libs/Music/Filter.h

   1 // Copyright 2007 "Gilles Degottex"
   2
   3 // This file is part of "Music"
   4
   5 // "Music" is free software; you can redistribute it and/or modify
   6 // it under the terms of the GNU Lesser General Public License as published by
   7 // the Free Software Foundation; either version 2.1 of the License, or
   8 // (at your option) any later version.
   9 //
  10 // "Music" is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13 // GNU Lesser General Public License for more details.
  14 //
  15 // You should have received a copy of the GNU Lesser General Public License
  16 // along with this program; if not, write to the Free Software
  17 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18
  19
  20 #ifndef _Filter_h_
  21 #define _Filter_h_
  22
  23 #include <assert.h>
  24 #include <vector>
  25 #include <deque>
  26
  27 namespace Music
  28 {
  29         std::vector<double> fir1_lowpass(int n, double cutoff);
  30         std::vector<double> fir1_highpass(int n, double cutoff);
  31         std::vector<double> fir1_bandpass(int n, double low_cutoff, double high_cutoff);
  32
  33         /* Real-Time Filter
  34         */
  35         class RTFilter
  36         {
  37           public:
  38                 virtual double operator()(double v)=0;
  39
  40                 virtual int getLength()=0;
  41
  42                 virtual ~RTFilter(){}
  43         };
  44
  45         class FIRRTFilter : public RTFilter
  46         {
  47                 std::vector<double> m_imp_res;
  48                 std::deque<double> m_to_filter;
  49
  50           public:
  51                 FIRRTFilter(){m_imp_res=std::vector<double>(1, 1.0);}
  52                 FIRRTFilter(std::vector<double>& imp_res);
  53                 void setImpulseResponse(std::vector<double>& imp_res)   {m_imp_res=imp_res;}
  54
  55                 virtual int getLength()                                                                 {return m_imp_res.size();}
  56
  57                 virtual double operator()(double v);
  58         };
  59
  60         class RectangularHighPassRTFilter : public RTFilter
  61         {
  62                 int m_N;
  63                 std::deque<double> m_summed_values;
  64                 double m_sum;
  65
  66           public:
  67                 RectangularHighPassRTFilter(int N=0);
  68
  69                 void reset(int N);
  70                 virtual int getLength()                                                                 {return m_N;}
  71
  72                 virtual double operator()(double v);
  73         };
  74         class RectangularLowPassRTFilter : public RTFilter
  75         {
  76           public:
  77                 virtual double operator()(double v);
  78         };
  79         class RectangularBandPassRTFilter : public RTFilter
  80         {
  81           public:
  82                 virtual double operator()(double v);
  83         };
  84
  85         class DummyRTFilter : public RTFilter
  86         {
  87           public:
  88                 DummyRTFilter() {}
  89
  90                 virtual int getLength()                                                                 {return 1;}
  91
  92                 virtual double operator()(double v)     {return v;}
  93         };
  94 }
  95
  96 #endif // _Filter_h_