opus/silk/quant_LTP_gains.c

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#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "main.h"
#include "tuning_parameters.h"

void silk_quant_LTP_gains(
    opus_int16                  B_Q14[ MAX_NB_SUBFR * LTP_ORDER ],          /* I/O  (un)quantized LTP gains         */
    opus_int8                   cbk_index[ MAX_NB_SUBFR ],                  /* O    Codebook Index                  */
    opus_int8                   *periodicity_index,                         /* O    Periodicity Index               */
	opus_int32					*sum_log_gain_Q7,							/* I/O  Cumulative max prediction gain  */
    const opus_int32            W_Q18[ MAX_NB_SUBFR*LTP_ORDER*LTP_ORDER ],  /* I    Error Weights in Q18            */
    opus_int                    mu_Q9,                                      /* I    Mu value (R/D tradeoff)         */
    opus_int                    lowComplexity,                              /* I    Flag for low complexity         */
    const opus_int              nb_subfr                                    /* I    number of subframes             */
)
{
    opus_int             j, k, cbk_size;
    opus_int8            temp_idx[ MAX_NB_SUBFR ];
    const opus_uint8     *cl_ptr_Q5;
    const opus_int8      *cbk_ptr_Q7;
    const opus_uint8     *cbk_gain_ptr_Q7;
    const opus_int16     *b_Q14_ptr;
    const opus_int32     *W_Q18_ptr;
    opus_int32           rate_dist_Q14_subfr, rate_dist_Q14, min_rate_dist_Q14;
	opus_int32           sum_log_gain_tmp_Q7, best_sum_log_gain_Q7, max_gain_Q7, gain_Q7;

    /***************************************************/
    /* iterate over different codebooks with different */
    /* rates/distortions, and choose best */
    /***************************************************/
    min_rate_dist_Q14 = silk_int32_MAX;
    best_sum_log_gain_Q7 = 0;
    for( k = 0; k < 3; k++ ) {
        /* Safety margin for pitch gain control, to take into account factors
           such as state rescaling/rewhitening. */
        opus_int32 gain_safety = SILK_FIX_CONST( 0.4, 7 );

        cl_ptr_Q5  = silk_LTP_gain_BITS_Q5_ptrs[ k ];
        cbk_ptr_Q7 = silk_LTP_vq_ptrs_Q7[        k ];
        cbk_gain_ptr_Q7 = silk_LTP_vq_gain_ptrs_Q7[ k ];
        cbk_size   = silk_LTP_vq_sizes[          k ];

        /* Set up pointer to first subframe */
        W_Q18_ptr = W_Q18;
        b_Q14_ptr = B_Q14;

        rate_dist_Q14 = 0;
		sum_log_gain_tmp_Q7 = *sum_log_gain_Q7;
        for( j = 0; j < nb_subfr; j++ ) {
			max_gain_Q7 = silk_log2lin( ( SILK_FIX_CONST( MAX_SUM_LOG_GAIN_DB / 6.0, 7 ) - sum_log_gain_tmp_Q7 ) 
										+ SILK_FIX_CONST( 7, 7 ) ) - gain_safety;

            silk_VQ_WMat_EC(
                &temp_idx[ j ],         /* O    index of best codebook vector                           */
                &rate_dist_Q14_subfr,   /* O    best weighted quantization error + mu * rate            */
				&gain_Q7,               /* O    sum of absolute LTP coefficients                        */
                b_Q14_ptr,              /* I    input vector to be quantized                            */
                W_Q18_ptr,              /* I    weighting matrix                                        */
                cbk_ptr_Q7,             /* I    codebook                                                */
                cbk_gain_ptr_Q7,        /* I    codebook effective gains                                */
                cl_ptr_Q5,              /* I    code length for each codebook vector                    */
                mu_Q9,                  /* I    tradeoff between weighted error and rate                */
				max_gain_Q7,            /* I    maximum sum of absolute LTP coefficients                */
                cbk_size                /* I    number of vectors in codebook                           */
            );

            rate_dist_Q14 = silk_ADD_POS_SAT32( rate_dist_Q14, rate_dist_Q14_subfr );
            sum_log_gain_tmp_Q7 = silk_max(0, sum_log_gain_tmp_Q7
                                + silk_lin2log( gain_safety + gain_Q7 ) - SILK_FIX_CONST( 7, 7 ));

            b_Q14_ptr += LTP_ORDER;
            W_Q18_ptr += LTP_ORDER * LTP_ORDER;
        }

        /* Avoid never finding a codebook */
        rate_dist_Q14 = silk_min( silk_int32_MAX - 1, rate_dist_Q14 );

        if( rate_dist_Q14 < min_rate_dist_Q14 ) {
            min_rate_dist_Q14 = rate_dist_Q14;
            *periodicity_index = (opus_int8)k;
            silk_memcpy( cbk_index, temp_idx, nb_subfr * sizeof( opus_int8 ) );
			best_sum_log_gain_Q7 = sum_log_gain_tmp_Q7;
        }

        /* Break early in low-complexity mode if rate distortion is below threshold */
        if( lowComplexity && ( rate_dist_Q14 < silk_LTP_gain_middle_avg_RD_Q14 ) ) {
            break;
        }
    }

    cbk_ptr_Q7 = silk_LTP_vq_ptrs_Q7[ *periodicity_index ];
    for( j = 0; j < nb_subfr; j++ ) {
        for( k = 0; k < LTP_ORDER; k++ ) {
            B_Q14[ j * LTP_ORDER + k ] = silk_LSHIFT( cbk_ptr_Q7[ cbk_index[ j ] * LTP_ORDER + k ], 7 );
        }
    }
	*sum_log_gain_Q7 = best_sum_log_gain_Q7;
}