/* libSoX effect: Upsample (zero stuff)    (c) 2011 robs@users.sourceforge.net * * Sometimes filters perform better at higher sampling rates, so e.g. *   sox -r 48k input output upsample 4 filter rate 48k vol 4 * * This library is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation; either version 2.1 of the License, or (at * your option) any later version. * * This library is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser * General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this library; if not, write to the Free Software Foundation, * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA */ #include "sox_i.h" typedef struct {unsigned factor, pos;} priv_t; static int soxcreate(sox_effect_t * effp, int argc, char * * argv){  priv_t * p = (priv_t *)effp->priv;  p->factor = 2;  --argc, ++argv;  do {NUMERIC_PARAMETER(factor, 1, 256); USED(argv);} while (0);  return argc? lsx_usage(effp) : SOX_SUCCESS;} static int start(sox_effect_t * effp){  priv_t * p = (priv_t *) effp->priv;  effp->out_signal.rate = effp->in_signal.rate * p->factor;  return p->factor == 1? SOX_EFF_NULL : SOX_SUCCESS;} static int flow(sox_effect_t * effp, const sox_sample_t * ibuf,    sox_sample_t * obuf, size_t * isamp, size_t * osamp){  priv_t * p = (priv_t *)effp->priv;  size_t ilen = *isamp, olen = *osamp;  while (sox_true) {    for (; p->pos && olen; p->pos = (p->pos + 1) % p->factor, --olen)      *obuf++ = 0;    if (!ilen || !olen)      break;    *obuf++ = *ibuf++;    --olen, --ilen;    ++p->pos;  }  *isamp -= ilen, *osamp -= olen;  return SOX_SUCCESS;} sox_effect_handler_t const * lsx_upsample_effect_fn(void){  static sox_effect_handler_t handler = {"upsample", "[factor (2)]",    SOX_EFF_RATE | SOX_EFF_MODIFY, soxcreate, start, flow, NULL, NULL, NULL, sizeof(priv_t)};  return &handler;}