cannam@0: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
cannam@0: /*
cannam@0:     QM DSP Library
cannam@0: 
cannam@0:     Centre for Digital Music, Queen Mary, University of London.
Chris@84:     This file 2005-2006 Christian Landone.
Chris@84: 
Chris@84:     This program is free software; you can redistribute it and/or
Chris@84:     modify it under the terms of the GNU General Public License as
Chris@84:     published by the Free Software Foundation; either version 2 of the
Chris@84:     License, or (at your option) any later version.  See the file
Chris@84:     COPYING included with this distribution for more information.
cannam@0: */
cannam@0: 
cannam@0: #ifndef DECIMATOR_H
cannam@0: #define DECIMATOR_H
cannam@0: 
Chris@150: /**
Chris@150:  * Decimator carries out a fast downsample by a power-of-two
Chris@150:  * factor. Only a limited number of factors are supported, from two to
Chris@150:  * whatever getHighestSupportedFactor() returns. This is much faster
Chris@150:  * than Resampler but has a worse signal-noise ratio.
Chris@150:  */
cannam@0: class Decimator  
cannam@0: {
cannam@0: public:
cannam@54:     /**
cannam@54:      * Construct a Decimator to operate on input blocks of length
cannam@54:      * inLength, with decimation factor decFactor.  inLength should be
cannam@54:      * a multiple of decFactor.  Output blocks will be of length
cannam@54:      * inLength / decFactor.
cannam@54:      *
cannam@54:      * decFactor must be a power of two.  The highest supported factor
cannam@54:      * is obtained through getHighestSupportedFactor(); for higher
cannam@54:      * factors, you will need to chain more than one decimator.
cannam@54:      */
cannam@0:     Decimator( unsigned int inLength, unsigned int decFactor );
cannam@0:     virtual ~Decimator();
cannam@0: 
Chris@163:     /**
Chris@163:      * Process inLength samples (as supplied to constructor) from src
Chris@163:      * and write inLength / decFactor samples to dst.  Note that src
Chris@163:      * and dst may be the same or overlap (an intermediate buffer is
Chris@163:      * used).
Chris@163:      */
Chris@163:     void process( const double* src, double* dst );
Chris@163: 
Chris@163:     /**
Chris@163:      * Process inLength samples (as supplied to constructor) from src
Chris@163:      * and write inLength / decFactor samples to dst.  Note that src
Chris@163:      * and dst may be the same or overlap (an intermediate buffer is
Chris@163:      * used).
Chris@163:      */
Chris@163:     void process( const float* src, float* dst );
Chris@163: 
cannam@22:     int getFactor() const { return m_decFactor; }
cannam@22:     static int getHighestSupportedFactor() { return 8; }
cannam@22: 
Chris@163:     void resetFilter();
Chris@163: 
cannam@0: private:
cannam@0:     void deInitialise();
cannam@0:     void initialise( unsigned int inLength, unsigned int decFactor );
cannam@55:     void doAntiAlias( const double* src, double* dst, unsigned int length );
cannam@55:     void doAntiAlias( const float* src, double* dst, unsigned int length );
cannam@0: 
cannam@0:     unsigned int m_inputLength;
cannam@0:     unsigned int m_outputLength;
cannam@0:     unsigned int m_decFactor;
cannam@0: 
cannam@0:     double Input;
cannam@0:     double Output ;
cannam@0: 
cannam@0:     double o1,o2,o3,o4,o5,o6,o7;
cannam@0: 
cannam@0:     double a[ 9 ];
cannam@0:     double b[ 9 ];
cannam@0: 	
cannam@0:     double* decBuffer;
cannam@0: };
cannam@0: 
cannam@0: #endif //