c@225: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
c@225: 
c@225: /*
c@225:     QM DSP Library
c@225: 
c@225:     Centre for Digital Music, Queen Mary, University of London.
c@309:     This file 2005-2006 Christian Landone.
c@309: 
c@309:     This program is free software; you can redistribute it and/or
c@309:     modify it under the terms of the GNU General Public License as
c@309:     published by the Free Software Foundation; either version 2 of the
c@309:     License, or (at your option) any later version.  See the file
c@309:     COPYING included with this distribution for more information.
c@225: */
c@225: 
c@225: #include "Decimator.h"
c@225: 
c@247: #include <iostream>
c@247: 
c@225: //////////////////////////////////////////////////////////////////////
c@225: // Construction/Destruction
c@225: //////////////////////////////////////////////////////////////////////
c@225: 
cannam@499: Decimator::Decimator( int inLength, int decFactor )
c@225: {
c@225:     m_inputLength = 0;
c@225:     m_outputLength = 0;
c@225:     m_decFactor = 1;
c@225: 
c@225:     initialise( inLength, decFactor );
c@225: }
c@225: 
c@225: Decimator::~Decimator()
c@225: {
c@225:     deInitialise();
c@225: }
c@225: 
cannam@499: void Decimator::initialise( int inLength, int decFactor)
c@225: {
c@225:     m_inputLength = inLength;
c@225:     m_decFactor = decFactor;
c@225:     m_outputLength = m_inputLength / m_decFactor;
c@225: 
c@225:     decBuffer = new double[ m_inputLength ];
c@225: 
c@247:     // If adding new factors here, add them to
c@247:     // getHighestSupportedFactor in the header as well
c@247: 
cannam@483:     if(m_decFactor == 8) {
cannam@483: 
c@247:         //////////////////////////////////////////////////
c@247:         b[0] = 0.060111378492136;
c@247:         b[1] = -0.257323420830598;
c@247:         b[2] = 0.420583503165928;
c@247:         b[3] = -0.222750785197418;
c@247:         b[4] = -0.222750785197418;
c@247:         b[5] = 0.420583503165928;
c@247:         b[6] = -0.257323420830598;
c@247:         b[7] = 0.060111378492136;
c@247: 
c@247:         a[0] = 1;
c@247:         a[1] = -5.667654878577432;
c@247:         a[2] = 14.062452278088417;
c@247:         a[3] = -19.737303840697738;
c@247:         a[4] = 16.889698874608641;
c@247:         a[5] = -8.796600612325928;
c@247:         a[6] = 2.577553446979888;
c@247:         a[7] = -0.326903916815751;
c@247:         //////////////////////////////////////////////////
c@225: 
cannam@483:     } else if( m_decFactor == 4 ) {
cannam@483:         
cannam@483:         //////////////////////////////////////////////////
cannam@483:         b[ 0 ] = 0.10133306904918619;
cannam@483:         b[ 1 ] = -0.2447523353702363;
cannam@483:         b[ 2 ] = 0.33622528590120965;
cannam@483:         b[ 3 ] = -0.13936581560633518;
cannam@483:         b[ 4 ] = -0.13936581560633382;
cannam@483:         b[ 5 ] = 0.3362252859012087;
cannam@483:         b[ 6 ] = -0.2447523353702358;
cannam@483:         b[ 7 ] = 0.10133306904918594;
c@225: 
cannam@483:         a[ 0 ] = 1;
cannam@483:         a[ 1 ] = -3.9035590278139427;
cannam@483:         a[ 2 ] = 7.5299379980621133;
cannam@483:         a[ 3 ] = -8.6890803793177511;
cannam@483:         a[ 4 ] = 6.4578667096099176;
cannam@483:         a[ 5 ] = -3.0242979431223631;
cannam@483:         a[ 6 ] = 0.83043385136748382;
cannam@483:         a[ 7 ] = -0.094420800837809335;
cannam@483:         //////////////////////////////////////////////////
cannam@483: 
cannam@483:     } else if( m_decFactor == 2 ) {
cannam@483:         
cannam@483:         //////////////////////////////////////////////////
cannam@483:         b[ 0 ] = 0.20898944260075727;
cannam@483:         b[ 1 ] = 0.40011234879814367;
cannam@483:         b[ 2 ] = 0.819741973072733;
cannam@483:         b[ 3 ] = 1.0087419911682323;
cannam@483:         b[ 4 ] = 1.0087419911682325;
cannam@483:         b[ 5 ] = 0.81974197307273156;
cannam@483:         b[ 6 ] = 0.40011234879814295;
cannam@483:         b[ 7 ] = 0.20898944260075661;
cannam@483: 
cannam@483:         a[ 0 ] = 1;
cannam@483:         a[ 1 ] = 0.0077331184208358217;
cannam@483:         a[ 2 ] = 1.9853971155964376;
cannam@483:         a[ 3 ] = 0.19296739275341004;
cannam@483:         a[ 4 ] = 1.2330748872852182;
cannam@483:         a[ 5 ] = 0.18705341389316466;
cannam@483:         a[ 6 ] = 0.23659265908013868;
cannam@483:         a[ 7 ] = 0.032352924250533946;
cannam@483: 
cannam@483:     } else {
cannam@483:         
c@247:         if ( m_decFactor != 1 ) {
c@247:             std::cerr << "WARNING: Decimator::initialise: unsupported decimation factor " << m_decFactor << ", no antialiasing filter will be used" << std::endl;
c@247:         }
c@247: 
cannam@483:         //////////////////////////////////////////////////
cannam@483:         b[ 0 ] = 1;
cannam@483:         b[ 1 ] = 0;
cannam@483:         b[ 2 ] = 0;
cannam@483:         b[ 3 ] = 0;
cannam@483:         b[ 4 ] = 0;
cannam@483:         b[ 5 ] = 0;
cannam@483:         b[ 6 ] = 0;
cannam@483:         b[ 7 ] = 0;
c@225: 
cannam@483:         a[ 0 ] = 1;
cannam@483:         a[ 1 ] = 0;
cannam@483:         a[ 2 ] = 0;
cannam@483:         a[ 3 ] = 0;
cannam@483:         a[ 4 ] = 0;
cannam@483:         a[ 5 ] = 0;
cannam@483:         a[ 6 ] = 0;
cannam@483:         a[ 7 ] = 0;
c@225:     }
c@225: 
c@225:     resetFilter();
c@225: }
c@225: 
c@225: void Decimator::deInitialise()
c@225: {
c@225:     delete [] decBuffer;
c@225: }
c@225: 
c@225: void Decimator::resetFilter()
c@225: {
c@225:     Input = Output = 0;
c@225: 
c@225:     o1=o2=o3=o4=o5=o6=o7=0;
c@225: }
c@225: 
cannam@499: void Decimator::doAntiAlias(const double *src, double *dst, int length)
c@225: {
cannam@499:     for (int i = 0; i < length; i++ ) {
cannam@483:         
cannam@483:         Input = (double)src[ i ];
c@225: 
cannam@483:         Output = Input * b[ 0 ] + o1;
c@225: 
cannam@483:         o1 = Input * b[ 1 ] - Output * a[ 1 ] + o2;
cannam@483:         o2 = Input * b[ 2 ] - Output * a[ 2 ] + o3;
cannam@483:         o3 = Input * b[ 3 ] - Output * a[ 3 ] + o4;
cannam@483:         o4 = Input * b[ 4 ] - Output * a[ 4 ] + o5;
cannam@483:         o5 = Input * b[ 5 ] - Output * a[ 5 ] + o6;
cannam@483:         o6 = Input * b[ 6 ] - Output * a[ 6 ] + o7;
cannam@483:         o7 = Input * b[ 7 ] - Output * a[ 7 ] ;
c@225: 
cannam@483:         dst[ i ] = Output;
c@225:     }
c@225: }
c@225: 
cannam@499: void Decimator::doAntiAlias(const float *src, double *dst, int length)
c@280: {
cannam@499:     for (int i = 0; i < length; i++ ) {
cannam@483:         
cannam@483:         Input = (double)src[ i ];
c@280: 
cannam@483:         Output = Input * b[ 0 ] + o1;
c@280: 
cannam@483:         o1 = Input * b[ 1 ] - Output * a[ 1 ] + o2;
cannam@483:         o2 = Input * b[ 2 ] - Output * a[ 2 ] + o3;
cannam@483:         o3 = Input * b[ 3 ] - Output * a[ 3 ] + o4;
cannam@483:         o4 = Input * b[ 4 ] - Output * a[ 4 ] + o5;
cannam@483:         o5 = Input * b[ 5 ] - Output * a[ 5 ] + o6;
cannam@483:         o6 = Input * b[ 6 ] - Output * a[ 6 ] + o7;
cannam@483:         o7 = Input * b[ 7 ] - Output * a[ 7 ] ;
c@280: 
cannam@483:         dst[ i ] = Output;
c@280:     }
c@280: }
c@280: 
c@247: void Decimator::process(const double *src, double *dst)
c@225: {
c@388:     if (m_decFactor == 1) {
cannam@499:         for (int i = 0; i < m_outputLength; i++ ) {
c@388:             dst[i] = src[i];
c@388:         }
c@388:         return;
c@225:     }
c@388:         
c@388:     doAntiAlias( src, decBuffer, m_inputLength );
c@388: 
cannam@501:     int idx = 0;
c@225: 
cannam@499:     for (int i = 0; i < m_outputLength; i++ ) {
cannam@483:         dst[ idx++ ] = decBuffer[ m_decFactor * i ];
c@225:     }
c@225: }
c@280: 
c@280: void Decimator::process(const float *src, float *dst)
c@280: {
c@388:     if (m_decFactor == 1) {
cannam@499:         for (int i = 0; i < m_outputLength; i++ ) {
c@388:             dst[i] = src[i];
c@388:         }
c@388:         return;
c@280:     }
c@388: 
c@388:     doAntiAlias( src, decBuffer, m_inputLength );
c@388: 
cannam@499:     int idx = 0;
c@280: 
cannam@499:     for (int i = 0; i < m_outputLength; i++ ) {
cannam@483:         dst[ idx++ ] = decBuffer[ m_decFactor * i ];
c@280:     }
c@280: }