ref: 310af750eb5726b4143a43208f2bc03677c6f5db
dir: /silk/SKP_Silk_find_LTP_FLP.c/
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#include "SKP_Silk_main_FLP.h"
#include "SKP_Silk_tuning_parameters.h"
void SKP_Silk_find_LTP_FLP(
SKP_float b[ MAX_NB_SUBFR * LTP_ORDER ], /* O LTP coefs */
SKP_float WLTP[ MAX_NB_SUBFR * LTP_ORDER * LTP_ORDER ], /* O Weight for LTP quantization */
SKP_float *LTPredCodGain, /* O LTP coding gain */
const SKP_float r_lpc[], /* I LPC residual */
const SKP_int lag[ MAX_NB_SUBFR ], /* I LTP lags */
const SKP_float Wght[ MAX_NB_SUBFR ], /* I Weights */
const SKP_int subfr_length, /* I Subframe length */
const SKP_int nb_subfr, /* I number of subframes */
const SKP_int mem_offset /* I Number of samples in LTP memory */
)
{
SKP_int i, k;
SKP_float *b_ptr, temp, *WLTP_ptr;
SKP_float LPC_res_nrg, LPC_LTP_res_nrg;
SKP_float d[ MAX_NB_SUBFR ], m, g, delta_b[ LTP_ORDER ];
SKP_float w[ MAX_NB_SUBFR ], nrg[ MAX_NB_SUBFR ], regu;
SKP_float Rr[ LTP_ORDER ], rr[ MAX_NB_SUBFR ];
const SKP_float *r_ptr, *lag_ptr;
b_ptr = b;
WLTP_ptr = WLTP;
r_ptr = &r_lpc[ mem_offset ];
for( k = 0; k < nb_subfr; k++ ) {
lag_ptr = r_ptr - ( lag[ k ] + LTP_ORDER / 2 );
SKP_Silk_corrMatrix_FLP( lag_ptr, subfr_length, LTP_ORDER, WLTP_ptr );
SKP_Silk_corrVector_FLP( lag_ptr, r_ptr, subfr_length, LTP_ORDER, Rr );
rr[ k ] = ( SKP_float )SKP_Silk_energy_FLP( r_ptr, subfr_length );
regu = 1.0f + rr[ k ] +
matrix_ptr( WLTP_ptr, 0, 0, LTP_ORDER ) +
matrix_ptr( WLTP_ptr, LTP_ORDER-1, LTP_ORDER-1, LTP_ORDER );
regu *= LTP_DAMPING / 3;
SKP_Silk_regularize_correlations_FLP( WLTP_ptr, &rr[ k ], regu, LTP_ORDER );
SKP_Silk_solve_LDL_FLP( WLTP_ptr, LTP_ORDER, Rr, b_ptr );
/* Calculate residual energy */
nrg[ k ] = SKP_Silk_residual_energy_covar_FLP( b_ptr, WLTP_ptr, Rr, rr[ k ], LTP_ORDER );
temp = Wght[ k ] / ( nrg[ k ] * Wght[ k ] + 0.01f * subfr_length );
SKP_Silk_scale_vector_FLP( WLTP_ptr, temp, LTP_ORDER * LTP_ORDER );
w[ k ] = matrix_ptr( WLTP_ptr, LTP_ORDER / 2, LTP_ORDER / 2, LTP_ORDER );
r_ptr += subfr_length;
b_ptr += LTP_ORDER;
WLTP_ptr += LTP_ORDER * LTP_ORDER;
}
/* Compute LTP coding gain */
if( LTPredCodGain != NULL ) {
LPC_LTP_res_nrg = 1e-6f;
LPC_res_nrg = 0.0f;
for( k = 0; k < nb_subfr; k++ ) {
LPC_res_nrg += rr[ k ] * Wght[ k ];
LPC_LTP_res_nrg += nrg[ k ] * Wght[ k ];
}
SKP_assert( LPC_LTP_res_nrg > 0 );
*LTPredCodGain = 3.0f * SKP_Silk_log2( LPC_res_nrg / LPC_LTP_res_nrg );
}
/* Smoothing */
/* d = sum( B, 1 ); */
b_ptr = b;
for( k = 0; k < nb_subfr; k++ ) {
d[ k ] = 0;
for( i = 0; i < LTP_ORDER; i++ ) {
d[ k ] += b_ptr[ i ];
}
b_ptr += LTP_ORDER;
}
/* m = ( w * d' ) / ( sum( w ) + 1e-3 ); */
temp = 1e-3f;
for( k = 0; k < nb_subfr; k++ ) {
temp += w[ k ];
}
m = 0;
for( k = 0; k < nb_subfr; k++ ) {
m += d[ k ] * w[ k ];
}
m = m / temp;
b_ptr = b;
for( k = 0; k < nb_subfr; k++ ) {
g = LTP_SMOOTHING / ( LTP_SMOOTHING + w[ k ] ) * ( m - d[ k ] );
temp = 0;
for( i = 0; i < LTP_ORDER; i++ ) {
delta_b[ i ] = SKP_max_float( b_ptr[ i ], 0.1f );
temp += delta_b[ i ];
}
temp = g / temp;
for( i = 0; i < LTP_ORDER; i++ ) {
b_ptr[ i ] = b_ptr[ i ] + delta_b[ i ] * temp;
}
b_ptr += LTP_ORDER;
}
}