decode.c

ISO mp3 sources (distribution 10) Layer 1/2/3, C Source, 512 k Sources of the Mpeg 1,2 layer 1,2

   int i_stereo = (fr_ps->header->mode == MPG_MD_JOINT_STEREO) &&
                  (fr_ps->header->mode_ext & 0x1);
   int js_bound;  /* frequency line that marks the beggining of the zero part */  
   int sfb,next_sfb_boundary;
   int i,j,sb,ss,ch;
   short is_pos[SBLIMIT*SSLIMIT]; 
   double is_ratio[SBLIMIT*SSLIMIT];
   double io;
   double FAR k[2][SBLIMIT*SSLIMIT];

   int lsf	= (fr_ps->header->version == MPEG_PHASE2_LSF);

    if(  (gr_info->scalefac_compress % 2) == 1)
     {
       io = (double)0.707106781188;
     }
     else
     {
       io = (double)0.840896415256;
     }


   sfreq=fr_ps->header->sampling_frequency + (fr_ps->header->version * 3);

  
   /* intialization */
   for ( i=0; i<SBLIMIT*SSLIMIT; i++ )
      is_pos[i] = 7;

   if ((stereo == 2) && i_stereo )
   {  if (gr_info->window_switching_flag && (gr_info->block_type == 2))
      {  if( gr_info->mixed_block_flag )
         {  int max_sfb = 0;

            for ( j=0; j<3; j++ )
            {  int sfbcnt;
               sfbcnt = 2;
               for( sfb=12; sfb >=3; sfb-- )
               {  int lines;
                  lines = sfBandIndex[sfreq].s[sfb+1]-sfBandIndex[sfreq].s[sfb];
                  i = 3*sfBandIndex[sfreq].s[sfb] + (j+1) * lines - 1;
                  while ( lines > 0 )
                  {  if ( xr[1][i/SSLIMIT][i%SSLIMIT] != 0.0 )
                     {  sfbcnt = sfb;
                        sfb = -10;
                        lines = -10;
                     }
                     lines--;
                     i--;
                  }
               }
               sfb = sfbcnt + 1;

               if ( sfb > max_sfb )
                  max_sfb = sfb;

               while( sfb<12 )
               {  sb = sfBandIndex[sfreq].s[sfb+1]-sfBandIndex[sfreq].s[sfb];
                  i = 3*sfBandIndex[sfreq].s[sfb] + j * sb;
                  for ( ; sb > 0; sb--)
                  {  is_pos[i] = (*scalefac)[1].s[j][sfb];
                     if ( is_pos[i] != 7 )
                         if( lsf )
                         {
                              III_i_stereo_k_values(is_pos[i],io,i,k);
                         }
                         else
                         {
                             is_ratio[i] = tan((double)is_pos[i] * (PI / 12));
                         }
                     i++;
                  }
                  sfb++;
               }

               sb = sfBandIndex[sfreq].s[12]-sfBandIndex[sfreq].s[11];
               sfb = 3*sfBandIndex[sfreq].s[11] + j * sb;
               sb = sfBandIndex[sfreq].s[13]-sfBandIndex[sfreq].s[12];

               i = 3*sfBandIndex[sfreq].s[11] + j * sb;
               for ( ; sb > 0; sb-- )
               {  is_pos[i] = is_pos[sfb];
                  is_ratio[i] = is_ratio[sfb];
                  k[0][i] = k[0][sfb];
                  k[1][i] = k[1][sfb];
                  i++;
               }
             }
             if ( max_sfb <= 3 )
             {  i = 2;
                ss = 17;
                sb = -1;
                while ( i >= 0 )
                {  if ( xr[1][i][ss] != 0.0 )
                   {  sb = i*18+ss;
                      i = -1;
                   } else
                   {  ss--;
                      if ( ss < 0 )
                      {  i--;
                         ss = 17;
                      }
                   }
                }
                i = 0;
                while ( sfBandIndex[sfreq].l[i] <= sb )
                   i++;
                sfb = i;
                i = sfBandIndex[sfreq].l[i];
                for ( ; sfb<8; sfb++ )
                {  sb = sfBandIndex[sfreq].l[sfb+1]-sfBandIndex[sfreq].l[sfb];
                   for ( ; sb > 0; sb--)
                   {  is_pos[i] = (*scalefac)[1].l[sfb];
                      if ( is_pos[i] != 7 )
                         if ( lsf )
                         {
                              III_i_stereo_k_values(is_pos[i],io,i,k);
                         }
                         else
                         {
                             is_ratio[i] = tan((double)is_pos[i] * (PI / 12));
                         }
                      i++;
                   }
                }
            }
         } else
         {  for ( j=0; j<3; j++ )
            {  int sfbcnt;
               sfbcnt = -1;
               for( sfb=12; sfb >=0; sfb-- )
               {  int lines;
                  lines = sfBandIndex[sfreq].s[sfb+1]-sfBandIndex[sfreq].s[sfb];
                  i = 3*sfBandIndex[sfreq].s[sfb] + (j+1) * lines - 1;
                  while ( lines > 0 )
                  {  if ( xr[1][i/SSLIMIT][i%SSLIMIT] != 0.0 )
                     {  sfbcnt = sfb;
                        sfb = -10;
                        lines = -10;
                     }
                     lines--;
                     i--;
                  }
               }
               sfb = sfbcnt + 1;
               while( sfb<12 )
               {  sb = sfBandIndex[sfreq].s[sfb+1]-sfBandIndex[sfreq].s[sfb];
                  i = 3*sfBandIndex[sfreq].s[sfb] + j * sb;
                  for ( ; sb > 0; sb--)
                  {  is_pos[i] = (*scalefac)[1].s[j][sfb];
                     if ( is_pos[i] != 7 )
                         if( lsf )
                         {
                              III_i_stereo_k_values(is_pos[i],io,i,k);
                         }
                         else
                         {
                             is_ratio[i] = tan( (double)is_pos[i] * (PI / 12));
                         }
                     i++;
                  }
                  sfb++;
               }

               sb = sfBandIndex[sfreq].s[12]-sfBandIndex[sfreq].s[11];
               sfb = 3*sfBandIndex[sfreq].s[11] + j * sb;
               sb = sfBandIndex[sfreq].s[13]-sfBandIndex[sfreq].s[12];

               i = 3*sfBandIndex[sfreq].s[11] + j * sb;
               for ( ; sb > 0; sb-- )
               {  is_pos[i] = is_pos[sfb];
                  is_ratio[i] = is_ratio[sfb];
                  k[0][i] = k[0][sfb];
                  k[1][i] = k[1][sfb];
                  i++;
               }
            }
         }
      } else
      {  i = 31;
         ss = 17;
         sb = 0;
         while ( i >= 0 )
         {  if ( xr[1][i][ss] != 0.0 )
            {  sb = i*18+ss;
               i = -1;
            } else
            {  ss--;
               if ( ss < 0 )
               {  i--;
                  ss = 17;
               }
            }
         }
         i = 0;
         while ( sfBandIndex[sfreq].l[i] <= sb )
            i++;
         sfb = i;
         i = sfBandIndex[sfreq].l[i];
         for ( ; sfb<21; sfb++ )
         {  sb = sfBandIndex[sfreq].l[sfb+1] - sfBandIndex[sfreq].l[sfb];
            for ( ; sb > 0; sb--)
            {  is_pos[i] = (*scalefac)[1].l[sfb];
               if ( is_pos[i] != 7 )
                     if( lsf )
                     {
                           III_i_stereo_k_values(is_pos[i],io,i,k);
                     }
                     else
                     {
                          is_ratio[i] = tan((double)is_pos[i] * (PI / 12));
                     }
               i++;
            }
         }
         sfb = sfBandIndex[sfreq].l[20];
         for ( sb = 576 - sfBandIndex[sfreq].l[21]; sb > 0; sb-- )
         {  is_pos[i] = is_pos[sfb];
            is_ratio[i] = is_ratio[sfb];
            k[0][i] = k[0][sfb];
            k[1][i] = k[1][sfb];
            i++;
         }
      }
   }

   for(ch=0;ch<2;ch++)
      for(sb=0;sb<SBLIMIT;sb++)
         for(ss=0;ss<SSLIMIT;ss++) 
            lr[ch][sb][ss] = 0;

   if (stereo==2) 
      for(sb=0;sb<SBLIMIT;sb++)
         for(ss=0;ss<SSLIMIT;ss++) {
            i = (sb*18)+ss;
            if ( is_pos[i] == 7 ) {
               if ( ms_stereo ) {
                  lr[0][sb][ss] = (xr[0][sb][ss]+xr[1][sb][ss])/(double)1.41421356;
                  lr[1][sb][ss] = (xr[0][sb][ss]-xr[1][sb][ss])/(double)1.41421356;
               }
               else {
                  lr[0][sb][ss] = xr[0][sb][ss];
                  lr[1][sb][ss] = xr[1][sb][ss];
               }
            }
            else if (i_stereo ) {
                if ( lsf )
                {
                  lr[0][sb][ss] = xr[0][sb][ss] * k[0][i];
                  lr[1][sb][ss] = xr[0][sb][ss] * k[1][i]; 
                }
               else
                {
                  lr[0][sb][ss] = xr[0][sb][ss] * (is_ratio[i]/(1+is_ratio[i]));
                  lr[1][sb][ss] = xr[0][sb][ss] * (1/(1+is_ratio[i])); 
                }
            }
            else {
               printf("Error in streo processing\n");
            }
         }
   else  /* mono , bypass xr[0][][] to lr[0][][]*/
      for(sb=0;sb<SBLIMIT;sb++)
         for(ss=0;ss<SSLIMIT;ss++)
            lr[0][sb][ss] = xr[0][sb][ss];

}

double Ci[8]={-0.6,-0.535,-0.33,-0.185,-0.095,-0.041,-0.0142,-0.0037};


void III_antialias(xr, hybridIn, gr_info, fr_ps)
double xr[SBLIMIT][SSLIMIT];    
double hybridIn[SBLIMIT][SSLIMIT];
struct gr_info_s *gr_info;             
frame_params *fr_ps;            
{
   static int    init = 1;
   static double ca[8],cs[8];
   double        bu,bd;  /* upper and lower butterfly inputs */
   int           ss,sb,sblim;

   if (init) {
      int i;
      double    sq;
      for (i=0;i<8;i++) {
         sq=sqrt(1.0+Ci[i]*Ci[i]);
         cs[i] = 1.0/sq;
         ca[i] = Ci[i]/sq;
      }
      init = 0;
   }
   
   /* clear all inputs */  
      
    for(sb=0;sb<SBLIMIT;sb++)
       for(ss=0;ss<SSLIMIT;ss++)
          hybridIn[sb][ss] = xr[sb][ss];

   if  (gr_info->window_switching_flag && (gr_info->block_type == 2) &&
       !gr_info->mixed_block_flag ) return;

   if ( gr_info->window_switching_flag && gr_info->mixed_block_flag &&
     (gr_info->block_type == 2))
      sblim = 1;
   else
      sblim = SBLIMIT-1;

   /* 31 alias-reduction operations between each pair of sub-bands */
   /* with 8 butterflies between each pair                         */

   for(sb=0;sb<sblim;sb++)   
      for(ss=0;ss<8;ss++) {      
         bu = xr[sb][17-ss];
         bd = xr[sb+1][ss];
         hybridIn[sb][17-ss] = (bu * cs[ss]) - (bd * ca[ss]);
         hybridIn[sb+1][ss] = (bd * cs[ss]) + (bu * ca[ss]);
         }  
}

void inv_mdct(in, out, block_type)
double in[18];
double out[36];
int block_type;
{
/*------------------------------------------------------------------*/
/*                                                                  */
/*    Function: Calculation of the inverse MDCT                     */
/*    In the case of short blocks the 3 output vectors are already  */
/*    overlapped and added in this modul.                           */
/*                                                                  */
/*    New layer3                                                    */
/*                                                                  */
/*------------------------------------------------------------------*/

int     k,i,m,N,p;
double  tmp[12],sum;
static  double  win[4][36];
static  int init=0;
static  double COS[4*36];

    if(init==0){

    /* type 0 */
      for(i=0;i<36;i++)
         win[0][i] = sin( PI/36 *(i+0.5) );

    /* type 1*/
      for(i=0;i<18;i++)
         win[1][i] = sin( PI/36 *(i+0.5) );
      for(i=18;i<24;i++)
         win[1][i] = 1.0;
      for(i=24;i<30;i++)
         win[1][i] = sin( PI/12 *(i+0.5-18) );
      for(i=30;i<36;i++)
         win[1][i] = 0.0;

    /* type 3*/
      for(i=0;i<6;i++)
         win[3][i] = 0.0;
      for(i=6;i<12;i++)
         win[3][i] = sin( PI/12 *(i+0.5-6) );
      for(i=12;i<18;i++)
         win[3][i] =1.0;
      for(i=18;i<36;i++)
         win[3][i] = sin( PI/36*(i+0.5) );

    /* type 2*/
      for(i=0;i<12;i++)
         win[2][i] = sin( PI/12*(i+0.5) ) ;
      for(i=12;i<36;i++)
         win[2][i] = 0.0 ;

      for (i=0; i<4*36; i++)
         COS[i] = cos(PI/(2