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: 
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: 
Chris@155: #ifndef DECIMATORB_H
Chris@155: #define DECIMATORB_H
Chris@155: 
Chris@155: #include <vector>
cannam@0: 
Chris@150: /**
Chris@155:  * DecimatorB carries out a fast downsample by a power-of-two
Chris@155:  * factor. It only knows how to decimate by a factor of 2, and will
Chris@155:  * use repeated decimation for higher factors. A Butterworth filter of
Chris@155:  * order 6 is used for the lowpass filter.
Chris@150:  */
Chris@155: class DecimatorB
cannam@0: {
cannam@0: public:
cannam@22:     void process( const double* src, double* dst );
cannam@55:     void process( const float* src, float* dst );
cannam@0: 
cannam@54:     /**
Chris@155:      * Construct a DecimatorB 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:      *
Chris@155:      * decFactor must be a power of two.
cannam@54:      */
Chris@155:     DecimatorB(int inLength, int decFactor);
Chris@155:     virtual ~DecimatorB();
cannam@0: 
cannam@22:     int getFactor() const { return m_decFactor; }
cannam@22: 
cannam@0: private:
cannam@0:     void deInitialise();
Chris@155:     void initialise(int inLength, int decFactor);
Chris@155:     void doAntiAlias(const double* src, double* dst, int length, int filteridx);
Chris@155:     void doProcess();
cannam@0: 
Chris@155:     int m_inputLength;
Chris@155:     int m_outputLength;
Chris@155:     int m_decFactor;
cannam@0: 
Chris@155:     std::vector<std::vector<double> > m_o;
cannam@0: 
Chris@155:     double m_a[7];
Chris@155:     double m_b[7];
cannam@0: 	
Chris@155:     double *m_aaBuffer;
Chris@155:     double *m_tmpBuffer;
cannam@0: };
cannam@0: 
Chris@155: #endif
Chris@155: