diff dsp/phasevocoder/PhaseVocoder.cpp @ 0:d7116e3183f8

* Queen Mary C++ DSP library

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dsp/phasevocoder/PhaseVocoder.cpp	Wed Apr 05 17:35:59 2006 +0000
@@ -0,0 +1,97 @@
+/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
+
+/*
+    QM DSP Library
+
+    Centre for Digital Music, Queen Mary, University of London.
+    This file copyright 2005-2006 Christian Landone.
+    All rights reserved.
+*/
+
+#include "PhaseVocoder.h"
+#include "dsp/transforms/FFT.h"
+#include <math.h>
+
+//////////////////////////////////////////////////////////////////////
+// Construction/Destruction
+//////////////////////////////////////////////////////////////////////
+
+PhaseVocoder::PhaseVocoder()
+{
+
+}
+
+PhaseVocoder::~PhaseVocoder()
+{
+
+}
+
+void PhaseVocoder::FFTShift(unsigned int size, double *src)
+{
+    // IN-place Rotation of FFT arrays
+    unsigned int i;
+
+    shiftBuffer = new double[size/2];
+
+    for( i = 0; i < size/2; i++)
+    {
+	shiftBuffer[ i ] = src[ i ];
+	src[ i ] = src[ i + size/2];
+    }
+	
+    for( i =size/2; i < size;  i++)
+    {
+	src[ i ] = shiftBuffer[ i -(size/2)];
+    }
+
+    delete [] shiftBuffer;
+
+}
+
+void PhaseVocoder::process(unsigned int size, double *src, double *mag, double *theta)
+{
+
+    // Primary Interface to Phase Vocoder
+    realOut = new double[ size ];
+    imagOut = new double[ size ];
+
+    FFTShift( size, src);
+	
+    coreFFT( size, src, 0, realOut, imagOut);
+
+    getMagnitude( size/2, mag, realOut, imagOut);
+    getPhase( size/2, theta, realOut, imagOut);
+
+    delete [] realOut;
+    delete [] imagOut;
+}
+
+
+void PhaseVocoder::coreFFT( unsigned int NumSamples, double *RealIn, double* ImagIn, double *RealOut, double *ImagOut)
+{
+    // This function is taken from a standard freeware implementation defined in FFT.h
+    // TODO: Use  FFTW
+    FFT::process( NumSamples,0, RealIn, ImagIn, RealOut, ImagOut );
+}
+
+void PhaseVocoder::getMagnitude(unsigned int size, double *mag, double *real, double *imag)
+{	
+    unsigned int j;
+
+    for( j = 0; j < size; j++)
+    {
+	mag[ j ] = sqrt( real[ j ] * real[ j ] + imag[ j ] * imag[ j ]);
+    }
+}
+
+void PhaseVocoder::getPhase(unsigned int size, double *theta, double *real, double *imag)
+{
+    unsigned int k;
+
+    // Phase Angle "matlab" style 
+    //Watch out for quadrant mapping  !!!
+    for( k = 0; k < size; k++)
+    {
+	theta[ k ] = atan2( -imag[ k ], real[ k ]);
+    }	
+}