ref: 2d5b2941c9b541683937a66e92632461b7edd7fe
dir: /src/splice.c/
/* libSoX effect: splice audio Copyright (c) 2008-9 robs@users.sourceforge.net
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at
* your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
* General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "sox_i.h"
static double difference(
const sox_sample_t * a, const sox_sample_t * b, size_t length)
{
double diff = 0;
size_t i = 0;
#define _ diff += sqr((double)a[i] - b[i]), ++i; /* Loop optimisation */
do {_ _ _ _ _ _ _ _} while (i < length); /* N.B. length ≡ 0 (mod 8) */
#undef _
return diff;
}
/* Find where the two segments are most alike over the overlap period. */
static size_t best_overlap_position(sox_sample_t const * f1,
sox_sample_t const * f2, size_t overlap, size_t search, size_t channels)
{
size_t i, best_pos = 0;
double diff, least_diff = difference(f2, f1, channels * overlap);
for (i = 1; i < search; ++i) { /* linear search */
diff = difference(f2 + channels * i, f1, channels * overlap);
if (diff < least_diff)
least_diff = diff, best_pos = i;
}
return best_pos;
}
typedef struct {
enum {Cosine_2, Cosine_4, Triangular} fade_type;
unsigned nsplices; /* Number of splices requested */
struct {
char * str; /* Command-line argument to parse for this splice */
size_t overlap; /* Number of samples to overlap */
size_t search; /* Number of samples to search */
size_t start; /* Start splicing when in_pos equals this */
} * splices;
size_t in_pos; /* Number of samples read from the input stream */
unsigned splices_pos; /* Number of splices completed so far */
size_t buffer_pos; /* Number of samples through the current splice */
size_t max_buffer_size;
sox_sample_t * buffer;
unsigned state;
} priv_t;
static void splice(sox_effect_t * effp, const sox_sample_t * in1, const
sox_sample_t * in2, sox_sample_t * output, size_t overlap, size_t channels)
{
priv_t * p = (priv_t *)effp->priv;
size_t i, j, k = 0;
if (p->fade_type == Cosine_4) {
double fade_step = M_PI_2 / overlap;
for (i = 0; i < overlap; ++i) {
double fade_in = sin(i * fade_step);
double fade_out = cos(i * fade_step); /* constant RMS level (`power') */
for (j = 0; j < channels; ++j, ++k) {
double d = in1[k] * fade_out + in2[k] * fade_in;
output[k] = SOX_ROUND_CLIP_COUNT(d, effp->clips); /* Might clip */
}
}
}
else if (p->fade_type == Cosine_2) {
double fade_step = M_PI / overlap;
for (i = 0; i < overlap; ++i) {
double fade_in = .5 - .5 * cos(i * fade_step);
double fade_out = 1 - fade_in; /* constant peak level (`gain') */
for (j = 0; j < channels; ++j, ++k) {
double d = in1[k] * fade_out + in2[k] * fade_in;
output[k] = SOX_ROUND_CLIP_COUNT(d, effp->clips); /* Should not clip */
}
}
}
else /* Triangular */ {
double fade_step = 1. / overlap;
for (i = 0; i < overlap; ++i) {
double fade_in = fade_step * i;
double fade_out = 1 - fade_in; /* constant peak level (`gain') */
for (j = 0; j < channels; ++j, ++k) {
double d = in1[k] * fade_out + in2[k] * fade_in;
output[k] = SOX_ROUND_CLIP_COUNT(d, effp->clips); /* Should not clip */
}
}
}
}
static size_t do_splice(sox_effect_t * effp,
sox_sample_t * f, size_t overlap, size_t search, size_t channels)
{
size_t offset = search? best_overlap_position(
f, f + overlap * channels, overlap, search, channels) : 0;
splice(effp, f, f + (overlap + offset) * channels,
f + (overlap + offset) * channels, overlap, channels);
return overlap + offset;
}
static int parse(sox_effect_t * effp, char * * argv, sox_rate_t rate)
{
priv_t * p = (priv_t *)effp->priv;
char const * next;
size_t i, buffer_size;
p->max_buffer_size = 0;
for (i = 0; i < p->nsplices; ++i) {
if (argv) /* 1st parse only */
p->splices[i].str = lsx_strdup(argv[i]);
p->splices[i].overlap = rate * 0.01 + .5;
p->splices[i].search = p->fade_type == Cosine_4? 0 : p->splices[i].overlap;
next = lsx_parsesamples(rate, p->splices[i].str, &p->splices[i].start, 't');
if (next == NULL) break;
if (*next == ',') {
next = lsx_parsesamples(rate, next + 1, &p->splices[i].overlap, 't');
if (next == NULL) break;
p->splices[i].overlap *= 2;
if (*next == ',') {
next = lsx_parsesamples(rate, next + 1, &p->splices[i].search, 't');
if (next == NULL) break;
p->splices[i].search *= 2;
}
}
if (*next != '\0') break;
p->splices[i].overlap = max(p->splices[i].overlap + 4, 16);
p->splices[i].overlap &= ~7; /* Make divisible by 8 for loop optimisation */
if (i > 0 && p->splices[i].start <= p->splices[i-1].start) break;
if (p->splices[i].start < p->splices[i].overlap) break;
p->splices[i].start -= p->splices[i].overlap;
buffer_size = 2 * p->splices[i].overlap + p->splices[i].search;
p->max_buffer_size = max(p->max_buffer_size, buffer_size);
}
if (i < p->nsplices)
return lsx_usage(effp);
return SOX_SUCCESS;
}
static int create(sox_effect_t * effp, int argc, char * * argv)
{
priv_t * p = (priv_t *)effp->priv;
--argc, ++argv;
if (argc) {
if (!strcmp(*argv, "-t")) p->fade_type = Triangular, --argc, ++argv;
else if (!strcmp(*argv, "-q")) p->fade_type = Cosine_4 , --argc, ++argv;
else if (!strcmp(*argv, "-h")) p->fade_type = Cosine_2 , --argc, ++argv;
}
p->splices = lsx_calloc(p->nsplices = argc, sizeof(*p->splices));
return parse(effp, argv, 1e5); /* No rate yet; parse with dummy */
}
static int start(sox_effect_t * effp)
{
priv_t * p = (priv_t *)effp->priv;
unsigned i;
parse(effp, 0, effp->in_signal.rate); /* Re-parse now rate is known */
p->buffer = lsx_calloc(p->max_buffer_size * effp->in_signal.channels, sizeof(*p->buffer));
p->in_pos = p->buffer_pos = p->splices_pos = 0;
p->state = p->splices_pos != p->nsplices && p->in_pos == p->splices[p->splices_pos].start;
for (i = 0; i < p->nsplices; ++i)
if (p->splices[i].overlap) {
if (p->fade_type == Cosine_4 && effp->in_signal.mult)
*effp->in_signal.mult *= pow(.5, .5);
return SOX_SUCCESS;
}
return SOX_EFF_NULL;
}
static int flow(sox_effect_t * effp, const sox_sample_t * ibuf,
sox_sample_t * obuf, size_t * isamp, size_t * osamp)
{
priv_t * p = (priv_t *)effp->priv;
size_t c, idone = 0, odone = 0;
*isamp /= effp->in_signal.channels;
*osamp /= effp->in_signal.channels;
while (sox_true) {
copying:
if (p->state == 0) {
for (; idone < *isamp && odone < *osamp; ++idone, ++odone, ++p->in_pos) {
if (p->splices_pos != p->nsplices && p->in_pos == p->splices[p->splices_pos].start) {
p->state = 1;
goto buffering;
}
for (c = 0; c < effp->in_signal.channels; ++c)
*obuf++ = *ibuf++;
}
break;
}
buffering:
if (p->state == 1) {
size_t buffer_size = (2 * p->splices[p->splices_pos].overlap + p->splices[p->splices_pos].search) * effp->in_signal.channels;
for (; idone < *isamp; ++idone, ++p->in_pos) {
if (p->buffer_pos == buffer_size) {
p->buffer_pos = do_splice(effp, p->buffer,
p->splices[p->splices_pos].overlap,
p->splices[p->splices_pos].search,
(size_t)effp->in_signal.channels) * effp->in_signal.channels;
p->state = 2;
goto flushing;
break;
}
for (c = 0; c < effp->in_signal.channels; ++c)
p->buffer[p->buffer_pos++] = *ibuf++;
}
break;
}
flushing:
if (p->state == 2) {
size_t buffer_size = (2 * p->splices[p->splices_pos].overlap + p->splices[p->splices_pos].search) * effp->in_signal.channels;
for (; odone < *osamp; ++odone) {
if (p->buffer_pos == buffer_size) {
p->buffer_pos = 0;
++p->splices_pos;
p->state = p->splices_pos != p->nsplices && p->in_pos == p->splices[p->splices_pos].start;
goto copying;
}
for (c = 0; c < effp->in_signal.channels; ++c)
*obuf++ = p->buffer[p->buffer_pos++];
}
break;
}
}
*isamp = idone * effp->in_signal.channels;
*osamp = odone * effp->in_signal.channels;
return SOX_SUCCESS;
}
static int drain(sox_effect_t * effp, sox_sample_t * obuf, size_t * osamp)
{
size_t isamp = 0;
return flow(effp, 0, obuf, &isamp, osamp);
}
static int stop(sox_effect_t * effp)
{
priv_t * p = (priv_t *)effp->priv;
if (p->splices_pos != p->nsplices)
lsx_warn("Input audio too short; splices not made: %u", p->nsplices - p->splices_pos);
free(p->buffer);
return SOX_SUCCESS;
}
static int lsx_kill(sox_effect_t * effp)
{
priv_t * p = (priv_t *)effp->priv;
unsigned i;
for (i = 0; i < p->nsplices; ++i)
free(p->splices[i].str);
free(p->splices);
return SOX_SUCCESS;
}
sox_effect_handler_t const * lsx_splice_effect_fn(void)
{
static sox_effect_handler_t handler = {
"splice", "[-h|-t|-q] {position[,excess[,leeway]]}"
"\n -h Half sine fade (default); constant gain (for correlated audio)"
"\n -t Triangular (linear) fade; constant gain (for correlated audio)"
"\n -q Quarter sine fade; constant power (for correlated audio e.g. x-fade)"
"\n position The length of part 1 (including the excess)"
"\n excess At the end of part 1 & the start of part2 (default 0.005)"
"\n leeway Before part2 (default 0.005; set to 0 for cross-fade)",
SOX_EFF_MCHAN | SOX_EFF_LENGTH,
create, start, flow, drain, stop, lsx_kill, sizeof(priv_t)
};
return &handler;
}