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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 <algorithm>
#include <cmath>
#include <iterator>
#include <stdexcept>
#include "alnumbers.h"
#include "bs2b.h"
namespace {
/* Set up all data. */
void init(Bs2b::bs2b *bs2b)
{
float Fc_lo, Fc_hi;
float G_lo, G_hi;
switch(bs2b->level)
{
case Bs2b::LowCLevel: /* Low crossfeed level */
Fc_lo = 360.0f;
Fc_hi = 501.0f;
G_lo = 0.398107170553497f;
G_hi = 0.205671765275719f;
break;
case Bs2b::MiddleCLevel: /* Middle crossfeed level */
Fc_lo = 500.0f;
Fc_hi = 711.0f;
G_lo = 0.459726988530872f;
G_hi = 0.228208484414988f;
break;
case Bs2b::HighCLevel: /* 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::LowECLevel: /* Low easy crossfeed level */
Fc_lo = 360.0f;
Fc_hi = 494.0f;
G_lo = 0.316227766016838f;
G_hi = 0.168236228897329f;
break;
case Bs2b::MiddleECLevel: /* Middle easy crossfeed level */
Fc_lo = 500.0f;
Fc_hi = 689.0f;
G_lo = 0.354813389233575f;
G_hi = 0.187169483835901f;
break;
case Bs2b::HighECLevel: /* High easy crossfeed level */
default:
bs2b->level = Bs2b::HighECLevel;
Fc_lo = 700.0f;
Fc_hi = 975.0f;
G_lo = 0.398107170553497f;
G_hi = 0.205671765275719f;
break;
}
float g{1.0f / (1.0f - G_hi + G_lo)};
/* $fc = $Fc / $s;
* $d = 1 / 2 / pi / $fc;
* $x = exp(-1 / $d);
*/
float x{ std::exp(-al::numbers::pi_v<float>*2.0f*Fc_lo/static_cast<float>(bs2b->srate))};
bs2b->b1_lo = x;
bs2b->a0_lo = G_lo * (1.0f - x) * g;
x = std::exp(-al::numbers::pi_v<float>*2.0f*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;
}
} // namespace
/* Exported functions.
* See descriptions in "bs2b.h"
*/
namespace Bs2b {
void bs2b::set_params(int level_, int srate_)
{
if(srate_ < 1)
throw std::runtime_error{"BS2B srate < 1"};
level = level_;
srate = srate_;
init(this);
}
void bs2b::clear()
{
history.fill(bs2b::t_last_sample{});
}
void bs2b::cross_feed(float *RESTRICT Left, float *RESTRICT Right, size_t SamplesToDo)
{
const float a0lo{a0_lo};
const float b1lo{b1_lo};
const float a0hi{a0_hi};
const float a1hi{a1_hi};
const float b1hi{b1_hi};
std::array<std::array<float,2>,128> samples;
for(size_t base{0};base < SamplesToDo;)
{
const size_t todo{std::min(samples.size(), SamplesToDo-base)};
/* Process left input */
float z_lo{history[0].lo};
float z_hi{history[0].hi};
for(size_t i{0};i < todo;i++)
{
const float x{Left[i]};
float y{a0hi*x + z_hi};
z_hi = a1hi*x + b1hi*y;
samples[i][0] = y;
y = a0lo*x + z_lo;
z_lo = b1lo*y;
samples[i][1] = y;
}
history[0].lo = z_lo;
history[0].hi = z_hi;
/* Process right input */
z_lo = history[1].lo;
z_hi = history[1].hi;
for(size_t i{0};i < todo;i++)
{
const float x{Right[i]};
float y{a0lo*x + z_lo};
z_lo = b1lo*y;
samples[i][0] += y;
y = a0hi*x + z_hi;
z_hi = a1hi*x + b1hi*y;
samples[i][1] += y;
}
history[1].lo = z_lo;
history[1].hi = z_hi;
for(size_t i{0};i < todo;i++)
*(Left++) = samples[i][0];
for(size_t i{0};i < todo;i++)
*(Right++) = samples[i][1];
base += todo;
}
}
} // namespace Bs2b
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