opus/silk/silk_decode_indices.c

/***********************************************************************
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***********************************************************************/

#include "silk_main.h"

/* Decode side-information parameters from payload */
void silk_decode_indices(
    silk_decoder_state      *psDec,             /* I/O  State                                       */
    ec_dec                      *psRangeDec,        /* I/O  Compressor data structure                   */
    SKP_int                     FrameIndex,         /* I    Frame number                                */
    SKP_int                     decode_LBRR         /* I    Flag indicating LBRR data is being decoded  */
)
{
    SKP_int   i, k, Ix, condCoding;
    SKP_int   decode_absolute_lagIndex, delta_lagIndex;
    SKP_int16 ec_ix[ MAX_LPC_ORDER ];
    SKP_uint8 pred_Q8[ MAX_LPC_ORDER ];

    /* Use conditional coding if previous frame available */
    if( FrameIndex > 0 && ( decode_LBRR == 0 || psDec->LBRR_flags[ FrameIndex - 1 ] == 1 ) ) {
        condCoding = 1;
    } else {
        condCoding = 0;
    }

    /*******************************************/
    /* Decode signal type and quantizer offset */
    /*******************************************/
    if( decode_LBRR || psDec->VAD_flags[ FrameIndex ] ) {
        Ix = ec_dec_icdf( psRangeDec, silk_type_offset_VAD_iCDF, 8 ) + 2;
    } else {
        Ix = ec_dec_icdf( psRangeDec, silk_type_offset_no_VAD_iCDF, 8 );
    }
    psDec->indices.signalType      = (SKP_int8)SKP_RSHIFT( Ix, 1 );
    psDec->indices.quantOffsetType = (SKP_int8)( Ix & 1 );

    /****************/
    /* Decode gains */
    /****************/
    /* First subframe */    
    if( condCoding ) {
        /* Conditional coding */
        psDec->indices.GainsIndices[ 0 ] = (SKP_int8)ec_dec_icdf( psRangeDec, silk_delta_gain_iCDF, 8 );
    } else {
        /* Independent coding, in two stages: MSB bits followed by 3 LSBs */
        psDec->indices.GainsIndices[ 0 ]  = (SKP_int8)SKP_LSHIFT( ec_dec_icdf( psRangeDec, silk_gain_iCDF[ psDec->indices.signalType ], 8 ), 3 );
        psDec->indices.GainsIndices[ 0 ] += (SKP_int8)ec_dec_icdf( psRangeDec, silk_uniform8_iCDF, 8 );
    }

    /* Remaining subframes */
    for( i = 1; i < psDec->nb_subfr; i++ ) {
        psDec->indices.GainsIndices[ i ] = (SKP_int8)ec_dec_icdf( psRangeDec, silk_delta_gain_iCDF, 8 );
    }
        
    /**********************/
    /* Decode LSF Indices */
    /**********************/
    psDec->indices.NLSFIndices[ 0 ] = (SKP_int8)ec_dec_icdf( psRangeDec, &psDec->psNLSF_CB->CB1_iCDF[ ( psDec->indices.signalType >> 1 ) * psDec->psNLSF_CB->nVectors ], 8 );
    silk_NLSF_unpack( ec_ix, pred_Q8, psDec->psNLSF_CB, psDec->indices.NLSFIndices[ 0 ] );
    SKP_assert( psDec->psNLSF_CB->order == psDec->LPC_order );
    for( i = 0; i < psDec->psNLSF_CB->order; i++ ) {
        Ix = ec_dec_icdf( psRangeDec, &psDec->psNLSF_CB->ec_iCDF[ ec_ix[ i ] ], 8 );
        if( Ix == 0 ) {
            Ix -= ec_dec_icdf( psRangeDec, silk_NLSF_EXT_iCDF, 8 );
        } else if( Ix == 2 * NLSF_QUANT_MAX_AMPLITUDE ) {
            Ix += ec_dec_icdf( psRangeDec, silk_NLSF_EXT_iCDF, 8 );
        }
        psDec->indices.NLSFIndices[ i+1 ] = (SKP_int8)( Ix - NLSF_QUANT_MAX_AMPLITUDE );
    }

    /* Decode LSF interpolation factor */
    if( psDec->nb_subfr == MAX_NB_SUBFR ) {
        psDec->indices.NLSFInterpCoef_Q2 = (SKP_int8)ec_dec_icdf( psRangeDec, silk_NLSF_interpolation_factor_iCDF, 8 );
    } else {
        psDec->indices.NLSFInterpCoef_Q2 = 4;
    }
        
    if( psDec->indices.signalType == TYPE_VOICED ) 
    {
        /*********************/
        /* Decode pitch lags */
        /*********************/
        /* Get lag index */
        decode_absolute_lagIndex = 1;
        if( condCoding && psDec->ec_prevSignalType == TYPE_VOICED ) {
            /* Decode Delta index */
            delta_lagIndex = (SKP_int16)ec_dec_icdf( psRangeDec, silk_pitch_delta_iCDF, 8 );
            if( delta_lagIndex > 0 ) {
                delta_lagIndex = delta_lagIndex - 9;
                psDec->indices.lagIndex = (SKP_int16)( psDec->ec_prevLagIndex + delta_lagIndex );
                decode_absolute_lagIndex = 0;
            }
        }
        if( decode_absolute_lagIndex ) {
            /* Absolute decoding */
            psDec->indices.lagIndex  = (SKP_int16)ec_dec_icdf( psRangeDec, silk_pitch_lag_iCDF, 8 ) * SKP_RSHIFT( psDec->fs_kHz, 1 );
            psDec->indices.lagIndex += (SKP_int16)ec_dec_icdf( psRangeDec, psDec->pitch_lag_low_bits_iCDF, 8 );
        }
        psDec->ec_prevLagIndex = psDec->indices.lagIndex;

        /* Get countour index */
        psDec->indices.contourIndex = (SKP_int8)ec_dec_icdf( psRangeDec, psDec->pitch_contour_iCDF, 8 );
            
        /********************/
        /* Decode LTP gains */
        /********************/
        /* Decode PERIndex value */
        psDec->indices.PERIndex = (SKP_int8)ec_dec_icdf( psRangeDec, silk_LTP_per_index_iCDF, 8 );

        for( k = 0; k < psDec->nb_subfr; k++ ) {
            psDec->indices.LTPIndex[ k ] = (SKP_int8)ec_dec_icdf( psRangeDec, silk_LTP_gain_iCDF_ptrs[ psDec->indices.PERIndex ], 8 );
        }

        /**********************/
        /* Decode LTP scaling */
        /**********************/
        if( !condCoding ) {
            psDec->indices.LTP_scaleIndex = (SKP_int8)ec_dec_icdf( psRangeDec, silk_LTPscale_iCDF, 8 );
        } else {
            psDec->indices.LTP_scaleIndex = 0;
        }
    }
    psDec->ec_prevSignalType = psDec->indices.signalType;

    /***************/
    /* Decode seed */
    /***************/
    psDec->indices.Seed = (SKP_int8)ec_dec_icdf( psRangeDec, silk_uniform4_iCDF, 8 );
}