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Diffstat (limited to 'apps/plugins/pdbox/PDa/extra/lowshelf.c')
-rw-r--r--apps/plugins/pdbox/PDa/extra/lowshelf.c93
1 files changed, 1 insertions, 92 deletions
diff --git a/apps/plugins/pdbox/PDa/extra/lowshelf.c b/apps/plugins/pdbox/PDa/extra/lowshelf.c
index 52c30d839d..ba32b6dba8 100644
--- a/apps/plugins/pdbox/PDa/extra/lowshelf.c
+++ b/apps/plugins/pdbox/PDa/extra/lowshelf.c
@@ -88,95 +88,4 @@ void lowshelf_setup(void)
88 class_addfloat(lowshelf_class,lowshelf_float); 88 class_addfloat(lowshelf_class,lowshelf_float);
89} 89}
90 90
91 91
92/* (C) Guenter Geiger <geiger@epy.co.at> */
93
94
95/*
96
97 These filter coefficients computations are taken from
98 http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt
99
100 written by Robert Bristow-Johnson
101
102*/
103
104#include "m_pd.h"
105#ifdef NT
106#pragma warning( disable : 4244 )
107#pragma warning( disable : 4305 )
108#endif
109#include <math.h>
110#include "filters.h"
111
112
113
114/* ------------------- lowshelf ----------------------------*/
115
116static t_class *lowshelf_class;
117
118void lowshelf_bang(t_rbjfilter *x)
119{
120 t_atom at[5];
121 t_float omega = e_omega(x->x_freq,x->x_rate);
122 t_float A = e_A(x->x_gain);
123 t_float cs = cos(omega);
124 t_float sn = sin(omega);
125 t_float beta = e_beta(A,x->x_bw*0.01);
126
127 t_float b0 = A*((A+1) - (A-1)*cs + beta*sn);
128 t_float b1 = 2.*A*((A-1) - (A+1)*cs);
129 t_float b2 = A*((A+1) - (A-1)*cs - beta*sn);
130 t_float a0 = ((A+1) + (A-1)*cs + beta*sn);
131 t_float a1 = -2.*((A-1) + (A+1)*cs);
132 t_float a2 = ((A+1) + (A-1)*cs - beta*sn);
133
134/* post("bang %f %f %f",x->x_freq, x->x_gain, x->x_bw); */
135
136 if (!check_stability(-a1/a0,-a2/a0,b0/a0,b1/a0,b2/a0)) {
137 post("lowshelf: filter unstable -> resetting");
138 a0=1.;a1=0.;a2=0.;
139 b0=1.;b1=0.;b2=0.;
140 }
141
142 SETFLOAT(at,-a1/a0);
143 SETFLOAT(at+1,-a2/a0);
144 SETFLOAT(at+2,b0/a0);
145 SETFLOAT(at+3,b1/a0);
146 SETFLOAT(at+4,b2/a0);
147
148 outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
149}
150
151
152void lowshelf_float(t_rbjfilter *x,t_floatarg f)
153{
154 x->x_freq = f;
155 lowshelf_bang(x);
156}
157
158
159static void *lowshelf_new(t_floatarg f,t_floatarg g,t_floatarg bw)
160{
161 t_rbjfilter *x = (t_rbjfilter *)pd_new(lowshelf_class);
162
163 x->x_rate = 44100.0;
164 outlet_new(&x->x_obj,&s_float);
165 floatinlet_new(&x->x_obj, &x->x_gain);
166 floatinlet_new(&x->x_obj, &x->x_bw);
167 if (f > 0.) x->x_freq = f;
168 if (bw > 0.) x->x_bw = bw;
169 if (g != 0.) x->x_gain = g;
170 return (x);
171}
172
173
174void lowshelf_setup(void)
175{
176 lowshelf_class = class_new(gensym("lowshelf"), (t_newmethod)lowshelf_new, 0,
177 sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,A_DEFFLOAT,0);
178 class_addbang(lowshelf_class,lowshelf_bang);
179 class_addfloat(lowshelf_class,lowshelf_float);
180}
181
182