ref: c27ff4b238f71616c59168d2d46c044b5797c89d
dir: /src/biquad.c/
/* libSoX Biquad filter common functions (c) 2006-7 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 "biquad.h"
#include <string.h>
typedef biquad_t priv_t;
#define p (*(priv_t *)effp->priv)
static char const * const width_str[] = {
"band-width(Hz)",
"band-width(Hz, no warp)", /* deprecated */
"band-width(octaves)",
"Q",
"slope",
};
static char const all_width_types[] = "hboqs";
int sox_biquad_getopts(sox_effect_t * effp, int n, char **argv,
int min_args, int max_args, int fc_pos, int width_pos, int gain_pos,
char const * allowed_width_types, filter_t filter_type)
{
char width_type = *allowed_width_types;
char dummy; /* To check for extraneous chars. */
p.filter_type = filter_type;
if (n < min_args || n > max_args ||
(n > fc_pos && (sscanf(argv[fc_pos], "%lf %c", &p.fc, &dummy) != 1 || p.fc <= 0)) ||
(n > width_pos && ((unsigned)(sscanf(argv[width_pos], "%lf%c %c", &p.width, &width_type, &dummy)-1) > 1 || p.width <= 0)) ||
(n > gain_pos && sscanf(argv[gain_pos], "%lf %c", &p.gain, &dummy) != 1) ||
!strchr(allowed_width_types, width_type) || (width_type == 's' && p.width > 1))
return lsx_usage(effp);
p.width_type = strchr(all_width_types, width_type) - all_width_types;
if (p.width_type >= strlen(all_width_types))
p.width_type = 0;
return SOX_SUCCESS;
}
int sox_biquad_start(sox_effect_t * effp)
{
/* Simplify: */
p.b2 /= p.a0;
p.b1 /= p.a0;
p.b0 /= p.a0;
p.a2 /= p.a0;
p.a1 /= p.a0;
if (effp->global_info->plot == sox_plot_octave) {
printf(
"%% GNU Octave file (may also work with MATLAB(R) )\n"
"title('SoX effect: %s gain=%g frequency=%g %s=%g (rate=%g)')\n"
"xlabel('Frequency (Hz)')\n"
"ylabel('Amplitude Response (dB)')\n"
"Fs=%g;minF=10;maxF=Fs/2;\n"
"axis([minF maxF -35 25])\n"
"sweepF=logspace(log10(minF),log10(maxF),200);\n"
"grid on\n"
"[h,w]=freqz([%g %g %g],[1 %g %g],sweepF,Fs);\n"
"semilogx(w,20*log10(h))\n"
"disp('Hit return to continue')\n"
"pause\n"
, effp->handler.name, p.gain, p.fc, width_str[p.width_type], p.width
, effp->in_signal.rate, effp->in_signal.rate
, p.b0, p.b1, p.b2, p.a1, p.a2);
return SOX_EOF;
}
if (effp->global_info->plot == sox_plot_gnuplot) {
printf(
"# gnuplot file\n"
"set title 'SoX effect: %s gain=%g frequency=%g %s=%g (rate=%g)'\n"
"set xlabel 'Frequency (Hz)'\n"
"set ylabel 'Amplitude Response (dB)'\n"
"Fs=%g\n"
"b0=%g; b1=%g; b2=%g; a1=%g; a2=%g\n"
"o=2*pi/Fs\n"
"H(f)=sqrt((b0*b0+b1*b1+b2*b2+2.*(b0*b1+b1*b2)*cos(f*o)+2.*(b0*b2)*cos(2.*f*o))/(1.+a1*a1+a2*a2+2.*(a1+a1*a2)*cos(f*o)+2.*a2*cos(2.*f*o)))\n"
"set logscale x\n"
"set grid xtics ytics\n"
"set key off\n"
"plot [f=10:Fs/2] [-35:25] 20*log10(H(f))\n"
"pause -1 'Hit return to continue'\n"
, effp->handler.name, p.gain, p.fc, width_str[p.width_type], p.width
, effp->in_signal.rate, effp->in_signal.rate
, p.b0, p.b1, p.b2, p.a1, p.a2);
return SOX_EOF;
}
p.o2 = p.o1 = p.i2 = p. i1 = 0;
return SOX_SUCCESS;
}
int sox_biquad_flow(sox_effect_t * effp, const sox_sample_t *ibuf,
sox_sample_t *obuf, sox_size_t *isamp, sox_size_t *osamp)
{
sox_size_t len = *isamp = *osamp = min(*isamp, *osamp);
while (len--) {
double o0 = *ibuf*p.b0 + p.i1*p.b1 + p.i2*p.b2 - p.o1*p.a1 - p.o2*p.a2;
p.i2 = p.i1, p.i1 = *ibuf++;
p.o2 = p.o1, p.o1 = o0;
*obuf++ = SOX_ROUND_CLIP_COUNT(o0, effp->clips);
}
return SOX_SUCCESS;
}