lowpassfilter.h

/*************************************************************************

  Copyright 2011-2013 Ibrahim Sha'ath

  This file is part of LibKeyFinder.

  LibKeyFinder 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 3 of the License, or
  (at your option) any later version.

  LibKeyFinder is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with LibKeyFinder.  If not, see <http://www.gnu.org/licenses/>.

*************************************************************************/

#ifndef LOWPASSFILTER_H
#define LOWPASSFILTER_H

#include <cmath>
#include <vector>

#include "audiodata.h"
#include "binode.h"
#include "ringbuffer.h"
#include "fftadapter.h"
#include "windowfunctions.h"
#include "workspace.h"

namespace KeyFinder {

  class LowPassFilter {
  public:
    LowPassFilter(
      unsigned int order,
      unsigned int frameRate,
      float cornerFrequency,
      unsigned int fftFrameSize
    );
    void filter(
      AudioData& audio,
      Workspace& workspace,
      unsigned int shortcutFactor = 1
    ) const;
  protected:
    unsigned int order;
    unsigned int delay;         // always order / 2
    unsigned int impulseLength; // always order + 1
    float gain;
    std::vector<float> coefficients;
  };

}

#endif