1/**************************************************************************/
2/* audio_effect_distortion.cpp */
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. */
10/* */
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13/* "Software"), to deal in the Software without restriction, including */
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21/* */
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29/**************************************************************************/
30
31#include "audio_effect_distortion.h"
32#include "core/math/math_funcs.h"
33#include "servers/audio_server.h"
34
35void AudioEffectDistortionInstance::process(const AudioFrame *p_src_frames, AudioFrame *p_dst_frames, int p_frame_count) {
36 const float *src = (const float *)p_src_frames;
37 float *dst = (float *)p_dst_frames;
38
39 //float lpf_c=expf(-Math_TAU*keep_hf_hz.get()/(mix_rate*(float)OVERSAMPLE));
40 float lpf_c = expf(-Math_TAU * base->keep_hf_hz / (AudioServer::get_singleton()->get_mix_rate()));
41 float lpf_ic = 1.0 - lpf_c;
42
43 float drive_f = base->drive;
44 float pregain_f = Math::db_to_linear(base->pre_gain);
45 float postgain_f = Math::db_to_linear(base->post_gain);
46
47 float atan_mult = pow(10, drive_f * drive_f * 3.0) - 1.0 + 0.001;
48 float atan_div = 1.0 / (atanf(atan_mult) * (1.0 + drive_f * 8));
49
50 float lofi_mult = powf(2.0, 2.0 + (1.0 - drive_f) * 14); //goes from 16 to 2 bits
51
52 for (int i = 0; i < p_frame_count * 2; i++) {
53 float out = undenormalize(src[i] * lpf_ic + lpf_c * h[i & 1]);
54 h[i & 1] = out;
55 float a = out;
56 float ha = src[i] - out; //high freqs
57 a *= pregain_f;
58
59 switch (base->mode) {
60 case AudioEffectDistortion::MODE_CLIP: {
61 float a_sign = a < 0 ? -1.0f : 1.0f;
62 a = powf(abs(a), 1.0001 - drive_f) * a_sign;
63 if (a > 1.0) {
64 a = 1.0;
65 } else if (a < (-1.0)) {
66 a = -1.0;
67 }
68
69 } break;
70 case AudioEffectDistortion::MODE_ATAN: {
71 a = atanf(a * atan_mult) * atan_div;
72
73 } break;
74 case AudioEffectDistortion::MODE_LOFI: {
75 a = floorf(a * lofi_mult + 0.5) / lofi_mult;
76
77 } break;
78 case AudioEffectDistortion::MODE_OVERDRIVE: {
79 const double x = a * 0.686306;
80 const double z = 1 + exp(sqrt(fabs(x)) * -0.75);
81 a = (expf(x) - expf(-x * z)) / (expf(x) + expf(-x));
82 } break;
83 case AudioEffectDistortion::MODE_WAVESHAPE: {
84 float x = a;
85 float k = 2 * drive_f / (1.00001 - drive_f);
86
87 a = (1.0 + k) * x / (1.0 + k * fabsf(x));
88
89 } break;
90 }
91
92 dst[i] = a * postgain_f + ha;
93 }
94}
95
96Ref<AudioEffectInstance> AudioEffectDistortion::instantiate() {
97 Ref<AudioEffectDistortionInstance> ins;
98 ins.instantiate();
99 ins->base = Ref<AudioEffectDistortion>(this);
100 ins->h[0] = 0;
101 ins->h[1] = 0;
102
103 return ins;
104}
105
106void AudioEffectDistortion::set_mode(Mode p_mode) {
107 mode = p_mode;
108}
109
110AudioEffectDistortion::Mode AudioEffectDistortion::get_mode() const {
111 return mode;
112}
113
114void AudioEffectDistortion::set_pre_gain(float p_pre_gain) {
115 pre_gain = p_pre_gain;
116}
117
118float AudioEffectDistortion::get_pre_gain() const {
119 return pre_gain;
120}
121
122void AudioEffectDistortion::set_keep_hf_hz(float p_keep_hf_hz) {
123 keep_hf_hz = p_keep_hf_hz;
124}
125
126float AudioEffectDistortion::get_keep_hf_hz() const {
127 return keep_hf_hz;
128}
129
130void AudioEffectDistortion::set_drive(float p_drive) {
131 drive = p_drive;
132}
133
134float AudioEffectDistortion::get_drive() const {
135 return drive;
136}
137
138void AudioEffectDistortion::set_post_gain(float p_post_gain) {
139 post_gain = p_post_gain;
140}
141
142float AudioEffectDistortion::get_post_gain() const {
143 return post_gain;
144}
145
146void AudioEffectDistortion::_bind_methods() {
147 ClassDB::bind_method(D_METHOD("set_mode", "mode"), &AudioEffectDistortion::set_mode);
148 ClassDB::bind_method(D_METHOD("get_mode"), &AudioEffectDistortion::get_mode);
149
150 ClassDB::bind_method(D_METHOD("set_pre_gain", "pre_gain"), &AudioEffectDistortion::set_pre_gain);
151 ClassDB::bind_method(D_METHOD("get_pre_gain"), &AudioEffectDistortion::get_pre_gain);
152
153 ClassDB::bind_method(D_METHOD("set_keep_hf_hz", "keep_hf_hz"), &AudioEffectDistortion::set_keep_hf_hz);
154 ClassDB::bind_method(D_METHOD("get_keep_hf_hz"), &AudioEffectDistortion::get_keep_hf_hz);
155
156 ClassDB::bind_method(D_METHOD("set_drive", "drive"), &AudioEffectDistortion::set_drive);
157 ClassDB::bind_method(D_METHOD("get_drive"), &AudioEffectDistortion::get_drive);
158
159 ClassDB::bind_method(D_METHOD("set_post_gain", "post_gain"), &AudioEffectDistortion::set_post_gain);
160 ClassDB::bind_method(D_METHOD("get_post_gain"), &AudioEffectDistortion::get_post_gain);
161
162 ADD_PROPERTY(PropertyInfo(Variant::INT, "mode", PROPERTY_HINT_ENUM, "Clip,ATan,LoFi,Overdrive,Wave Shape"), "set_mode", "get_mode");
163 ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "pre_gain", PROPERTY_HINT_RANGE, "-60,60,0.01,suffix:dB"), "set_pre_gain", "get_pre_gain");
164 ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "keep_hf_hz", PROPERTY_HINT_RANGE, "1,20500,1,suffix:Hz"), "set_keep_hf_hz", "get_keep_hf_hz");
165 ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "drive", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_drive", "get_drive");
166 ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "post_gain", PROPERTY_HINT_RANGE, "-80,24,0.01,suffix:dB"), "set_post_gain", "get_post_gain");
167
168 BIND_ENUM_CONSTANT(MODE_CLIP);
169 BIND_ENUM_CONSTANT(MODE_ATAN);
170 BIND_ENUM_CONSTANT(MODE_LOFI);
171 BIND_ENUM_CONSTANT(MODE_OVERDRIVE);
172 BIND_ENUM_CONSTANT(MODE_WAVESHAPE);
173}
174
175AudioEffectDistortion::AudioEffectDistortion() {
176 mode = MODE_CLIP;
177 pre_gain = 0;
178 post_gain = 0;
179 keep_hf_hz = 16000;
180 drive = 0;
181}
182