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/*-
* Copyright (c) 2005 Boris Mikhaylov
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include "config.h"
#include <math.h>
#include "bs2b.h"
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
/* Single pole IIR filter.
* O[n] = a0*I[n] + a1*I[n-1] + b1*O[n-1]
*/
/* Lowpass filter */
#define lo_filter(in, out_1) (bs2b->a0_lo*(in) + bs2b->b1_lo*(out_1))
/* Highboost filter */
#define hi_filter(in, in_1, out_1) (bs2b->a0_hi*(in) + bs2b->a1_hi*(in_1) + bs2b->b1_hi*(out_1))
/* Set up all data. */
static void init(struct bs2b *bs2b)
{
double Fc_lo, Fc_hi;
double G_lo, G_hi;
double x;
if ((bs2b->srate > 192000) || (bs2b->srate < 2000))
bs2b->srate = BS2B_DEFAULT_SRATE;
switch(bs2b->level)
{
case BS2B_LOW_CLEVEL: /* Low crossfeed level */
Fc_lo = 360.0;
Fc_hi = 501.0;
G_lo = 0.398107170553497;
G_hi = 0.205671765275719;
break;
case BS2B_MIDDLE_CLEVEL: /* Middle crossfeed level */
Fc_lo = 500.0;
Fc_hi = 711.0;
G_lo = 0.459726988530872;
G_hi = 0.228208484414988;
break;
case BS2B_HIGH_CLEVEL: /* High crossfeed level (virtual speakers are closer to itself) */
Fc_lo = 700.0;
Fc_hi = 1021.0;
G_lo = 0.530884444230988;
G_hi = 0.250105790667544;
break;
case BS2B_LOW_ECLEVEL: /* Low easy crossfeed level */
Fc_lo = 360.0;
Fc_hi = 494.0;
G_lo = 0.316227766016838;
G_hi = 0.168236228897329;
break;
case BS2B_MIDDLE_ECLEVEL: /* Middle easy crossfeed level */
Fc_lo = 500.0;
Fc_hi = 689.0;
G_lo = 0.354813389233575;
G_hi = 0.187169483835901;
break;
default: /* High easy crossfeed level */
bs2b->level = BS2B_HIGH_ECLEVEL;
Fc_lo = 700.0;
Fc_hi = 975.0;
G_lo = 0.398107170553497;
G_hi = 0.205671765275719;
break;
} /* switch */
/* $fc = $Fc / $s;
* $d = 1 / 2 / pi / $fc;
* $x = exp(-1 / $d);
*/
x = exp(-2.0 * M_PI * Fc_lo / bs2b->srate);
bs2b->b1_lo = x;
bs2b->a0_lo = G_lo * (1.0 - x);
x = exp(-2.0 * M_PI * Fc_hi / bs2b->srate);
bs2b->b1_hi = x;
bs2b->a0_hi = 1.0 - G_hi * (1.0 - x);
bs2b->a1_hi = -x;
bs2b->gain = 1.0 / (1.0 - G_hi + G_lo);
} /* init */
/* Exported functions.
* See descriptions in "bs2b.h"
*/
void bs2b_set_level(struct bs2b *bs2b, int level)
{
if(level == bs2b->level)
return;
bs2b->level = level;
init(bs2b);
} /* bs2b_set_level */
int bs2b_get_level(struct bs2b *bs2b)
{
return bs2b->level;
} /* bs2b_get_level */
void bs2b_set_srate(struct bs2b *bs2b, int srate)
{
if (srate == bs2b->srate)
return;
bs2b->srate = srate;
init(bs2b);
} /* bs2b_set_srate */
int bs2b_get_srate(struct bs2b *bs2b)
{
return bs2b->srate;
} /* bs2b_get_srate */
void bs2b_clear(struct bs2b *bs2b)
{
int loopv = sizeof(bs2b->last_sample);
while (loopv)
{
((char *)&bs2b->last_sample)[--loopv] = 0;
}
} /* bs2b_clear */
int bs2b_is_clear(struct bs2b *bs2b)
{
int loopv = sizeof(bs2b->last_sample);
while (loopv)
{
if (((char *)&bs2b->last_sample)[--loopv] != 0)
return 0;
}
return 1;
} /* bs2b_is_clear */
void bs2b_cross_feed(struct bs2b *bs2b, float *sample)
{
/* Lowpass filter */
bs2b->last_sample.lo[0] = lo_filter(sample[0], bs2b->last_sample.lo[0]);
bs2b->last_sample.lo[1] = lo_filter(sample[1], bs2b->last_sample.lo[1]);
/* Highboost filter */
bs2b->last_sample.hi[0] = hi_filter(sample[0], bs2b->last_sample.asis[0], bs2b->last_sample.hi[0]);
bs2b->last_sample.hi[1] = hi_filter(sample[1], bs2b->last_sample.asis[1], bs2b->last_sample.hi[1]);
bs2b->last_sample.asis[0] = sample[0];
bs2b->last_sample.asis[1] = sample[1];
/* Crossfeed */
sample[0] = bs2b->last_sample.hi[0] + bs2b->last_sample.lo[1];
sample[1] = bs2b->last_sample.hi[1] + bs2b->last_sample.lo[0];
/* Bass boost cause allpass attenuation */
sample[0] *= bs2b->gain;
sample[1] *= bs2b->gain;
/* Clipping of overloaded samples */
#if 0
if (sample[0] > 1.0)
sample[0] = 1.0;
if (sample[0] < -1.0)
sample[0] = -1.0;
if (sample[1] > 1.0)
sample[1] = 1.0;
if (sample[1] < -1.0)
sample[1] = -1.0;
#endif
} /* bs2b_cross_feed */
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