freeswitch/libs/silk/src/SKP_Silk_decode_parameters_v4.c

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#include "SKP_Silk_main.h"

/* Decode parameters from payload */
void SKP_Silk_decode_parameters_v4(
    SKP_Silk_decoder_state      *psDec,                                 /* I/O  State                                    */
    SKP_Silk_decoder_control    *psDecCtrl,                             /* I/O  Decoder control                          */
    SKP_int                     q[ MAX_FRAME_LENGTH ],                  /* O    Excitation signal                        */
    const SKP_int               fullDecoding                            /* I    Flag to tell if only arithmetic decoding */
)
{
    SKP_int   i, k, Ix, nBytesUsed;
    SKP_int   pNLSF_Q15[ MAX_LPC_ORDER ], pNLSF0_Q15[ MAX_LPC_ORDER ];
    const SKP_int16 *cbk_ptr_Q14;
    const SKP_Silk_NLSF_CB_struct *psNLSF_CB = NULL;
    SKP_Silk_range_coder_state  *psRC = &psDec->sRC;
    
    psDec->FrameTermination       = SKP_SILK_MORE_FRAMES;
    psDecCtrl->sigtype            = psDec->sigtype[ psDec->nFramesDecoded ];
    psDecCtrl->QuantOffsetType    = psDec->QuantOffsetType[ psDec->nFramesDecoded ];
    psDec->vadFlag                = psDec->vadFlagBuf[ psDec->nFramesDecoded ];
    psDecCtrl->NLSFInterpCoef_Q2  = psDec->NLSFInterpCoef_Q2[ psDec->nFramesDecoded ];
    psDecCtrl->Seed               = psDec->Seed[ psDec->nFramesDecoded ];

    /* Dequant Gains */
    SKP_Silk_gains_dequant( psDecCtrl->Gains_Q16, psDec->GainsIndices[ psDec->nFramesDecoded ], &psDec->LastGainIndex, psDec->nFramesDecoded );
    /****************/
    /* Decode NLSFs */
    /****************/

    /* Set pointer to NLSF VQ CB for the current signal type */
    psNLSF_CB = psDec->psNLSF_CB[ psDecCtrl->sigtype ];

    /* From the NLSF path, decode an NLSF vector */
    SKP_Silk_NLSF_MSVQ_decode( pNLSF_Q15, psNLSF_CB, psDec->NLSFIndices[ psDec->nFramesDecoded ], psDec->LPC_order );

    /* Convert NLSF parameters to AR prediction filter coefficients */
    SKP_Silk_NLSF2A_stable( psDecCtrl->PredCoef_Q12[ 1 ], pNLSF_Q15, psDec->LPC_order );
    
    /* If just reset, e.g., because internal Fs changed, do not allow interpolation */
    /* improves the case of packet loss in the first frame after a switch           */
    if( psDec->first_frame_after_reset == 1 ) {
        psDecCtrl->NLSFInterpCoef_Q2 = 4;
    }

    if( psDecCtrl->NLSFInterpCoef_Q2 < 4 ) {
        /* Calculation of the interpolated NLSF0 vector from the interpolation factor, */ 
        /* the previous NLSF1, and the current NLSF1                                   */
        for( i = 0; i < psDec->LPC_order; i++ ) {
            pNLSF0_Q15[ i ] = psDec->prevNLSF_Q15[ i ] + SKP_RSHIFT( SKP_MUL( psDecCtrl->NLSFInterpCoef_Q2, 
                ( pNLSF_Q15[ i ] - psDec->prevNLSF_Q15[ i ] ) ), 2 );
        }

        /* Convert NLSF parameters to AR prediction filter coefficients */
        SKP_Silk_NLSF2A_stable( psDecCtrl->PredCoef_Q12[ 0 ], pNLSF0_Q15, psDec->LPC_order );
    } else {
        /* Copy LPC coefficients for first half from second half */
        SKP_memcpy( psDecCtrl->PredCoef_Q12[ 0 ], psDecCtrl->PredCoef_Q12[ 1 ], 
            psDec->LPC_order * sizeof( SKP_int16 ) );
    }

    SKP_memcpy( psDec->prevNLSF_Q15, pNLSF_Q15, psDec->LPC_order * sizeof( SKP_int ) );

    /* After a packet loss do BWE of LPC coefs */
    if( psDec->lossCnt ) {
        SKP_Silk_bwexpander( psDecCtrl->PredCoef_Q12[ 0 ], psDec->LPC_order, BWE_AFTER_LOSS_Q16 );
        SKP_Silk_bwexpander( psDecCtrl->PredCoef_Q12[ 1 ], psDec->LPC_order, BWE_AFTER_LOSS_Q16 );
    }

    if( psDecCtrl->sigtype == SIG_TYPE_VOICED ) {
        /*********************/
        /* Decode pitch lags */
        /*********************/
        
        /* Decode pitch values */
        SKP_Silk_decode_pitch( psDec->lagIndex[ psDec->nFramesDecoded ], 
            psDec->contourIndex[ psDec->nFramesDecoded ], psDecCtrl->pitchL, psDec->fs_kHz );

        /********************/
        /* Decode LTP gains */
        /********************/
        psDecCtrl->PERIndex = psDec->PERIndex[ psDec->nFramesDecoded ];
        
        /* Decode Codebook Index */
        cbk_ptr_Q14 = SKP_Silk_LTP_vq_ptrs_Q14[ psDecCtrl->PERIndex ]; /* set pointer to start of codebook */

        for( k = 0; k < NB_SUBFR; k++ ) {
            Ix = psDec->LTPIndex[ psDec->nFramesDecoded ][ k ];
            for( i = 0; i < LTP_ORDER; i++ ) {
                psDecCtrl->LTPCoef_Q14[ SKP_SMULBB( k, LTP_ORDER ) + i ] = cbk_ptr_Q14[ SKP_SMULBB( Ix, LTP_ORDER ) + i ];
            }
        }

        /**********************/
        /* Decode LTP scaling */
        /**********************/
        Ix = psDec->LTP_scaleIndex[ psDec->nFramesDecoded ];
        psDecCtrl->LTP_scale_Q14 = SKP_Silk_LTPScales_table_Q14[ Ix ];
    } else {
        SKP_memset( psDecCtrl->pitchL,      0, NB_SUBFR * sizeof( SKP_int ) );
        SKP_memset( psDecCtrl->LTPCoef_Q14, 0, NB_SUBFR * LTP_ORDER * sizeof( SKP_int16 ) );
        psDecCtrl->PERIndex      = 0;
        psDecCtrl->LTP_scale_Q14 = 0;
    }

    /*********************************************/
    /* Decode quantization indices of excitation */
    /*********************************************/
    SKP_Silk_decode_pulses( psRC, psDecCtrl, q, psDec->frame_length );

    /****************************************/
    /* get number of bytes used so far      */
    /****************************************/
    SKP_Silk_range_coder_get_length( psRC, &nBytesUsed );
    psDec->nBytesLeft = psRC->bufferLength - nBytesUsed;
    if( psDec->nBytesLeft < 0 ) {
        psRC->error = RANGE_CODER_READ_BEYOND_BUFFER;
    }

    /****************************************/
    /* check remaining bits in last byte    */
    /****************************************/
    if( psDec->nBytesLeft == 0 ) {
        SKP_Silk_range_coder_check_after_decoding( psRC );
    }

    if( psDec->nFramesInPacket == (psDec->nFramesDecoded + 1)) {
        /* To indicate the packet has been fully decoded */
        psDec->FrameTermination = SKP_SILK_LAST_FRAME;
    }
}