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Diffstat (limited to 'demos/mobile/guitartuner/src/fastfouriertransformer.cpp')
| -rw-r--r-- | demos/mobile/guitartuner/src/fastfouriertransformer.cpp | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/demos/mobile/guitartuner/src/fastfouriertransformer.cpp b/demos/mobile/guitartuner/src/fastfouriertransformer.cpp new file mode 100644 index 0000000..9158fd4 --- /dev/null +++ b/demos/mobile/guitartuner/src/fastfouriertransformer.cpp @@ -0,0 +1,184 @@ +/**************************************************************************** +** +** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies). +** All rights reserved. +** Contact: Nokia Corporation (qt-info@nokia.com) +** +** This file is part of the QtDeclarative module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:BSD$ +** You may use this file under the terms of the BSD license as follows: +** +** "Redistribution and use in source and binary forms, with or without +** modification, are permitted provided that the following conditions are +** met: +** * Redistributions of source code must retain the above copyright +** notice, this list of conditions and the following disclaimer. +** * Redistributions in binary form must reproduce the above copyright +** notice, this list of conditions and the following disclaimer in +** the documentation and/or other materials provided with the +** distribution. +** * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor +** the names of its contributors may be used to endorse or promote +** products derived from this software without specific prior written +** permission. +** +** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE." +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#include "fastfouriertransformer.h" +#include "math.h" + +#define STIN inline +#define __STATIC + +#include "fftpack.c" + +// called by __ogg_fdrffti +__STATIC void drfti1(int n, float *wa, int *ifac); +void __ogg_fdrffti(int n, float *wsave, int *ifac); +void __ogg_fdcosqi(int n, float *wsave, int *ifac); +// called by drftf1 +STIN void dradf2(int ido,int l1,float *cc,float *ch,float *wa1); +// called by drftf1 +STIN void dradf4(int ido,int l1,float *cc,float *ch,float *wa1, + float *wa2,float *wa3); +// called by drftf1 +STIN void dradfg(int ido,int ip,int l1,int idl1,float *cc,float *c1, + float *c2,float *ch,float *ch2,float *wa); +// called by drftf1 +STIN void drftf1(int n,float *c,float *ch,float *wa,int *ifac); +void __ogg_fdrfftf(int n,float *r,float *wsave,int *ifac); +STIN void dcsqf1(int n,float *x,float *w,float *xh,int *ifac); +void __ogg_fdcosqf(int n,float *x,float *wsave,int *ifac); +STIN void dradb2(int ido,int l1,float *cc,float *ch,float *wa1); +STIN void dradb3(int ido,int l1,float *cc,float *ch,float *wa1, + float *wa2); +STIN void dradb4(int ido,int l1,float *cc,float *ch,float *wa1, + float *wa2,float *wa3); +STIN void dradbg(int ido,int ip,int l1,int idl1,float *cc,float *c1, + float *c2,float *ch,float *ch2,float *wa); +STIN void drftb1(int n, float *c, float *ch, float *wa, int *ifac); +void __ogg_fdrfftb(int n, float *r, float *wsave, int *ifac); +STIN void dcsqb1(int n,float *x,float *w,float *xh,int *ifac); +void __ogg_fdcosqb(int n,float *x,float *wsave,int *ifac); + +FastFourierTransformer::FastFourierTransformer(QObject *parent) : + QObject(parent), + m_waveFloat(0), + m_workingArray(0), + m_ifac(0), + m_last_n(-1) +{ +} + +FastFourierTransformer::~FastFourierTransformer() +{ + if (m_waveFloat != 0) { + delete [] m_waveFloat; + } + if (m_workingArray != 0) { + delete [] m_workingArray; + } + if (m_ifac != 0) { + delete [] m_ifac; + } +} + +/** + * Prepares the arrays to be of length n. + */ +void FastFourierTransformer::reserve(int n) +{ + Q_ASSERT(n>0); + if (m_waveFloat != 0) { + delete [] m_waveFloat; + } + if (m_workingArray != 0) { + delete [] m_workingArray; + } + if (m_ifac != 0) { + delete [] m_ifac; + } + m_workingArray = new float[2*n+15]; + m_waveFloat = new float[n]; + m_ifac = new int[n]; + __ogg_fdrffti(n, m_workingArray, m_ifac); + m_last_n = n; +} + +/** + * Calculates the Fast Fourier Transformation (FFT). + */ +void FastFourierTransformer::calculateFFT(QList<qint16> wave) +{ + const int n = wave.size(); + if (m_last_n != n) { + reserve(n); + } + for (int i = 0; i < n; i++) { + m_waveFloat[i] = (float) wave.at(i); + } + + __ogg_fdrfftf(n, m_waveFloat, m_workingArray, m_ifac); + +} + +/** + * Returns the index which corresponds to the maximum density + * of the FFT. + */ +int FastFourierTransformer::getMaximumDensityIndex() +{ + const int halfN = m_last_n / 2; + float maxDensity = 0; + int maxDensityIndex = 0; + float densitySquared = 0.f; + for (int k = 1; k < halfN; k++) { + // Here, we calculate the frequency k/N. + // k=1, the wave oscillation time is N, and the frequency + // is 1/sample. + // k=2, the wave oscillation time is N/2, and the frequency + // is 2/sample. + // k=3, the wave oscillation time is N/3, and the frequency + // is 3/sample. + // Note, that the documentation is for Fortran, so indexes in the + // documentation does not match. + // The sine and cosine coefficients are obtained thus as follows: + const float cosCoefficient = qAbs(m_waveFloat[2*k-1]); + const float sinCoefficient = qAbs(m_waveFloat[2*k]); + + densitySquared = sinCoefficient*sinCoefficient + cosCoefficient*cosCoefficient; + if (densitySquared > maxDensity) { + maxDensity = densitySquared; + maxDensityIndex = k; + } + } + + if (m_cutOffForDensitySquared < maxDensity) { + return maxDensityIndex; + } + else { + return -1; + } +} + +/** + * Sets the cutoff density. + */ +void FastFourierTransformer::setCutOffForDensity(float cutoff) +{ + m_cutOffForDensitySquared = cutoff*cutoff; +} |