1/**************************************************************************/
2/* eq_filter.cpp */
3/**************************************************************************/
4/* This file is part of: */
5/* GODOT ENGINE */
6/* https://godotengine.org */
7/**************************************************************************/
8/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
9/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
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21/* */
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29/**************************************************************************/
30
31#include "eq_filter.h"
32
33#include "core/error/error_macros.h"
34#include "core/math/math_funcs.h"
35
36#include <math.h>
37
38#define POW2(v) ((v) * (v))
39
40/* Helper */
41static int solve_quadratic(double a, double b, double c, double *r1, double *r2) {
42 //solves quadractic and returns number of roots
43
44 double base = 2 * a;
45 if (base == 0.0f) {
46 return 0;
47 }
48
49 double squared = b * b - 4 * a * c;
50 if (squared < 0.0) {
51 return 0;
52 }
53
54 squared = sqrt(squared);
55
56 *r1 = (-b + squared) / base;
57 *r2 = (-b - squared) / base;
58
59 if (*r1 == *r2) {
60 return 1;
61 } else {
62 return 2;
63 }
64}
65
66EQ::BandProcess::BandProcess() {
67 c1 = c2 = c3 = history.a1 = history.a2 = history.a3 = 0;
68 history.b1 = history.b2 = history.b3 = 0;
69}
70
71void EQ::recalculate_band_coefficients() {
72#define BAND_LOG(m_f) (log((m_f)) / log(2.))
73
74 for (int i = 0; i < band.size(); i++) {
75 double octave_size;
76
77 double frq = band[i].freq;
78
79 if (i == 0) {
80 octave_size = BAND_LOG(band[1].freq) - BAND_LOG(frq);
81 } else if (i == (band.size() - 1)) {
82 octave_size = BAND_LOG(frq) - BAND_LOG(band[i - 1].freq);
83 } else {
84 double next = BAND_LOG(band[i + 1].freq) - BAND_LOG(frq);
85 double prev = BAND_LOG(frq) - BAND_LOG(band[i - 1].freq);
86 octave_size = (next + prev) / 2.0;
87 }
88
89 double frq_l = round(frq / pow(2.0, octave_size / 2.0));
90
91 double side_gain2 = POW2(Math_SQRT12);
92 double th = Math_TAU * frq / mix_rate;
93 double th_l = Math_TAU * frq_l / mix_rate;
94
95 double c2a = side_gain2 * POW2(cos(th)) - 2.0 * side_gain2 * cos(th_l) * cos(th) + side_gain2 - POW2(sin(th_l));
96
97 double c2b = 2.0 * side_gain2 * POW2(cos(th_l)) + side_gain2 * POW2(cos(th)) - 2.0 * side_gain2 * cos(th_l) * cos(th) - side_gain2 + POW2(sin(th_l));
98
99 double c2c = 0.25 * side_gain2 * POW2(cos(th)) - 0.5 * side_gain2 * cos(th_l) * cos(th) + 0.25 * side_gain2 - 0.25 * POW2(sin(th_l));
100
101 //printf("band %i, precoefs = %f,%f,%f\n",i,c2a,c2b,c2c);
102
103 // Default initializing to silence compiler warning about potential uninitialized use.
104 // Both variables are properly set in _solve_quadratic before use, or we continue if roots == 0.
105 double r1 = 0, r2 = 0; //roots
106 int roots = solve_quadratic(c2a, c2b, c2c, &r1, &r2);
107
108 ERR_CONTINUE(roots == 0);
109
110 band.write[i].c1 = 2.0 * ((0.5 - r1) / 2.0);
111 band.write[i].c2 = 2.0 * r1;
112 band.write[i].c3 = 2.0 * (0.5 + r1) * cos(th);
113 //printf("band %i, coefs = %f,%f,%f\n",i,(float)bands[i].c1,(float)bands[i].c2,(float)bands[i].c3);
114 }
115}
116
117void EQ::set_preset_band_mode(Preset p_preset) {
118 band.clear();
119
120#define PUSH_BANDS(m_bands) \
121 for (int i = 0; i < m_bands; i++) { \
122 Band b; \
123 b.freq = bands[i]; \
124 b.c1 = b.c2 = b.c3 = 0; \
125 band.push_back(b); \
126 }
127
128 switch (p_preset) {
129 case PRESET_6_BANDS: {
130 static const double bands[] = { 32, 100, 320, 1e3, 3200, 10e3 };
131 PUSH_BANDS(6);
132
133 } break;
134
135 case PRESET_8_BANDS: {
136 static const double bands[] = { 32, 72, 192, 512, 1200, 3000, 7500, 16e3 };
137
138 PUSH_BANDS(8);
139 } break;
140
141 case PRESET_10_BANDS: {
142 static const double bands[] = { 31.25, 62.5, 125, 250, 500, 1e3, 2e3, 4e3, 8e3, 16e3 };
143
144 PUSH_BANDS(10);
145
146 } break;
147
148 case PRESET_21_BANDS: {
149 static const double bands[] = { 22, 32, 44, 63, 90, 125, 175, 250, 350, 500, 700, 1e3, 1400, 2e3, 2800, 4e3, 5600, 8e3, 11e3, 16e3, 22e3 };
150 PUSH_BANDS(21);
151
152 } break;
153
154 case PRESET_31_BANDS: {
155 static const double bands[] = { 20, 25, 31.5, 40, 50, 63, 80, 100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1e3, 1250, 1600, 2e3, 2500, 3150, 4e3, 5e3, 6300, 8e3, 10e3, 12500, 16e3, 20e3 };
156 PUSH_BANDS(31);
157 } break;
158 };
159
160 recalculate_band_coefficients();
161}
162
163int EQ::get_band_count() const {
164 return band.size();
165}
166
167float EQ::get_band_frequency(int p_band) {
168 ERR_FAIL_INDEX_V(p_band, band.size(), 0);
169 return band[p_band].freq;
170}
171
172void EQ::set_bands(const Vector<float> &p_bands) {
173 band.resize(p_bands.size());
174 for (int i = 0; i < p_bands.size(); i++) {
175 band.write[i].freq = p_bands[i];
176 }
177
178 recalculate_band_coefficients();
179}
180
181void EQ::set_mix_rate(float p_mix_rate) {
182 mix_rate = p_mix_rate;
183 recalculate_band_coefficients();
184}
185
186EQ::BandProcess EQ::get_band_processor(int p_band) const {
187 EQ::BandProcess band_proc;
188
189 ERR_FAIL_INDEX_V(p_band, band.size(), band_proc);
190
191 band_proc.c1 = band[p_band].c1;
192 band_proc.c2 = band[p_band].c2;
193 band_proc.c3 = band[p_band].c3;
194
195 return band_proc;
196}
197
198EQ::EQ() {
199 mix_rate = 44100;
200}
201
202EQ::~EQ() {
203}
204