Alc/bs2b.c

   1 /*-
   2  * Copyright (c) 2005 Boris Mikhaylov
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining
   5  * a copy of this software and associated documentation files (the
   6  * "Software"), to deal in the Software without restriction, including
   7  * without limitation the rights to use, copy, modify, merge, publish,
   8  * distribute, sublicense, and/or sell copies of the Software, and to
   9  * permit persons to whom the Software is furnished to do so, subject to
  10  * the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be
  13  * included in all copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  16  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  17  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  18  * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
  19  * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  20  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  21  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 #include "config.h"
  25
  26 #include <math.h>
  27 #include <string.h>
  28
  29 #include "bs2b.h"
  30 #include "alu.h"
  31
  32 #ifndef M_PI
  33 #define M_PI  3.14159265358979323846
  34 #endif
  35
  36 /* Set up all data. */
  37 static void init(struct bs2b *bs2b)
  38 {
  39     float Fc_lo, Fc_hi;
  40     float G_lo,  G_hi;
  41     float x, g;
  42
  43     bs2b->srate = clampi(bs2b->srate, 2000, 192000);
  44
  45     switch(bs2b->level)
  46     {
  47     case BS2B_LOW_CLEVEL: /* Low crossfeed level */
  48         Fc_lo = 360.0f;
  49         Fc_hi = 501.0f;
  50         G_lo  = 0.398107170553497f;
  51         G_hi  = 0.205671765275719f;
  52         break;
  53
  54     case BS2B_MIDDLE_CLEVEL: /* Middle crossfeed level */
  55         Fc_lo = 500.0f;
  56         Fc_hi = 711.0f;
  57         G_lo  = 0.459726988530872f;
  58         G_hi  = 0.228208484414988f;
  59         break;
  60
  61     case BS2B_HIGH_CLEVEL: /* High crossfeed level (virtual speakers are closer to itself) */
  62         Fc_lo = 700.0f;
  63         Fc_hi = 1021.0f;
  64         G_lo  = 0.530884444230988f;
  65         G_hi  = 0.250105790667544f;
  66         break;
  67
  68     case BS2B_LOW_ECLEVEL: /* Low easy crossfeed level */
  69         Fc_lo = 360.0f;
  70         Fc_hi = 494.0f;
  71         G_lo  = 0.316227766016838f;
  72         G_hi  = 0.168236228897329f;
  73         break;
  74
  75     case BS2B_MIDDLE_ECLEVEL: /* Middle easy crossfeed level */
  76         Fc_lo = 500.0f;
  77         Fc_hi = 689.0f;
  78         G_lo  = 0.354813389233575f;
  79         G_hi  = 0.187169483835901f;
  80         break;
  81
  82     default: /* High easy crossfeed level */
  83         bs2b->level = BS2B_HIGH_ECLEVEL;
  84
  85         Fc_lo = 700.0f;
  86         Fc_hi = 975.0f;
  87         G_lo  = 0.398107170553497f;
  88         G_hi  = 0.205671765275719f;
  89         break;
  90     } /* switch */
  91
  92     g = 1.0f / (1.0f - G_hi + G_lo);
  93
  94     /* $fc = $Fc / $s;
  95      * $d  = 1 / 2 / pi / $fc;
  96      * $x  = exp(-1 / $d);
  97      */
  98     x           = expf(-2.0f * F_PI * Fc_lo / bs2b->srate);
  99     bs2b->b1_lo = x;
 100     bs2b->a0_lo = G_lo * (1.0f - x) * g;
 101
 102     x           = expf(-2.0f * F_PI * Fc_hi / bs2b->srate);
 103     bs2b->b1_hi = x;
 104     bs2b->a0_hi = (1.0f - G_hi * (1.0f - x)) * g;
 105     bs2b->a1_hi = -x * g;
 106 } /* init */
 107
 108 /* Exported functions.
 109  * See descriptions in "bs2b.h"
 110  */
 111
 112 void bs2b_set_level(struct bs2b *bs2b, int level)
 113 {
 114     if(level == bs2b->level)
 115         return;
 116     bs2b->level = level;
 117     init(bs2b);
 118 } /* bs2b_set_level */
 119
 120 int bs2b_get_level(struct bs2b *bs2b)
 121 {
 122     return bs2b->level;
 123 } /* bs2b_get_level */
 124
 125 void bs2b_set_srate(struct bs2b *bs2b, int srate)
 126 {
 127     if (srate == bs2b->srate)
 128         return;
 129     bs2b->srate = srate;
 130     init(bs2b);
 131 } /* bs2b_set_srate */
 132
 133 int bs2b_get_srate(struct bs2b *bs2b)
 134 {
 135     return bs2b->srate;
 136 } /* bs2b_get_srate */
 137
 138 void bs2b_clear(struct bs2b *bs2b)
 139 {
 140     memset(&bs2b->last_sample, 0, sizeof(bs2b->last_sample));
 141 } /* bs2b_clear */
 142
 143 extern inline void bs2b_cross_feed(struct bs2b *bs2b, float *restrict samples);