1/**************************************************************************/
2/* audio_filter_sw.h */
3/**************************************************************************/
4/* This file is part of: */
5/* GODOT ENGINE */
6/* https://godotengine.org */
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8/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
9/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
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29/**************************************************************************/
30
31#ifndef AUDIO_FILTER_SW_H
32#define AUDIO_FILTER_SW_H
33
34#include "core/math/math_funcs.h"
35
36class AudioFilterSW {
37public:
38 struct Coeffs {
39 float a1 = 0.0f;
40 float a2 = 0.0f;
41 float b0 = 0.0f;
42 float b1 = 0.0f;
43 float b2 = 0.0f;
44 };
45
46 enum Mode {
47 BANDPASS,
48 HIGHPASS,
49 LOWPASS,
50 NOTCH,
51 PEAK,
52 BANDLIMIT,
53 LOWSHELF,
54 HIGHSHELF
55 };
56
57 class Processor { // Simple filter processor.
58 AudioFilterSW *filter = nullptr;
59 Coeffs coeffs;
60 // History.
61 float ha1 = 0.0f;
62 float ha2 = 0.0f;
63 float hb1 = 0.0f;
64 float hb2 = 0.0f;
65 Coeffs incr_coeffs;
66
67 public:
68 void set_filter(AudioFilterSW *p_filter, bool p_clear_history = true);
69 void process(float *p_samples, int p_amount, int p_stride = 1, bool p_interpolate = false);
70 void update_coeffs(int p_interp_buffer_len = 0);
71 _ALWAYS_INLINE_ void process_one(float &p_sample);
72 _ALWAYS_INLINE_ void process_one_interp(float &p_sample);
73
74 Processor();
75 };
76
77private:
78 float cutoff = 5000.0f;
79 float resonance = 0.5f;
80 float gain = 1.0f;
81 float sampling_rate = 44100.0f;
82 int stages = 1;
83 Mode mode = LOWPASS;
84
85public:
86 float get_response(float p_freq, Coeffs *p_coeffs);
87
88 void set_mode(Mode p_mode);
89 void set_cutoff(float p_cutoff);
90 void set_resonance(float p_resonance);
91 void set_gain(float p_gain);
92 void set_sampling_rate(float p_srate);
93 void set_stages(int p_stages); //adjust for multiple stages
94
95 void prepare_coefficients(Coeffs *p_coeffs);
96
97 AudioFilterSW() {}
98};
99
100/* inline methods */
101
102void AudioFilterSW::Processor::process_one(float &p_sample) {
103 float pre = p_sample;
104 p_sample = (p_sample * coeffs.b0 + hb1 * coeffs.b1 + hb2 * coeffs.b2 + ha1 * coeffs.a1 + ha2 * coeffs.a2);
105 ha2 = ha1;
106 hb2 = hb1;
107 hb1 = pre;
108 ha1 = p_sample;
109}
110
111void AudioFilterSW::Processor::process_one_interp(float &p_sample) {
112 float pre = p_sample;
113 p_sample = (p_sample * coeffs.b0 + hb1 * coeffs.b1 + hb2 * coeffs.b2 + ha1 * coeffs.a1 + ha2 * coeffs.a2);
114 ha2 = ha1;
115 hb2 = hb1;
116 hb1 = pre;
117 ha1 = p_sample;
118
119 coeffs.b0 += incr_coeffs.b0;
120 coeffs.b1 += incr_coeffs.b1;
121 coeffs.b2 += incr_coeffs.b2;
122 coeffs.a1 += incr_coeffs.a1;
123 coeffs.a2 += incr_coeffs.a2;
124}
125
126#endif // AUDIO_FILTER_SW_H
127