95 lines
2.1 KiB
C
95 lines
2.1 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 */
|
|
|
|
/* ------------------- bandpass ----------------------------*/
|
|
|
|
static t_class *bandpass_class;
|
|
|
|
void bandpass_bang(t_rbjfilter *x)
|
|
{
|
|
t_atom at[5];
|
|
t_float omega = e_omega(x->x_freq,x->x_rate);
|
|
t_float alpha = e_alpha(x->x_bw* 0.01,omega);
|
|
t_float b1 = 0.;
|
|
t_float b0 = alpha;
|
|
t_float b2 = -alpha;
|
|
t_float a0 = 1 + alpha;
|
|
t_float a1 = -2.*cos(omega);
|
|
t_float a2 = 1 - alpha;
|
|
|
|
/* 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("bandpass: 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 bandpass_float(t_rbjfilter *x,t_floatarg f)
|
|
{
|
|
x->x_freq = f;
|
|
bandpass_bang(x);
|
|
}
|
|
|
|
|
|
static void *bandpass_new(t_floatarg f,t_floatarg bw)
|
|
{
|
|
t_rbjfilter *x = (t_rbjfilter *)pd_new(bandpass_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;
|
|
return (x);
|
|
}
|
|
|
|
|
|
void bandpass_setup(void)
|
|
{
|
|
bandpass_class = class_new(gensym("bandpass"), (t_newmethod)bandpass_new, 0,
|
|
sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,0);
|
|
class_addbang(bandpass_class,bandpass_bang);
|
|
class_addfloat(bandpass_class,bandpass_float);
|
|
}
|
|
|
|
|
|
|
|
|