annotate src/Modules/BMM/ModuleGammatone.h @ 611:0fbaf443ec82

Carfac C++ revision 3, indluding more style improvements. The output structs are now classes again, and have separate storage methods for each output structure along with flags in the Run and RunSegment methods to allow for only storing NAPs if desired.

// Copyright 2009-2010, Thomas Walters
//
// AIM-C: A C++ implementation of the Auditory Image Model
// http://www.acousticscale.org/AIMC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

/*! \file
 *  \brief Slaney's gammatone filterbank
 *
 *  \author Thomas Walters <[e-mail]>
 *  \date created 2009/11/13
 *  \version \$Id$
 *
 * This is the version of the IIR gammatone used in Slaney's Auditory toolbox.
 * The original verison as described in Apple Tech. Report #35 has a problem
 * with the high-order coefficients at low centre frequencies and high sample
 * rates. Since it is important that AIM-C can deal with these cases (for
 * example for the Gaussian features), I've reiplemeted Slaney's alternative
 * version which uses a cascade of four second-order filters in place of the 
 * eighth-order filter.
 */
#ifndef _AIMC_MODULES_BMM_GAMMATONE_H_
#define _AIMC_MODULES_BMM_GAMMATONE_H_

#include <vector>

#include "Support/Module.h"
#include "Support/Parameters.h"
#include "Support/SignalBank.h"

namespace aimc {
using std::vector;
class ModuleGammatone : public Module {
 public:
  explicit ModuleGammatone(Parameters *params);
  virtual ~ModuleGammatone();
  /*! \brief Process a buffer
   */
  virtual void Process(const SignalBank &input);

 private:
  virtual bool InitializeInternal(const SignalBank& input);
  virtual void ResetInternal();

  // Filter coefficients
  vector<vector<double> > b1_;
  vector<vector<double> > b2_;
  vector<vector<double> > b3_;
  vector<vector<double> > b4_;
  vector<vector<double> > a_;

  vector<vector<double> > state_1_;
  vector<vector<double> > state_2_;
  vector<vector<double> > state_3_;
  vector<vector<double> > state_4_;

  vector<double> centre_frequencies_;
  int num_channels_;
  double max_frequency_;
  double min_frequency_;
};
}  // namespace aimc
#endif  // _AIMC_MODULES_BMM_GAMMATONE_H_