ref: 9a849169fa19af7a0572ea52d473b591a47877f1
dir: /src/reverb.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.
* Lance Norskog And Sundry Contributors are not responsible for
* the consequences of using this software.
*/
/*
** Echo effect. based on:
**
** echoplex.c - echo generator
**
** Copyright (C) 1989 by Jef Poskanzer.
**
** Permission to use, copy, modify, and distribute this software and its
** documentation for any purpose and without fee is hereby granted, provided
** that the above copyright notice appear in all copies and that both that
** copyright notice and this permission notice appear in supporting
** documentation. This software is provided "as is" without express or
** implied warranty.
*/
/*
* Changes to old "echo.c" now called "reverb.c":
*
* The effect name changes from "echo" to "reverb" (see Guitar FX FAQ) for
* the difference in its defintion.
* The idea of the echoplexer is modified and enhanceb by an automatic
* setting of each decay for realistic reverb.
* Some bugs are fixed concerning malloc and fade-outs.
* Added an output volume (gain-out) avoiding saturation or clipping.
*
*
* Reverb effect for dsp.
*
* Flow diagram scheme for n delays ( 1 <= n <= MAXREVERB )
*
* * gain-in +---+ * gain-out
* ibuff ----------->| |------------------------------------> obuff
* | | * decay 1
* | |<------------------------+
* | + | * decay 2 |
* | |<--------------------+ |
* | | * decay n | |
* | |<----------------+ | |
* +---+ | | |
* | _________ | | |
* | | | | | |
* +---->| delay n |---+ | |
* . |_________| | |
* . | |
* . _________ | |
* | | | | |
* +---->| delay 2 |-------+ |
* | |_________| |
* | |
* | _________ |
* | | | |
* +---->| delay 1 |-----------+
* |_________|
*
*
*
* Usage:
* reverb gain-out reverb-time delay-1 [ delay-2 ... delay-n ]
*
* Where:
* gain-out : 0.0 ... volume
* reverb-time : > 0.0 msec
* delay-1 ... delay-n : > 0.0 msec
*
* Note:
* gain-in is automatically adjusted avoiding saturation and clipping of
* the output. decay-1 to decay-n are computed such that at reverb-time
* the input will be 60 dB of the original input for the given delay-1
* to delay-n. delay-1 to delay-n specify the time when the first bounce
* of the input will appear. A proper setting for delay-1 to delay-n
* depends on the choosen reverb-time (see hint).
*
* Hint:
* a realstic reverb effect can be obtained using for a given reverb-time "t"
* delays in the range of "t/2 ... t/4". Each delay should not be an integer
* of any other.
*
*/
/*
* Sound Tools reverb effect file.
*/
#include <stdlib.h> /* Harmless, and prototypes atof() etc. --dgc */
#include <math.h>
#include "st_i.h"
#define REVERB_FADE_THRESH 10
#define DELAY_BUFSIZ ( 50L * ST_MAXRATE )
#define MAXREVERBS 8
/* Private data for SKEL file */
typedef struct reverbstuff {
int counter;
int numdelays;
float *reverbbuf;
float in_gain, out_gain, time;
float delay[MAXREVERBS], decay[MAXREVERBS];
long samples[MAXREVERBS], maxsamples;
st_sample_t pl, ppl, pppl;
} *reverb_t;
/*
* Process options
*/
int st_reverb_getopts(eff_t effp, int n, char **argv)
{
reverb_t reverb = (reverb_t) effp->priv;
int i;
reverb->numdelays = 0;
reverb->maxsamples = 0;
if ( n < 3 )
{
st_fail(st_reverb_effect.usage);
return (ST_EOF);
}
if ( n - 2 > MAXREVERBS )
{
st_fail("reverb: to many dalays, use less than %i delays",
MAXREVERBS);
return (ST_EOF);
}
i = 0;
sscanf(argv[i++], "%f", &reverb->out_gain);
sscanf(argv[i++], "%f", &reverb->time);
while (i < n) {
/* Linux bug and it's cleaner. */
sscanf(argv[i++], "%f", &reverb->delay[reverb->numdelays]);
reverb->numdelays++;
}
return (ST_SUCCESS);
}
/*
* Prepare for processing.
*/
int st_reverb_start(eff_t effp)
{
reverb_t reverb = (reverb_t) effp->priv;
int i;
reverb->in_gain = 1.0;
if ( reverb->out_gain < 0.0 )
{
st_fail("reverb: gain-out must be positive");
return (ST_EOF);
}
if ( reverb->out_gain > 1.0 )
st_warn("reverb: warnig >>> gain-out can cause saturation of output <<<");
if ( reverb->time < 0.0 )
{
st_fail("reverb: reverb-time must be positive");
return (ST_EOF);
}
for(i = 0; i < reverb->numdelays; i++) {
reverb->samples[i] = reverb->delay[i] * effp->ininfo.rate / 1000.0;
if ( reverb->samples[i] < 1 )
{
st_fail("reverb: delay must be positive!\n");
return (ST_EOF);
}
if ( reverb->samples[i] > DELAY_BUFSIZ )
{
st_fail("reverb: delay must be less than %g seconds!\n",
DELAY_BUFSIZ / (float) effp->ininfo.rate );
return(ST_EOF);
}
/* Compute a realistic decay */
reverb->decay[i] = (float) pow(10.0,(-3.0 * reverb->delay[i] / reverb->time));
if ( reverb->samples[i] > reverb->maxsamples )
reverb->maxsamples = reverb->samples[i];
}
if (! (reverb->reverbbuf = (float *) malloc(sizeof (float) * reverb->maxsamples)))
{
st_fail("reverb: Cannot malloc %d bytes!\n",
sizeof(float) * reverb->maxsamples);
return(ST_EOF);
}
for ( i = 0; i < reverb->maxsamples; ++i )
reverb->reverbbuf[i] = 0.0;
reverb->pppl = reverb->ppl = reverb->pl = 0x7fffff; /* fade-outs */
reverb->counter = 0;
/* Compute the input volume carefully */
for ( i = 0; i < reverb->numdelays; i++ )
reverb->in_gain *=
( 1.0 - ( reverb->decay[i] * reverb->decay[i] ));
return (ST_SUCCESS);
}
/*
* Processed signed long samples from ibuf to obuf.
* Return number of samples processed.
*/
int st_reverb_flow(eff_t effp, st_sample_t *ibuf, st_sample_t *obuf,
st_size_t *isamp, st_size_t *osamp)
{
reverb_t reverb = (reverb_t) effp->priv;
int len, done;
int i, j;
float d_in, d_out;
st_sample_t out;
i = reverb->counter;
len = ((*isamp > *osamp) ? *osamp : *isamp);
for(done = 0; done < len; done++) {
/* Store delays as 24-bit signed longs */
d_in = (float) *ibuf++ / 256;
d_in = d_in * reverb->in_gain;
/* Mix decay of delay and input as output */
for ( j = 0; j < reverb->numdelays; j++ )
d_in +=
reverb->reverbbuf[(i + reverb->maxsamples - reverb->samples[j]) % reverb->maxsamples] * reverb->decay[j];
d_out = d_in * reverb->out_gain;
out = st_clip24((st_sample_t) d_out);
*obuf++ = out * 256;
reverb->reverbbuf[i] = d_in;
i++; /* XXX need a % maxsamples here ? */
i %= reverb->maxsamples;
}
reverb->counter = i;
/* processed all samples */
return (ST_SUCCESS);
}
/*
* Drain out reverb lines.
*/
int st_reverb_drain(eff_t effp, st_sample_t *obuf, st_size_t *osamp)
{
reverb_t reverb = (reverb_t) effp->priv;
float d_in, d_out;
st_sample_t out, l;
int i, j;
st_size_t done;
i = reverb->counter;
done = 0;
/* drain out delay samples */
do {
d_in = 0;
d_out = 0;
for ( j = 0; j < reverb->numdelays; ++j )
d_in +=
reverb->reverbbuf[(i + reverb->maxsamples - reverb->samples[j]) % reverb->maxsamples] * reverb->decay[j];
d_out = d_in * reverb->out_gain;
out = st_clip24((st_sample_t) d_out);
obuf[done++] = out * 256;
reverb->reverbbuf[i] = d_in;
l = st_clip24((st_sample_t) d_in);
reverb->pppl = reverb->ppl;
reverb->ppl = reverb->pl;
reverb->pl = l;
i++; /* need a % maxsamples here ? */
i %= reverb->maxsamples;
} while((done < *osamp) &&
((abs(reverb->pl) + abs(reverb->ppl) + abs(reverb->pppl)) > REVERB_FADE_THRESH));
reverb->counter = i;
*osamp = done;
return (ST_SUCCESS);
}
/*
* Clean up reverb effect.
*/
int st_reverb_stop(eff_t effp)
{
reverb_t reverb = (reverb_t) effp->priv;
free((char *) reverb->reverbbuf);
reverb->reverbbuf = (float *) -1; /* guaranteed core dump */
return (ST_SUCCESS);
}
st_effect_t st_reverb_effect = {
"reverb",
"Usage: reverb gain-out reverb-time delay [ delay ... ]",
0,
st_reverb_getopts,
st_reverb_start,
st_reverb_flow,
st_reverb_drain,
st_reverb_stop
};