ref: 1e4f76215b8d22020b844a3bba701194f9f7a508
dir: /src/speed.c/
/* Sound Tools Effect: Adjust the audio speed (pitch and tempo together)
*
* (c) 2006 robs@users.sourceforge.net
*
* See LICENSE file for further copyright information.
*
* 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 "st_i.h"
#include <math.h>
#include <string.h>
static int getopts(eff_t effp, int n, char * * argv)
{
bool is_cents = false;
double speed;
/* Be quietly compatible with the old speed effect: */
if (n != 0 && strcmp(*argv, "-c") == 0)
is_cents = 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->globalinfo->speed *= is_cents? pow(2, speed/1200) : speed;
return ST_SUCCESS;
}
}
}
st_fail(effp->h->usage);
return ST_EOF;
}
st_effect_t const * st_speed_effect_fn(void)
{
static st_effect_t driver = {
"speed", "Usage: speed factor[c]", ST_EFF_NULL,
getopts, NULL, NULL, NULL, NULL};
return &driver;
}