apps/plugins/pdbox/PDa/extra/highshelf.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 /* ------------------- highshelf ----------------------------*/
  23
  24 static t_class *highshelf_class;
  25
  26 void highshelf_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 A = e_A(x->x_gain);
  31      t_float cs = cos(omega);
  32      t_float sn = sin(omega);
  33      t_float beta = e_beta(A,x->x_bw* 0.01);
  34
  35      t_float b0 =    A*((A+1) + (A-1)*cs + beta*sn);
  36      t_float b1 =-2.*A*((A-1) + (A+1)*cs);
  37      t_float b2 =    A*((A+1) + (A-1)*cs - beta*sn);
  38      t_float a0 =      ((A+1) - (A-1)*cs + beta*sn);
  39      t_float a1 =   2.*((A-1) - (A+1)*cs);
  40      t_float a2 =      ((A+1) - (A-1)*cs - beta*sn);
  41
  42 /*     post("bang %f %f %f",x->x_freq, x->x_gain, x->x_bw);*/
  43
  44      if (!check_stability(-a1/a0,-a2/a0,b0/a0,b1/a0,b2/a0)) {
  45        post("highshelf: filter unstable -> resetting");
  46        a0=1.;a1=0.;a2=0.;
  47        b0=1.;b1=0.;b2=0.;
  48      }
  49
  50      SETFLOAT(at,-a1/a0);
  51      SETFLOAT(at+1,-a2/a0);
  52      SETFLOAT(at+2,b0/a0);
  53      SETFLOAT(at+3,b1/a0);
  54      SETFLOAT(at+4,b2/a0);
  55
  56      outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
  57 }
  58
  59
  60 void highshelf_float(t_rbjfilter *x,t_floatarg f)
  61 {
  62      x->x_freq = f;
  63      highshelf_bang(x);
  64 }
  65
  66
  67 static void *highshelf_new(t_floatarg f,t_floatarg g,t_floatarg bw)
  68 {
  69     t_rbjfilter *x = (t_rbjfilter *)pd_new(highshelf_class);
  70
  71     x->x_rate = 44100.0;
  72     outlet_new(&x->x_obj,&s_float);
  73     floatinlet_new(&x->x_obj, &x->x_gain);
  74     floatinlet_new(&x->x_obj, &x->x_bw);
  75     if (f > 0.) x->x_freq = f;
  76     if (bw > 0.) x->x_bw = bw;
  77     if (g != 0.) x->x_gain = g;
  78     return (x);
  79 }
  80
  81
  82 void highshelf_setup(void)
  83 {
  84     highshelf_class = class_new(gensym("highshelf"), (t_newmethod)highshelf_new, 0,
  85                                 sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,A_DEFFLOAT,0);
  86     class_addbang(highshelf_class,highshelf_bang);
  87     class_addfloat(highshelf_class,highshelf_float);
  88 }
  89
  90
  91 /* (C) Guenter Geiger <geiger@epy.co.at> */
  92
  93
  94 /*
  95
  96  These filter coefficients computations are taken from
  97  http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt
  98
  99  written by Robert Bristow-Johnson
 100
 101 */
 102
 103 #include "m_pd.h"
 104 #ifdef NT
 105 #pragma warning( disable : 4244 )
 106 #pragma warning( disable : 4305 )
 107 #endif
 108 #include <math.h>
 109 #include "filters.h"
 110
 111
 112 /* ------------------- highshelf ----------------------------*/
 113
 114 static t_class *highshelf_class;
 115
 116 void highshelf_bang(t_rbjfilter *x)
 117 {
 118      t_atom at[5];
 119      t_float omega = e_omega(x->x_freq,x->x_rate);
 120      t_float A = e_A(x->x_gain);
 121      t_float cs = cos(omega);
 122      t_float sn = sin(omega);
 123      t_float beta = e_beta(A,x->x_bw* 0.01);
 124
 125      t_float b0 =    A*((A+1) + (A-1)*cs + beta*sn);
 126      t_float b1 =-2.*A*((A-1) + (A+1)*cs);
 127      t_float b2 =    A*((A+1) + (A-1)*cs - beta*sn);
 128      t_float a0 =      ((A+1) - (A-1)*cs + beta*sn);
 129      t_float a1 =   2.*((A-1) - (A+1)*cs);
 130      t_float a2 =      ((A+1) - (A-1)*cs - beta*sn);
 131
 132 /*     post("bang %f %f %f",x->x_freq, x->x_gain, x->x_bw);*/
 133
 134      if (!check_stability(-a1/a0,-a2/a0,b0/a0,b1/a0,b2/a0)) {
 135        post("highshelf: filter unstable -> resetting");
 136        a0=1.;a1=0.;a2=0.;
 137        b0=1.;b1=0.;b2=0.;
 138      }
 139
 140      SETFLOAT(at,-a1/a0);
 141      SETFLOAT(at+1,-a2/a0);
 142      SETFLOAT(at+2,b0/a0);
 143      SETFLOAT(at+3,b1/a0);
 144      SETFLOAT(at+4,b2/a0);
 145
 146      outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
 147 }
 148
 149
 150 void highshelf_float(t_rbjfilter *x,t_floatarg f)
 151 {
 152      x->x_freq = f;
 153      highshelf_bang(x);
 154 }
 155
 156
 157 static void *highshelf_new(t_floatarg f,t_floatarg g,t_floatarg bw)
 158 {
 159     t_rbjfilter *x = (t_rbjfilter *)pd_new(highshelf_class);
 160
 161     x->x_rate = 44100.0;
 162     outlet_new(&x->x_obj,&s_float);
 163     floatinlet_new(&x->x_obj, &x->x_gain);
 164     floatinlet_new(&x->x_obj, &x->x_bw);
 165     if (f > 0.) x->x_freq = f;
 166     if (bw > 0.) x->x_bw = bw;
 167     if (g != 0.) x->x_gain = g;
 168     return (x);
 169 }
 170
 171
 172 void highshelf_setup(void)
 173 {
 174     highshelf_class = class_new(gensym("highshelf"), (t_newmethod)highshelf_new, 0,
 175                                 sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,A_DEFFLOAT,0);
 176     class_addbang(highshelf_class,highshelf_bang);
 177     class_addfloat(highshelf_class,highshelf_float);
 178 }
 179
 180