1 /* libSoX effect: Upsample (zero stuff) (c) 2011 robs@users.sourceforge.net
2 *
3 * Sometimes filters perform better at higher sampling rates, so e.g.
4 * sox -r 48k input output upsample 4 filter rate 48k vol 4
5 *
6 * This library is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU Lesser General Public License as published by
8 * the Free Software Foundation; either version 2.1 of the License, or (at
9 * your option) any later version.
10 *
11 * This library is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public License
17 * along with this library; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 #include "sox_i.h"
22
23 typedef struct {unsigned factor, pos;} priv_t;
24
create(sox_effect_t * effp,int argc,char ** argv)25 static int create(sox_effect_t * effp, int argc, char * * argv)
26 {
27 priv_t * p = (priv_t *)effp->priv;
28 p->factor = 2;
29 --argc, ++argv;
30 do {NUMERIC_PARAMETER(factor, 1, 256)} while (0);
31 return argc? lsx_usage(effp) : SOX_SUCCESS;
32 }
33
start(sox_effect_t * effp)34 static int start(sox_effect_t * effp)
35 {
36 priv_t * p = (priv_t *) effp->priv;
37 effp->out_signal.rate = effp->in_signal.rate * p->factor;
38 return p->factor == 1? SOX_EFF_NULL : SOX_SUCCESS;
39 }
40
flow(sox_effect_t * effp,const sox_sample_t * ibuf,sox_sample_t * obuf,size_t * isamp,size_t * osamp)41 static int flow(sox_effect_t * effp, const sox_sample_t * ibuf,
42 sox_sample_t * obuf, size_t * isamp, size_t * osamp)
43 {
44 priv_t * p = (priv_t *)effp->priv;
45 size_t ilen = *isamp, olen = *osamp;
46 while (sox_true) {
47 for (; p->pos && olen; p->pos = (p->pos + 1) % p->factor, --olen)
48 *obuf++ = 0;
49 if (!ilen || !olen)
50 break;
51 *obuf++ = *ibuf++;
52 --olen, --ilen;
53 ++p->pos;
54 }
55 *isamp -= ilen, *osamp -= olen;
56 return SOX_SUCCESS;
57 }
58
lsx_upsample_effect_fn(void)59 sox_effect_handler_t const * lsx_upsample_effect_fn(void)
60 {
61 static sox_effect_handler_t handler = {"upsample", "[factor (2)]",
62 SOX_EFF_RATE | SOX_EFF_MODIFY, create, start, flow, NULL, NULL, NULL, sizeof(priv_t)};
63 return &handler;
64 }
65