diff options
Diffstat (limited to 'alc/bs2b.cpp')
| -rw-r--r-- | alc/bs2b.cpp | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/alc/bs2b.cpp b/alc/bs2b.cpp new file mode 100644 index 00000000..00207bc0 --- /dev/null +++ b/alc/bs2b.cpp @@ -0,0 +1,183 @@ +/*- + * 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 <algorithm> +#include <cmath> +#include <iterator> + +#include "bs2b.h" +#include "math_defs.h" + + +/* Set up all data. */ +static void init(struct bs2b *bs2b) +{ + float Fc_lo, Fc_hi; + float G_lo, G_hi; + float x, g; + + switch(bs2b->level) + { + case BS2B_LOW_CLEVEL: /* Low crossfeed level */ + Fc_lo = 360.0f; + Fc_hi = 501.0f; + G_lo = 0.398107170553497f; + G_hi = 0.205671765275719f; + break; + + case BS2B_MIDDLE_CLEVEL: /* Middle crossfeed level */ + Fc_lo = 500.0f; + Fc_hi = 711.0f; + G_lo = 0.459726988530872f; + G_hi = 0.228208484414988f; + break; + + case BS2B_HIGH_CLEVEL: /* High crossfeed level (virtual speakers are closer to itself) */ + Fc_lo = 700.0f; + Fc_hi = 1021.0f; + G_lo = 0.530884444230988f; + G_hi = 0.250105790667544f; + break; + + case BS2B_LOW_ECLEVEL: /* Low easy crossfeed level */ + Fc_lo = 360.0f; + Fc_hi = 494.0f; + G_lo = 0.316227766016838f; + G_hi = 0.168236228897329f; + break; + + case BS2B_MIDDLE_ECLEVEL: /* Middle easy crossfeed level */ + Fc_lo = 500.0f; + Fc_hi = 689.0f; + G_lo = 0.354813389233575f; + G_hi = 0.187169483835901f; + break; + + default: /* High easy crossfeed level */ + bs2b->level = BS2B_HIGH_ECLEVEL; + + Fc_lo = 700.0f; + Fc_hi = 975.0f; + G_lo = 0.398107170553497f; + G_hi = 0.205671765275719f; + break; + } /* switch */ + + g = 1.0f / (1.0f - G_hi + G_lo); + + /* $fc = $Fc / $s; + * $d = 1 / 2 / pi / $fc; + * $x = exp(-1 / $d); + */ + x = std::exp(-al::MathDefs<float>::Tau() * Fc_lo / static_cast<float>(bs2b->srate)); + bs2b->b1_lo = x; + bs2b->a0_lo = G_lo * (1.0f - x) * g; + + x = std::exp(-al::MathDefs<float>::Tau() * Fc_hi / static_cast<float>(bs2b->srate)); + bs2b->b1_hi = x; + bs2b->a0_hi = (1.0f - G_hi * (1.0f - x)) * g; + bs2b->a1_hi = -x * g; +} /* init */ + + +/* Exported functions. + * See descriptions in "bs2b.h" + */ + +void bs2b_set_params(struct bs2b *bs2b, int level, int srate) +{ + if(srate <= 0) srate = 1; + + bs2b->level = level; + bs2b->srate = srate; + init(bs2b); +} /* bs2b_set_params */ + +int bs2b_get_level(struct bs2b *bs2b) +{ + return bs2b->level; +} /* bs2b_get_level */ + +int bs2b_get_srate(struct bs2b *bs2b) +{ + return bs2b->srate; +} /* bs2b_get_srate */ + +void bs2b_clear(struct bs2b *bs2b) +{ + std::fill(std::begin(bs2b->history), std::end(bs2b->history), bs2b::t_last_sample{}); +} /* bs2b_clear */ + +void bs2b_cross_feed(struct bs2b *bs2b, float *Left, float *Right, size_t SamplesToDo) +{ + const float a0_lo{bs2b->a0_lo}; + const float b1_lo{bs2b->b1_lo}; + const float a0_hi{bs2b->a0_hi}; + const float a1_hi{bs2b->a1_hi}; + const float b1_hi{bs2b->b1_hi}; + float lsamples[128][2]; + float rsamples[128][2]; + + for(size_t base{0};base < SamplesToDo;) + { + const size_t todo{std::min<size_t>(128, SamplesToDo-base)}; + + /* Process left input */ + float z_lo{bs2b->history[0].lo}; + float z_hi{bs2b->history[0].hi}; + for(size_t i{0};i < todo;i++) + { + lsamples[i][0] = a0_lo*Left[i] + z_lo; + z_lo = b1_lo*lsamples[i][0]; + + lsamples[i][1] = a0_hi*Left[i] + z_hi; + z_hi = a1_hi*Left[i] + b1_hi*lsamples[i][1]; + } + bs2b->history[0].lo = z_lo; + bs2b->history[0].hi = z_hi; + + /* Process right input */ + z_lo = bs2b->history[1].lo; + z_hi = bs2b->history[1].hi; + for(size_t i{0};i < todo;i++) + { + rsamples[i][0] = a0_lo*Right[i] + z_lo; + z_lo = b1_lo*rsamples[i][0]; + + rsamples[i][1] = a0_hi*Right[i] + z_hi; + z_hi = a1_hi*Right[i] + b1_hi*rsamples[i][1]; + } + bs2b->history[1].lo = z_lo; + bs2b->history[1].hi = z_hi; + + /* Crossfeed */ + for(size_t i{0};i < todo;i++) + *(Left++) = lsamples[i][1] + rsamples[i][0]; + for(size_t i{0};i < todo;i++) + *(Right++) = rsamples[i][1] + lsamples[i][0]; + + base += todo; + } +} /* bs2b_cross_feed */ |