libsidplayfp
1.0.3
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00001 /* 00002 * This file is part of libsidplayfp, a SID player engine. 00003 * 00004 * Copyright 2011-2013 Leandro Nini <drfiemost@users.sourceforge.net> 00005 * Copyright 2007-2010 Antti Lankila 00006 * 00007 * This program is free software; you can redistribute it and/or modify 00008 * it under the terms of the GNU General Public License as published by 00009 * the Free Software Foundation; either version 2 of the License, or 00010 * (at your option) any later version. 00011 * 00012 * This program is distributed in the hope that it will be useful, 00013 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00015 * GNU General Public License for more details. 00016 * 00017 * You should have received a copy of the GNU General Public License 00018 * along with this program; if not, write to the Free Software 00019 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. 00020 */ 00021 00022 #ifndef TWOPASSSINCRESAMPLER_H 00023 #define TWOPASSSINCRESAMPLER_H 00024 00025 #include <math.h> 00026 00027 #include "Resampler.h" 00028 #include "SincResampler.h" 00029 00030 namespace reSIDfp 00031 { 00032 00038 class TwoPassSincResampler : public Resampler 00039 { 00040 private: 00041 SincResampler* s1; 00042 SincResampler* s2; 00043 00044 public: 00045 TwoPassSincResampler(double clockFrequency, double samplingFrequency, 00046 double highestAccurateFrequency) 00047 { 00048 /* Calculation according to Laurent Ganier. It evaluates to about 120 kHz at typical settings. 00049 * Some testing around the chosen value seems to confirm that this does work. */ 00050 const double intermediateFrequency = 2. * highestAccurateFrequency 00051 + sqrt(2. * highestAccurateFrequency * clockFrequency 00052 * (samplingFrequency - 2. * highestAccurateFrequency) / samplingFrequency); 00053 s1 = new SincResampler(clockFrequency, intermediateFrequency, highestAccurateFrequency); 00054 s2 = new SincResampler(intermediateFrequency, samplingFrequency, highestAccurateFrequency); 00055 } 00056 00057 ~TwoPassSincResampler() 00058 { 00059 delete s1; 00060 delete s2; 00061 } 00062 00063 bool input(int sample) 00064 { 00065 return s1->input(sample) && s2->input(s1->output()); 00066 } 00067 00068 int output() const 00069 { 00070 return s2->output(); 00071 } 00072 00073 void reset() 00074 { 00075 s1->reset(); 00076 s2->reset(); 00077 } 00078 }; 00079 00080 } // namespace reSIDfp 00081 00082 #endif