summaryrefslogtreecommitdiffstatshomepage
path: root/src/emu/audio_effects/filter.cpp
blob: 3f71d44b89d349009c38ed16a0c5d1320d337880 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
// license:BSD-3-Clause
// copyright-holders:Olivier Galibert

#include "emu.h"
#include "filter.h"
#include "xmlfile.h"

// This effect implements a couple of very standard biquad filters,
// one lowpass and one highpass.

// Formulas taken from:

// [Zölzer 2011] "DAFX: Digital Audio Effects", Udo Zölzer, Second Edition, Wiley publishing, 2011 (Table 2.2)


audio_effect_filter::audio_effect_filter(speaker_device *speaker, u32 sample_rate, audio_effect *def) :
	audio_effect(speaker, sample_rate, def)
{
	m_history.resize(m_channels);

	// Minimal init to avoid using uninitialized values when reset_*
	// recomputes filters
	m_fl = m_fh = 1000;
	m_ql = m_qh = DEFAULT_Q;

	reset_all();
}

void audio_effect_filter::reset_lowpass_active()
{
	audio_effect_filter *d = static_cast<audio_effect_filter *>(m_default);
	m_isset_lowpass_active = false;
	m_lowpass_active = d ? d->lowpass_active() : false;
	build_lowpass();
}

void audio_effect_filter::reset_highpass_active()
{
	audio_effect_filter *d = static_cast<audio_effect_filter *>(m_default);
	m_isset_highpass_active = false;
	m_highpass_active = d ? d->highpass_active() : true;
	build_highpass();
}

void audio_effect_filter::reset_fl()
{
	audio_effect_filter *d = static_cast<audio_effect_filter *>(m_default);
	m_isset_fl = false;
	m_fl = d ? d->fl() : 8000;
	build_lowpass();
}

void audio_effect_filter::reset_ql()
{
	audio_effect_filter *d = static_cast<audio_effect_filter *>(m_default);
	m_isset_ql = false;
	m_ql = d ? d->ql() : DEFAULT_Q;
	build_lowpass();
}

void audio_effect_filter::reset_fh()
{
	audio_effect_filter *d = static_cast<audio_effect_filter *>(m_default);
	m_isset_fh = false;
	m_fh = d ? d->fh() : 20;
	build_highpass();
}

void audio_effect_filter::reset_qh()
{
	audio_effect_filter *d = static_cast<audio_effect_filter *>(m_default);
	m_isset_qh = false;
	m_qh = d ? d->qh() : DEFAULT_Q;
	build_highpass();
}

void audio_effect_filter::reset_all()
{
	reset_lowpass_active();
	reset_highpass_active();
	reset_fl();
	reset_fh();
	reset_ql();
	reset_qh();
}

void audio_effect_filter::config_load(util::xml::data_node const *ef_node)
{
	if(ef_node->has_attribute("lowpass_active")) {
		m_lowpass_active = ef_node->get_attribute_int("lowpass_active", 0);
		m_isset_lowpass_active = true;
	} else
		reset_lowpass_active();

	if(ef_node->has_attribute("fl")) {
		m_fl = ef_node->get_attribute_int("fl", 0);
		m_isset_fl = true;
	} else
		reset_fl();

	if(ef_node->has_attribute("ql")) {
		m_ql = ef_node->get_attribute_float("ql", 0);
		m_isset_ql = true;
	} else
		reset_ql();

	if(ef_node->has_attribute("highpass_active")) {
		m_highpass_active = ef_node->get_attribute_int("highpass_active", 0);
		m_isset_highpass_active = true;
	} else
		reset_highpass_active();

	if(ef_node->has_attribute("fh")) {
		m_fh = ef_node->get_attribute_int("fh", 0);
		m_isset_fh = true;
	} else
		reset_fh();

	if(ef_node->has_attribute("qh")) {
		m_qh = ef_node->get_attribute_float("qh", 0);
		m_isset_qh = true;
	} else
		reset_qh();

	build_highpass();
	build_lowpass();
}

void audio_effect_filter::config_save(util::xml::data_node *ef_node) const
{
	if(m_isset_lowpass_active)
		ef_node->set_attribute_int("lowpass_active", m_lowpass_active);
	if(m_isset_fl)
		ef_node->set_attribute_int("fl", m_fl);
	if(m_isset_ql)
		ef_node->set_attribute_float("ql", m_ql);
	if(m_isset_highpass_active)
		ef_node->set_attribute_int("highpass_active", m_highpass_active);
	if(m_isset_fh)
		ef_node->set_attribute_int("fh", m_fh);
	if(m_isset_qh)
		ef_node->set_attribute_float("qh", m_qh);
}

void audio_effect_filter::default_changed()
{
	if(!m_isset_lowpass_active)
		reset_lowpass_active();
	if(!m_isset_highpass_active)
		reset_highpass_active();
	if(!m_isset_fl)
		reset_fl();
	if(!m_isset_fh)
		reset_fh();
	if(!m_isset_ql)
		reset_ql();
	if(!m_isset_qh)
		reset_qh();
}

void audio_effect_filter::apply(const emu::detail::output_buffer_flat<sample_t> &src, emu::detail::output_buffer_flat<sample_t> &dest)
{
	if(!m_lowpass_active && !m_highpass_active) {
		copy(src, dest);
		return;
	}

	u32 samples = src.available_samples();
	dest.prepare_space(samples);

	for(u32 channel = 0; channel != m_channels; channel++) {
		const sample_t *srcd = src.ptrs(channel, 0);
		sample_t *destd = dest.ptrw(channel, 0);
		for(u32 sample = 0; sample != samples; sample++) {
			m_history[channel][0].push(*srcd++);
			m_filter[0].apply(m_history[channel][0], m_history[channel][1]);
			m_filter[1].apply(m_history[channel][1], m_history[channel][2]);
			*destd++ = m_history[channel][2].m_v0;
		}
	}

	dest.commit(samples);
}

void audio_effect_filter::set_lowpass_active(bool active)
{
	m_isset_lowpass_active = true;
	m_lowpass_active = active;
	build_lowpass();
}

void audio_effect_filter::set_highpass_active(bool active)
{
	m_isset_highpass_active = true;
	m_highpass_active = active;
	build_highpass();
}

void audio_effect_filter::set_fl(u32 f)
{
	m_isset_fl = true;
	m_fl = f;
	build_lowpass();
}

void audio_effect_filter::set_fh(u32 f)
{
	m_isset_fh = true;
	m_fh = f;
	build_highpass();
}

void audio_effect_filter::set_ql(float q)
{
	m_isset_ql = true;
	m_ql = q;
	build_lowpass();
}

void audio_effect_filter::set_qh(float q)
{
	m_isset_qh = true;
	m_qh = q;
	build_highpass();
}

void audio_effect_filter::build_highpass()
{
	auto &fi = m_filter[0];
	if(!m_highpass_active) {
		fi.clear();
		return;
	}

	float sr = m_sample_rate;
	float fh = std::clamp(float(m_fh), 1.0f, sr/2.0f - 1.0f);

	float K = tan(M_PI*fh/sr);
	float K2 = K*K;
	float Q = m_qh;

	float d = K2*Q + K + Q;
	fi.m_b0 = Q/d;
	fi.m_b1 = -2*Q/d;
	fi.m_b2 = fi.m_b0;
	fi.m_a1 = 2*Q*(K2-1)/d;
	fi.m_a2 = (K2*Q - K + Q)/d;
}

void audio_effect_filter::build_lowpass()
{
	auto &fi = m_filter[1];
	if(!m_lowpass_active) {
		fi.clear();
		return;
	}

	float sr = m_sample_rate;
	float fl = std::clamp(float(m_fl), 1.0f, sr/2.0f - 1.0f);

	float K = tan(M_PI*fl/sr);
	float K2 = K*K;
	float Q = m_ql;

	float d = K2*Q + K + Q;
	fi.m_b0 = K2*Q/d;
	fi.m_b1 = 2*K2*Q /d;
	fi.m_b2 = fi.m_b0;
	fi.m_a1 = 2*Q*(K2-1)/d;
	fi.m_a2 = (K2*Q - K + Q)/d;
}