ref: f6a42c50c040196f3f830d3e51d405d5ae2b8982
dir: /src/phaser.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.
*/
/*
* Phaser effect.
*
* Flow diagram scheme:
*
* * gain-in +---+ * gain-out
* ibuff ----------->| |----------------------------------> obuff
* | + | * decay
* | |<------------+
* +---+ _______ |
* | | | |
* +---| delay |---+
* |_______|
* /|\
* |
* +---------------+ +------------------+
* | Delay control |<-----| modulation speed |
* +---------------+ +------------------+
*
*
* The delay is controled by a sine or triangle modulation.
*
* Usage:
* phaser gain-in gain-out delay decay speed [ -s | -t ]
*
* Where:
* gain-in, decay : 0.0 ... 1.0 volume
* gain-out : 0.0 ... volume
* delay : 0.0 ... 5.0 msec
* speed : 0.1 ... 2.0 Hz modulation
* -s : modulation by sine (default)
* -t : modulation by triangle
*
* Note:
* when decay is close to 1.0, the samples may begin clipping or the output
* can saturate!
*
* Hint:
* in-gain < ( 1 - decay * decay )
* 1 / out-gain > gain-in / ( 1 - decay )
*
*/
/*
* Sound Tools phaser effect file.
*/
#include <stdlib.h> /* Harmless, and prototypes atof() etc. --dgc */
#include <math.h>
#include <string.h>
#include "st.h"
#define MOD_SINE 0
#define MOD_TRIANGLE 1
/* Private data for SKEL file */
typedef struct phaserstuff {
int modulation;
int counter;
int phase;
double *phaserbuf;
float in_gain, out_gain;
float delay, decay;
float speed;
long length;
int *lookup_tab;
long maxsamples, fade_out;
} *phaser_t;
/* Private data for SKEL file */
LONG phaser_clip24(l)
LONG l;
{
if (l >= ((LONG)1 << 24))
return ((LONG)1 << 24) - 1;
else if (l <= -((LONG)1 << 24))
return -((LONG)1 << 24) + 1;
else
return l;
}
/* This was very painful. We need a sine library. */
void phaser_sine(buf, len, depth)
int *buf;
long len;
long depth;
{
long i;
double val;
for (i = 0; i < len; i++) {
val = sin((double)i/(double)len * 2.0 * M_PI);
buf[i] = (int) ((1.0 + val) * depth / 2.0);
}
}
void phaser_triangle(buf, len, depth)
int *buf;
long len;
long depth;
{
long i;
double val;
for (i = 0; i < len / 2; i++) {
val = i * 2.0 / len;
buf[i] = (int) (val * depth);
}
for (i = len / 2; i < len ; i++) {
val = (len - i) * 2.0 / len;
buf[i] = (int) (val * depth);
}
}
/*
* Process options
*/
void phaser_getopts(effp, n, argv)
eff_t effp;
int n;
char **argv;
{
phaser_t phaser = (phaser_t) effp->priv;
if (!((n == 5) || (n == 6)))
fail("Usage: phaser gain-in gain-out delay decay speed [ -s | -t ]");
sscanf(argv[0], "%f", &phaser->in_gain);
sscanf(argv[1], "%f", &phaser->out_gain);
sscanf(argv[2], "%f", &phaser->delay);
sscanf(argv[3], "%f", &phaser->decay);
sscanf(argv[4], "%f", &phaser->speed);
phaser->modulation = MOD_SINE;
if ( n == 6 ) {
if ( !strcmp(argv[5], "-s"))
phaser->modulation = MOD_SINE;
else if ( ! strcmp(argv[5], "-t"))
phaser->modulation = MOD_TRIANGLE;
else
fail("Usage: phaser gain-in gain-out delay decay speed [ -s | -t ]");
}
}
/*
* Prepare for processing.
*/
void phaser_start(effp)
eff_t effp;
{
phaser_t phaser = (phaser_t) effp->priv;
int i;
phaser->maxsamples = phaser->delay * effp->ininfo.rate / 1000.0;
if ( phaser->delay < 0.0 )
fail("phaser: delay must be positive!\n");
if ( phaser->delay > 5.0 )
fail("phaser: delay must be less than 5.0 msec!\n");
if ( phaser->speed < 0.1 )
fail("phaser: speed must be more than 0.1 Hz!\n");
if ( phaser->speed > 2.0 )
fail("phaser: speed must be less than 2.0 Hz!\n");
if ( phaser->decay < 0.0 )
fail("phaser: decay must be positive!\n" );
if ( phaser->decay >= 1.0 )
fail("phaser: decay must be less that 1.0!\n" );
/* Be nice and check the hint with warning, if... */
if ( phaser->in_gain > ( 1.0 - phaser->decay * phaser->decay ) )
warn("phaser: warning >>> gain-in can cause saturation or clipping of output <<<");
if ( phaser->in_gain / ( 1.0 - phaser->decay ) > 1.0 / phaser->out_gain )
warn("phaser: warning >>> gain-out can cause saturation or clipping of output <<<");
phaser->length = effp->ininfo.rate / phaser->speed;
if (! (phaser->phaserbuf =
(double *) malloc(sizeof (double) * phaser->maxsamples)))
fail("phaser: Cannot malloc %d bytes!\n",
sizeof(double) * phaser->maxsamples);
for ( i = 0; i < phaser->maxsamples; i++ )
phaser->phaserbuf[i] = 0.0;
if (! (phaser->lookup_tab =
(int *) malloc(sizeof (int) * phaser->length)))
fail("phaser: Cannot malloc %d bytes!\n",
sizeof(int) * phaser->length);
if ( phaser->modulation == MOD_SINE )
phaser_sine(phaser->lookup_tab, phaser->length,
phaser->maxsamples - 1);
else
phaser_triangle(phaser->lookup_tab, phaser->length,
phaser->maxsamples - 1);
phaser->counter = 0;
phaser->phase = 0;
phaser->fade_out = phaser->maxsamples;
}
/*
* Processed signed long samples from ibuf to obuf.
* Return number of samples processed.
*/
void phaser_flow(effp, ibuf, obuf, isamp, osamp)
eff_t effp;
LONG *ibuf, *obuf;
int *isamp, *osamp;
{
phaser_t phaser = (phaser_t) effp->priv;
int len, done;
double d_in, d_out;
LONG 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_in = d_in * phaser->in_gain;
d_in += phaser->phaserbuf[(phaser->maxsamples +
phaser->counter - phaser->lookup_tab[phaser->phase]) %
phaser->maxsamples] * phaser->decay * -1.0;
/* Adjust the output volume and size to 24 bit */
d_out = d_in * phaser->out_gain;
out = phaser_clip24((LONG) d_out);
*obuf++ = out * 256;
/* Mix decay of delay and input */
phaser->phaserbuf[phaser->counter] = d_in;
phaser->counter =
( phaser->counter + 1 ) % phaser->maxsamples;
phaser->phase = ( phaser->phase + 1 ) % phaser->length;
}
/* processed all samples */
}
/*
* Drain out reverb lines.
*/
void phaser_drain(effp, obuf, osamp)
eff_t effp;
LONG *obuf;
int *osamp;
{
phaser_t phaser = (phaser_t) effp->priv;
int done;
double d_in, d_out;
LONG out;
done = 0;
while ( ( done < *osamp ) && ( done < phaser->fade_out ) ) {
d_in = 0;
d_out = 0;
/* Compute output first */
d_in += phaser->phaserbuf[(phaser->maxsamples +
phaser->counter - phaser->lookup_tab[phaser->phase]) %
phaser->maxsamples] * phaser->decay * -1.0;
/* Adjust the output volume and size to 24 bit */
d_out = d_in * phaser->out_gain;
out = phaser_clip24((LONG) d_out);
*obuf++ = out * 256;
/* Mix decay of delay and input */
phaser->phaserbuf[phaser->counter] = d_in;
phaser->counter =
( phaser->counter + 1 ) % phaser->maxsamples;
phaser->phase = ( phaser->phase + 1 ) % phaser->length;
done++;
phaser->fade_out--;
}
/* samples playd, it remains */
*osamp = done;
}
/*
* Clean up phaser effect.
*/
void phaser_stop(effp)
eff_t effp;
{
phaser_t phaser = (phaser_t) effp->priv;
free((char *) phaser->phaserbuf);
phaser->phaserbuf = (double *) -1; /* guaranteed core dump */
free((char *) phaser->lookup_tab);
phaser->lookup_tab = (int *) -1; /* guaranteed core dump */
}