diff options
Diffstat (limited to 'libs/qm-dsp/dsp/rateconversion/Decimator.cpp')
| -rw-r--r-- | libs/qm-dsp/dsp/rateconversion/Decimator.cpp | 226 |
1 files changed, 226 insertions, 0 deletions
diff --git a/libs/qm-dsp/dsp/rateconversion/Decimator.cpp b/libs/qm-dsp/dsp/rateconversion/Decimator.cpp new file mode 100644 index 0000000000..c150ee0e11 --- /dev/null +++ b/libs/qm-dsp/dsp/rateconversion/Decimator.cpp @@ -0,0 +1,226 @@ +/* -*- 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 ]; + } +} |