1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/Alc/bs2b.c	Tue Oct 25 13:02:31 2011 -0700
     1.3 @@ -0,0 +1,201 @@
     1.4 +/*-
     1.5 + * Copyright (c) 2005 Boris Mikhaylov
     1.6 + *
     1.7 + * Permission is hereby granted, free of charge, to any person obtaining
     1.8 + * a copy of this software and associated documentation files (the
     1.9 + * "Software"), to deal in the Software without restriction, including
    1.10 + * without limitation the rights to use, copy, modify, merge, publish,
    1.11 + * distribute, sublicense, and/or sell copies of the Software, and to
    1.12 + * permit persons to whom the Software is furnished to do so, subject to
    1.13 + * the following conditions:
    1.14 + *
    1.15 + * The above copyright notice and this permission notice shall be
    1.16 + * included in all copies or substantial portions of the Software.
    1.17 + *
    1.18 + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    1.19 + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    1.20 + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
    1.21 + * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
    1.22 + * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
    1.23 + * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    1.24 + * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    1.25 + */
    1.26 +
    1.27 +#include "config.h"
    1.28 +
    1.29 +#include <math.h>
    1.30 +
    1.31 +#include "bs2b.h"
    1.32 +
    1.33 +#ifndef M_PI
    1.34 +#define M_PI  3.14159265358979323846
    1.35 +#endif
    1.36 +
    1.37 +/* Single pole IIR filter.
    1.38 + * O[n] = a0*I[n] + a1*I[n-1] + b1*O[n-1]
    1.39 + */
    1.40 +
    1.41 +/* Lowpass filter */
    1.42 +#define lo_filter(in, out_1) (bs2b->a0_lo*(in) + bs2b->b1_lo*(out_1))
    1.43 +
    1.44 +/* Highboost filter */
    1.45 +#define hi_filter(in, in_1, out_1) (bs2b->a0_hi*(in) + bs2b->a1_hi*(in_1) + bs2b->b1_hi*(out_1))
    1.46 +
    1.47 +/* Set up all data. */
    1.48 +static void init(struct bs2b *bs2b)
    1.49 +{
    1.50 +    double Fc_lo, Fc_hi;
    1.51 +    double G_lo,  G_hi;
    1.52 +    double x;
    1.53 +
    1.54 +    if ((bs2b->srate > 192000) || (bs2b->srate < 2000))
    1.55 +        bs2b->srate = BS2B_DEFAULT_SRATE;
    1.56 +
    1.57 +    switch(bs2b->level)
    1.58 +    {
    1.59 +    case BS2B_LOW_CLEVEL: /* Low crossfeed level */
    1.60 +        Fc_lo = 360.0;
    1.61 +        Fc_hi = 501.0;
    1.62 +        G_lo  = 0.398107170553497;
    1.63 +        G_hi  = 0.205671765275719;
    1.64 +        break;
    1.65 +
    1.66 +    case BS2B_MIDDLE_CLEVEL: /* Middle crossfeed level */
    1.67 +        Fc_lo = 500.0;
    1.68 +        Fc_hi = 711.0;
    1.69 +        G_lo  = 0.459726988530872;
    1.70 +        G_hi  = 0.228208484414988;
    1.71 +        break;
    1.72 +
    1.73 +    case BS2B_HIGH_CLEVEL: /* High crossfeed level (virtual speakers are closer to itself) */
    1.74 +        Fc_lo = 700.0;
    1.75 +        Fc_hi = 1021.0;
    1.76 +        G_lo  = 0.530884444230988;
    1.77 +        G_hi  = 0.250105790667544;
    1.78 +        break;
    1.79 +
    1.80 +    case BS2B_LOW_ECLEVEL: /* Low easy crossfeed level */
    1.81 +        Fc_lo = 360.0;
    1.82 +        Fc_hi = 494.0;
    1.83 +        G_lo  = 0.316227766016838;
    1.84 +        G_hi  = 0.168236228897329;
    1.85 +        break;
    1.86 +
    1.87 +    case BS2B_MIDDLE_ECLEVEL: /* Middle easy crossfeed level */
    1.88 +        Fc_lo = 500.0;
    1.89 +        Fc_hi = 689.0;
    1.90 +        G_lo  = 0.354813389233575;
    1.91 +        G_hi  = 0.187169483835901;
    1.92 +        break;
    1.93 +
    1.94 +    default: /* High easy crossfeed level */
    1.95 +        bs2b->level = BS2B_HIGH_ECLEVEL;
    1.96 +
    1.97 +        Fc_lo = 700.0;
    1.98 +        Fc_hi = 975.0;
    1.99 +        G_lo  = 0.398107170553497;
   1.100 +        G_hi  = 0.205671765275719;
   1.101 +        break;
   1.102 +    } /* switch */
   1.103 +
   1.104 +    /* $fc = $Fc / $s;
   1.105 +     * $d  = 1 / 2 / pi / $fc;
   1.106 +     * $x  = exp(-1 / $d);
   1.107 +     */
   1.108 +
   1.109 +    x           = exp(-2.0 * M_PI * Fc_lo / bs2b->srate);
   1.110 +    bs2b->b1_lo = x;
   1.111 +    bs2b->a0_lo = G_lo * (1.0 - x);
   1.112 +
   1.113 +    x           = exp(-2.0 * M_PI * Fc_hi / bs2b->srate);
   1.114 +    bs2b->b1_hi = x;
   1.115 +    bs2b->a0_hi = 1.0 - G_hi * (1.0 - x);
   1.116 +    bs2b->a1_hi = -x;
   1.117 +
   1.118 +    bs2b->gain  = 1.0 / (1.0 - G_hi + G_lo);
   1.119 +} /* init */
   1.120 +
   1.121 +/* Exported functions.
   1.122 + * See descriptions in "bs2b.h"
   1.123 + */
   1.124 +
   1.125 +void bs2b_set_level(struct bs2b *bs2b, int level)
   1.126 +{
   1.127 +    if(level == bs2b->level)
   1.128 +        return;
   1.129 +    bs2b->level = level;
   1.130 +    init(bs2b);
   1.131 +} /* bs2b_set_level */
   1.132 +
   1.133 +int bs2b_get_level(struct bs2b *bs2b)
   1.134 +{
   1.135 +    return bs2b->level;
   1.136 +} /* bs2b_get_level */
   1.137 +
   1.138 +void bs2b_set_srate(struct bs2b *bs2b, int srate)
   1.139 +{
   1.140 +    if (srate == bs2b->srate)
   1.141 +        return;
   1.142 +    bs2b->srate = srate;
   1.143 +    init(bs2b);
   1.144 +} /* bs2b_set_srate */
   1.145 +
   1.146 +int bs2b_get_srate(struct bs2b *bs2b)
   1.147 +{
   1.148 +    return bs2b->srate;
   1.149 +} /* bs2b_get_srate */
   1.150 +
   1.151 +void bs2b_clear(struct bs2b *bs2b)
   1.152 +{
   1.153 +    int loopv = sizeof(bs2b->last_sample);
   1.154 +
   1.155 +    while (loopv)
   1.156 +    {
   1.157 +        ((char *)&bs2b->last_sample)[--loopv] = 0;
   1.158 +    }
   1.159 +} /* bs2b_clear */
   1.160 +
   1.161 +int bs2b_is_clear(struct bs2b *bs2b)
   1.162 +{
   1.163 +    int loopv = sizeof(bs2b->last_sample);
   1.164 +
   1.165 +    while (loopv)
   1.166 +    {
   1.167 +        if (((char *)&bs2b->last_sample)[--loopv] != 0)
   1.168 +            return 0;
   1.169 +    }
   1.170 +    return 1;
   1.171 +} /* bs2b_is_clear */
   1.172 +
   1.173 +void bs2b_cross_feed(struct bs2b *bs2b, float *sample)
   1.174 +{
   1.175 +    /* Lowpass filter */
   1.176 +    bs2b->last_sample.lo[0] = lo_filter(sample[0], bs2b->last_sample.lo[0]);
   1.177 +    bs2b->last_sample.lo[1] = lo_filter(sample[1], bs2b->last_sample.lo[1]);
   1.178 +
   1.179 +    /* Highboost filter */
   1.180 +    bs2b->last_sample.hi[0] = hi_filter(sample[0], bs2b->last_sample.asis[0], bs2b->last_sample.hi[0]);
   1.181 +    bs2b->last_sample.hi[1] = hi_filter(sample[1], bs2b->last_sample.asis[1], bs2b->last_sample.hi[1]);
   1.182 +    bs2b->last_sample.asis[0] = sample[0];
   1.183 +    bs2b->last_sample.asis[1] = sample[1];
   1.184 +
   1.185 +    /* Crossfeed */
   1.186 +    sample[0] = bs2b->last_sample.hi[0] + bs2b->last_sample.lo[1];
   1.187 +    sample[1] = bs2b->last_sample.hi[1] + bs2b->last_sample.lo[0];
   1.188 +
   1.189 +    /* Bass boost cause allpass attenuation */
   1.190 +    sample[0] *= bs2b->gain;
   1.191 +    sample[1] *= bs2b->gain;
   1.192 +
   1.193 +    /* Clipping of overloaded samples */
   1.194 +#if 0
   1.195 +    if (sample[0] > 1.0)
   1.196 +        sample[0] = 1.0;
   1.197 +    if (sample[0] < -1.0)
   1.198 +        sample[0] = -1.0;
   1.199 +    if (sample[1] > 1.0)
   1.200 +        sample[1] = 1.0;
   1.201 +    if (sample[1] < -1.0)
   1.202 +        sample[1] = -1.0;
   1.203 +#endif
   1.204 +} /* bs2b_cross_feed */