ref: b2f339168bf5b666f96067daf4de4c9f07f51c92
dir: /src/pan.c/
/*
* (c) 20/03/2000 Fabien COELHO <fabien@coelho.net> for sox.
*
* Same copyright as SOX. See Sox (and Sun?;-)
*
* Change panorama of sound file with basic linear volume interpolation.
* The human ear is not sensible to phases? What about delay? too short?
*
* Volume is kept constant (?).
* Beware of saturations!
* Operations are carried out on doubles.
* Can handle different number of channels.
* Cannot handle rate change.
*
* Initially based on avg effect.
* pan 0.0 basically behaves as avg.
*/
#include "st_i.h"
#include <string.h>
static st_effect_t st_pan_effect;
/* structure to hold pan parameter */
typedef struct {
double dir; /* direction, from left (-1.0) to right (1.0) */
} * pan_t;
/*
* Process options
*/
static int st_pan_getopts(eff_t effp, int n, char **argv)
{
pan_t pan = (pan_t) effp->priv;
pan->dir = 0.0; /* default is no change */
if (n && (!sscanf(argv[0], "%lf", &pan->dir) ||
pan->dir < -1.0 || pan->dir > 1.0))
{
st_fail(st_pan_effect.usage);
return ST_EOF;
}
return ST_SUCCESS;
}
/*
* Start processing
*/
static int st_pan_start(eff_t effp)
{
if (effp->outinfo.channels==1)
st_warn("PAN onto a mono channel...");
if (effp->outinfo.rate != effp->ininfo.rate)
{
st_fail("PAN cannot handle different rates (in=%ld, out=%ld)"
" use resample or rate", effp->ininfo.rate, effp->outinfo.rate);
return ST_EOF;
}
return ST_SUCCESS;
}
#define UNEXPECTED_CHANNELS \
st_fail("unexpected number of channels (in=%d, out=%d)", ich, och); \
free(ibuf_copy); \
return ST_EOF
/*
* Process either isamp or osamp samples, whichever is smaller.
*/
static int st_pan_flow(eff_t effp, const st_sample_t *ibuf, st_sample_t *obuf,
st_size_t *isamp, st_size_t *osamp)
{
pan_t pan = (pan_t) effp->priv;
st_size_t len, done;
st_sample_t *ibuf_copy;
char ich, och;
double left, right, dir, hdir;
ibuf_copy = (st_sample_t *)xmalloc(*isamp * sizeof(st_sample_t));
memcpy(ibuf_copy, ibuf, *isamp * sizeof(st_sample_t));
dir = pan->dir; /* -1 <= dir <= 1 */
hdir = 0.5 * dir; /* -0.5 <= hdir <= 0.5 */
left = 0.5 - hdir; /* 0 <= left <= 1 */
right = 0.5 + hdir; /* 0 <= right <= 1 */
ich = effp->ininfo.channels;
och = effp->outinfo.channels;
len = min(*osamp/och,*isamp/ich);
/* report back how much is processed. */
*isamp = len*ich;
*osamp = len*och;
/* 9 different cases to handle: (1,2,4) X (1,2,4) */
switch (och) {
case 1: /* pan on mono channel... not much sense. just avg. */
switch (ich) {
case 1: /* simple copy */
for (done=0; done<len; done++)
*obuf++ = *ibuf_copy++;
break;
case 2: /* average 2 */
for (done=0; done<len; done++)
{
double f;
f = 0.5*ibuf_copy[0] + 0.5*ibuf_copy[1];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
*obuf++ = f;
ibuf_copy += 2;
}
break;
case 4: /* average 4 */
for (done=0; done<len; done++)
{
double f;
f = 0.25*ibuf_copy[0] + 0.25*ibuf_copy[1] +
0.25*ibuf_copy[2] + 0.25*ibuf_copy[3];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
*obuf++ = f;
ibuf_copy += 4;
}
break;
default:
UNEXPECTED_CHANNELS;
break;
} /* end first switch in channel */
break;
case 2:
switch (ich) {
case 1: /* linear */
for (done=0; done<len; done++)
{
double f;
f = left * ibuf_copy[0];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[0] = f;
f = right * ibuf_copy[0];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[1] = f;
obuf += 2;
ibuf_copy++;
}
break;
case 2: /* linear panorama.
* I'm not sure this is the right way to do it.
*/
if (dir <= 0.0) /* to the left */
{
register double volume, cll, clr, cr;
volume = 1.0 - 0.5*dir;
cll = volume*(1.5-left);
clr = volume*(left-0.5);
cr = volume*(1.0+dir);
for (done=0; done<len; done++)
{
double f;
f = cll * ibuf_copy[0] + clr * ibuf_copy[1];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[0] = f;
f = cr * ibuf_copy[1];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[1] = f;
obuf += 2;
ibuf_copy += 2;
}
}
else /* to the right */
{
register double volume, cl, crl, crr;
volume = 1.0 + 0.5*dir;
cl = volume*(1.0-dir);
crl = volume*(right-0.5);
crr = volume*(1.5-right);
for (done=0; done<len; done++)
{
double f;
f = cl * ibuf_copy[0];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[0] = f;
f = crl * ibuf_copy[0] + crr * ibuf_copy[1];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[1] = f;
obuf += 2;
ibuf_copy += 2;
}
}
break;
case 4:
if (dir <= 0.0) /* to the left */
{
register double volume, cll, clr, cr;
volume = 1.0 - 0.5*dir;
cll = volume*(1.5-left);
clr = volume*(left-0.5);
cr = volume*(1.0+dir);
for (done=0; done<len; done++)
{
register double ibuf0, ibuf1, f;
/* build stereo signal */
ibuf0 = 0.5*ibuf_copy[0] + 0.5*ibuf_copy[2];
ibuf1 = 0.5*ibuf_copy[1] + 0.5*ibuf_copy[3];
/* pan it */
f = cll * ibuf0 + clr * ibuf1;
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[0] = f;
f = cr * ibuf1;
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[1] = f;
obuf += 2;
ibuf_copy += 4;
}
}
else /* to the right */
{
register double volume, cl, crl, crr;
volume = 1.0 + 0.5*dir;
cl = volume*(1.0-dir);
crl = volume*(right-0.5);
crr = volume*(1.5-right);
for (done=0; done<len; done++)
{
register double ibuf0, ibuf1, f;
ibuf0 = 0.5*ibuf_copy[0] + 0.5*ibuf_copy[2];
ibuf1 = 0.5*ibuf_copy[1] + 0.5*ibuf_copy[3];
f = cl * ibuf0;
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[0] = f;
f = crl * ibuf0 + crr * ibuf1;
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[1] = f;
obuf += 2;
ibuf_copy += 4;
}
}
break;
default:
UNEXPECTED_CHANNELS;
break;
} /* end second switch in channel */
break;
case 4:
switch (ich) {
case 1: /* linear */
{
register double cr, cl;
cl = 0.5*left;
cr = 0.5*right;
for (done=0; done<len; done++)
{
double f;
f = cl * ibuf_copy[0];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[2] = obuf[0] = f;
f = cr * ibuf_copy[0];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
ibuf_copy[3] = obuf[1] = f;
obuf += 4;
ibuf_copy++;
}
}
break;
case 2: /* simple linear panorama */
if (dir <= 0.0) /* to the left */
{
register double volume, cll, clr, cr;
volume = 0.5 - 0.25*dir;
cll = volume * (1.5-left);
clr = volume * (left-0.5);
cr = volume * (1.0+dir);
for (done=0; done<len; done++)
{
double f;
f = cll * ibuf_copy[0] + clr * ibuf_copy[1];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[2] = obuf[0] = f;
f = cr * ibuf_copy[1];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
ibuf_copy[3] = obuf[1] = f;
obuf += 4;
ibuf_copy += 2;
}
}
else /* to the right */
{
register double volume, cl, crl, crr;
volume = 0.5 + 0.25*dir;
cl = volume * (1.0-dir);
crl = volume * (right-0.5);
crr = volume * (1.5-right);
for (done=0; done<len; done++)
{
double f;
f = cl * ibuf_copy[0];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[2] = obuf[0] =f ;
f = crl * ibuf_copy[0] + crr * ibuf_copy[1];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
ibuf_copy[3] = obuf[1] = f;
obuf += 4;
ibuf_copy += 2;
}
}
break;
case 4:
/* maybe I could improve the formula to reverse...
also, turn only by quarters.
*/
if (dir <= 0.0) /* to the left */
{
register double cown, cright;
cright = -dir;
cown = 1.0 + dir;
for (done=0; done<len; done++)
{
double f;
f = cown*ibuf_copy[0] + cright*ibuf_copy[1];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[0] = f;
f = cown*ibuf_copy[1] + cright*ibuf_copy[3];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[1] = f;
f = cown*ibuf_copy[2] + cright*ibuf_copy[0];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[2] = f;
f = cown*ibuf_copy[3] + cright*ibuf_copy[2];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[3] = f;
obuf += 4;
ibuf_copy += 4;
}
}
else /* to the right */
{
register double cleft, cown;
cleft = dir;
cown = 1.0 - dir;
for (done=0; done<len; done++)
{
double f;
f = cleft*ibuf_copy[2] + cown*ibuf_copy[0];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[0] = f;
f = cleft*ibuf_copy[0] + cown*ibuf_copy[1];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[1] = f;
f = cleft*ibuf_copy[3] + cown*ibuf_copy[2];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[2] = f;
f = cleft*ibuf_copy[1] + cown*ibuf_copy[3];
ST_SAMPLE_CLIP_COUNT(f, effp->clips);
obuf[3] = f;
obuf += 4;
ibuf_copy += 4;
}
}
break;
default:
UNEXPECTED_CHANNELS;
break;
} /* end third switch in channel */
break;
default:
UNEXPECTED_CHANNELS;
break;
} /* end switch out channel */
free(ibuf_copy);
return ST_SUCCESS;
}
/*
* FIXME: Add a stop function with statistics on right, left, and output amplitudes.
*/
static st_effect_t st_pan_effect = {
"pan",
"Usage: pan direction (in [-1.0 .. 1.0])",
ST_EFF_MCHAN | ST_EFF_CHAN,
st_pan_getopts,
st_pan_start,
st_pan_flow,
st_effect_nothing_drain,
st_effect_nothing,
st_effect_nothing
};
const st_effect_t *st_pan_effect_fn(void)
{
return &st_pan_effect;
}