apps/plugins/pdbox/PDa/extra/equalizer.c

   1 /* (C) Guenter Geiger <geiger@epy.co.at> */
   2
   3
   4 /*
   5
   6  These filter coefficients computations are taken from
   7  http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt
   8
   9  written by Robert Bristow-Johnson
  10
  11 */
  12
  13 #include "m_pd.h"
  14 #ifdef NT
  15 #pragma warning( disable : 4244 )
  16 #pragma warning( disable : 4305 )
  17 #endif
  18 #include <math.h>
  19 #include "filters.h"
  20
  21
  22
  23 /* ------------------- equ ----------------------------*/
  24 static t_class *equ_class;
  25
  26 void equ_bang(t_rbjfilter *x)
  27 {
  28      t_atom at[5];
  29      t_float omega = e_omega(x->x_freq,x->x_rate);
  30      t_float alpha = e_alpha(x->x_bw*0.01,omega);
  31      t_float b0 = 1 + alpha*e_A(x->x_gain);
  32      t_float b1 = -2.*cos(omega);
  33      t_float b2 = 1 - alpha*e_A(x->x_gain);
  34      t_float a0 = 1 + alpha/e_A(x->x_gain);
  35      t_float a1 = -2.*cos(omega);
  36      t_float a2 = 1 - alpha/e_A(x->x_gain);
  37
  38 /*      post("bang %f %f %f",x->x_freq, x->x_gain, x->x_bw);*/
  39
  40      if (!check_stability(-a1/a0,-a2/a0,b0/a0,b1/a0,b2/a0)) {
  41        post("equ: filter unstable -> resetting");
  42        a0=1.;a1=0.;a2=0.;
  43        b0=1.;b1=0.;b2=0.;
  44      }
  45
  46      SETFLOAT(at,-a1/a0);
  47      SETFLOAT(at+1,-a2/a0);
  48      SETFLOAT(at+2,b0/a0);
  49      SETFLOAT(at+3,b1/a0);
  50      SETFLOAT(at+4,b2/a0);
  51
  52      outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
  53 }
  54
  55
  56 void equ_float(t_rbjfilter *x,t_floatarg f)
  57 {
  58      x->x_freq = f;
  59      equ_bang(x);
  60 }
  61
  62
  63 static void *equ_new(t_floatarg f,t_floatarg g,t_floatarg bw)
  64 {
  65     t_rbjfilter *x = (t_rbjfilter *)pd_new(equ_class);
  66
  67     x->x_rate = 44100.0;
  68     outlet_new(&x->x_obj,&s_float);
  69     floatinlet_new(&x->x_obj, &x->x_gain);
  70     floatinlet_new(&x->x_obj, &x->x_bw);
  71     if (f > 0.) x->x_freq = f;
  72     if (bw > 0.) x->x_bw = bw;
  73     if (g != 0.) x->x_gain = g;
  74     return (x);
  75 }
  76
  77
  78 void equalizer_setup(void)
  79 {
  80     equ_class = class_new(gensym("equalizer"), (t_newmethod)equ_new, 0,
  81                                 sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,A_DEFFLOAT,0);
  82     class_addbang(equ_class,equ_bang);
  83     class_addfloat(equ_class,equ_float);
  84 }
  85
  86
  87
  88
  89
  90 /* (C) Guenter Geiger <geiger@epy.co.at> */
  91
  92
  93 /*
  94
  95  These filter coefficients computations are taken from
  96  http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt
  97
  98  written by Robert Bristow-Johnson
  99
 100 */
 101
 102 #include "m_pd.h"
 103 #ifdef NT
 104 #pragma warning( disable : 4244 )
 105 #pragma warning( disable : 4305 )
 106 #endif
 107 #include <math.h>
 108 #include "filters.h"
 109
 110
 111
 112 /* ------------------- equ ----------------------------*/
 113 static t_class *equ_class;
 114
 115 void equ_bang(t_rbjfilter *x)
 116 {
 117      t_atom at[5];
 118      t_float omega = e_omega(x->x_freq,x->x_rate);
 119      t_float alpha = e_alpha(x->x_bw*0.01,omega);
 120      t_float b0 = 1 + alpha*e_A(x->x_gain);
 121      t_float b1 = -2.*cos(omega);
 122      t_float b2 = 1 - alpha*e_A(x->x_gain);
 123      t_float a0 = 1 + alpha/e_A(x->x_gain);
 124      t_float a1 = -2.*cos(omega);
 125      t_float a2 = 1 - alpha/e_A(x->x_gain);
 126
 127 /*      post("bang %f %f %f",x->x_freq, x->x_gain, x->x_bw);*/
 128
 129      if (!check_stability(-a1/a0,-a2/a0,b0/a0,b1/a0,b2/a0)) {
 130        post("equ: filter unstable -> resetting");
 131        a0=1.;a1=0.;a2=0.;
 132        b0=1.;b1=0.;b2=0.;
 133      }
 134
 135      SETFLOAT(at,-a1/a0);
 136      SETFLOAT(at+1,-a2/a0);
 137      SETFLOAT(at+2,b0/a0);
 138      SETFLOAT(at+3,b1/a0);
 139      SETFLOAT(at+4,b2/a0);
 140
 141      outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
 142 }
 143
 144
 145 void equ_float(t_rbjfilter *x,t_floatarg f)
 146 {
 147      x->x_freq = f;
 148      equ_bang(x);
 149 }
 150
 151
 152 static void *equ_new(t_floatarg f,t_floatarg g,t_floatarg bw)
 153 {
 154     t_rbjfilter *x = (t_rbjfilter *)pd_new(equ_class);
 155
 156     x->x_rate = 44100.0;
 157     outlet_new(&x->x_obj,&s_float);
 158     floatinlet_new(&x->x_obj, &x->x_gain);
 159     floatinlet_new(&x->x_obj, &x->x_bw);
 160     if (f > 0.) x->x_freq = f;
 161     if (bw > 0.) x->x_bw = bw;
 162     if (g != 0.) x->x_gain = g;
 163     return (x);
 164 }
 165
 166
 167 void equalizer_setup(void)
 168 {
 169     equ_class = class_new(gensym("equalizer"), (t_newmethod)equ_new, 0,
 170                                 sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,A_DEFFLOAT,0);
 171     class_addbang(equ_class,equ_bang);
 172     class_addfloat(equ_class,equ_float);
 173 }
 174
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