ref: 24d4bb8b96debd999d0451e5a319c45a581ddff1
dir: /src/mixer.c/
/* 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.
*
* Channel duplication code by Graeme W. Gill - 93/5/18
* General-purpose panning by Geoffrey H. Kuenning -- 2000/11/28
*/
/*
* libSoX stereo/quad -> mono mixdown effect file.
* and mono/stereo -> stereo/quad channel duplication.
*/
#include "sox_i.h"
#include <ctype.h>
#include <string.h>
#include <stdlib.h>
typedef struct {
/* How to generate each output channel. sources[i][j] */
/* represents the fraction of channel i that should be passed */
/* through to channel j on output, and so forth. Channel 0 is */
/* left front, channel 1 is right front, and 2 and 3 are left */
/* and right rear, respectively. (GHK) */
double sources[4][4];
int num_pans;
int mix; /* How are we mixing it? */
} priv_t;
/* MIX_CENTER is shorthand to mix channels together at 50% each */
#define MIX_CENTER 0
#define MIX_SPECIFIED 1
/*
* Process options
*/
static int getopts(sox_effect_t * effp, int argc, char **argv)
{
priv_t * mixer = (priv_t *) effp->priv;
double* pans = &mixer->sources[0][0];
int i;
--argc, ++argv;
for (i = 0; i < 16; i++)
pans[i] = 0.0;
mixer->mix = MIX_CENTER;
mixer->num_pans = 0;
/* Parse parameters. Since we don't yet know the number of */
/* input and output channels, we'll record the information for */
/* later. */
if (argc == 1) {
if (!strcmp(argv[0], "-l")) mixer->mix = 'l';
else if (!strcmp(argv[0], "-r")) mixer->mix = 'r';
else if (!strcmp(argv[0], "-f")) mixer->mix = 'f';
else if (!strcmp(argv[0], "-b")) mixer->mix = 'b';
else if (!strcmp(argv[0], "-1")) mixer->mix = '1';
else if (!strcmp(argv[0], "-2")) mixer->mix = '2';
else if (!strcmp(argv[0], "-3")) mixer->mix = '3';
else if (!strcmp(argv[0], "-4")) mixer->mix = '4';
else if (argv[0][0] == '-' && !isdigit((int)argv[0][1])
&& argv[0][1] != '.')
return lsx_usage(effp);
else {
int commas;
char *s;
mixer->mix = MIX_SPECIFIED;
pans[0] = atof(argv[0]);
for (s = argv[0], commas = 0; *s; ++s) {
if (*s == ',') {
++commas;
if (commas >= 16) {
lsx_fail("mixer can only take up to 16 pan values");
return (SOX_EOF);
}
pans[commas] = atof(s+1);
}
}
mixer->num_pans = commas + 1;
}
}
else if (argc == 0) {
mixer->mix = MIX_CENTER;
}
else
return lsx_usage(effp);
return (SOX_SUCCESS);
}
/*
* Start processing
*/
static int start(sox_effect_t * effp)
{
/*
Hmmm, this is tricky. Lemme think:
channel orders are [0][0],[0][1], etc.
i.e., 0->0, 0->1, 0->2, 0->3, 1->0, 1->1, ...
trailing zeros are omitted
L/R balance is x= -1 for left only, 1 for right only
1->1 channel effects:
changing volume by x is x,0,0,0
1->2 channel effects:
duplicating everywhere is 1,1,0,0
1->4 channel effects:
duplicating everywhere is 1,1,1,1
2->1 channel effects:
left only is 1,0,0,0 0,0,0,0
right only is 0,0,0,0 1,0,0,0
left+right is 0.5,0,0,0 0.5,0,0,0
left-right is 1,0,0,0 -1,0,0,0
2->2 channel effects:
L/R balance can be done several ways. The standard stereo
way is both the easiest and the most sensible:
min(1-x,1),0,0,0 0,min(1+x,1),0,0
left to both is 1,1,0,0
right to both is 0,0,0,0 1,1,0,0
left+right to both is 0.5,0.5,0,0 0.5,0.5,0,0
left-right to both is 1,1,0,0 -1,-1,0,0
left-right to left, right-left to right is 1,-1,0,0 -1,1,0,0
2->4 channel effects:
front duplicated into rear is 1,0,1,0 0,1,0,1
front swapped into rear (why?) is 1,0,0,1 0,1,1,0
front put into rear as mono (why?) is 1,0,0.5,0.5 0,1,0.5,0.5
4->1 channel effects:
left front only is 1,0,0,0
left only is 0.5,0,0,0 0,0,0,0 0.5,0,0,0
etc.
4->2 channel effects:
merge front/back is 0.5,0,0,0 0,0.5,0,0 0.5,0,0,0 0,0.5,0,0
selections similar to above
4->4 channel effects:
left front to all is 1,1,1,1 0,0,0,0
right front to all is 0,0,0,0 1,1,1,1
left f/r to all f/r is 1,1,0,0 0,0,0,0 0,0,1,1 0,0,0,0
etc.
The interesting cases from above (deserving of abbreviations of
less than 16 numbers) are:
0) n->n volume change (1 number)
1) 1->n duplication (0 numbers)
2) 2->1 mixdown (0 or 2 numbers)
3) 2->2 balance (1 number)
4) 2->2 fully general mix (4 numbers)
5) 2->4 duplication (0 numbers)
6) 4->1 mixdown (0 or 4 numbers)
7) 4->2 mixdown (0, or 2 numbers)
8) 4->4 balance (1 or 2 numbers)
The above has one ambiguity: n->n volume change conflicts with
n->n balance for n != 1. In such a case, we'll prefer
balance, since there is already a volume effect in vol.c.
GHK 2000/11/28
*/
priv_t * mixer = (priv_t *) effp->priv;
double pans[16];
int i, j;
int ichan, ochan;
for (i = 0; i < 16; i++)
pans[i] = ((double*)&mixer->sources[0][0])[i];
ichan = effp->in_signal.channels;
ochan = effp->out_signal.channels;
if (ochan == -1) {
lsx_fail("Output must have known number of channels");
return(SOX_EOF);
}
if ((ichan != 1 && ichan != 2 && ichan != 4 &&
mixer->mix != MIX_CENTER && ochan != 1)
|| (ochan != 1 && ochan != 2 && ochan != 4)) {
lsx_fail("Can't mix %d -> %d channels", ichan, ochan);
return (SOX_EOF);
}
/* Handle the special-case flags */
switch (mixer->mix) {
case MIX_CENTER:
if (ichan == ochan)
return SOX_EFF_NULL;
break; /* Code below will handle this case */
case 'l':
if (ichan == 2 && ochan == 1)
{
pans[0] = 1.0;
pans[1] = 0.0;
mixer->num_pans = 2;
}
else if (ichan == 4 && ochan == 1)
{
pans[0] = 0.5;
pans[1] = 0.0;
pans[2] = 0.5;
pans[3] = 0.0;
mixer->num_pans = 4;
}
else
{
lsx_fail("Can't mix -%c %d -> %d channels", mixer->mix, ichan, ochan);
return SOX_EOF;
}
break;
case 'r':
if (ichan == 2 && ochan == 1)
{
pans[0] = 0.0;
pans[1] = 1.0;
mixer->num_pans = 2;
}
else if (ichan == 4 && ochan == 1)
{
pans[0] = 0.0;
pans[1] = 0.5;
pans[2] = 0.0;
pans[3] = 0.5;
mixer->num_pans = 4;
}
else
{
lsx_fail("Can't mix -%c %d -> %d channels", mixer->mix, ichan, ochan);
return SOX_EOF;
}
break;
case 'f':
if (ichan == 4 && ochan == 2)
{
pans[0] = 1.0;
pans[1] = 0.0;
mixer->num_pans = 2;
}
else if (ichan == 4 && ochan == 1)
{
pans[0] = 0.5;
pans[1] = 0.5;
pans[2] = 0.0;
pans[3] = 0.0;
mixer->num_pans = 4;
}
else
{
lsx_fail("Can't mix -%c %d -> %d channels", mixer->mix, ichan, ochan);
return SOX_EOF;
}
break;
case 'b':
if (ichan == 4 && ochan == 2)
{
pans[0] = 0.0;
pans[1] = 1.0;
mixer->num_pans = 2;
}
else if (ichan == 4 && ochan == 1)
{
pans[0] = 0.0;
pans[1] = 0.0;
pans[2] = 0.5;
pans[3] = 0.5;
mixer->num_pans = 4;
}
else
{
lsx_fail("Can't mix -%c %d -> %d channels", mixer->mix, ichan, ochan);
return SOX_EOF;
}
break;
case '1':
if (ichan == 2 && ochan == 1)
{
pans[0] = 1.0;
pans[1] = 0.0;
mixer->num_pans = 2;
}
else if (ichan == 4 && ochan == 1)
{
pans[0] = 1.0;
pans[1] = 0.0;
pans[2] = 0.0;
pans[3] = 0.0;
mixer->num_pans = 4;
}
else
{
lsx_fail("Can't mix -%c %d -> %d channels", mixer->mix, ichan, ochan);
return SOX_EOF;
}
break;
case '2':
if (ichan == 2 && ochan == 1)
{
pans[0] = 0.0;
pans[1] = 1.0;
mixer->num_pans = 2;
}
else if (ichan == 4 && ochan == 1)
{
pans[0] = 0.0;
pans[1] = 1.0;
pans[2] = 0.0;
pans[3] = 0.0;
mixer->num_pans = 4;
}
else
{
lsx_fail("Can't mix -%c %d -> %d channels", mixer->mix, ichan, ochan);
return SOX_EOF;
}
break;
case '3':
if (ichan == 4 && ochan == 1)
{
pans[0] = 0.0;
pans[1] = 0.0;
pans[2] = 1.0;
pans[3] = 0.0;
mixer->num_pans = 4;
}
else
{
lsx_fail("Can't mix -%c %d -> %d channels", mixer->mix, ichan, ochan);
return SOX_EOF;
}
break;
case '4':
if (ichan == 4 && ochan == 1)
{
pans[0] = 0.0;
pans[1] = 0.0;
pans[2] = 0.0;
pans[3] = 1.0;
mixer->num_pans = 4;
}
else
{
lsx_fail("Can't mix -%c %d -> %d channels", mixer->mix, ichan, ochan);
return SOX_EOF;
}
break;
case MIX_SPECIFIED:
break;
default:
lsx_fail("Unknown mix option");
return SOX_EOF;
}
/* If number of pans is 4 or less then its a shorthand
* representation. If user specified it, then we have
* garbage in our sources[][] array. Need to clear that
* now that all data is stored in pans[] array.
*/
if (mixer->num_pans <= 4)
{
for (i = 0; i < ichan; i++)
{
for (j = 0; j < ochan; j++)
{
mixer->sources[i][j] = 0;
}
}
}
/* If the number of pans given is 4 or fewer, handle the special */
/* cases listed in the comments above. The code is lengthy but */
/* straightforward. */
if (mixer->num_pans == 0) {
/* CASE 1 */
if (ichan == 1 && ochan > ichan) {
mixer->sources[0][0] = 1.0;
mixer->sources[0][1] = 1.0;
mixer->sources[0][2] = 1.0;
mixer->sources[0][3] = 1.0;
}
/* CASE 2, 6 */
else if (ochan == 1) {
mixer->sources[0][0] = 1.0 / ichan;
}
/* CASE 5 */
else if (ichan == 2 && ochan == 4) {
mixer->sources[0][0] = 1.0;
mixer->sources[0][2] = 1.0;
mixer->sources[1][1] = 1.0;
mixer->sources[1][3] = 1.0;
}
/* CASE 7 */
else if (ichan == 4 && ochan == 2) {
mixer->sources[0][0] = 0.5;
mixer->sources[1][1] = 0.5;
mixer->sources[2][0] = 0.5;
mixer->sources[3][1] = 0.5;
}
else {
lsx_fail("You must specify at least one mix level when using mixer with an unusual number of channels.");
return(SOX_EOF);
}
}
else if (mixer->num_pans == 1) {
/* Might be volume change or balance change */
/* CASE 3 and CASE 8 */
if ((ichan == 2 || ichan == 4) && ichan == ochan) {
/* -1 is left only, 1 is right only */
if (pans[0] <= 0.0) {
mixer->sources[1][1] = pans[0] + 1.0;
if (mixer->sources[1][1] < 0.0)
mixer->sources[1][1] = 0.0;
mixer->sources[0][0] = 1.0;
}
else {
mixer->sources[0][0] = 1.0 - pans[0];
if (mixer->sources[0][0] < 0.0)
mixer->sources[0][0] = 0.0;
mixer->sources[1][1] = 1.0;
}
if (ichan == 4) {
mixer->sources[2][2] = mixer->sources[0][0];
mixer->sources[3][3] = mixer->sources[1][1];
}
}
else
{
lsx_fail("Invalid options while not mixing");
return SOX_EOF;
}
}
else if (mixer->num_pans == 2) {
/* CASE 2 */
if (ichan == 2 && ochan == 1) {
mixer->sources[0][0] = pans[0];
mixer->sources[1][0] = pans[1];
}
/* CASE 7 */
else if (ichan == 4 && ochan == 2) {
mixer->sources[0][0] = pans[0];
mixer->sources[1][1] = pans[0];
mixer->sources[2][0] = pans[1];
mixer->sources[3][1] = pans[1];
}
/* CASE 8 */
else if (ichan == 4 && ochan == 4) {
/* pans[0] is front -> front, pans[1] is for back */
mixer->sources[0][0] = pans[0];
mixer->sources[1][1] = pans[0];
mixer->sources[2][2] = pans[1];
mixer->sources[3][3] = pans[1];
}
else
{
lsx_fail("Invalid options for this channel combination");
return SOX_EOF;
}
}
else if (mixer->num_pans == 3) {
lsx_fail("Invalid options while not mixing");
return SOX_EOF;
}
else if (mixer->num_pans == 4) {
/* CASE 4 */
if (ichan == 2 && ochan == 2) {
/* Shorthand for 2-channel case */
mixer->sources[0][0] = pans[0];
mixer->sources[0][1] = pans[1];
mixer->sources[1][0] = pans[2];
mixer->sources[1][1] = pans[3];
}
/* CASE 6 */
else if (ichan == 4 && ochan == 1) {
mixer->sources[0][0] = pans[0];
mixer->sources[1][0] = pans[1];
mixer->sources[2][0] = pans[2];
mixer->sources[3][0] = pans[3];
}
else
{
lsx_fail("Invalid options for this channel combination");
return SOX_EOF;
}
}
if (effp->in_signal.mult) {
double max_sum = 0;
for (j = 0; j < (int)effp->out_signal.channels; ++j) {
double sum = 0;
for (i = 0; i < (int)effp->in_signal.channels; ++i)
sum += fabs(mixer->sources[mixer->mix == MIX_CENTER? 0 : i][j]);
max_sum = max(max_sum, sum);
}
if (max_sum > 1)
*effp->in_signal.mult /= max_sum;
}
if (effp->in_signal.channels != effp->out_signal.channels)
return SOX_SUCCESS;
for (i = 0; i < (int)effp->in_signal.channels; ++i)
for (j = 0; j < (int)effp->out_signal.channels; ++j)
if (mixer->sources[i][j] != (i == j))
return SOX_SUCCESS;
return SOX_EFF_NULL;
}
/*
* Process either isamp or osamp samples, whichever is smaller.
*/
static int flow(sox_effect_t * effp, const sox_sample_t *ibuf, sox_sample_t *obuf,
size_t *isamp, size_t *osamp)
{
priv_t * mixer = (priv_t *) effp->priv;
size_t len, done;
int ichan, ochan;
int i, j;
double samp;
ichan = effp->in_signal.channels;
ochan = effp->out_signal.channels;
len = *isamp / ichan;
if (len > *osamp / ochan)
len = *osamp / ochan;
for (done = 0; done < len; done++, ibuf += ichan, obuf += ochan) {
for (j = 0; j < ochan; j++) {
samp = 0.0;
for (i = 0; i < ichan; i++)
samp += ibuf[i] * mixer->sources[mixer->mix == MIX_CENTER? 0 : i][j];
SOX_SAMPLE_CLIP_COUNT(samp, effp->clips);
obuf[j] = samp;
}
}
*isamp = len * ichan;
*osamp = len * ochan;
return (SOX_SUCCESS);
}
sox_effect_handler_t const * lsx_mixer_effect_fn(void)
{
static sox_effect_handler_t handler = {
"mixer",
"[ -l | -r | -f | -b | -1 | -2 | -3 | -4 | n,n,n...,n ]",
SOX_EFF_MCHAN | SOX_EFF_CHAN | SOX_EFF_GAIN | SOX_EFF_DEPRECATED,
getopts, start, flow, 0, 0, 0, sizeof(priv_t)
};
return &handler;
}