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