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