winamp/Src/external_dependencies/openmpt-trunk/include/soundtouch/source/SoundTouch/PeakFinder.h

////////////////////////////////////////////////////////////////////////////////
///
/// The routine detects highest value on an array of values and calculates the 
/// precise peak location as a mass-center of the 'hump' around the peak value.
///
/// Author        : Copyright (c) Olli Parviainen
/// Author e-mail : oparviai 'at' iki.fi
/// SoundTouch WWW: http://www.surina.net/soundtouch
///
////////////////////////////////////////////////////////////////////////////////
//
// License :
//
//  SoundTouch audio processing library
//  Copyright (c) Olli Parviainen
//
//  This library is free software; you can redistribute it and/or
//  modify it under the terms of the GNU Lesser General Public
//  License as published by the Free Software Foundation; either
//  version 2.1 of the License, or (at your option) any later version.
//
//  This library 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
//  Lesser General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public
//  License along with this library; if not, write to the Free Software
//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
////////////////////////////////////////////////////////////////////////////////

#ifndef _PeakFinder_H_
#define _PeakFinder_H_

namespace soundtouch
{

class PeakFinder
{
protected:
    /// Min, max allowed peak positions within the data vector
    int minPos, maxPos;

    /// Calculates the mass center between given vector items.
    double calcMassCenter(const float *data, ///< Data vector.
                         int firstPos,      ///< Index of first vector item belonging to the peak.
                         int lastPos        ///< Index of last vector item belonging to the peak.
                         ) const;

    /// Finds the data vector index where the monotoniously decreasing signal crosses the
    /// given level.
    int   findCrossingLevel(const float *data,  ///< Data vector.
                            float level,        ///< Goal crossing level.
                            int peakpos,        ///< Peak position index within the data vector.
                            int direction       /// Direction where to proceed from the peak: 1 = right, -1 = left.
                            ) const;

    // Finds real 'top' of a peak hump from neighnourhood of the given 'peakpos'.
    int findTop(const float *data, int peakpos) const;


    /// Finds the 'ground' level, i.e. smallest level between two neighbouring peaks, to right- 
    /// or left-hand side of the given peak position.
    int   findGround(const float *data,     /// Data vector.
                     int peakpos,           /// Peak position index within the data vector.
                     int direction          /// Direction where to proceed from the peak: 1 = right, -1 = left.
                     ) const;

    /// get exact center of peak near given position by calculating local mass of center
    double getPeakCenter(const float *data, int peakpos) const;

public:
    /// Constructor. 
    PeakFinder();

    /// Detect exact peak position of the data vector by finding the largest peak 'hump'
    /// and calculating the mass-center location of the peak hump.
    ///
    /// \return The location of the largest base harmonic peak hump.
    double detectPeak(const float *data, /// Data vector to be analyzed. The data vector has
                                        /// to be at least 'maxPos' items long.
                     int minPos,        ///< Min allowed peak location within the vector data.
                     int maxPos         ///< Max allowed peak location within the vector data.
                     );
};

}

#endif // _PeakFinder_H_