Commit bcf997fd1504ceda8deefbf5675c8a0e8623651b
2020-02-17T08:08:06
Butterworth bandpass second order filter
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
diff --git a/Makefile.am b/Makefile.am
index d68670e..49621d9 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -89,6 +89,7 @@ lib_LTLIBRARIES += librtbuf_signal.la
librtbuf_signal_la_LIBADD = ${SIGNAL_LIBS} librtbuf_music.la librtbuf.la
librtbuf_signal_la_SOURCES = \
rtbuf_signal.c \
+ rtbuf_signal_bandpass2.c \
rtbuf_signal_delay.c \
rtbuf_signal_flanger.c \
rtbuf_signal_hipass.c \
diff --git a/rtbuf_signal.c b/rtbuf_signal.c
index ffeaa10..c679dab 100644
--- a/rtbuf_signal.c
+++ b/rtbuf_signal.c
@@ -27,6 +27,24 @@ const double g_rtbuf_signal_sample_half = 0.5;
const double g_rtbuf_signal_sample_one = 1.0;
const double g_rtbuf_signal_default_frequency = 220.0;
+s_rtbuf_lib_proc_in g_rtbuf_signal_bandpass2_in[] = {
+ { "signal", RTBUF_SIGNAL_TYPE, 0.0, -1.0, 1.0 },
+ { "cutoff", RTBUF_SIGNAL_TYPE, 400.0, 0.0, RTBUF_SIGNAL_SAMPLERATE / 2.0 },
+ { "qfactor", RTBUF_SIGNAL_TYPE, 1.0, 0.0, 1000.0 },
+ { 0, 0, 0.0, 0.0, 0.0 } };
+
+s_rtbuf_lib_proc_out g_rtbuf_signal_bandpass2_out[] = {
+ { "signal", RTBUF_SIGNAL_TYPE },
+ { "x1", RTBUF_SIGNAL_SAMPLE_TYPE },
+ { "x2", RTBUF_SIGNAL_SAMPLE_TYPE },
+ { "x3", RTBUF_SIGNAL_SAMPLE_TYPE },
+ { "x4", RTBUF_SIGNAL_SAMPLE_TYPE },
+ { "y1", RTBUF_SIGNAL_SAMPLE_TYPE },
+ { "y2", RTBUF_SIGNAL_SAMPLE_TYPE },
+ { "y3", RTBUF_SIGNAL_SAMPLE_TYPE },
+ { "y4", RTBUF_SIGNAL_SAMPLE_TYPE },
+ { 0, 0 } };
+
s_rtbuf_lib_proc_in g_rtbuf_signal_delay_in[] = {
{ "signal", RTBUF_SIGNAL_TYPE, 0.0, -1.0, 1.0 },
{ "delay", RTBUF_SIGNAL_TYPE, 0.4, 0.0, RTBUF_SIGNAL_DELAY_MAX },
@@ -229,6 +247,8 @@ s_rtbuf_lib_proc_out g_rtbuf_signal_square_out[] = {
const char *rtbuf_lib_name = "signal";
unsigned long rtbuf_lib_ver = RTBUF_LIB_VER;
s_rtbuf_lib_proc rtbuf_lib_proc[] = {
+ { "bandpass2", rtbuf_signal_bandpass2, rtbuf_signal_bandpass2_start, 0,
+ g_rtbuf_signal_bandpass2_in, g_rtbuf_signal_bandpass2_out },
{ "delay", rtbuf_signal_delay, rtbuf_signal_delay_start, 0,
g_rtbuf_signal_delay_in, g_rtbuf_signal_delay_out },
{ "flanger", rtbuf_signal_flanger, rtbuf_signal_flanger_start, 0,
diff --git a/rtbuf_signal.h b/rtbuf_signal.h
index 60b06ba..e74c0a4 100644
--- a/rtbuf_signal.h
+++ b/rtbuf_signal.h
@@ -59,6 +59,32 @@ const double g_rtbuf_signal_sample_one;
const double g_rtbuf_signal_sample_2pi;
const double g_rtbuf_signal_default_frequency;
+/* butterworth bandpass filter, second order */
+
+#pragma pack(push,1)
+typedef struct rtbuf_signal_bandpass2_data {
+ t_rtbuf_signal signal;
+ t_rtbuf_signal_sample x1;
+ t_rtbuf_signal_sample x2;
+ t_rtbuf_signal_sample x3;
+ t_rtbuf_signal_sample x4;
+ t_rtbuf_signal_sample y1;
+ t_rtbuf_signal_sample y2;
+ t_rtbuf_signal_sample y3;
+ t_rtbuf_signal_sample y4;
+} s_rtbuf_signal_bandpass2_data;
+#pragma pack(pop)
+
+enum {
+ RTBUF_SIGNAL_BANDPASS_IN_SIGNAL = 0,
+ RTBUF_SIGNAL_BANDPASS_IN_CUTOFF,
+ RTBUF_SIGNAL_BANDPASS_IN_QFACTOR,
+ RTBUF_SIGNAL_BANDPASS_INS
+};
+
+int rtbuf_signal_bandpass2 (s_rtbuf *rtb);
+int rtbuf_signal_bandpass2_start (s_rtbuf *rtb);
+
/* delay */
#define RTBUF_SIGNAL_DELAY_MAX 10
diff --git a/rtbuf_signal_bandpass2.c b/rtbuf_signal_bandpass2.c
new file mode 100644
index 0000000..cde5741
--- /dev/null
+++ b/rtbuf_signal_bandpass2.c
@@ -0,0 +1,134 @@
+/*
+ * Copyright 2020 Thomas de Grivel <thoxdg@gmail.com> +33614550127
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+/* Butterworth bandpass second order filter
+s: 2*f*(1-z)/(1+z) $
+B2: (q*(s/w+w/s))^2+sqrt(2)*(q*(s/w+w/s))+1 $
+H: 1/B2 $
+ratsimp(H);
+ 2 2 4 2 2 2 2 2
+(%o25) (4 f w z - 8 f w z + 4 f w )
+ 2 4 3/2 3 2 2 2 2 7/2 3 4 2 4
+/((q w - 2 f q w + (8 f q + 4 f ) w - 2 f q w + 16 f q ) z
+ 2 4 5/2 3 9/2 3 4 2 3
+ + (4 q w - 2 f q w + 2 f q w - 64 f q ) z
+ 2 4 2 2 2 2 4 2 2
+ + (6 q w + ((- 16 f q ) - 8 f ) w + 96 f q ) z
+ 2 4 5/2 3 9/2 3 4 2 2 4 3/2 3
+ + (4 q w + 2 f q w - 2 f q w - 64 f q ) z + q w + 2 f q w
+ 2 2 2 2 7/2 3 4 2
+ + (8 f q + 4 f ) w + 2 f q w + 16 f q )
+
+a: q2 w4 + sqrt(2)^3 f q w3 + (8 f2 q2 + 4 f2) w2 + sqrt(2)^7 f3 q w + 16 f4 q2;
+b: 4 q2 w4 + sqrt(2)^5 f q w3 - sqrt(2)^9 f3 q w - 64 f4 q2;
+c: 6 q2 w4 - 2 (8 f2 q2 + 4 f2) w2 + 96 f4 q2;
+d: 4 q2 w4 - sqrt(2)^5 f q w3 + sqrt(2)^9 f3 q w - 64 f4 q2;
+e: q2 w4 - sqrt(2)^3 f q w3 + (8 f2 q2 + 4 f2) w2 - sqrt(2)^7 f3 q w + 16 f4 q2;
+-----------------------------------------------------------------------------------
+a: q2 w4 + sqrt(2)^3 f q w3 + (2 q2 + 1) 4 f2 w2 + sqrt(2)^7 f3 q w + 16 f4 q2;
+b: 4 q2 w4 + sqrt(2)^5 f q w3 - sqrt(2)^9 f3 q w - 64 f4 q2;
+c: 6 q2 w4 - 2 (2 q2 + 1) 4 f2 w2 + 96 f4 q2;
+d: 4 q2 w4 - sqrt(2)^5 f q w3 + sqrt(2)^9 f3 q w - 64 f4 q2;
+e: q2 w4 - sqrt(2)^3 f q w3 + (2 q2 + 1) 4 f2 w2 - sqrt(2)^7 f3 q w + 16 f4 q2;
+-----------------------------------------------------------------------------------
+y: (4 f2 w2 (x4 - 2 x2 + x) - (b y1 + c y2 + d y3 + e y4)) / a;
+*/
+#include <math.h>
+#include "rtbuf.h"
+#include "rtbuf_signal.h"
+
+const double sqrt2_2 = M_SQRT2 * M_SQRT2;
+
+int rtbuf_signal_bandpass2_start (s_rtbuf *rtb)
+{
+ s_rtbuf_signal_bandpass2_data *data;
+ assert(rtb->proc->out_bytes == sizeof(*data));
+ data = (s_rtbuf_signal_bandpass2_data*) rtb->data;
+ data->x1 = 0.0;
+ data->x2 = 0.0;
+ data->x3 = 0.0;
+ data->x4 = 0.0;
+ data->y1 = 0.0;
+ data->y2 = 0.0;
+ data->y3 = 0.0;
+ data->y4 = 0.0;
+ return 0;
+}
+
+int rtbuf_signal_bandpass2 (s_rtbuf *rtb)
+{
+ s_rtbuf_signal_fun in;
+ s_rtbuf_signal_fun cutoff;
+ s_rtbuf_signal_fun qfactor;
+ s_rtbuf_signal_bandpass2_data *data;
+ unsigned int i = 0;
+ const double sqrt2_3 = sqrt2_2 * M_SQRT2;
+ const double sqrt2_5 = sqrt2_3 * sqrt2_2;
+ const double sqrt2_7 = sqrt2_5 * sqrt2_2;
+ const double sqrt2_9 = sqrt2_7 * sqrt2_2;
+ const double f = RTBUF_SIGNAL_SAMPLERATE;
+ const double f2 = f * f;
+ const double f3 = f2 * f;
+ const double f4 = f2 * f2;
+ rtbuf_signal_fun(rtb, RTBUF_SIGNAL_BANDPASS_IN_SIGNAL, &in);
+ rtbuf_signal_fun(rtb, RTBUF_SIGNAL_BANDPASS_IN_CUTOFF, &cutoff);
+ rtbuf_signal_fun(rtb, RTBUF_SIGNAL_BANDPASS_IN_QFACTOR, &qfactor);
+ data = (s_rtbuf_signal_bandpass2_data*) rtb->data;
+ while (i < RTBUF_SIGNAL_SAMPLES) {
+ const double x = in.sample_fun(in.signal, i);
+ const double fc = cutoff.sample_fun(cutoff.signal, i);
+ const double q = qfactor.sample_fun(qfactor.signal, i);
+ const double q2 = q * q;
+ const double f4q2 = f4 * q2;
+ const double _16f4q2 = 16.0 * f4q2;
+ const double _64f4q2 = 64.0 * f4q2;
+ const double w = 2.0 * M_PI * fc;
+ const double f3qw = f3 * q * w;
+ const double sqrt2_7f3qw = sqrt2_7 * f3qw;
+ const double sqrt2_9f3qw = sqrt2_9 * f3qw;
+ const double w2 = w * w;
+ const double _4f2w2 = 4.0 * f2 * w2;
+ const double _2q2_1_4f2w2 = (2.0 * q2 + 1.0) * _4f2w2;
+ const double w3 = w2 * w;
+ const double fqw3 = f * q * w3;
+ const double sqrt2_3fqw3 = sqrt2_3 * fqw3;
+ const double sqrt2_5fqw3 = sqrt2_5 * fqw3;
+ const double w4 = w2 * w2;
+ const double q2w4 = q2 * w4;
+ const double _4q2w4 = 4.0 * q2w4;
+ const double a = q2w4 + sqrt2_3fqw3 + _2q2_1_4f2w2 + sqrt2_7f3qw + _16f4q2;
+ const double b = _4q2w4 + sqrt2_5fqw3 - sqrt2_9f3qw - _64f4q2;
+ const double c = 6.0 * q2w4 - 2.0 * _2q2_1_4f2w2 + 96.0 * f4q2;
+ const double d = _4q2w4 - sqrt2_5fqw3 + sqrt2_9f3qw - _64f4q2;
+ const double e = q2w4 - sqrt2_3fqw3 + _2q2_1_4f2w2 - sqrt2_7f3qw + _16f4q2;
+ data->signal[i] = (_4f2w2 * (x
+ - 2.0 * data->x2
+ + data->x4)
+ - (b * data->y1
+ + c * data->y2
+ + d * data->y3
+ + e * data->y4)) / a;
+ data->x4 = data->x3;
+ data->x3 = data->x2;
+ data->x2 = data->x1;
+ data->x1 = x;
+ data->y4 = data->y3;
+ data->y3 = data->y2;
+ data->y2 = data->y1;
+ data->y1 = data->signal[i];
+ i++;
+ }
+ return 0;
+}
diff --git a/test_synth b/test_synth
index 1f6c4b6..d0d8e68 100644
--- a/test_synth
+++ b/test_synth
@@ -27,7 +27,7 @@ bind LP00 signal Limiter00 signal
set Flanger01 = new signal flanger
bind Synth00 signal Flanger01 signal
-set HP01 = new signal hipass5
+set HP01 = new signal bandpass2
bind Flanger01 signal HP01 signal
set Limiter01 = new dynamic limiter