1 /* libSoX Effect: Adjust the audio speed (pitch and tempo together)
2 * (c) 2006,8 robs@users.sourceforge.net
3 *
4 * This library is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU Lesser General Public License as published by
6 * the Free Software Foundation; either version 2.1 of the License, or (at
7 * your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
12 * General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public License
15 * along with this library; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 *
18 *
19 * Adjustment is given as the ratio of the new speed to the old speed, or as
20 * a number of cents (100ths of a semitone) to change. Speed change is
21 * actually performed by whichever resampling effect is in effect.
22 */
23
24 #include "sox_i.h"
25 #include <string.h>
26
27 typedef struct {
28 double factor;
29 } priv_t;
30
getopts(sox_effect_t * effp,int argc,char ** argv)31 static int getopts(sox_effect_t * effp, int argc, char * * argv)
32 {
33 priv_t * p = (priv_t *) effp->priv;
34 sox_bool is_cents = sox_false;
35
36 --argc, ++argv;
37 if (argc == 1) {
38 char c, dummy;
39 int scanned = sscanf(*argv, "%lf%c %c", &p->factor, &c, &dummy);
40 if (scanned == 1 || (scanned == 2 && c == 'c')) {
41 is_cents |= scanned == 2;
42 if (is_cents || p->factor > 0) {
43 p->factor = is_cents? pow(2., p->factor / 1200) : p->factor;
44 return SOX_SUCCESS;
45 }
46 }
47 }
48 return lsx_usage(effp);
49 }
50
start(sox_effect_t * effp)51 static int start(sox_effect_t * effp)
52 {
53 priv_t * p = (priv_t *) effp->priv;
54
55 if (p->factor == 1)
56 return SOX_EFF_NULL;
57
58 effp->out_signal.rate = effp->in_signal.rate * p->factor;
59
60 effp->out_signal.length = effp->in_signal.length;
61 /* audio length if measured in samples doesn't change */
62
63 return SOX_SUCCESS;
64 }
65
lsx_speed_effect_fn(void)66 sox_effect_handler_t const * lsx_speed_effect_fn(void)
67 {
68 static sox_effect_handler_t handler = {
69 "speed", "factor[c]",
70 SOX_EFF_MCHAN | SOX_EFF_RATE | SOX_EFF_LENGTH | SOX_EFF_MODIFY,
71 getopts, start, lsx_flow_copy, 0, 0, 0, sizeof(priv_t)};
72 return &handler;
73 }
74