ref: d30bc6087f69337abc0c2363e317bb6f79d6034b
dir: /src/speed.c/
/*
* 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 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,
* Fifth Floor, 51 Franklin Street, Boston, MA 02111-1301, USA.
*/
/* libSoX Effect: Adjust the audio speed (pitch and tempo together)
*
* (c) 2006 robs@users.sourceforge.net
*
* 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 <math.h>
#include <string.h>
static int getopts(sox_effect_t * effp, int n, char * * argv)
{
sox_bool is_cents = sox_false;
double speed;
/* Be quietly compatible with the old speed effect: */
if (n != 0 && strcmp(*argv, "-c") == 0)
is_cents = sox_true, ++argv, --n;
if (n == 1) {
char c, dummy;
int scanned = sscanf(*argv, "%lf%c %c", &speed, &c, &dummy);
if (scanned == 1 || (scanned == 2 && c == 'c')) {
is_cents |= scanned == 2;
if (is_cents || speed > 0) {
effp->global_info->speed *= is_cents? pow(2., speed/1200) : speed;
return SOX_SUCCESS;
}
}
}
return sox_usage(effp);
}
sox_effect_handler_t const *sox_speed_effect_fn(void)
{
static sox_effect_handler_t handler = {
"speed", "factor[c]", SOX_EFF_NULL|SOX_EFF_LENGTH,
getopts, 0, 0, 0, 0, 0};
return &handler;
}