cannam@0: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
cannam@0: 
cannam@0: /*
cannam@0:     QM DSP Library
cannam@0: 
cannam@0:     Centre for Digital Music, Queen Mary, University of London.
cannam@0:     This file copyright 2005-2006 Christian Landone.
cannam@0:     All rights reserved.
cannam@0: */
cannam@0: 
cannam@0: #include "Decimator.h"
cannam@0: 
cannam@0: //////////////////////////////////////////////////////////////////////
cannam@0: // Construction/Destruction
cannam@0: //////////////////////////////////////////////////////////////////////
cannam@0: 
cannam@0: Decimator::Decimator( unsigned int inLength, unsigned int decFactor )
cannam@0: {
cannam@0: 
cannam@0:     m_inputLength = 0;
cannam@0:     m_outputLength = 0;
cannam@0:     m_decFactor = 1;
cannam@0: 
cannam@0:     initialise( inLength, decFactor );
cannam@0: }
cannam@0: 
cannam@0: Decimator::~Decimator()
cannam@0: {
cannam@0:     deInitialise();
cannam@0: }
cannam@0: 
cannam@0: void Decimator::initialise( unsigned int inLength, unsigned int decFactor)
cannam@0: {
cannam@0:     m_inputLength = inLength;
cannam@0:     m_decFactor = decFactor;
cannam@0:     m_outputLength = m_inputLength / m_decFactor;
cannam@0: 
cannam@0:     decBuffer = new double[ m_inputLength ];
cannam@0: 
cannam@0:     if( m_decFactor == 4 )
cannam@0:     {
cannam@0: 	//////////////////////////////////////////////////
cannam@0: 	b[ 0 ] = 0.10133306904918619;
cannam@0: 	b[ 1 ] = -0.2447523353702363;
cannam@0: 	b[ 2 ] = 0.33622528590120965;
cannam@0: 	b[ 3 ] = -0.13936581560633518;
cannam@0: 	b[ 4 ] = -0.13936581560633382;
cannam@0: 	b[ 5 ] = 0.3362252859012087;
cannam@0: 	b[ 6 ] = -0.2447523353702358;
cannam@0: 	b[ 7 ] = 0.10133306904918594;
cannam@0: 
cannam@0: 	a[ 0 ] = 1;
cannam@0: 	a[ 1 ] = -3.9035590278139427;
cannam@0: 	a[ 2 ] = 7.5299379980621133;
cannam@0: 	a[ 3 ] = -8.6890803793177511;
cannam@0: 	a[ 4 ] = 6.4578667096099176;
cannam@0: 	a[ 5 ] = -3.0242979431223631;
cannam@0: 	a[ 6 ] = 0.83043385136748382;
cannam@0: 	a[ 7 ] = -0.094420800837809335;
cannam@0: 	//////////////////////////////////////////////////
cannam@0:     }
cannam@0:     else if( m_decFactor == 2 )
cannam@0:     {
cannam@0: 	//////////////////////////////////////////////////
cannam@0: 	b[ 0 ] = 0.20898944260075727;
cannam@0: 	b[ 1 ] = 0.40011234879814367;
cannam@0: 	b[ 2 ] = 0.819741973072733;
cannam@0: 	b[ 3 ] = 1.0087419911682323;
cannam@0: 	b[ 4 ] = 1.0087419911682325;
cannam@0: 	b[ 5 ] = 0.81974197307273156;
cannam@0: 	b[ 6 ] = 0.40011234879814295;
cannam@0: 	b[ 7 ] = 0.20898944260075661;
cannam@0: 
cannam@0: 	a[ 0 ] = 1;
cannam@0: 	a[ 1 ] = 0.0077331184208358217;
cannam@0: 	a[ 2 ] = 1.9853971155964376;
cannam@0: 	a[ 3 ] = 0.19296739275341004;
cannam@0: 	a[ 4 ] = 1.2330748872852182;
cannam@0: 	a[ 5 ] = 0.18705341389316466;
cannam@0: 	a[ 6 ] = 0.23659265908013868;
cannam@0: 	a[ 7 ] = 0.032352924250533946;
cannam@0:     }
cannam@0:     else
cannam@0:     {
cannam@0: 	//////////////////////////////////////////////////
cannam@0: 	b[ 0 ] = 1;
cannam@0: 	b[ 1 ] = 0;
cannam@0: 	b[ 2 ] = 0;
cannam@0: 	b[ 3 ] = 0;
cannam@0: 	b[ 4 ] = 0;
cannam@0: 	b[ 5 ] = 0;
cannam@0: 	b[ 6 ] = 0;
cannam@0: 	b[ 7 ] = 0;
cannam@0: 
cannam@0: 	a[ 0 ] = 1;
cannam@0: 	a[ 1 ] = 0;
cannam@0: 	a[ 2 ] = 0;
cannam@0: 	a[ 3 ] = 0;
cannam@0: 	a[ 4 ] = 0;
cannam@0: 	a[ 5 ] = 0;
cannam@0: 	a[ 6 ] = 0;
cannam@0: 	a[ 7 ] = 0;
cannam@0:     }
cannam@0: 
cannam@0:     resetFilter();
cannam@0: }
cannam@0: 
cannam@0: void Decimator::deInitialise()
cannam@0: {
cannam@0:     delete [] decBuffer;
cannam@0: }
cannam@0: 
cannam@0: void Decimator::resetFilter()
cannam@0: {
cannam@0:     Input = Output = 0;
cannam@0: 
cannam@0:     o1=o2=o3=o4=o5=o6=o7=0;
cannam@0: }
cannam@0: 
cannam@0: void Decimator::doAntiAlias(double *src, double *dst, unsigned int length)
cannam@0: {
cannam@0: 
cannam@0:     for( unsigned int i = 0; i < length; i++ )
cannam@0:     {
cannam@0: 	Input = (double)src[ i ];
cannam@0: 
cannam@0: 	Output = Input * b[ 0 ] + o1;
cannam@0: 
cannam@0: 	o1 = Input * b[ 1 ] - Output * a[ 1 ] + o2;
cannam@0: 	o2 = Input * b[ 2 ] - Output * a[ 2 ] + o3;
cannam@0: 	o3 = Input * b[ 3 ] - Output * a[ 3 ] + o4;
cannam@0: 	o4 = Input * b[ 4 ] - Output * a[ 4 ] + o5;
cannam@0: 	o5 = Input * b[ 5 ] - Output * a[ 5 ] + o6;
cannam@0: 	o6 = Input * b[ 6 ] - Output * a[ 6 ] + o7;
cannam@0: 	o7 = Input * b[ 7 ] - Output * a[ 7 ] ;
cannam@0: 
cannam@0: 	dst[ i ] = Output;
cannam@0:     }
cannam@0: 
cannam@0: }
cannam@0: 
cannam@0: void Decimator::process(double *src, double *dst)
cannam@0: {
cannam@0:     if( m_decFactor != 1 )
cannam@0:     {
cannam@0: 	doAntiAlias( src, decBuffer, m_inputLength );
cannam@0:     }
cannam@0:     unsigned idx = 0;
cannam@0: 
cannam@0:     for( unsigned int i = 0; i < m_outputLength; i++ )
cannam@0:     {
cannam@0: 	dst[ idx++ ] = decBuffer[ m_decFactor * i ];
cannam@0:     }
cannam@0: }