uint_t l; */
  /* for now, 44100, adsgn */
  a[0] =  1.00000000000000000000000000000000000000000000000000000; 
  a[1] = -4.01957618111583236952810693765059113502502441406250000; 
  a[2] =  6.18940644292069386267485242569819092750549316406250000; 
  a[3] = -4.45319890354411640487342083360999822616577148437500000; 
  a[4] =  1.42084294962187751565352300531230866909027099609375000; 
  a[5] = -0.14182547383030480458998567883099894970655441284179688; 
  a[6] =  0.00435117723349511334451911181986361043527722358703613; 
  b[0] =  0.25574112520425740235907596797915175557136535644531250;
  b[1] = -0.51148225040851391653973223583307117223739624023437500;
  b[2] = -0.25574112520426162120656954357400536537170410156250000;
  b[3] =  1.02296450081703405032840237254276871681213378906250000;
  b[4] = -0.25574112520426051098354491841746494174003601074218750;
  b[5] = -0.51148225040851369449512731080176308751106262207031250;
  b[6] =  0.25574112520425729133677350546349771320819854736328125;
  /* DBG: filter coeffs at creation time */
  /*
  for (l=0; l<f->order; l++){
    AUBIO_DBG("a[%d]=\t%1.16f\tb[%d]=\t%1.16f\n",l,a[l],l,b[l]);
  }
  */
  f->a = a;
  f->b = b;
  return f;
}

aubio_filter_t * new_aubio_cdsgn_filter(uint_t samplerate) {
  aubio_filter_t * f = new_aubio_filter(samplerate, 5);
  lsmp_t * a = f->a;
  lsmp_t * b = f->b;
  /* uint_t l; */
  /* for now, 44100, cdsgn */
  a[0] =  1.000000000000000000000000000000000000000000000000000000000000; 
  a[1] = -2.134674963687040794013682898366823792457580566406250000000000; 
  a[2] =  1.279333533236063358273781886964570730924606323242187500000000; 
  a[3] = -0.149559846089396208945743182994192466139793395996093750000000; 
  a[4] =  0.004908700174624848651394604104325480875559151172637939453125; 
  b[0] =  0.217008561949218803377448239189106971025466918945312500000000;
  b[1] = -0.000000000000000222044604925031308084726333618164062500000000;
  b[2] = -0.434017123898438272888711253472138196229934692382812500000000;
  b[3] =  0.000000000000000402455846426619245903566479682922363281250000;
  b[4] =  0.217008561949218969910901932962588034570217132568359375000000;
  /* DBG: filter coeffs at creation time */
  /*
  for (l=0; l<f->order; l++){
    AUBIO_DBG("a[%d]=\t%1.16f\tb[%d]=\t%1.16f\n",l,a[l],l,b[l]);
  }
  */
  f->a = a;
  f->b = b;
  return f;
}

aubio_filter_t * new_aubio_filter(uint_t samplerate, uint_t order) {
  aubio_filter_t * f = AUBIO_NEW(aubio_filter_t);
  lsmp_t * x = f->x;
  lsmp_t * y = f->y;
  lsmp_t * a = f->a;
  lsmp_t * b = f->b;
  uint_t l;
  f->order = order;
  a = AUBIO_ARRAY(lsmp_t,f->order);
  b = AUBIO_ARRAY(lsmp_t,f->order);
  x = AUBIO_ARRAY(lsmp_t,f->order);
  y = AUBIO_ARRAY(lsmp_t,f->order);
  /* initial states to zeros */
  for (l=0; l<f->order; l++){
    x[l] = 0.;
    y[l] = 0.;
  }
  f->x = x;
  f->y = y;
  f->a = a;
  f->b = b;
  return f;
}

void del_aubio_filter(aubio_filter_t * f) {
  AUBIO_FREE(f->a);
  AUBIO_FREE(f->b);
  AUBIO_FREE(f->x);
  AUBIO_FREE(f->y);
  AUBIO_FREE(f);
  return;
}