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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
35void 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