ref: aac924f5cc55696f9771c3ed1a7a7f2d049e19dd
dir: /src/compand.c/
/* libSoX compander effect
*
* Written by Nick Bailey (nick@bailey-family.org.uk or
* n.bailey@elec.gla.ac.uk)
*
* Copyright 1999 Chris Bagwell And Nick Bailey
* This source code is freely redistributable and may be used for
* any purpose. This copyright notice must be maintained.
* Chris Bagwell And Nick Bailey are not responsible for
* the consequences of using this software.
*/
#include "sox_i.h"
#include <string.h>
#include <stdlib.h>
#include "compandt.h"
/*
* Compressor/expander effect for libSoX.
*
* Flow diagram for one channel:
*
* ------------ ---------------
* | | | | ---
* ibuff ---+---| integrator |--->| transfer func |--->| |
* | | | | | | |
* | ------------ --------------- | | * gain
* | | * |----------->obuff
* | ------- | |
* | | | | |
* +----->| delay |-------------------------->| |
* | | ---
* -------
*/
#define compand_usage \
"attack1,decay1{,attack2,decay2} [soft-knee-dB:]in-dB1[,out-dB1]{,in-dB2,out-dB2} [gain [initial-volume-dB [delay]]]\n" \
"\twhere {} means optional and repeatable and [] means optional.\n" \
"\tdB values are floating point or -inf'; times are in seconds."
/*
* Note: clipping can occur if the transfer function pushes things too
* close to 0 dB. In that case, use a negative gain, or reduce the
* output level of the transfer function.
*/
typedef struct {
sox_compandt_t transfer_fn;
struct {
double attack_times[2]; /* 0:attack_time, 1:decay_time */
double volume; /* Current "volume" of each channel */
} * channels;
unsigned expectedChannels;/* Also flags that channels aren't to be treated
individually when = 1 and input not mono */
double delay; /* Delay to apply before companding */
sox_sample_t *delay_buf; /* Old samples, used for delay processing */
ptrdiff_t delay_buf_size;/* Size of delay_buf in samples */
ptrdiff_t delay_buf_index; /* Index into delay_buf */
ptrdiff_t delay_buf_cnt; /* No. of active entries in delay_buf */
int delay_buf_full; /* Shows buffer situation (important for drain) */
} priv_t;
static int getopts(sox_effect_t * effp, int n, char * * argv)
{
priv_t * l = (priv_t *) effp->priv;
char * s;
char dummy; /* To check for extraneous chars. */
unsigned pairs, i, j, commas;
if (n < 2 || n > 5)
return lsx_usage(effp);
/* Start by checking the attack and decay rates */
for (s = argv[0], commas = 0; *s; ++s) if (*s == ',') ++commas;
if ((commas % 2) == 0) {
lsx_fail("there must be an even number of attack/decay parameters");
return SOX_EOF;
}
pairs = 1 + commas/2;
l->channels = lsx_calloc(pairs, sizeof(*l->channels));
l->expectedChannels = pairs;
/* Now tokenise the rates string and set up these arrays. Keep
them in seconds at the moment: we don't know the sample rate yet. */
for (i = 0, s = strtok(argv[0], ","); s != NULL; ++i) {
for (j = 0; j < 2; ++j) {
if (sscanf(s, "%lf %c", &l->channels[i].attack_times[j], &dummy) != 1) {
lsx_fail("syntax error trying to read attack/decay time");
return SOX_EOF;
} else if (l->channels[i].attack_times[j] < 0) {
lsx_fail("attack & decay times can't be less than 0 seconds");
return SOX_EOF;
}
s = strtok(NULL, ",");
}
}
if (!lsx_compandt_parse(&l->transfer_fn, argv[1], n>2 ? argv[2] : 0))
return SOX_EOF;
/* Set the initial "volume" to be attibuted to the input channels.
Unless specified, choose 0dB otherwise clipping will
result if the user has seleced a long attack time */
for (i = 0; i < l->expectedChannels; ++i) {
double init_vol_dB = 0;
if (n > 3 && sscanf(argv[3], "%lf %c", &init_vol_dB, &dummy) != 1) {
lsx_fail("syntax error trying to read initial volume");
return SOX_EOF;
} else if (init_vol_dB > 0) {
lsx_fail("initial volume is relative to maximum volume so can't exceed 0dB");
return SOX_EOF;
}
l->channels[i].volume = pow(10., init_vol_dB / 20);
}
/* If there is a delay, store it. */
if (n > 4 && sscanf(argv[4], "%lf %c", &l->delay, &dummy) != 1) {
lsx_fail("syntax error trying to read delay value");
return SOX_EOF;
} else if (l->delay < 0) {
lsx_fail("delay can't be less than 0 seconds");
return SOX_EOF;
}
return SOX_SUCCESS;
}
static int start(sox_effect_t * effp)
{
priv_t * l = (priv_t *) effp->priv;
unsigned i, j;
lsx_debug("%i input channel(s) expected: actually %i",
l->expectedChannels, effp->out_signal.channels);
for (i = 0; i < l->expectedChannels; ++i)
lsx_debug("Channel %i: attack = %g decay = %g", i,
l->channels[i].attack_times[0], l->channels[i].attack_times[1]);
if (!lsx_compandt_show(&l->transfer_fn, effp->global_info->plot))
return SOX_EOF;
/* Convert attack and decay rates using number of samples */
for (i = 0; i < l->expectedChannels; ++i)
for (j = 0; j < 2; ++j)
if (l->channels[i].attack_times[j] > 1.0/effp->out_signal.rate)
l->channels[i].attack_times[j] = 1.0 -
exp(-1.0/(effp->out_signal.rate * l->channels[i].attack_times[j]));
else
l->channels[i].attack_times[j] = 1.0;
/* Allocate the delay buffer */
l->delay_buf_size = l->delay * effp->out_signal.rate * effp->out_signal.channels;
if (l->delay_buf_size > 0)
l->delay_buf = lsx_calloc((size_t)l->delay_buf_size, sizeof(*l->delay_buf));
l->delay_buf_index = 0;
l->delay_buf_cnt = 0;
l->delay_buf_full= 0;
return SOX_SUCCESS;
}
/*
* Update a volume value using the given sample
* value, the attack rate and decay rate
*/
static void doVolume(double *v, double samp, priv_t * l, int chan)
{
double s = -samp / SOX_SAMPLE_MIN;
double delta = s - *v;
if (delta > 0.0) /* increase volume according to attack rate */
*v += delta * l->channels[chan].attack_times[0];
else /* reduce volume according to decay rate */
*v += delta * l->channels[chan].attack_times[1];
}
static int flow(sox_effect_t * effp, const sox_sample_t *ibuf, sox_sample_t *obuf,
size_t *isamp, size_t *osamp)
{
priv_t * l = (priv_t *) effp->priv;
int len = (*isamp > *osamp) ? *osamp : *isamp;
int filechans = effp->out_signal.channels;
int idone,odone;
for (idone = 0,odone = 0; idone < len; ibuf += filechans) {
int chan;
/* Maintain the volume fields by simulating a leaky pump circuit */
for (chan = 0; chan < filechans; ++chan) {
if (l->expectedChannels == 1 && filechans > 1) {
/* User is expecting same compander for all channels */
int i;
double maxsamp = 0.0;
for (i = 0; i < filechans; ++i) {
double rect = fabs((double)ibuf[i]);
if (rect > maxsamp) maxsamp = rect;
}
doVolume(&l->channels[0].volume, maxsamp, l, 0);
break;
} else
doVolume(&l->channels[chan].volume, fabs((double)ibuf[chan]), l, chan);
}
/* Volume memory is updated: perform compand */
for (chan = 0; chan < filechans; ++chan) {
int ch = l->expectedChannels > 1 ? chan : 0;
double level_in_lin = l->channels[ch].volume;
double level_out_lin = lsx_compandt(&l->transfer_fn, level_in_lin);
double checkbuf;
if (l->delay_buf_size <= 0) {
checkbuf = ibuf[chan] * level_out_lin;
SOX_SAMPLE_CLIP_COUNT(checkbuf, effp->clips);
obuf[odone++] = checkbuf;
idone++;
} else {
if (l->delay_buf_cnt >= l->delay_buf_size) {
l->delay_buf_full=1; /* delay buffer is now definitely full */
checkbuf = l->delay_buf[l->delay_buf_index] * level_out_lin;
SOX_SAMPLE_CLIP_COUNT(checkbuf, effp->clips);
obuf[odone] = checkbuf;
odone++;
idone++;
} else {
l->delay_buf_cnt++;
idone++; /* no "odone++" because we did not fill obuf[...] */
}
l->delay_buf[l->delay_buf_index++] = ibuf[chan];
l->delay_buf_index %= l->delay_buf_size;
}
}
}
*isamp = idone; *osamp = odone;
return (SOX_SUCCESS);
}
static int drain(sox_effect_t * effp, sox_sample_t *obuf, size_t *osamp)
{
priv_t * l = (priv_t *) effp->priv;
size_t chan, done = 0;
if (l->delay_buf_full == 0)
l->delay_buf_index = 0;
while (done < *osamp && l->delay_buf_cnt > 0)
for (chan = 0; chan < effp->out_signal.channels; ++chan) {
int c = l->expectedChannels > 1 ? chan : 0;
double level_in_lin = l->channels[c].volume;
double level_out_lin = lsx_compandt(&l->transfer_fn, level_in_lin);
obuf[done++] = l->delay_buf[l->delay_buf_index++] * level_out_lin;
l->delay_buf_index %= l->delay_buf_size;
l->delay_buf_cnt--;
}
*osamp = done;
return l->delay_buf_cnt > 0 ? SOX_SUCCESS : SOX_EOF;
}
static int stop(sox_effect_t * effp)
{
priv_t * l = (priv_t *) effp->priv;
free(l->delay_buf);
return SOX_SUCCESS;
}
static int kill(sox_effect_t * effp)
{
priv_t * l = (priv_t *) effp->priv;
lsx_compandt_kill(&l->transfer_fn);
free(l->channels);
return SOX_SUCCESS;
}
sox_effect_handler_t const * sox_compand_effect_fn(void)
{
static sox_effect_handler_t handler = {
"compand", compand_usage, SOX_EFF_MCHAN,
getopts, start, flow, drain, stop, kill, sizeof(priv_t)
};
return &handler;
}