FDCombFilter.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 "Complex.hxx"
#include "FDCombFilter.hxx"

#define CLASS "FDCombFilter"

namespace CLAM {


        /* Processing  object Method  implementations */

        FDCombFilter::FDCombFilter(const Config &c)
                : mFreq("Frequency",this)
        {
                mFreq.DoControl(0);
                Configure(c);
        }

        FDCombFilter::~FDCombFilter()
        {}


        /* The supervised Do() function */

        bool  FDCombFilter::Do() 
        {
                CLAM_ASSERT(false,CLASS"::Do(): Supervised mode not implemented");
                return false;
        }

        
        /* The  unsupervised Do() function */
        bool  FDCombFilter::Do(const Spectrum& input, Spectrum& output)
        {
                if (mFreq.GetLastValue() <= 0) return false;

                output.SetSize(input.GetSize());
                Spectrum tmpSpec=input;
                bool wasDB=false;
                if(output.GetScale()==EScale::eLog)
                {
                        wasDB=true;
                        output.SetScale(EScale::eLinear);
                }
                
                tmpSpec.ToLinear();

                
                TData samplingRate=input.GetSpectralRange()*2;
                const TSize sizeSpectrum=input.GetSize();
                TData pitch=mFreq.GetLastValue();
                TData period = pitch /  samplingRate * sizeSpectrum * 2.0; 
                DataArray & inputMag = input.GetMagBuffer();
                DataArray & inputPhase = input.GetPhaseBuffer();
                DataArray & outputMag = output.GetMagBuffer();
                DataArray & outputPhase = output.GetPhaseBuffer();
                
                TData twoPiOverPeriod = TWO_PI/period;
                TData oneOverTwo = 1./2.0;
                for(unsigned i=0; i<sizeSpectrum; i++)
                {
                        //todo: this loop is very inefficient because of the sin and cos but there are ways of optimizing
                        //these kind of iterative sine computations
                        TData combReal = (1.f +CLAM_cos(i*twoPiOverPeriod)) * oneOverTwo;
                        TData combImag = (1.f -CLAM_sin(i*twoPiOverPeriod)) * oneOverTwo;
                        
                        TData mag=inputMag[i];
                        TData phase=inputPhase[i];
                        TData real=mag*CLAM_cos(phase);
                        TData imag=mag*CLAM_sin(phase);

                        TData newReal=real*combReal-imag*combImag;
                        TData newImag=real*combImag+imag*combReal;
                        TData newMag=CLAM_sqrt(newReal*newReal+newImag*newImag);
                        TData newPhase=CLAM_atan2(newImag,newReal);
                        
                        outputMag[i] = newMag;
                        outputPhase[i] = newPhase;
                }

                if(wasDB) output.ToDB();

                return true;
        }


};//namespace CLAM