SpectralCombTriang.cxx

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/*
 * Copyright (c) 2001-2004 MUSIC TECHNOLOGY GROUP (MTG)
 *                         UNIVERSITAT POMPEU FABRA
 *
 *
 * This program 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 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#include "SpectralCombTriang.hxx"
#include "ProcessingFactory.hxx"

namespace CLAM
{

namespace Hidden
{
        static const char * metadata[] = {
                "key", "SpectralCombTriang",
        //      "category", "Spectral Transformations",
        //      "description", "SpectralCombTriang",
                0
        };
        static FactoryRegistrator<ProcessingFactory, SpectralCombTriang> reg = metadata;
}


bool SpectralCombTriang::Do(const Spectrum& in, Spectrum& out)
{
        if (!mConfig.GetPreserveOuts())
        {
                out = in; //TODO big cludge for streaming
        }
        DataArray& inMag = in.GetMagBuffer();
        DataArray& outMag = out.GetMagBuffer();
        
        int spectrumSize = in.GetSize();
        
        TData spectralResolution = spectrumSize/in.GetSpectralRange();
        int fundamental = Round(mFundamentalCtl.GetLastValue()* spectralResolution);
        
        int i;
        int n;
        n = 0;
        int bandlimit = fundamental;
        //control expected in dB
        TData overallGain = log2lin(mAmount.GetLastValue());
        for(i = 0; i<spectrumSize; i++)
        {
                if(i > bandlimit)
                {
                        n++;
                        bandlimit = fundamental * n;
                }
                outMag[i] = inMag[i]*GetGain(fundamental, i, n)*overallGain;
        }
        return true;
}

TData SpectralCombTriang::GetGain(int fundamental, int binPos, int bandNum)
{
        //first we find whether the binPos is on a positive or negative slope part
        //auxiliary data
        TData period = fundamental;
        
        //compute mid point
        int midPoint = int (period * 0.5);
        
        bool ascending = false;
        if ((binPos - fundamental*bandNum)> midPoint || bandNum == 0) ascending = true;
        
                
        //compute linear equation y = ax + b
        //first the 'a'
        TData a = 2/fundamental;
        if (!ascending) a = -a;
        //now the 'b'
        TData b = 1;
        if(ascending) b = 0;
        //now the x
        int x;
        if (bandNum==0) x = binPos;
        else if(ascending) x = binPos - int(fundamental*bandNum + midPoint);
        else x = binPos - int(fundamental * bandNum);
        
        //ready to compute the gain
        return a*x + b;
}


}