ref: 9abe8822ba60526b4f02fb0fbf4634f4eb9bf51d
dir: /src/sinc.c/
/* Effect: sinc filters 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"
#include "dft_filter.h"
#include <string.h>
typedef struct {
dft_filter_priv_t base;
double att, beta, phase, Fc0, Fc1, tbw0, tbw1;
int num_taps[2];
sox_bool round;
} priv_t;
static int create(sox_effect_t * effp, int argc, char * * argv)
{
priv_t * p = (priv_t *)effp->priv;
dft_filter_priv_t * b = &p->base;
char * parse_ptr = argv[0];
int i = 0;
lsx_getopt_t optstate;
lsx_getopt_init(argc, argv, "+ra:b:p:MILt:n:", NULL, lsx_getopt_flag_none, 1, &optstate);
b->filter_ptr = &b->filter;
p->phase = 50;
p->beta = -1;
while (i < 2) {
int c = 1;
while (c && (c = lsx_getopt(&optstate)) != -1) switch (c) {
char * parse_ptr2;
case 'r': p->round = sox_true; break;
GETOPT_NUMERIC(optstate, 'a', att, 40 , 180)
GETOPT_NUMERIC(optstate, 'b', beta, 0 , 256)
GETOPT_NUMERIC(optstate, 'p', phase, 0, 100)
case 'M': p->phase = 0; break;
case 'I': p->phase = 25; break;
case 'L': p->phase = 50; break;
GETOPT_NUMERIC(optstate, 'n', num_taps[1], 11, 32767)
case 't': p->tbw1 = lsx_parse_frequency(optstate.arg, &parse_ptr2);
if (p->tbw1 < 1 || *parse_ptr2) return lsx_usage(effp);
break;
default: c = 0;
}
if ((p->att && p->beta >= 0) || (p->tbw1 && p->num_taps[1]))
return lsx_usage(effp);
if (!i || !p->Fc1)
p->tbw0 = p->tbw1, p->num_taps[0] = p->num_taps[1];
if (!i++ && optstate.ind < argc) {
if (*(parse_ptr = argv[optstate.ind++]) != '-')
p->Fc0 = lsx_parse_frequency(parse_ptr, &parse_ptr);
if (*parse_ptr == '-')
p->Fc1 = lsx_parse_frequency(parse_ptr + 1, &parse_ptr);
}
}
return optstate.ind != argc || p->Fc0 < 0 || p->Fc1 < 0 || *parse_ptr ?
lsx_usage(effp) : SOX_SUCCESS;
}
static void invert(double * h, int n)
{
int i;
for (i = 0; i < n; ++i)
h[i] = -h[i];
h[(n - 1) / 2] += 1;
}
static double * lpf(double Fn, double Fc, double tbw, int * num_taps, double att, double * beta, sox_bool round)
{
int n = *num_taps;
if ((Fc /= Fn) <= 0 || Fc >= 1) {
*num_taps = 0;
return NULL;
}
att = att? att : 120;
lsx_kaiser_params(att, Fc, (tbw? tbw / Fn : .05) * .5, beta, num_taps);
if (!n) {
n = *num_taps;
*num_taps = range_limit(n, 11, 32767);
if (round)
*num_taps = 1 + 2 * (int)((int)((*num_taps / 2) * Fc + .5) / Fc + .5);
lsx_report("num taps = %i (from %i)", *num_taps, n);
}
return lsx_make_lpf(*num_taps |= 1, Fc, *beta, 0., 1., sox_false);
}
static int start(sox_effect_t * effp)
{
priv_t * p = (priv_t *)effp->priv;
dft_filter_t * f = p->base.filter_ptr;
if (!f->num_taps) {
double Fn = effp->in_signal.rate * .5;
double * h[2];
int i, n, post_peak, longer;
if (p->Fc0 >= Fn || p->Fc1 >= Fn) {
lsx_fail("filter frequency must be less than sample-rate / 2");
return SOX_EOF;
}
h[0] = lpf(Fn, p->Fc0, p->tbw0, &p->num_taps[0], p->att, &p->beta,p->round);
h[1] = lpf(Fn, p->Fc1, p->tbw1, &p->num_taps[1], p->att, &p->beta,p->round);
if (h[0])
invert(h[0], p->num_taps[0]);
longer = p->num_taps[1] > p->num_taps[0];
n = p->num_taps[longer];
if (h[0] && h[1]) {
for (i = 0; i < p->num_taps[!longer]; ++i)
h[longer][i + (n - p->num_taps[!longer])/2] += h[!longer][i];
if (p->Fc0 < p->Fc1)
invert(h[longer], n);
free(h[!longer]);
}
if (p->phase != 50)
lsx_fir_to_phase(&h[longer], &n, &post_peak, p->phase);
else post_peak = n >> 1;
if (effp->global_info->plot != sox_plot_off) {
char title[100];
sprintf(title, "SoX effect: sinc filter freq=%g-%g",
p->Fc0, p->Fc1? p->Fc1 : Fn);
lsx_plot_fir(h[longer], n, effp->in_signal.rate,
effp->global_info->plot, title, -p->beta * 10 - 25, 5.);
return SOX_EOF;
}
lsx_set_dft_filter(f, h[longer], n, post_peak);
}
return lsx_dft_filter_effect_fn()->start(effp);
}
sox_effect_handler_t const * lsx_sinc_effect_fn(void)
{
static sox_effect_handler_t handler;
handler = *lsx_dft_filter_effect_fn();
handler.name = "sinc";
handler.usage = "[-a att|-b beta] [-p phase|-M|-I|-L] [-t tbw|-n taps] [freqHP][-freqLP [-t tbw|-n taps]]";
handler.getopts = create;
handler.start = start;
handler.priv_size = sizeof(priv_t);
return &handler;
}