ref: 9893fc49678c0ac7568ed8b95711f6ffae7ce8de
dir: /src/echos.c/
/*
* August 24, 1998
* Copyright (C) 1998 Juergen Mueller And Sundry Contributors
* This source code is freely redistributable and may be used for
* any purpose. This copyright notice must be maintained.
* Juergen Mueller And Sundry Contributors are not responsible for
* the consequences of using this software.
*/
/*
* Echos effect for dsp.
*
* Flow diagram scheme for n delays ( 1 <= n <= MAX_ECHOS ):
*
* * gain-in ___
* ibuff --+--------------------------------------------------->| |
* | * decay 1 | |
* | +----------------------------------->| |
* | | * decay 2 | + |
* | | +--------------------->| |
* | | | * decay n | |
* | _________ | _________ | _________ +--->|___|
* | | | | | | | | | | |
* +-->| delay 1 |-+-| delay 2 |-+...-| delay n |--+ | * gain-out
* |_________| |_________| |_________| |
* +----->obuff
*
* Usage:
* echos gain-in gain-out delay-1 decay-1 [delay-2 decay-2 ... delay-n decay-n]
*
* Where:
* gain-in, decay-1 ... decay-n : 0.0 ... 1.0 volume
* gain-out : 0.0 ... volume
* delay-1 ... delay-n : > 0.0 msec
*
* Note:
* when decay is close to 1.0, the samples can begin clipping and the output
* can saturate!
*
* Hint:
* 1 / out-gain > gain-in ( 1 + decay-1 + ... + decay-n )
*
*/
/*
* Sound Tools reverb effect file.
*/
#include <stdlib.h> /* Harmless, and prototypes atof() etc. --dgc */
#include <math.h>
#include "st_i.h"
static st_effect_t st_echos_effect;
#define DELAY_BUFSIZ ( 50 * ST_MAXRATE )
#define MAX_ECHOS 7 /* 24 bit x ( 1 + MAX_ECHOS ) = */
/* 24 bit x 8 = 32 bit !!! */
/* Private data for SKEL file */
typedef struct echosstuff {
int counter[MAX_ECHOS];
int num_delays;
double *delay_buf;
float in_gain, out_gain;
float delay[MAX_ECHOS], decay[MAX_ECHOS];
st_ssize_t samples[MAX_ECHOS], pointer[MAX_ECHOS];
st_size_t sumsamples;
} *echos_t;
/* Private data for SKEL file */
/*
* Process options
*/
static int st_echos_getopts(eff_t effp, int n, char **argv)
{
echos_t echos = (echos_t) effp->priv;
int i;
echos->num_delays = 0;
if ((n < 4) || (n % 2))
{
st_fail(st_echos_effect.usage);
return (ST_EOF);
}
i = 0;
sscanf(argv[i++], "%f", &echos->in_gain);
sscanf(argv[i++], "%f", &echos->out_gain);
while (i < n) {
/* Linux bug and it's cleaner. */
sscanf(argv[i++], "%f", &echos->delay[echos->num_delays]);
sscanf(argv[i++], "%f", &echos->decay[echos->num_delays]);
echos->num_delays++;
if ( echos->num_delays > MAX_ECHOS )
{
st_fail("echos: to many delays, use less than %i delays",
MAX_ECHOS);
return (ST_EOF);
}
}
echos->sumsamples = 0;
return (ST_SUCCESS);
}
/*
* Prepare for processing.
*/
static int st_echos_start(eff_t effp)
{
echos_t echos = (echos_t) effp->priv;
int i;
float sum_in_volume;
unsigned long j;
if ( echos->in_gain < 0.0 )
{
st_fail("echos: gain-in must be positive!");
return (ST_EOF);
}
if ( echos->in_gain > 1.0 )
{
st_fail("echos: gain-in must be less than 1.0!");
return (ST_EOF);
}
if ( echos->out_gain < 0.0 )
{
st_fail("echos: gain-in must be positive!");
return (ST_EOF);
}
for ( i = 0; i < echos->num_delays; i++ ) {
echos->samples[i] = echos->delay[i] * effp->ininfo.rate / 1000.0;
if ( echos->samples[i] < 1 )
{
st_fail("echos: delay must be positive!");
return (ST_EOF);
}
if ( echos->samples[i] > (st_ssize_t)DELAY_BUFSIZ )
{
st_fail("echos: delay must be less than %g seconds!",
DELAY_BUFSIZ / (float) effp->ininfo.rate );
return (ST_EOF);
}
if ( echos->decay[i] < 0.0 )
{
st_fail("echos: decay must be positive!" );
return (ST_EOF);
}
if ( echos->decay[i] > 1.0 )
{
st_fail("echos: decay must be less than 1.0!" );
return (ST_EOF);
}
echos->counter[i] = 0;
echos->pointer[i] = echos->sumsamples;
echos->sumsamples += echos->samples[i];
}
echos->delay_buf = (double *) xmalloc(sizeof (double) * echos->sumsamples);
for ( j = 0; j < echos->sumsamples; ++j )
echos->delay_buf[j] = 0.0;
/* Be nice and check the hint with warning, if... */
sum_in_volume = 1.0;
for ( i = 0; i < echos->num_delays; i++ )
sum_in_volume += echos->decay[i];
if ( sum_in_volume * echos->in_gain > 1.0 / echos->out_gain )
st_warn("echos: warning >>> gain-out can cause saturation of output <<<");
return (ST_SUCCESS);
}
/*
* Processed signed long samples from ibuf to obuf.
* Return number of samples processed.
*/
static int st_echos_flow(eff_t effp, const st_sample_t *ibuf, st_sample_t *obuf,
st_size_t *isamp, st_size_t *osamp)
{
echos_t echos = (echos_t) effp->priv;
int len, done;
int j;
double d_in, d_out;
st_sample_t out;
len = ((*isamp > *osamp) ? *osamp : *isamp);
for(done = 0; done < len; done++) {
/* Store delays as 24-bit signed longs */
d_in = (double) *ibuf++ / 256;
/* Compute output first */
d_out = d_in * echos->in_gain;
for ( j = 0; j < echos->num_delays; j++ ) {
d_out += echos->delay_buf[echos->counter[j] + echos->pointer[j]] * echos->decay[j];
}
/* Adjust the output volume and size to 24 bit */
d_out = d_out * echos->out_gain;
out = ST_24BIT_CLIP_COUNT((st_sample_t) d_out, effp->clips);
*obuf++ = out * 256;
/* Mix decay of delays and input */
for ( j = 0; j < echos->num_delays; j++ ) {
if ( j == 0 )
echos->delay_buf[echos->counter[j] + echos->pointer[j]] = d_in;
else
echos->delay_buf[echos->counter[j] + echos->pointer[j]] =
echos->delay_buf[echos->counter[j-1] + echos->pointer[j-1]] + d_in;
}
/* Adjust the counters */
for ( j = 0; j < echos->num_delays; j++ )
echos->counter[j] =
( echos->counter[j] + 1 ) % echos->samples[j];
}
/* processed all samples */
return (ST_SUCCESS);
}
/*
* Drain out reverb lines.
*/
static int st_echos_drain(eff_t effp, st_sample_t *obuf, st_size_t *osamp)
{
echos_t echos = (echos_t) effp->priv;
double d_in, d_out;
st_sample_t out;
int j;
st_size_t done;
done = 0;
/* drain out delay samples */
while ( ( done < *osamp ) && ( done < echos->sumsamples ) ) {
d_in = 0;
d_out = 0;
for ( j = 0; j < echos->num_delays; j++ ) {
d_out += echos->delay_buf[echos->counter[j] + echos->pointer[j]] * echos->decay[j];
}
/* Adjust the output volume and size to 24 bit */
d_out = d_out * echos->out_gain;
out = ST_24BIT_CLIP_COUNT((st_sample_t) d_out, effp->clips);
*obuf++ = out * 256;
/* Mix decay of delays and input */
for ( j = 0; j < echos->num_delays; j++ ) {
if ( j == 0 )
echos->delay_buf[echos->counter[j] + echos->pointer[j]] = d_in;
else
echos->delay_buf[echos->counter[j] + echos->pointer[j]] =
echos->delay_buf[echos->counter[j-1] + echos->pointer[j-1]];
}
/* Adjust the counters */
for ( j = 0; j < echos->num_delays; j++ )
echos->counter[j] =
( echos->counter[j] + 1 ) % echos->samples[j];
done++;
echos->sumsamples--;
};
/* samples played, it remains */
*osamp = done;
if (echos->sumsamples == 0)
return ST_EOF;
else
return ST_SUCCESS;
}
/*
* Clean up echos effect.
*/
static int st_echos_stop(eff_t effp)
{
echos_t echos = (echos_t) effp->priv;
free((char *) echos->delay_buf);
echos->delay_buf = (double *) -1; /* guaranteed core dump */
return (ST_SUCCESS);
}
static st_effect_t st_echos_effect = {
"echos",
"Usage: echos gain-in gain-out delay decay [ delay decay ... ]",
0,
st_echos_getopts,
st_echos_start,
st_echos_flow,
st_echos_drain,
st_echos_stop,
st_effect_nothing
};
const st_effect_t *st_echos_effect_fn(void)
{
return &st_echos_effect;
}