Resampler.h
/*
* This file is part of libsidplayfp, a SID player engine.
*
* Copyright 2011-2020 Leandro Nini <drfiemost@users.sourceforge.net>
* Copyright 2007-2010 Antti Lankila
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#ifndef RESAMPLER_H
#define RESAMPLER_H
#include <cmath>
#include "sidcxx11.h"
#include "siddefs-fp.h"
namespace reSIDfp
{
class Resampler
{
protected:
inline short softClip(int x) const
{
constexpr int threshold = 28000;
if (likely(x < threshold))
return x;
constexpr double t = threshold / 32768.;
constexpr double a = 1. - t;
constexpr double b = 1. / a;
double value = static_cast<double>(x - threshold) / 32768.;
value = t + a * tanh(b * value);
return static_cast<short>(value * 32768.);
}
virtual int output() const = 0;
Resampler() {}
public:
virtual ~Resampler() {}
virtual bool input(int sample) = 0;
short getOutput() const
{
return softClip(output());
}
virtual void reset() = 0;
};
} // namespace reSIDfp
#endif
reSIDfp::Resampler
Definition Resampler.h:39
reSIDfp::Resampler::getOutput
short getOutput() const
Definition Resampler.h:76
reSIDfp::Resampler::input
virtual bool input(int sample)=0