1 /* Effect: firfit filter Copyright (c) 2009 robs@users.sourceforge.net
2 *
3 * This library is free software; you can redistribute it and/or modify it
4 * under the terms of the GNU Lesser General Public License as published by
5 * the Free Software Foundation; either version 2.1 of the License, or (at
6 * your option) any later version.
7 *
8 * This library is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU Lesser General Public License
14 * along with this library; if not, write to the Free Software Foundation,
15 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
16 */
17
18 /* This is W.I.P. hence marked SOX_EFF_ALPHA for now.
19 * Need to add other interpolation types e.g. linear, bspline, window types,
20 * and filter length, maybe phase response type too.
21 */
22
23 #include "sox_i.h"
24 #include "dft_filter.h"
25
26 typedef struct {
27 dft_filter_priv_t base;
28 char const * filename;
29 struct {double f, gain;} * knots;
30 int num_knots, n;
31 } priv_t;
32
create(sox_effect_t * effp,int argc,char ** argv)33 static int create(sox_effect_t * effp, int argc, char **argv)
34 {
35 priv_t * p = (priv_t *)effp->priv;
36 dft_filter_priv_t * b = &p->base;
37 b->filter_ptr = &b->filter;
38 --argc, ++argv;
39 if (argc == 1)
40 p->filename = argv[0], --argc;
41 p->n = 2047;
42 return argc? lsx_usage(effp) : SOX_SUCCESS;
43 }
44
make_filter(sox_effect_t * effp)45 static double * make_filter(sox_effect_t * effp)
46 {
47 priv_t * p = (priv_t *)effp->priv;
48 double * log_freqs, * gains, * d, * work, * h;
49 sox_rate_t rate = effp->in_signal.rate;
50 int i, work_len;
51
52 lsx_valloc(log_freqs , p->num_knots);
53 lsx_valloc(gains, p->num_knots);
54 lsx_valloc(d , p->num_knots);
55 for (i = 0; i < p->num_knots; ++i) {
56 log_freqs[i] = log(max(p->knots[i].f, 1));
57 gains[i] = p->knots[i].gain;
58 }
59 lsx_prepare_spline3(log_freqs, gains, p->num_knots, HUGE_VAL, HUGE_VAL, d);
60
61 for (work_len = 8192; work_len < rate / 2; work_len <<= 1);
62 work = lsx_calloc(work_len + 2, sizeof(*work));
63 lsx_valloc(h, p->n);
64
65 for (i = 0; i <= work_len; i += 2) {
66 double f = rate * 0.5 * i / work_len;
67 double spl1 = f < max(p->knots[0].f, 1)? gains[0] :
68 f > p->knots[p->num_knots - 1].f? gains[p->num_knots - 1] :
69 lsx_spline3(log_freqs, gains, d, p->num_knots, log(f));
70 work[i] = dB_to_linear(spl1);
71 }
72 LSX_PACK(work, work_len);
73 lsx_safe_rdft(work_len, -1, work);
74 for (i = 0; i < p->n; ++i)
75 h[i] = work[(work_len - p->n / 2 + i) % work_len] * 2. / work_len;
76 lsx_apply_blackman_nutall(h, p->n);
77
78 free(work);
79 return h;
80 }
81
read_knots(sox_effect_t * effp)82 static sox_bool read_knots(sox_effect_t * effp)
83 {
84 priv_t * p = (priv_t *) effp->priv;
85 FILE * file = lsx_open_input_file(effp, p->filename, sox_true);
86 sox_bool result = sox_false;
87 int num_converted = 1;
88 char c;
89
90 if (file) {
91 lsx_valloc(p->knots, 1);
92 while (fscanf(file, " #%*[^\n]%c", &c) >= 0) {
93 num_converted = fscanf(file, "%lf %lf",
94 &p->knots[p->num_knots].f, &p->knots[p->num_knots].gain);
95 if (num_converted == 2) {
96 if (p->num_knots && p->knots[p->num_knots].f <= p->knots[p->num_knots - 1].f) {
97 lsx_fail("knot frequencies must be strictly increasing");
98 break;
99 }
100 lsx_revalloc(p->knots, ++p->num_knots + 1);
101 } else if (num_converted != 0)
102 break;
103 }
104 lsx_report("%i knots", p->num_knots);
105 if (feof(file) && num_converted != 1)
106 result = sox_true;
107 else lsx_fail("error reading knot file `%s', line number %u", p->filename, 1 + p->num_knots);
108 if (file != stdin)
109 fclose(file);
110 }
111 return result;
112 }
113
start(sox_effect_t * effp)114 static int start(sox_effect_t * effp)
115 {
116 priv_t * p = (priv_t *) effp->priv;
117 dft_filter_t * f = p->base.filter_ptr;
118
119 if (!f->num_taps) {
120 double * h;
121 if (!p->num_knots && !read_knots(effp))
122 return SOX_EOF;
123 h = make_filter(effp);
124 if (effp->global_info->plot != sox_plot_off) {
125 lsx_plot_fir(h, p->n, effp->in_signal.rate,
126 effp->global_info->plot, "SoX effect: firfit", -30., +30.);
127 return SOX_EOF;
128 }
129 lsx_set_dft_filter(f, h, p->n, p->n >> 1);
130 }
131 return lsx_dft_filter_effect_fn()->start(effp);
132 }
133
lsx_firfit_effect_fn(void)134 sox_effect_handler_t const * lsx_firfit_effect_fn(void)
135 {
136 static sox_effect_handler_t handler;
137 handler = *lsx_dft_filter_effect_fn();
138 handler.name = "firfit";
139 handler.usage = "[knots-file]";
140 handler.flags |= SOX_EFF_ALPHA;
141 handler.getopts = create;
142 handler.start = start;
143 handler.priv_size = sizeof(priv_t);
144 return &handler;
145 }
146