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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 OPUS_INLINE void silk_CNG_exc(
     37     opus_int32                       exc_Q14[],          /* O    CNG excitation signal Q10                   */
     38     opus_int32                       exc_buf_Q14[],      /* I    Random samples buffer Q10                   */
     39     opus_int                         length,             /* I    Length                                      */
     40     opus_int32                       *rand_seed          /* I/O  Seed to random index generator              */
     41 )
     42 {
     43     opus_int32 seed;
     44     opus_int   i, idx, exc_mask;
     45 
     46     exc_mask = CNG_BUF_MASK_MAX;
     47     while( exc_mask > length ) {
     48         exc_mask = silk_RSHIFT( exc_mask, 1 );
     49     }
     50 
     51     seed = *rand_seed;
     52     for( i = 0; i < length; i++ ) {
     53         seed = silk_RAND( seed );
     54         idx = (opus_int)( silk_RSHIFT( seed, 24 ) & exc_mask );
     55         silk_assert( idx >= 0 );
     56         silk_assert( idx <= CNG_BUF_MASK_MAX );
     57         exc_Q14[ i ] = exc_buf_Q14[ idx ];
     58     }
     59     *rand_seed = seed;
     60 }
     61 
     62 void silk_CNG_Reset(
     63     silk_decoder_state          *psDec                          /* I/O  Decoder state                               */
     64 )
     65 {
     66     opus_int i, NLSF_step_Q15, NLSF_acc_Q15;
     67 
     68     NLSF_step_Q15 = silk_DIV32_16( silk_int16_MAX, psDec->LPC_order + 1 );
     69     NLSF_acc_Q15 = 0;
     70     for( i = 0; i < psDec->LPC_order; i++ ) {
     71         NLSF_acc_Q15 += NLSF_step_Q15;
     72         psDec->sCNG.CNG_smth_NLSF_Q15[ i ] = NLSF_acc_Q15;
     73     }
     74     psDec->sCNG.CNG_smth_Gain_Q16 = 0;
     75     psDec->sCNG.rand_seed = 3176576;
     76 }
     77 
     78 /* Updates CNG estimate, and applies the CNG when packet was lost   */
     79 void silk_CNG(
     80     silk_decoder_state          *psDec,                         /* I/O  Decoder state                               */
     81     silk_decoder_control        *psDecCtrl,                     /* I/O  Decoder control                             */
     82     opus_int16                  frame[],                        /* I/O  Signal                                      */
     83     opus_int                    length                          /* I    Length of residual                          */
     84 )
     85 {
     86     opus_int   i, subfr;
     87     opus_int32 LPC_pred_Q10, max_Gain_Q16, gain_Q16, gain_Q10;
     88     opus_int16 A_Q12[ MAX_LPC_ORDER ];
     89     silk_CNG_struct *psCNG = &psDec->sCNG;
     90     SAVE_STACK;
     91 
     92     if( psDec->fs_kHz != psCNG->fs_kHz ) {
     93         /* Reset state */
     94         silk_CNG_Reset( psDec );
     95 
     96         psCNG->fs_kHz = psDec->fs_kHz;
     97     }
     98     if( psDec->lossCnt == 0 && psDec->prevSignalType == TYPE_NO_VOICE_ACTIVITY ) {
     99         /* Update CNG parameters */
    100 
    101         /* Smoothing of LSF's  */
    102         for( i = 0; i < psDec->LPC_order; i++ ) {
    103             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 );
    104         }
    105         /* Find the subframe with the highest gain */
    106         max_Gain_Q16 = 0;
    107         subfr        = 0;
    108         for( i = 0; i < psDec->nb_subfr; i++ ) {
    109             if( psDecCtrl->Gains_Q16[ i ] > max_Gain_Q16 ) {
    110                 max_Gain_Q16 = psDecCtrl->Gains_Q16[ i ];
    111                 subfr        = i;
    112             }
    113         }
    114         /* Update CNG excitation buffer with excitation from this subframe */
    115         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 ) );
    116         silk_memcpy(   psCNG->CNG_exc_buf_Q14, &psDec->exc_Q14[ subfr * psDec->subfr_length ], psDec->subfr_length * sizeof( opus_int32 ) );
    117 
    118         /* Smooth gains */
    119         for( i = 0; i < psDec->nb_subfr; i++ ) {
    120             psCNG->CNG_smth_Gain_Q16 += silk_SMULWB( psDecCtrl->Gains_Q16[ i ] - psCNG->CNG_smth_Gain_Q16, CNG_GAIN_SMTH_Q16 );
    121         }
    122     }
    123 
    124     /* Add CNG when packet is lost or during DTX */
    125     if( psDec->lossCnt ) {
    126         VARDECL( opus_int32, CNG_sig_Q14 );
    127         ALLOC( CNG_sig_Q14, length + MAX_LPC_ORDER, opus_int32 );
    128 
    129         /* Generate CNG excitation */
    130         gain_Q16 = silk_SMULWW( psDec->sPLC.randScale_Q14, psDec->sPLC.prevGain_Q16[1] );
    131         if( gain_Q16 >= (1 << 21) || psCNG->CNG_smth_Gain_Q16 > (1 << 23) ) {
    132             gain_Q16 = silk_SMULTT( gain_Q16, gain_Q16 );
    133             gain_Q16 = silk_SUB_LSHIFT32(silk_SMULTT( psCNG->CNG_smth_Gain_Q16, psCNG->CNG_smth_Gain_Q16 ), gain_Q16, 5 );
    134             gain_Q16 = silk_LSHIFT32( silk_SQRT_APPROX( gain_Q16 ), 16 );
    135         } else {
    136             gain_Q16 = silk_SMULWW( gain_Q16, gain_Q16 );
    137             gain_Q16 = silk_SUB_LSHIFT32(silk_SMULWW( psCNG->CNG_smth_Gain_Q16, psCNG->CNG_smth_Gain_Q16 ), gain_Q16, 5 );
    138             gain_Q16 = silk_LSHIFT32( silk_SQRT_APPROX( gain_Q16 ), 8 );
    139         }
    140         gain_Q10 = silk_RSHIFT( gain_Q16, 6 );
    141 
    142         silk_CNG_exc( CNG_sig_Q14 + MAX_LPC_ORDER, psCNG->CNG_exc_buf_Q14, length, &psCNG->rand_seed );
    143 
    144         /* Convert CNG NLSF to filter representation */
    145         silk_NLSF2A( A_Q12, psCNG->CNG_smth_NLSF_Q15, psDec->LPC_order );
    146 
    147         /* Generate CNG signal, by synthesis filtering */
    148         silk_memcpy( CNG_sig_Q14, psCNG->CNG_synth_state, MAX_LPC_ORDER * sizeof( opus_int32 ) );
    149         for( i = 0; i < length; i++ ) {
    150             silk_assert( psDec->LPC_order == 10 || psDec->LPC_order == 16 );
    151             /* Avoids introducing a bias because silk_SMLAWB() always rounds to -inf */
    152             LPC_pred_Q10 = silk_RSHIFT( psDec->LPC_order, 1 );
    153             LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, CNG_sig_Q14[ MAX_LPC_ORDER + i -  1 ], A_Q12[ 0 ] );
    154             LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, CNG_sig_Q14[ MAX_LPC_ORDER + i -  2 ], A_Q12[ 1 ] );
    155             LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, CNG_sig_Q14[ MAX_LPC_ORDER + i -  3 ], A_Q12[ 2 ] );
    156             LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, CNG_sig_Q14[ MAX_LPC_ORDER + i -  4 ], A_Q12[ 3 ] );
    157             LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, CNG_sig_Q14[ MAX_LPC_ORDER + i -  5 ], A_Q12[ 4 ] );
    158             LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, CNG_sig_Q14[ MAX_LPC_ORDER + i -  6 ], A_Q12[ 5 ] );
    159             LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, CNG_sig_Q14[ MAX_LPC_ORDER + i -  7 ], A_Q12[ 6 ] );
    160             LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, CNG_sig_Q14[ MAX_LPC_ORDER + i -  8 ], A_Q12[ 7 ] );
    161             LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, CNG_sig_Q14[ MAX_LPC_ORDER + i -  9 ], A_Q12[ 8 ] );
    162             LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, CNG_sig_Q14[ MAX_LPC_ORDER + i - 10 ], A_Q12[ 9 ] );
    163             if( psDec->LPC_order == 16 ) {
    164                 LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, CNG_sig_Q14[ MAX_LPC_ORDER + i - 11 ], A_Q12[ 10 ] );
    165                 LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, CNG_sig_Q14[ MAX_LPC_ORDER + i - 12 ], A_Q12[ 11 ] );
    166                 LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, CNG_sig_Q14[ MAX_LPC_ORDER + i - 13 ], A_Q12[ 12 ] );
    167                 LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, CNG_sig_Q14[ MAX_LPC_ORDER + i - 14 ], A_Q12[ 13 ] );
    168                 LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, CNG_sig_Q14[ MAX_LPC_ORDER + i - 15 ], A_Q12[ 14 ] );
    169                 LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, CNG_sig_Q14[ MAX_LPC_ORDER + i - 16 ], A_Q12[ 15 ] );
    170             }
    171 
    172             /* Update states */
    173             CNG_sig_Q14[ MAX_LPC_ORDER + i ] = silk_ADD_LSHIFT( CNG_sig_Q14[ MAX_LPC_ORDER + i ], LPC_pred_Q10, 4 );
    174 
    175             /* Scale with Gain and add to input signal */
    176             frame[ i ] = (opus_int16)silk_ADD_SAT16( frame[ i ], silk_SAT16( silk_RSHIFT_ROUND( silk_SMULWW( CNG_sig_Q14[ MAX_LPC_ORDER + i ], gain_Q10 ), 8 ) ) );
    177 
    178         }
    179         silk_memcpy( psCNG->CNG_synth_state, &CNG_sig_Q14[ length ], MAX_LPC_ORDER * sizeof( opus_int32 ) );
    180     } else {
    181         silk_memset( psCNG->CNG_synth_state, 0, psDec->LPC_order *  sizeof( opus_int32 ) );
    182     }
    183     RESTORE_STACK;
    184 }
    185