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livetrax/libs/qm-dsp/dsp/signalconditioning/FiltFilt.cpp

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/* -*- 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 2005-2006 Christian Landone.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version. See the file
COPYING included with this distribution for more information.
*/
#include "FiltFilt.h"
//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////
FiltFilt::FiltFilt( FiltFiltConfig Config )
{
m_filtScratchIn = NULL;
m_filtScratchOut = NULL;
m_ord = 0;
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initialise( Config );
}
FiltFilt::~FiltFilt()
{
deInitialise();
}
void FiltFilt::initialise( FiltFiltConfig Config )
{
m_ord = Config.ord;
m_filterConfig.ord = Config.ord;
m_filterConfig.ACoeffs = Config.ACoeffs;
m_filterConfig.BCoeffs = Config.BCoeffs;
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m_filter = new Filter( m_filterConfig );
}
void FiltFilt::deInitialise()
{
delete m_filter;
}
void FiltFilt::process(double *src, double *dst, unsigned int length)
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{
unsigned int i;
if (length == 0) return;
unsigned int nFilt = m_ord + 1;
unsigned int nFact = 3 * ( nFilt - 1);
unsigned int nExt = length + 2 * nFact;
m_filtScratchIn = new double[ nExt ];
m_filtScratchOut = new double[ nExt ];
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for( i = 0; i< nExt; i++ )
{
m_filtScratchIn[ i ] = 0.0;
m_filtScratchOut[ i ] = 0.0;
}
// Edge transients reflection
double sample0 = 2 * src[ 0 ];
double sampleN = 2 * src[ length - 1 ];
unsigned int index = 0;
for( i = nFact; i > 0; i-- )
{
m_filtScratchIn[ index++ ] = sample0 - src[ i ];
}
index = 0;
for( i = 0; i < nFact; i++ )
{
m_filtScratchIn[ (nExt - nFact) + index++ ] = sampleN - src[ (length - 2) - i ];
}
index = 0;
for( i = 0; i < length; i++ )
{
m_filtScratchIn[ i + nFact ] = src[ i ];
}
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////////////////////////////////
// Do 0Ph filtering
m_filter->process( m_filtScratchIn, m_filtScratchOut, nExt);
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// reverse the series for FILTFILT
for ( i = 0; i < nExt; i++)
{
m_filtScratchIn[ i ] = m_filtScratchOut[ nExt - i - 1];
}
// do FILTER again
m_filter->process( m_filtScratchIn, m_filtScratchOut, nExt);
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// reverse the series back
for ( i = 0; i < nExt; i++)
{
m_filtScratchIn[ i ] = m_filtScratchOut[ nExt - i - 1 ];
}
for ( i = 0;i < nExt; i++)
{
m_filtScratchOut[ i ] = m_filtScratchIn[ i ];
}
index = 0;
for( i = 0; i < length; i++ )
{
dst[ index++ ] = m_filtScratchOut[ i + nFact ];
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}
delete [] m_filtScratchIn;
delete [] m_filtScratchOut;
}
void FiltFilt::reset()
{
}