libs/qm-dsp/dsp/rateconversion/Decimator.h

   1 /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
   2 /*
   3     QM DSP Library
   4
   5     Centre for Digital Music, Queen Mary, University of London.
   6     This file 2005-2006 Christian Landone.
   7
   8     This program is free software; you can redistribute it and/or
   9     modify it under the terms of the GNU General Public License as
  10     published by the Free Software Foundation; either version 2 of the
  11     License, or (at your option) any later version.  See the file
  12     COPYING included with this distribution for more information.
  13 */
  14
  15 #ifndef DECIMATOR_H
  16 #define DECIMATOR_H
  17
  18 class Decimator
  19 {
  20 public:
  21     void process( const double* src, double* dst );
  22     void process( const float* src, float* dst );
  23
  24     /**
  25      * Construct a Decimator to operate on input blocks of length
  26      * inLength, with decimation factor decFactor.  inLength should be
  27      * a multiple of decFactor.  Output blocks will be of length
  28      * inLength / decFactor.
  29      *
  30      * decFactor must be a power of two.  The highest supported factor
  31      * is obtained through getHighestSupportedFactor(); for higher
  32      * factors, you will need to chain more than one decimator.
  33      */
  34     Decimator( unsigned int inLength, unsigned int decFactor );
  35     virtual ~Decimator();
  36
  37     int getFactor() const { return m_decFactor; }
  38     static int getHighestSupportedFactor() { return 8; }
  39
  40 private:
  41     void resetFilter();
  42     void deInitialise();
  43     void initialise( unsigned int inLength, unsigned int decFactor );
  44     void doAntiAlias( const double* src, double* dst, unsigned int length );
  45     void doAntiAlias( const float* src, double* dst, unsigned int length );
  46
  47     unsigned int m_inputLength;
  48     unsigned int m_outputLength;
  49     unsigned int m_decFactor;
  50
  51     double Input;
  52     double Output ;
  53
  54     double o1,o2,o3,o4,o5,o6,o7;
  55
  56     double a[ 9 ];
  57     double b[ 9 ];
  58
  59     double* decBuffer;
  60 };
  61
  62 #endif //