mirror of https://github.com/PCSX2/pcsx2.git
182 lines
5.3 KiB
C++
182 lines
5.3 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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///
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/// Sample interpolation routine using 8-tap band-limited Shannon interpolation
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/// with kaiser window.
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///
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/// Notice. This algorithm is remarkably much heavier than linear or cubic
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/// interpolation, and not remarkably better than cubic algorithm. Thus mostly
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/// for experimental purposes
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///
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/// Author : Copyright (c) Olli Parviainen
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/// Author e-mail : oparviai 'at' iki.fi
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/// SoundTouch WWW: http://www.surina.net/soundtouch
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///
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////////////////////////////////////////////////////////////////////////////////
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//
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// License :
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//
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// SoundTouch audio processing library
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// Copyright (c) Olli Parviainen
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 2.1 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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//
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////////////////////////////////////////////////////////////////////////////////
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#include <math.h>
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#include "InterpolateShannon.h"
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#include "STTypes.h"
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using namespace soundtouch;
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/// Kaiser window with beta = 2.0
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/// Values scaled down by 5% to avoid overflows
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static const double _kaiser8[8] =
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{
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0.41778693317814,
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0.64888025049173,
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0.83508562409944,
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0.93887857733412,
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0.93887857733412,
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0.83508562409944,
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0.64888025049173,
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0.41778693317814
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};
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InterpolateShannon::InterpolateShannon()
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{
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fract = 0;
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}
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void InterpolateShannon::resetRegisters()
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{
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fract = 0;
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}
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#define PI 3.1415926536
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#define sinc(x) (sin(PI * (x)) / (PI * (x)))
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/// Transpose mono audio. Returns number of produced output samples, and
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/// updates "srcSamples" to amount of consumed source samples
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int InterpolateShannon::transposeMono(SAMPLETYPE *pdest,
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const SAMPLETYPE *psrc,
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int &srcSamples)
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{
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int i;
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int srcSampleEnd = srcSamples - 8;
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int srcCount = 0;
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i = 0;
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while (srcCount < srcSampleEnd)
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{
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double out;
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assert(fract < 1.0);
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out = psrc[0] * sinc(-3.0 - fract) * _kaiser8[0];
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out += psrc[1] * sinc(-2.0 - fract) * _kaiser8[1];
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out += psrc[2] * sinc(-1.0 - fract) * _kaiser8[2];
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if (fract < 1e-6)
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{
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out += psrc[3] * _kaiser8[3]; // sinc(0) = 1
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}
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else
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{
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out += psrc[3] * sinc(- fract) * _kaiser8[3];
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}
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out += psrc[4] * sinc( 1.0 - fract) * _kaiser8[4];
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out += psrc[5] * sinc( 2.0 - fract) * _kaiser8[5];
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out += psrc[6] * sinc( 3.0 - fract) * _kaiser8[6];
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out += psrc[7] * sinc( 4.0 - fract) * _kaiser8[7];
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pdest[i] = (SAMPLETYPE)out;
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i ++;
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// update position fraction
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fract += rate;
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// update whole positions
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int whole = (int)fract;
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fract -= whole;
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psrc += whole;
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srcCount += whole;
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}
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srcSamples = srcCount;
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return i;
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}
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/// Transpose stereo audio. Returns number of produced output samples, and
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/// updates "srcSamples" to amount of consumed source samples
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int InterpolateShannon::transposeStereo(SAMPLETYPE *pdest,
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const SAMPLETYPE *psrc,
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int &srcSamples)
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{
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int i;
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int srcSampleEnd = srcSamples - 8;
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int srcCount = 0;
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i = 0;
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while (srcCount < srcSampleEnd)
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{
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double out0, out1, w;
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assert(fract < 1.0);
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w = sinc(-3.0 - fract) * _kaiser8[0];
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out0 = psrc[0] * w; out1 = psrc[1] * w;
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w = sinc(-2.0 - fract) * _kaiser8[1];
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out0 += psrc[2] * w; out1 += psrc[3] * w;
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w = sinc(-1.0 - fract) * _kaiser8[2];
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out0 += psrc[4] * w; out1 += psrc[5] * w;
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w = _kaiser8[3] * ((fract < 1e-5) ? 1.0 : sinc(- fract)); // sinc(0) = 1
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out0 += psrc[6] * w; out1 += psrc[7] * w;
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w = sinc( 1.0 - fract) * _kaiser8[4];
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out0 += psrc[8] * w; out1 += psrc[9] * w;
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w = sinc( 2.0 - fract) * _kaiser8[5];
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out0 += psrc[10] * w; out1 += psrc[11] * w;
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w = sinc( 3.0 - fract) * _kaiser8[6];
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out0 += psrc[12] * w; out1 += psrc[13] * w;
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w = sinc( 4.0 - fract) * _kaiser8[7];
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out0 += psrc[14] * w; out1 += psrc[15] * w;
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pdest[2*i] = (SAMPLETYPE)out0;
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pdest[2*i+1] = (SAMPLETYPE)out1;
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i ++;
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// update position fraction
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fract += rate;
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// update whole positions
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int whole = (int)fract;
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fract -= whole;
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psrc += 2*whole;
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srcCount += whole;
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}
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srcSamples = srcCount;
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return i;
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}
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/// Transpose stereo audio. Returns number of produced output samples, and
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/// updates "srcSamples" to amount of consumed source samples
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int InterpolateShannon::transposeMulti(SAMPLETYPE *,
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const SAMPLETYPE *,
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int &)
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{
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// not implemented
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assert(false);
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return 0;
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}
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