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     11 - Neither the name of Internet Society, IETF or IETF Trust, nor the
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     14 permission.
     15 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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     24 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     25 POSSIBILITY OF SUCH DAMAGE.
     26 ***********************************************************************/
     27 
     28 #ifdef HAVE_CONFIG_H
     29 #include "config.h"
     30 #endif
     31 
     32 #include "main_FLP.h"
     33 #include "tuning_parameters.h"
     34 
     35 void silk_find_LTP_FLP(
     36     silk_float                      b[ MAX_NB_SUBFR * LTP_ORDER ],      /* O    LTP coefs                                   */
     37     silk_float                      WLTP[ MAX_NB_SUBFR * LTP_ORDER * LTP_ORDER ], /* O    Weight for LTP quantization       */
     38     silk_float                      *LTPredCodGain,                     /* O    LTP coding gain                             */
     39     const silk_float                r_lpc[],                            /* I    LPC residual                                */
     40     const opus_int                  lag[  MAX_NB_SUBFR ],               /* I    LTP lags                                    */
     41     const silk_float                Wght[ MAX_NB_SUBFR ],               /* I    Weights                                     */
     42     const opus_int                  subfr_length,                       /* I    Subframe length                             */
     43     const opus_int                  nb_subfr,                           /* I    number of subframes                         */
     44     const opus_int                  mem_offset                          /* I    Number of samples in LTP memory             */
     45 )
     46 {
     47     opus_int   i, k;
     48     silk_float *b_ptr, temp, *WLTP_ptr;
     49     silk_float LPC_res_nrg, LPC_LTP_res_nrg;
     50     silk_float d[ MAX_NB_SUBFR ], m, g, delta_b[ LTP_ORDER ];
     51     silk_float w[ MAX_NB_SUBFR ], nrg[ MAX_NB_SUBFR ], regu;
     52     silk_float Rr[ LTP_ORDER ], rr[ MAX_NB_SUBFR ];
     53     const silk_float *r_ptr, *lag_ptr;
     54 
     55     b_ptr    = b;
     56     WLTP_ptr = WLTP;
     57     r_ptr    = &r_lpc[ mem_offset ];
     58     for( k = 0; k < nb_subfr; k++ ) {
     59         lag_ptr = r_ptr - ( lag[ k ] + LTP_ORDER / 2 );
     60 
     61         silk_corrMatrix_FLP( lag_ptr, subfr_length, LTP_ORDER, WLTP_ptr );
     62         silk_corrVector_FLP( lag_ptr, r_ptr, subfr_length, LTP_ORDER, Rr );
     63 
     64         rr[ k ] = ( silk_float )silk_energy_FLP( r_ptr, subfr_length );
     65         regu = 1.0f + rr[ k ] +
     66             matrix_ptr( WLTP_ptr, 0, 0, LTP_ORDER ) +
     67             matrix_ptr( WLTP_ptr, LTP_ORDER-1, LTP_ORDER-1, LTP_ORDER );
     68         regu *= LTP_DAMPING / 3;
     69         silk_regularize_correlations_FLP( WLTP_ptr, &rr[ k ], regu, LTP_ORDER );
     70         silk_solve_LDL_FLP( WLTP_ptr, LTP_ORDER, Rr, b_ptr );
     71 
     72         /* Calculate residual energy */
     73         nrg[ k ] = silk_residual_energy_covar_FLP( b_ptr, WLTP_ptr, Rr, rr[ k ], LTP_ORDER );
     74 
     75         temp = Wght[ k ] / ( nrg[ k ] * Wght[ k ] + 0.01f * subfr_length );
     76         silk_scale_vector_FLP( WLTP_ptr, temp, LTP_ORDER * LTP_ORDER );
     77         w[ k ] = matrix_ptr( WLTP_ptr, LTP_ORDER / 2, LTP_ORDER / 2, LTP_ORDER );
     78 
     79         r_ptr    += subfr_length;
     80         b_ptr    += LTP_ORDER;
     81         WLTP_ptr += LTP_ORDER * LTP_ORDER;
     82     }
     83 
     84     /* Compute LTP coding gain */
     85     if( LTPredCodGain != NULL ) {
     86         LPC_LTP_res_nrg = 1e-6f;
     87         LPC_res_nrg     = 0.0f;
     88         for( k = 0; k < nb_subfr; k++ ) {
     89             LPC_res_nrg     += rr[  k ] * Wght[ k ];
     90             LPC_LTP_res_nrg += nrg[ k ] * Wght[ k ];
     91         }
     92 
     93         silk_assert( LPC_LTP_res_nrg > 0 );
     94         *LTPredCodGain = 3.0f * silk_log2( LPC_res_nrg / LPC_LTP_res_nrg );
     95     }
     96 
     97     /* Smoothing */
     98     /* d = sum( B, 1 ); */
     99     b_ptr = b;
    100     for( k = 0; k < nb_subfr; k++ ) {
    101         d[ k ] = 0;
    102         for( i = 0; i < LTP_ORDER; i++ ) {
    103             d[ k ] += b_ptr[ i ];
    104         }
    105         b_ptr += LTP_ORDER;
    106     }
    107     /* m = ( w * d' ) / ( sum( w ) + 1e-3 ); */
    108     temp = 1e-3f;
    109     for( k = 0; k < nb_subfr; k++ ) {
    110         temp += w[ k ];
    111     }
    112     m = 0;
    113     for( k = 0; k < nb_subfr; k++ ) {
    114         m += d[ k ] * w[ k ];
    115     }
    116     m = m / temp;
    117 
    118     b_ptr = b;
    119     for( k = 0; k < nb_subfr; k++ ) {
    120         g = LTP_SMOOTHING / ( LTP_SMOOTHING + w[ k ] ) * ( m - d[ k ] );
    121         temp = 0;
    122         for( i = 0; i < LTP_ORDER; i++ ) {
    123             delta_b[ i ] = silk_max_float( b_ptr[ i ], 0.1f );
    124             temp += delta_b[ i ];
    125         }
    126         temp = g / temp;
    127         for( i = 0; i < LTP_ORDER; i++ ) {
    128             b_ptr[ i ] = b_ptr[ i ] + delta_b[ i ] * temp;
    129         }
    130         b_ptr += LTP_ORDER;
    131     }
    132 }
    133