tsiry-sandratraina.com
A modern Music Player Daemon based on Rockbox open source high quality audio player
libadwaita
audio
rust
zig
deno
mpris
rockbox
mpd
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#ifdef ROCKBOX
14#include "plugin.h"
15#include "../../pdbox.h"
16#include "../src/m_pd.h"
17#include "../../math.h"
18#include "filters.h"
19#else /* ROCKBOX */
20#include "../src/m_pd.h"
21#ifdef NT
22#pragma warning( disable : 4244 )
23#pragma warning( disable : 4305 )
24#endif
25#include <math.h>
26#include "filters.h"
27#endif /* ROCKBOX */
28
29
30/* ------------------- equ ----------------------------*/
31static t_class *equ_class;
32
33void equ_bang(t_rbjfilter *x)
34{
35 t_atom at[5];
36 t_float omega = e_omega(x->x_freq,x->x_rate);
37 t_float alpha = e_alpha(x->x_bw*0.01,omega);
38 t_float b0 = 1 + alpha*e_A(x->x_gain);
39 t_float b1 = -2.*cos(omega);
40 t_float b2 = 1 - alpha*e_A(x->x_gain);
41 t_float a0 = 1 + alpha/e_A(x->x_gain);
42 t_float a1 = -2.*cos(omega);
43 t_float a2 = 1 - alpha/e_A(x->x_gain);
44
45/* post("bang %f %f %f",x->x_freq, x->x_gain, x->x_bw);*/
46
47 if (!check_stability(-a1/a0,-a2/a0,b0/a0,b1/a0,b2/a0)) {
48 post("equ: filter unstable -> resetting");
49 a0=1.;a1=0.;a2=0.;
50 b0=1.;b1=0.;b2=0.;
51 }
52
53 SETFLOAT(at,-a1/a0);
54 SETFLOAT(at+1,-a2/a0);
55 SETFLOAT(at+2,b0/a0);
56 SETFLOAT(at+3,b1/a0);
57 SETFLOAT(at+4,b2/a0);
58
59 outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
60}
61
62
63void equ_float(t_rbjfilter *x,t_floatarg f)
64{
65 x->x_freq = f;
66 equ_bang(x);
67}
68
69
70static void *equ_new(t_floatarg f,t_floatarg g,t_floatarg bw)
71{
72 t_rbjfilter *x = (t_rbjfilter *)pd_new(equ_class);
73
74 x->x_rate = 44100.0;
75 outlet_new(&x->x_obj,&s_float);
76 floatinlet_new(&x->x_obj, &x->x_gain);
77 floatinlet_new(&x->x_obj, &x->x_bw);
78 if (f > 0.) x->x_freq = f;
79 if (bw > 0.) x->x_bw = bw;
80 if (g != 0.) x->x_gain = g;
81 return (x);
82}
83
84
85void equalizer_setup(void)
86{
87 equ_class = class_new(gensym("equalizer"), (t_newmethod)equ_new, 0,
88 sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,A_DEFFLOAT,0);
89 class_addbang(equ_class,equ_bang);
90 class_addfloat(equ_class,equ_float);
91}
92
93