ref: 579fae4ab7d37423aee4d9cdf7a29f9d96c2b764
dir: /src/speed.c/
/* 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; }