/* libSoX Effect: Adjust the audio speed (pitch and tempo together) * (c) 2006,8 robs@users.sourceforge.net * * 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 * * * Adjustment is given as the ratio of the new speed to the old speed, or as * a number of cents (100ths of a semitone) to change.  Speed change is * actually performed by whichever resampling effect is in effect. */ #include "sox_i.h"#include <string.h> typedef struct {  double factor;} priv_t; static int getopts(sox_effect_t * effp, int argc, char * * argv){  priv_t * p = (priv_t *) effp->priv;  sox_bool is_cents = sox_false;   --argc, ++argv;  if (argc == 1) {    char c, dummy;    int scanned = sscanf(*argv, "%lf%c %c", &p->factor, &c, &dummy);    if (scanned == 1 || (scanned == 2 && c == 'c')) {      is_cents |= scanned == 2;      if (is_cents || p->factor > 0) {        p->factor = is_cents? pow(2., p->factor / 1200) : p->factor;        return SOX_SUCCESS;      }    }  }  return lsx_usage(effp);} static int start(sox_effect_t * effp){  priv_t * p = (priv_t *) effp->priv;   if (p->factor == 1)    return SOX_EFF_NULL;   effp->out_signal.rate = effp->in_signal.rate * p->factor;   effp->out_signal.length = effp->in_signal.length;    /* audio length if measured in samples doesn't change */   return SOX_SUCCESS;} sox_effect_handler_t const * lsx_speed_effect_fn(void){  static sox_effect_handler_t handler = {    "speed", "factor[c]",    SOX_EFF_MCHAN | SOX_EFF_RATE | SOX_EFF_LENGTH | SOX_EFF_MODIFY,    getopts, start, lsx_flow_copy, 0, 0, 0, sizeof(priv_t)};  return &handler;}