1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/libsoundtouch/src/InterpolateShannon.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,185 @@
1.4 +////////////////////////////////////////////////////////////////////////////////
1.5 +///
1.6 +/// Sample interpolation routine using 8-tap band-limited Shannon interpolation
1.7 +/// with kaiser window.
1.8 +///
1.9 +/// Notice. This algorithm is remarkably much heavier than linear or cubic
1.10 +/// interpolation, and not remarkably better than cubic algorithm. Thus mostly
1.11 +/// for experimental purposes
1.12 +///
1.13 +/// Author : Copyright (c) Olli Parviainen
1.14 +/// Author e-mail : oparviai 'at' iki.fi
1.15 +/// SoundTouch WWW: http://www.surina.net/soundtouch
1.16 +///
1.17 +////////////////////////////////////////////////////////////////////////////////
1.18 +//
1.19 +// $Id: InterpolateShannon.cpp 195 2014-04-06 15:57:21Z oparviai $
1.20 +//
1.21 +////////////////////////////////////////////////////////////////////////////////
1.22 +//
1.23 +// License :
1.24 +//
1.25 +// SoundTouch audio processing library
1.26 +// Copyright (c) Olli Parviainen
1.27 +//
1.28 +// This library is free software; you can redistribute it and/or
1.29 +// modify it under the terms of the GNU Lesser General Public
1.30 +// License as published by the Free Software Foundation; either
1.31 +// version 2.1 of the License, or (at your option) any later version.
1.32 +//
1.33 +// This library is distributed in the hope that it will be useful,
1.34 +// but WITHOUT ANY WARRANTY; without even the implied warranty of
1.35 +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
1.36 +// Lesser General Public License for more details.
1.37 +//
1.38 +// You should have received a copy of the GNU Lesser General Public
1.39 +// License along with this library; if not, write to the Free Software
1.40 +// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
1.41 +//
1.42 +////////////////////////////////////////////////////////////////////////////////
1.43 +
1.44 +#include <math.h>
1.45 +#include "InterpolateShannon.h"
1.46 +#include "STTypes.h"
1.47 +
1.48 +using namespace soundtouch;
1.49 +
1.50 +
1.51 +/// Kaiser window with beta = 2.0
1.52 +/// Values scaled down by 5% to avoid overflows
1.53 +static const double _kaiser8[8] =
1.54 +{
1.55 + 0.41778693317814,
1.56 + 0.64888025049173,
1.57 + 0.83508562409944,
1.58 + 0.93887857733412,
1.59 + 0.93887857733412,
1.60 + 0.83508562409944,
1.61 + 0.64888025049173,
1.62 + 0.41778693317814
1.63 +};
1.64 +
1.65 +
1.66 +InterpolateShannon::InterpolateShannon()
1.67 +{
1.68 + fract = 0;
1.69 +}
1.70 +
1.71 +
1.72 +void InterpolateShannon::resetRegisters()
1.73 +{
1.74 + fract = 0;
1.75 +}
1.76 +
1.77 +
1.78 +#define PI 3.1415926536
1.79 +#define sinc(x) (sin(PI * (x)) / (PI * (x)))
1.80 +
1.81 +/// Transpose mono audio. Returns number of produced output samples, and
1.82 +/// updates "srcSamples" to amount of consumed source samples
1.83 +int InterpolateShannon::transposeMono(SAMPLETYPE *pdest,
1.84 + const SAMPLETYPE *psrc,
1.85 + int &srcSamples)
1.86 +{
1.87 + int i;
1.88 + int srcSampleEnd = srcSamples - 8;
1.89 + int srcCount = 0;
1.90 +
1.91 + i = 0;
1.92 + while (srcCount < srcSampleEnd)
1.93 + {
1.94 + double out;
1.95 + assert(fract < 1.0);
1.96 +
1.97 + out = psrc[0] * sinc(-3.0 - fract) * _kaiser8[0];
1.98 + out += psrc[1] * sinc(-2.0 - fract) * _kaiser8[1];
1.99 + out += psrc[2] * sinc(-1.0 - fract) * _kaiser8[2];
1.100 + if (fract < 1e-6)
1.101 + {
1.102 + out += psrc[3] * _kaiser8[3]; // sinc(0) = 1
1.103 + }
1.104 + else
1.105 + {
1.106 + out += psrc[3] * sinc(- fract) * _kaiser8[3];
1.107 + }
1.108 + out += psrc[4] * sinc( 1.0 - fract) * _kaiser8[4];
1.109 + out += psrc[5] * sinc( 2.0 - fract) * _kaiser8[5];
1.110 + out += psrc[6] * sinc( 3.0 - fract) * _kaiser8[6];
1.111 + out += psrc[7] * sinc( 4.0 - fract) * _kaiser8[7];
1.112 +
1.113 + pdest[i] = (SAMPLETYPE)out;
1.114 + i ++;
1.115 +
1.116 + // update position fraction
1.117 + fract += rate;
1.118 + // update whole positions
1.119 + int whole = (int)fract;
1.120 + fract -= whole;
1.121 + psrc += whole;
1.122 + srcCount += whole;
1.123 + }
1.124 + srcSamples = srcCount;
1.125 + return i;
1.126 +}
1.127 +
1.128 +
1.129 +/// Transpose stereo audio. Returns number of produced output samples, and
1.130 +/// updates "srcSamples" to amount of consumed source samples
1.131 +int InterpolateShannon::transposeStereo(SAMPLETYPE *pdest,
1.132 + const SAMPLETYPE *psrc,
1.133 + int &srcSamples)
1.134 +{
1.135 + int i;
1.136 + int srcSampleEnd = srcSamples - 8;
1.137 + int srcCount = 0;
1.138 +
1.139 + i = 0;
1.140 + while (srcCount < srcSampleEnd)
1.141 + {
1.142 + double out0, out1, w;
1.143 + assert(fract < 1.0);
1.144 +
1.145 + w = sinc(-3.0 - fract) * _kaiser8[0];
1.146 + out0 = psrc[0] * w; out1 = psrc[1] * w;
1.147 + w = sinc(-2.0 - fract) * _kaiser8[1];
1.148 + out0 += psrc[2] * w; out1 += psrc[3] * w;
1.149 + w = sinc(-1.0 - fract) * _kaiser8[2];
1.150 + out0 += psrc[4] * w; out1 += psrc[5] * w;
1.151 + w = _kaiser8[3] * ((fract < 1e-5) ? 1.0 : sinc(- fract)); // sinc(0) = 1
1.152 + out0 += psrc[6] * w; out1 += psrc[7] * w;
1.153 + w = sinc( 1.0 - fract) * _kaiser8[4];
1.154 + out0 += psrc[8] * w; out1 += psrc[9] * w;
1.155 + w = sinc( 2.0 - fract) * _kaiser8[5];
1.156 + out0 += psrc[10] * w; out1 += psrc[11] * w;
1.157 + w = sinc( 3.0 - fract) * _kaiser8[6];
1.158 + out0 += psrc[12] * w; out1 += psrc[13] * w;
1.159 + w = sinc( 4.0 - fract) * _kaiser8[7];
1.160 + out0 += psrc[14] * w; out1 += psrc[15] * w;
1.161 +
1.162 + pdest[2*i] = (SAMPLETYPE)out0;
1.163 + pdest[2*i+1] = (SAMPLETYPE)out1;
1.164 + i ++;
1.165 +
1.166 + // update position fraction
1.167 + fract += rate;
1.168 + // update whole positions
1.169 + int whole = (int)fract;
1.170 + fract -= whole;
1.171 + psrc += 2*whole;
1.172 + srcCount += whole;
1.173 + }
1.174 + srcSamples = srcCount;
1.175 + return i;
1.176 +}
1.177 +
1.178 +
1.179 +/// Transpose stereo audio. Returns number of produced output samples, and
1.180 +/// updates "srcSamples" to amount of consumed source samples
1.181 +int InterpolateShannon::transposeMulti(SAMPLETYPE *pdest,
1.182 + const SAMPLETYPE *psrc,
1.183 + int &srcSamples)
1.184 +{
1.185 + // not implemented
1.186 + assert(false);
1.187 + return 0;
1.188 +}
