BinauralBeats.cpp


         
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           /*
  Copyright (C) 2008-2009 Nasca Octavian Paul
  Author: Nasca Octavian Paul

  This program is free software; you can redistribute it and/or modify
  it under the terms of version 2 of the GNU General Public License 
  as published by the Free Software Foundation.

  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 (version 2) for more details.

  You should have received a copy of the GNU General Public License (version 2)
  along with this program; if not, write to the Free Software Foundation,
  Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
*/

#include <math.h>
#include <stdio.h>
#include "BinauralBeats.h"

//coefficients of allpass filters are found by Olli Niemitalo

const REALTYPE Hilbert::coefl[]={0.6923877778065, 0.9360654322959, 0.9882295226860, 0.9987488452737};
const REALTYPE Hilbert::coefr[]={0.4021921162426, 0.8561710882420, 0.9722909545651, 0.9952884791278};

BinauralBeats::BinauralBeats(int samplerate_){
    samplerate=samplerate_;
    hilbert_t=0.0;
};


void BinauralBeats::process(REALTYPE *smpsl,REALTYPE *smpsr,int nsmps,REALTYPE pos_percents){
//	for (int i=0;i<nsmps;i++) smpsl[i]=smpsr[i]=sin(30.0*M_PI*i*2.0/nsmps)*0.4;

	//printf(" enabled %d\n",pars.free_edit.get_enabled());
	if (pars.free_edit.get_enabled()){
		float mono=pars.mono*0.5;
		for (int i=0;i<nsmps;i++){
			REALTYPE inl=smpsl[i];
			REALTYPE inr=smpsr[i];
			REALTYPE outl=inl*(1.0-mono)+inr*mono;
			REALTYPE outr=inr*(1.0-mono)+inl*mono;

			smpsl[i]=outl;
			smpsr[i]=outr;
		};

		REALTYPE freq=pars.free_edit.get_value(pos_percents);

		freq*=0.5;//half down for left, half up for right
		for (int i=0;i<nsmps;i++){
			hilbert_t=fmod(hilbert_t+freq/samplerate,1.0);
			REALTYPE h1=0,h2=0;
			hl.process(smpsl[i],h1,h2);

			REALTYPE x=hilbert_t*2.0*M_PI;
			REALTYPE m1=h1*cos(x);
			REALTYPE m2=h2*sin(x);
			REALTYPE outl1=m1+m2;
			REALTYPE outl2=m1-m2;


			h1=0,h2=0;
			hr.process(smpsr[i],h1,h2);

			m1=h1*cos(x);
			m2=h2*sin(x);
			REALTYPE outr1=m1-m2;
			REALTYPE outr2=m1+m2;

			if (pars.reverse){
				smpsl[i]=outl1;
				smpsr[i]=outr1;
			}else{
				smpsl[i]=outl2;
				smpsr[i]=outr2;
			};

		};

	};
};