81 lines
2.5 KiB
Plaintext
81 lines
2.5 KiB
Plaintext
/*
|
|
* This file is part of libsidplayfp, a SID player engine.
|
|
*
|
|
* Copyright 2011-2014 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 TWOPASSSINCRESAMPLER_H
|
|
#define TWOPASSSINCRESAMPLER_H
|
|
|
|
#include <cmath>
|
|
|
|
#include <memory>
|
|
|
|
#include "Resampler.h"
|
|
#include "SincResampler.h"
|
|
|
|
namespace reSIDfp
|
|
{
|
|
|
|
/**
|
|
* Compose a more efficient SINC from chaining two other SINCs.
|
|
*/
|
|
class TwoPassSincResampler : public Resampler
|
|
{
|
|
private:
|
|
std::auto_ptr<SincResampler> const s1;
|
|
std::auto_ptr<SincResampler> const s2;
|
|
|
|
private:
|
|
TwoPassSincResampler(double clockFrequency, double samplingFrequency, double highestAccurateFrequency, double intermediateFrequency) :
|
|
s1(new SincResampler(clockFrequency, intermediateFrequency, highestAccurateFrequency)),
|
|
s2(new SincResampler(intermediateFrequency, samplingFrequency, highestAccurateFrequency))
|
|
{}
|
|
|
|
public:
|
|
static TwoPassSincResampler* create(double clockFrequency, double samplingFrequency, double highestAccurateFrequency)
|
|
{
|
|
// Calculation according to Laurent Ganier. It evaluates to about 120 kHz at typical settings.
|
|
// Some testing around the chosen value seems to confirm that this does work.
|
|
double const intermediateFrequency = 2. * highestAccurateFrequency
|
|
+ sqrt(2. * highestAccurateFrequency * clockFrequency
|
|
* (samplingFrequency - 2. * highestAccurateFrequency) / samplingFrequency);
|
|
return new TwoPassSincResampler(clockFrequency, samplingFrequency, highestAccurateFrequency, intermediateFrequency);
|
|
}
|
|
|
|
bool input(int sample)
|
|
{
|
|
return s1->input(sample) && s2->input(s1->output());
|
|
}
|
|
|
|
int output() const
|
|
{
|
|
return s2->output();
|
|
}
|
|
|
|
void reset()
|
|
{
|
|
s1->reset();
|
|
s2->reset();
|
|
}
|
|
};
|
|
|
|
} // namespace reSIDfp
|
|
|
|
#endif
|