98 lines
2.3 KiB
C
98 lines
2.3 KiB
C
/* (C) Guenter Geiger <geiger@epy.co.at> */
|
|
|
|
|
|
/*
|
|
|
|
These filter coefficients computations are taken from
|
|
http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt
|
|
|
|
written by Robert Bristow-Johnson
|
|
|
|
*/
|
|
|
|
#ifdef ROCKBOX
|
|
#include "plugin.h"
|
|
#include "../../pdbox.h"
|
|
#include "../src/m_pd.h"
|
|
#include "../../math.h"
|
|
#include "filters.h"
|
|
#else /* ROCKBOX */
|
|
#include "../src/m_pd.h"
|
|
#ifdef NT
|
|
#pragma warning( disable : 4244 )
|
|
#pragma warning( disable : 4305 )
|
|
#endif
|
|
#include <math.h>
|
|
#include "filters.h"
|
|
#endif /* ROCKBOX */
|
|
|
|
|
|
/* ------------------- lowshelf ----------------------------*/
|
|
|
|
static t_class *lowshelf_class;
|
|
|
|
void lowshelf_bang(t_rbjfilter *x)
|
|
{
|
|
t_atom at[5];
|
|
t_float omega = e_omega(x->x_freq,x->x_rate);
|
|
t_float A = e_A(x->x_gain);
|
|
t_float cs = cos(omega);
|
|
t_float sn = sin(omega);
|
|
t_float beta = e_beta(A,x->x_bw*0.01);
|
|
|
|
t_float b0 = A*((A+1) - (A-1)*cs + beta*sn);
|
|
t_float b1 = 2.*A*((A-1) - (A+1)*cs);
|
|
t_float b2 = A*((A+1) - (A-1)*cs - beta*sn);
|
|
t_float a0 = ((A+1) + (A-1)*cs + beta*sn);
|
|
t_float a1 = -2.*((A-1) + (A+1)*cs);
|
|
t_float a2 = ((A+1) + (A-1)*cs - beta*sn);
|
|
|
|
/* post("bang %f %f %f",x->x_freq, x->x_gain, x->x_bw); */
|
|
|
|
if (!check_stability(-a1/a0,-a2/a0,b0/a0,b1/a0,b2/a0)) {
|
|
post("lowshelf: filter unstable -> resetting");
|
|
a0=1.;a1=0.;a2=0.;
|
|
b0=1.;b1=0.;b2=0.;
|
|
}
|
|
|
|
SETFLOAT(at,-a1/a0);
|
|
SETFLOAT(at+1,-a2/a0);
|
|
SETFLOAT(at+2,b0/a0);
|
|
SETFLOAT(at+3,b1/a0);
|
|
SETFLOAT(at+4,b2/a0);
|
|
|
|
outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
|
|
}
|
|
|
|
|
|
void lowshelf_float(t_rbjfilter *x,t_floatarg f)
|
|
{
|
|
x->x_freq = f;
|
|
lowshelf_bang(x);
|
|
}
|
|
|
|
|
|
static void *lowshelf_new(t_floatarg f,t_floatarg g,t_floatarg bw)
|
|
{
|
|
t_rbjfilter *x = (t_rbjfilter *)pd_new(lowshelf_class);
|
|
|
|
x->x_rate = 44100.0;
|
|
outlet_new(&x->x_obj,&s_float);
|
|
floatinlet_new(&x->x_obj, &x->x_gain);
|
|
floatinlet_new(&x->x_obj, &x->x_bw);
|
|
if (f > 0.) x->x_freq = f;
|
|
if (bw > 0.) x->x_bw = bw;
|
|
if (g != 0.) x->x_gain = g;
|
|
return (x);
|
|
}
|
|
|
|
|
|
void lowshelf_setup(void)
|
|
{
|
|
lowshelf_class = class_new(gensym("lowshelf"), (t_newmethod)lowshelf_new, 0,
|
|
sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,A_DEFFLOAT,0);
|
|
class_addbang(lowshelf_class,lowshelf_bang);
|
|
class_addfloat(lowshelf_class,lowshelf_float);
|
|
}
|
|
|
|
|