1/**************************************************************************/
2/* eq_filter.h */
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. */
10/* */
11/* Permission is hereby granted, free of charge, to any person obtaining */
12/* a copy of this software and associated documentation files (the */
13/* "Software"), to deal in the Software without restriction, including */
14/* without limitation the rights to use, copy, modify, merge, publish, */
15/* distribute, sublicense, and/or sell copies of the Software, and to */
16/* permit persons to whom the Software is furnished to do so, subject to */
17/* the following conditions: */
18/* */
19/* The above copyright notice and this permission notice shall be */
20/* included in all copies or substantial portions of the Software. */
21/* */
22/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
23/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
24/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
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27/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
28/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
29/**************************************************************************/
30
31#ifndef EQ_FILTER_H
32#define EQ_FILTER_H
33
34#include "core/templates/vector.h"
35#include "core/typedefs.h"
36
37class EQ {
38public:
39 enum Preset {
40 PRESET_6_BANDS,
41 PRESET_8_BANDS,
42 PRESET_10_BANDS,
43 PRESET_21_BANDS,
44 PRESET_31_BANDS
45 };
46
47 class BandProcess {
48 friend class EQ;
49 float c1, c2, c3;
50 struct History {
51 float a1, a2, a3;
52 float b1, b2, b3;
53
54 } history;
55
56 public:
57 inline void process_one(float &p_data);
58
59 BandProcess();
60 };
61
62private:
63 struct Band {
64 float freq;
65 float c1, c2, c3;
66 };
67
68 Vector<Band> band;
69
70 float mix_rate;
71
72 void recalculate_band_coefficients();
73
74public:
75 void set_mix_rate(float p_mix_rate);
76
77 int get_band_count() const;
78 void set_preset_band_mode(Preset p_preset);
79 void set_bands(const Vector<float> &p_bands);
80 BandProcess get_band_processor(int p_band) const;
81 float get_band_frequency(int p_band);
82
83 EQ();
84 ~EQ();
85};
86
87/* Inline Function */
88
89inline void EQ::BandProcess::process_one(float &p_data) {
90 history.a1 = p_data;
91
92 history.b1 = c1 * (history.a1 - history.a3) + c3 * history.b2 - c2 * history.b3;
93
94 p_data = history.b1;
95
96 history.a3 = history.a2;
97 history.a2 = history.a1;
98 history.b3 = history.b2;
99 history.b2 = history.b1;
100}
101
102#endif // EQ_FILTER_H
103