ref: 7b8c07617896add470f0bbfb0045e2844d1f0ec2
dir: /src/biquad.c/
/*
* 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 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,
* Fifth Floor, 51 Franklin Street, Boston, MA 02111-1301, USA.
*/
/* Biquad filter common functions (c) 2006-7 robs@users.sourceforge.net */
#include "biquad.h"
#include <string.h>
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)
{
biquad_t p = (biquad_t) effp->priv;
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)) {
sox_fail(effp->handler.usage);
return SOX_EOF;
}
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)
{
biquad_t p = (biquad_t) effp->priv;
/* Simplify: */
p->b2 = p->b2/p->a0;
p->b1 = p->b1/p->a0;
p->b0 = p->b0/p->a0;
p->a2 = p->a2/p->a0;
p->a1 = 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=%u)')\n"
"xlabel('Frequency (Hz)')\n"
"ylabel('Amplitude Response (dB)')\n"
"Fs=%u;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->ininfo.rate, effp->ininfo.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=%u)'\n"
"set xlabel 'Frequency (Hz)'\n"
"set ylabel 'Amplitude Response (dB)'\n"
"Fs=%u.\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->ininfo.rate, effp->ininfo.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_ssample_t *ibuf,
sox_ssample_t *obuf, sox_size_t *isamp, sox_size_t *osamp)
{
biquad_t p = (biquad_t) effp->priv;
sox_size_t len = min(*isamp, *osamp);
*isamp = *osamp = len;
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;
}