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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 "Decimator.h"
#include <iostream>
//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////
Decimator::Decimator( unsigned int inLength, unsigned int decFactor )
{
m_inputLength = 0;
m_outputLength = 0;
m_decFactor = 1;
initialise( inLength, decFactor );
}
Decimator::~Decimator()
{
deInitialise();
}
void Decimator::initialise( unsigned int inLength, unsigned int decFactor)
{
m_inputLength = inLength;
m_decFactor = decFactor;
m_outputLength = m_inputLength / m_decFactor;
decBuffer = new double[ m_inputLength ];
// If adding new factors here, add them to
// getHighestSupportedFactor in the header as well
if(m_decFactor == 8)
{
//////////////////////////////////////////////////
b[0] = 0.060111378492136;
b[1] = -0.257323420830598;
b[2] = 0.420583503165928;
b[3] = -0.222750785197418;
b[4] = -0.222750785197418;
b[5] = 0.420583503165928;
b[6] = -0.257323420830598;
b[7] = 0.060111378492136;
a[0] = 1;
a[1] = -5.667654878577432;
a[2] = 14.062452278088417;
a[3] = -19.737303840697738;
a[4] = 16.889698874608641;
a[5] = -8.796600612325928;
a[6] = 2.577553446979888;
a[7] = -0.326903916815751;
//////////////////////////////////////////////////
}
else if( m_decFactor == 4 )
{
//////////////////////////////////////////////////
b[ 0 ] = 0.10133306904918619;
b[ 1 ] = -0.2447523353702363;
b[ 2 ] = 0.33622528590120965;
b[ 3 ] = -0.13936581560633518;
b[ 4 ] = -0.13936581560633382;
b[ 5 ] = 0.3362252859012087;
b[ 6 ] = -0.2447523353702358;
b[ 7 ] = 0.10133306904918594;
a[ 0 ] = 1;
a[ 1 ] = -3.9035590278139427;
a[ 2 ] = 7.5299379980621133;
a[ 3 ] = -8.6890803793177511;
a[ 4 ] = 6.4578667096099176;
a[ 5 ] = -3.0242979431223631;
a[ 6 ] = 0.83043385136748382;
a[ 7 ] = -0.094420800837809335;
//////////////////////////////////////////////////
}
else if( m_decFactor == 2 )
{
//////////////////////////////////////////////////
b[ 0 ] = 0.20898944260075727;
b[ 1 ] = 0.40011234879814367;
b[ 2 ] = 0.819741973072733;
b[ 3 ] = 1.0087419911682323;
b[ 4 ] = 1.0087419911682325;
b[ 5 ] = 0.81974197307273156;
b[ 6 ] = 0.40011234879814295;
b[ 7 ] = 0.20898944260075661;
a[ 0 ] = 1;
a[ 1 ] = 0.0077331184208358217;
a[ 2 ] = 1.9853971155964376;
a[ 3 ] = 0.19296739275341004;
a[ 4 ] = 1.2330748872852182;
a[ 5 ] = 0.18705341389316466;
a[ 6 ] = 0.23659265908013868;
a[ 7 ] = 0.032352924250533946;
}
else
{
if ( m_decFactor != 1 ) {
std::cerr << "WARNING: Decimator::initialise: unsupported decimation factor " << m_decFactor << ", no antialiasing filter will be used" << std::endl;
}
//////////////////////////////////////////////////
b[ 0 ] = 1;
b[ 1 ] = 0;
b[ 2 ] = 0;
b[ 3 ] = 0;
b[ 4 ] = 0;
b[ 5 ] = 0;
b[ 6 ] = 0;
b[ 7 ] = 0;
a[ 0 ] = 1;
a[ 1 ] = 0;
a[ 2 ] = 0;
a[ 3 ] = 0;
a[ 4 ] = 0;
a[ 5 ] = 0;
a[ 6 ] = 0;
a[ 7 ] = 0;
}
resetFilter();
}
void Decimator::deInitialise()
{
delete [] decBuffer;
}
void Decimator::resetFilter()
{
Input = Output = 0;
o1=o2=o3=o4=o5=o6=o7=0;
}
void Decimator::doAntiAlias(const double *src, double *dst, unsigned int length)
{
for( unsigned int i = 0; i < length; i++ )
{
Input = (double)src[ i ];
Output = Input * b[ 0 ] + o1;
o1 = Input * b[ 1 ] - Output * a[ 1 ] + o2;
o2 = Input * b[ 2 ] - Output * a[ 2 ] + o3;
o3 = Input * b[ 3 ] - Output * a[ 3 ] + o4;
o4 = Input * b[ 4 ] - Output * a[ 4 ] + o5;
o5 = Input * b[ 5 ] - Output * a[ 5 ] + o6;
o6 = Input * b[ 6 ] - Output * a[ 6 ] + o7;
o7 = Input * b[ 7 ] - Output * a[ 7 ] ;
dst[ i ] = Output;
}
}
void Decimator::doAntiAlias(const float *src, double *dst, unsigned int length)
{
for( unsigned int i = 0; i < length; i++ )
{
Input = (double)src[ i ];
Output = Input * b[ 0 ] + o1;
o1 = Input * b[ 1 ] - Output * a[ 1 ] + o2;
o2 = Input * b[ 2 ] - Output * a[ 2 ] + o3;
o3 = Input * b[ 3 ] - Output * a[ 3 ] + o4;
o4 = Input * b[ 4 ] - Output * a[ 4 ] + o5;
o5 = Input * b[ 5 ] - Output * a[ 5 ] + o6;
o6 = Input * b[ 6 ] - Output * a[ 6 ] + o7;
o7 = Input * b[ 7 ] - Output * a[ 7 ] ;
dst[ i ] = Output;
}
}
void Decimator::process(const double *src, double *dst)
{
if( m_decFactor != 1 )
{
doAntiAlias( src, decBuffer, m_inputLength );
}
unsigned idx = 0;
for( unsigned int i = 0; i < m_outputLength; i++ )
{
dst[ idx++ ] = decBuffer[ m_decFactor * i ];
}
}
void Decimator::process(const float *src, float *dst)
{
if( m_decFactor != 1 )
{
doAntiAlias( src, decBuffer, m_inputLength );
}
unsigned idx = 0;
for( unsigned int i = 0; i < m_outputLength; i++ )
{
dst[ idx++ ] = decBuffer[ m_decFactor * i ];
}
}
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