beat_detect.c

/*****************************************************************************
 * beat_detect.c: basic beat detection algorithm
 *****************************************************************************
 * Copyright (C) 2004 the VideoLAN team
 * $Id: beat_detect.c 11664 2005-07-09 06:17:09Z courmisch $
 *
 * Authors: Cyril Deguet <[email protected]>
 *          code from projectM http://xmms-projectm.sourceforge.net
 *
 * 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, USA.
 *****************************************************************************/

//
//by Peter Sperl
//
//Takes sound data from wherever and returns beat detection values
//Uses statistical Energy-Based methods. Very simple
//
//Some stuff was taken from Frederic Patin's beat-detection article, you'll find it online

#include <stdlib.h>
#include <stdio.h>
#include "engine_vars.h"

double beat_buffer[32][80],beat_instant[32],beat_history[32];
double *beat_val,*beat_att,*beat_variance;
int beat_buffer_pos;

double vol_buffer[80],vol_instant,vol_history;

void initBeatDetect()
{

  int x,y; 

  vol_instant=0;
  vol_history=0;

  for (y=0;y<80;y++)
    {
      vol_buffer[y]=0;
    }

  beat_buffer_pos=0;

  beat_val=(double *)malloc(32*sizeof(double));
  beat_att=(double *)malloc(32*sizeof(double));
  beat_variance=(double *)malloc(32*sizeof(double));

  for (x=0;x<32;x++)
    {
      beat_instant[x]=0;
      beat_history[x]=0;
      beat_val[x]=1.0;
      beat_att[x]=1.0;
      beat_variance[x]=0;
      for (y=0;y<80;y++)
        {
          beat_buffer[x][y]=0;
        }
    }

} 

void getBeatVals(double *vdataL,double *vdataR, double *vol)
{
  int linear=0;
  int x,y;

  vol_instant=0;

      for ( x=0;x<16;x++)
        {
          
          beat_instant[x]=0;
          for ( y=linear*2;y<(linear+8+x)*2;y++)
            {
              beat_instant[x]+=((vdataL[y]*vdataL[y])+(vdataR[y]*vdataR[y]))*(1.0/(8+x)); 
              vol_instant+=((vdataL[y]*vdataL[y])+(vdataR[y]*vdataR[y]))*(1.0/512.0);

            }
          
          linear=y/2;
          beat_history[x]-=(beat_buffer[x][beat_buffer_pos])*.0125;
          beat_buffer[x][beat_buffer_pos]=beat_instant[x];
          beat_history[x]+=(beat_instant[x])*.0125;
          
          beat_val[x]=(beat_instant[x])/(beat_history[x]);
          
          beat_att[x]+=(beat_instant[x])/(beat_history[x]);


          
        }
      
      vol_history-=(vol_buffer[beat_buffer_pos])*.0125;
      vol_buffer[beat_buffer_pos]=vol_instant;
      vol_history+=(vol_instant)*.0125;

      double temp2=0;
      mid=0;
      for(x=1;x<10;x++)
        {
         mid+=(beat_instant[x]);
          temp2+=(beat_history[x]);
         
        }
        
         mid=mid/(1.5*temp2);
         temp2=0;
         treb=0;
          for(x=10;x<16;x++)
            { 
              treb+=(beat_instant[x]);
              temp2+=(beat_history[x]);
            }
          treb=treb/(1.5*temp2);
          *vol=vol_instant/(1.5*vol_history);
  
          bass=(beat_instant[0])/(1.5*beat_history[0]);

          treb_att=.6 * treb_att + .4 * treb;
          mid_att=.6 * mid_att + .4 * mid;
          bass_att=.6 * bass_att + .4 * bass;
          //printf("%f %f %f %f\n",bass,mid,treb,*vol);
           // *vol=(beat_instant[3])/(beat_history[3]);
          beat_buffer_pos++;
          if( beat_buffer_pos>79)beat_buffer_pos=0;
        
}
void freeBeatDetect()
{
  free(beat_att);
  free(beat_val);
  free(beat_variance);
}

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