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      1 /***********************************************************************
      2 Copyright (c) 2006-2011, Skype Limited. All rights reserved.
      3 Redistribution and use in source and binary forms, with or without
      4 modification, are permitted provided that the following conditions
      5 are met:
      6 - Redistributions of source code must retain the above copyright notice,
      7 this list of conditions and the following disclaimer.
      8 - Redistributions in binary form must reproduce the above copyright
      9 notice, this list of conditions and the following disclaimer in the
     10 documentation and/or other materials provided with the distribution.
     11 - Neither the name of Internet Society, IETF or IETF Trust, nor the
     12 names of specific contributors, may be used to endorse or promote
     13 products derived from this software without specific prior written
     14 permission.
     15 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
     16 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     17 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     18 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
     19 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     20 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     21 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     22 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     23 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     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.h"
     33 #include "stack_alloc.h"
     34 
     35 /* Generates excitation for CNG LPC synthesis */
     36 static inline void silk_CNG_exc(
     37     opus_int32                       residual_Q10[],     /* O    CNG residual signal Q10                     */
     38     opus_int32                       exc_buf_Q14[],      /* I    Random samples buffer Q10                   */
     39     opus_int32                       Gain_Q16,           /* I    Gain to apply                               */
     40     opus_int                         length,             /* I    Length                                      */
     41     opus_int32                       *rand_seed          /* I/O  Seed to random index generator              */
     42 )
     43 {
     44     opus_int32 seed;
     45     opus_int   i, idx, exc_mask;
     46 
     47     exc_mask = CNG_BUF_MASK_MAX;
     48     while( exc_mask > length ) {
     49         exc_mask = silk_RSHIFT( exc_mask, 1 );
     50     }
     51 
     52     seed = *rand_seed;
     53     for( i = 0; i < length; i++ ) {
     54         seed = silk_RAND( seed );
     55         idx = (opus_int)( silk_RSHIFT( seed, 24 ) & exc_mask );
     56         silk_assert( idx >= 0 );
     57         silk_assert( idx <= CNG_BUF_MASK_MAX );
     58         residual_Q10[ i ] = (opus_int16)silk_SAT16( silk_SMULWW( exc_buf_Q14[ idx ], Gain_Q16 >> 4 ) );
     59     }
     60     *rand_seed = seed;
     61 }
     62 
     63 void silk_CNG_Reset(
     64     silk_decoder_state          *psDec                          /* I/O  Decoder state                               */
     65 )
     66 {
     67     opus_int i, NLSF_step_Q15, NLSF_acc_Q15;
     68 
     69     NLSF_step_Q15 = silk_DIV32_16( silk_int16_MAX, psDec->LPC_order + 1 );
     70     NLSF_acc_Q15 = 0;
     71     for( i = 0; i < psDec->LPC_order; i++ ) {
     72         NLSF_acc_Q15 += NLSF_step_Q15;
     73         psDec->sCNG.CNG_smth_NLSF_Q15[ i ] = NLSF_acc_Q15;
     74     }
     75     psDec->sCNG.CNG_smth_Gain_Q16 = 0;
     76     psDec->sCNG.rand_seed = 3176576;
     77 }
     78 
     79 /* Updates CNG estimate, and applies the CNG when packet was lost   */
     80 void silk_CNG(
     81     silk_decoder_state          *psDec,                         /* I/O  Decoder state                               */
     82     silk_decoder_control        *psDecCtrl,                     /* I/O  Decoder control                             */
     83     opus_int16                  frame[],                        /* I/O  Signal                                      */
     84     opus_int                    length                          /* I    Length of residual                          */
     85 )
     86 {
     87     opus_int   i, subfr;
     88     opus_int32 sum_Q6, max_Gain_Q16;
     89     opus_int16 A_Q12[ MAX_LPC_ORDER ];
     90     silk_CNG_struct *psCNG = &psDec->sCNG;
     91     SAVE_STACK;
     92 
     93     if( psDec->fs_kHz != psCNG->fs_kHz ) {
     94         /* Reset state */
     95         silk_CNG_Reset( psDec );
     96 
     97         psCNG->fs_kHz = psDec->fs_kHz;
     98     }
     99     if( psDec->lossCnt == 0 && psDec->prevSignalType == TYPE_NO_VOICE_ACTIVITY ) {
    100         /* Update CNG parameters */
    101 
    102         /* Smoothing of LSF's  */
    103         for( i = 0; i < psDec->LPC_order; i++ ) {
    104             psCNG->CNG_smth_NLSF_Q15[ i ] += silk_SMULWB( (opus_int32)psDec->prevNLSF_Q15[ i ] - (opus_int32)psCNG->CNG_smth_NLSF_Q15[ i ], CNG_NLSF_SMTH_Q16 );
    105         }
    106         /* Find the subframe with the highest gain */
    107         max_Gain_Q16 = 0;
    108         subfr        = 0;
    109         for( i = 0; i < psDec->nb_subfr; i++ ) {
    110             if( psDecCtrl->Gains_Q16[ i ] > max_Gain_Q16 ) {
    111                 max_Gain_Q16 = psDecCtrl->Gains_Q16[ i ];
    112                 subfr        = i;
    113             }
    114         }
    115         /* Update CNG excitation buffer with excitation from this subframe */
    116         silk_memmove( &psCNG->CNG_exc_buf_Q14[ psDec->subfr_length ], psCNG->CNG_exc_buf_Q14, ( psDec->nb_subfr - 1 ) * psDec->subfr_length * sizeof( opus_int32 ) );
    117         silk_memcpy(   psCNG->CNG_exc_buf_Q14, &psDec->exc_Q14[ subfr * psDec->subfr_length ], psDec->subfr_length * sizeof( opus_int32 ) );
    118 
    119         /* Smooth gains */
    120         for( i = 0; i < psDec->nb_subfr; i++ ) {
    121             psCNG->CNG_smth_Gain_Q16 += silk_SMULWB( psDecCtrl->Gains_Q16[ i ] - psCNG->CNG_smth_Gain_Q16, CNG_GAIN_SMTH_Q16 );
    122         }
    123     }
    124 
    125     /* Add CNG when packet is lost or during DTX */
    126     if( psDec->lossCnt ) {
    127         VARDECL( opus_int32, CNG_sig_Q10 );
    128 
    129         ALLOC( CNG_sig_Q10, length + MAX_LPC_ORDER, opus_int32 );
    130 
    131         /* Generate CNG excitation */
    132         silk_CNG_exc( CNG_sig_Q10 + MAX_LPC_ORDER, psCNG->CNG_exc_buf_Q14, psCNG->CNG_smth_Gain_Q16, length, &psCNG->rand_seed );
    133 
    134         /* Convert CNG NLSF to filter representation */
    135         silk_NLSF2A( A_Q12, psCNG->CNG_smth_NLSF_Q15, psDec->LPC_order );
    136 
    137         /* Generate CNG signal, by synthesis filtering */
    138         silk_memcpy( CNG_sig_Q10, psCNG->CNG_synth_state, MAX_LPC_ORDER * sizeof( opus_int32 ) );
    139         for( i = 0; i < length; i++ ) {
    140             silk_assert( psDec->LPC_order == 10 || psDec->LPC_order == 16 );
    141             /* Avoids introducing a bias because silk_SMLAWB() always rounds to -inf */
    142             sum_Q6 = silk_RSHIFT( psDec->LPC_order, 1 );
    143             sum_Q6 = silk_SMLAWB( sum_Q6, CNG_sig_Q10[ MAX_LPC_ORDER + i -  1 ], A_Q12[ 0 ] );
    144             sum_Q6 = silk_SMLAWB( sum_Q6, CNG_sig_Q10[ MAX_LPC_ORDER + i -  2 ], A_Q12[ 1 ] );
    145             sum_Q6 = silk_SMLAWB( sum_Q6, CNG_sig_Q10[ MAX_LPC_ORDER + i -  3 ], A_Q12[ 2 ] );
    146             sum_Q6 = silk_SMLAWB( sum_Q6, CNG_sig_Q10[ MAX_LPC_ORDER + i -  4 ], A_Q12[ 3 ] );
    147             sum_Q6 = silk_SMLAWB( sum_Q6, CNG_sig_Q10[ MAX_LPC_ORDER + i -  5 ], A_Q12[ 4 ] );
    148             sum_Q6 = silk_SMLAWB( sum_Q6, CNG_sig_Q10[ MAX_LPC_ORDER + i -  6 ], A_Q12[ 5 ] );
    149             sum_Q6 = silk_SMLAWB( sum_Q6, CNG_sig_Q10[ MAX_LPC_ORDER + i -  7 ], A_Q12[ 6 ] );
    150             sum_Q6 = silk_SMLAWB( sum_Q6, CNG_sig_Q10[ MAX_LPC_ORDER + i -  8 ], A_Q12[ 7 ] );
    151             sum_Q6 = silk_SMLAWB( sum_Q6, CNG_sig_Q10[ MAX_LPC_ORDER + i -  9 ], A_Q12[ 8 ] );
    152             sum_Q6 = silk_SMLAWB( sum_Q6, CNG_sig_Q10[ MAX_LPC_ORDER + i - 10 ], A_Q12[ 9 ] );
    153             if( psDec->LPC_order == 16 ) {
    154                 sum_Q6 = silk_SMLAWB( sum_Q6, CNG_sig_Q10[ MAX_LPC_ORDER + i - 11 ], A_Q12[ 10 ] );
    155                 sum_Q6 = silk_SMLAWB( sum_Q6, CNG_sig_Q10[ MAX_LPC_ORDER + i - 12 ], A_Q12[ 11 ] );
    156                 sum_Q6 = silk_SMLAWB( sum_Q6, CNG_sig_Q10[ MAX_LPC_ORDER + i - 13 ], A_Q12[ 12 ] );
    157                 sum_Q6 = silk_SMLAWB( sum_Q6, CNG_sig_Q10[ MAX_LPC_ORDER + i - 14 ], A_Q12[ 13 ] );
    158                 sum_Q6 = silk_SMLAWB( sum_Q6, CNG_sig_Q10[ MAX_LPC_ORDER + i - 15 ], A_Q12[ 14 ] );
    159                 sum_Q6 = silk_SMLAWB( sum_Q6, CNG_sig_Q10[ MAX_LPC_ORDER + i - 16 ], A_Q12[ 15 ] );
    160             }
    161 
    162             /* Update states */
    163             CNG_sig_Q10[ MAX_LPC_ORDER + i ] = silk_ADD_LSHIFT( CNG_sig_Q10[ MAX_LPC_ORDER + i ], sum_Q6, 4 );
    164 
    165             frame[ i ] = silk_ADD_SAT16( frame[ i ], silk_RSHIFT_ROUND( sum_Q6, 6 ) );
    166         }
    167         silk_memcpy( psCNG->CNG_synth_state, &CNG_sig_Q10[ length ], MAX_LPC_ORDER * sizeof( opus_int32 ) );
    168     } else {
    169         silk_memset( psCNG->CNG_synth_state, 0, psDec->LPC_order *  sizeof( opus_int32 ) );
    170     }
    171     RESTORE_STACK;
    172 }
    173