ref: 9f72db1f539ef08438ef679424a2c05d08c473d6
dir: /dyn.c/
#ifdef USE_DYN
/*
* July 5, 1991
* Copyright 1991 Lance Norskog And Sundry Contributors
* This source code is freely redistributable and may be used for
* any purpose. This copyright notice must be maintained.
* Lance Norskog And Sundry Contributors are not responsible for
* the consequences of using this software.
*/
/*
* Sound Tools dynamic compander effect file.
*
* Compresses or expands dynamic range, i.e. range between
* soft and loud sounds. U-law compression basically does this.
*
* Doesn't work. Giving up for now.
*/
#include <math.h>
#include "st.h"
/* Private data for DYN.C file */
typedef struct dyn{
int rest; /* bytes remaining in current block */
} *dyn_t;
/*
* Process options
*/
void dyn_getopts(effp, n, argv)
eff_t effp;
int n;
char **argv;
{
if (n)
fail("Copy effect takes no options.");
}
/*
* Prepare processing.
*/
void dyn_start(effp)
eff_t effp;
{
/* nothing to do */
/* stuff data into delaying effects here */
}
/*
* Processed signed long samples from ibuf to obuf.
* Return number of samples processed.
*/
void dyn_flow(effp, ibuf, obuf, isamp, osamp)
eff_t effp;
LONG *ibuf, *obuf;
int *isamp, *osamp;
{
int len, done;
LONG l;
double d, tmp;
int sign;
#define NORMIT (65536.0)
len = ((*isamp > *osamp) ? *osamp : *isamp);
for(done = 0; done < len; done++) {
d = *ibuf++;
if (d == 0.0)
l = 0;
else {
if (d < 0.0) {
d *= -1.0;
sign = -1;
} else
sign = 1;
d /= NORMIT;
tmp = log10(d);
tmp = pow(8.0, tmp);
tmp = tmp * NORMIT;
l = tmp * sign;
}
*obuf++ = l;
}
}
/*
* Drain out remaining samples if the effect generates any.
*/
void dyn_drain(effp, obuf, osamp)
LONG *obuf;
int *osamp;
{
*osamp = 0;
}
/*
* Do anything required when you stop reading samples.
* (free allocated memory, etc.)
*/
void dyn_stop(effp)
eff_t effp;
{
/* nothing to do */
}
#endif /* USE_DYN */