opus/silk/float/prefilter_FLP.c

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

#include "main_FLP.h"
#include "tuning_parameters.h"

/*
* Prefilter for finding Quantizer input signal
*/
static OPUS_INLINE void silk_prefilt_FLP(
    silk_prefilter_state_FLP    *P,                 /* I/O state */
    silk_float                  st_res[],           /* I */
    silk_float                  xw[],               /* O */
    silk_float                  *HarmShapeFIR,      /* I */
    silk_float                  Tilt,               /* I */
    silk_float                  LF_MA_shp,          /* I */
    silk_float                  LF_AR_shp,          /* I */
    opus_int                    lag,                /* I */
    opus_int                    length              /* I */
);

static void silk_warped_LPC_analysis_filter_FLP(
          silk_float                 state[],            /* I/O  State [order + 1]                       */
          silk_float                 res[],              /* O    Residual signal [length]                */
    const silk_float                 coef[],             /* I    Coefficients [order]                    */
    const silk_float                 input[],            /* I    Input signal [length]                   */
    const silk_float                 lambda,             /* I    Warping factor                          */
    const opus_int                   length,             /* I    Length of input signal                  */
    const opus_int                   order               /* I    Filter order (even)                     */
)
{
    opus_int     n, i;
    silk_float   acc, tmp1, tmp2;

    /* Order must be even */
    silk_assert( ( order & 1 ) == 0 );

    for( n = 0; n < length; n++ ) {
        /* Output of lowpass section */
        tmp2 = state[ 0 ] + lambda * state[ 1 ];
        state[ 0 ] = input[ n ];
        /* Output of allpass section */
        tmp1 = state[ 1 ] + lambda * ( state[ 2 ] - tmp2 );
        state[ 1 ] = tmp2;
        acc = coef[ 0 ] * tmp2;
        /* Loop over allpass sections */
        for( i = 2; i < order; i += 2 ) {
            /* Output of allpass section */
            tmp2 = state[ i ] + lambda * ( state[ i + 1 ] - tmp1 );
            state[ i ] = tmp1;
            acc += coef[ i - 1 ] * tmp1;
            /* Output of allpass section */
            tmp1 = state[ i + 1 ] + lambda * ( state[ i + 2 ] - tmp2 );
            state[ i + 1 ] = tmp2;
            acc += coef[ i ] * tmp2;
        }
        state[ order ] = tmp1;
        acc += coef[ order - 1 ] * tmp1;
        res[ n ] = input[ n ] - acc;
    }
}

/*
* silk_prefilter. Main prefilter function
*/
void silk_prefilter_FLP(
    silk_encoder_state_FLP          *psEnc,                             /* I/O  Encoder state FLP                           */
    const silk_encoder_control_FLP  *psEncCtrl,                         /* I    Encoder control FLP                         */
    silk_float                      xw[],                               /* O    Weighted signal                             */
    const silk_float                x[]                                 /* I    Speech signal                               */
)
{
    silk_prefilter_state_FLP *P = &psEnc->sPrefilt;
    opus_int   j, k, lag;
    silk_float HarmShapeGain, Tilt, LF_MA_shp, LF_AR_shp;
    silk_float B[ 2 ];
    const silk_float *AR1_shp;
    const silk_float *px;
    silk_float *pxw;
    silk_float HarmShapeFIR[ 3 ];
    silk_float st_res[ MAX_SUB_FRAME_LENGTH + MAX_LPC_ORDER ];

    /* Set up pointers */
    px  = x;
    pxw = xw;
    lag = P->lagPrev;
    for( k = 0; k < psEnc->sCmn.nb_subfr; k++ ) {
        /* Update Variables that change per sub frame */
        if( psEnc->sCmn.indices.signalType == TYPE_VOICED ) {
            lag = psEncCtrl->pitchL[ k ];
        }

        /* Noise shape parameters */
        HarmShapeGain = psEncCtrl->HarmShapeGain[ k ] * ( 1.0f - psEncCtrl->HarmBoost[ k ] );
        HarmShapeFIR[ 0 ] = 0.25f               * HarmShapeGain;
        HarmShapeFIR[ 1 ] = 32767.0f / 65536.0f * HarmShapeGain;
        HarmShapeFIR[ 2 ] = 0.25f               * HarmShapeGain;
        Tilt      =  psEncCtrl->Tilt[ k ];
        LF_MA_shp =  psEncCtrl->LF_MA_shp[ k ];
        LF_AR_shp =  psEncCtrl->LF_AR_shp[ k ];
        AR1_shp   = &psEncCtrl->AR1[ k * MAX_SHAPE_LPC_ORDER ];

        /* Short term FIR filtering */
        silk_warped_LPC_analysis_filter_FLP( P->sAR_shp, st_res, AR1_shp, px,
            (silk_float)psEnc->sCmn.warping_Q16 / 65536.0f, psEnc->sCmn.subfr_length, psEnc->sCmn.shapingLPCOrder );

        /* Reduce (mainly) low frequencies during harmonic emphasis */
        B[ 0 ] =  psEncCtrl->GainsPre[ k ];
        B[ 1 ] = -psEncCtrl->GainsPre[ k ] *
            ( psEncCtrl->HarmBoost[ k ] * HarmShapeGain + INPUT_TILT + psEncCtrl->coding_quality * HIGH_RATE_INPUT_TILT );
        pxw[ 0 ] = B[ 0 ] * st_res[ 0 ] + B[ 1 ] * P->sHarmHP;
        for( j = 1; j < psEnc->sCmn.subfr_length; j++ ) {
            pxw[ j ] = B[ 0 ] * st_res[ j ] + B[ 1 ] * st_res[ j - 1 ];
        }
        P->sHarmHP = st_res[ psEnc->sCmn.subfr_length - 1 ];

        silk_prefilt_FLP( P, pxw, pxw, HarmShapeFIR, Tilt, LF_MA_shp, LF_AR_shp, lag, psEnc->sCmn.subfr_length );

        px  += psEnc->sCmn.subfr_length;
        pxw += psEnc->sCmn.subfr_length;
    }
    P->lagPrev = psEncCtrl->pitchL[ psEnc->sCmn.nb_subfr - 1 ];
}

/*
* Prefilter for finding Quantizer input signal
*/
static OPUS_INLINE void silk_prefilt_FLP(
    silk_prefilter_state_FLP    *P,                 /* I/O state */
    silk_float                  st_res[],           /* I */
    silk_float                  xw[],               /* O */
    silk_float                  *HarmShapeFIR,      /* I */
    silk_float                  Tilt,               /* I */
    silk_float                  LF_MA_shp,          /* I */
    silk_float                  LF_AR_shp,          /* I */
    opus_int                    lag,                /* I */
    opus_int                    length              /* I */
)
{
    opus_int   i;
    opus_int   idx, LTP_shp_buf_idx;
    silk_float n_Tilt, n_LF, n_LTP;
    silk_float sLF_AR_shp, sLF_MA_shp;
    silk_float *LTP_shp_buf;

    /* To speed up use temp variables instead of using the struct */
    LTP_shp_buf     = P->sLTP_shp;
    LTP_shp_buf_idx = P->sLTP_shp_buf_idx;
    sLF_AR_shp      = P->sLF_AR_shp;
    sLF_MA_shp      = P->sLF_MA_shp;

    for( i = 0; i < length; i++ ) {
        if( lag > 0 ) {
            silk_assert( HARM_SHAPE_FIR_TAPS == 3 );
            idx = lag + LTP_shp_buf_idx;
            n_LTP  = LTP_shp_buf[ ( idx - HARM_SHAPE_FIR_TAPS / 2 - 1) & LTP_MASK ] * HarmShapeFIR[ 0 ];
            n_LTP += LTP_shp_buf[ ( idx - HARM_SHAPE_FIR_TAPS / 2    ) & LTP_MASK ] * HarmShapeFIR[ 1 ];
            n_LTP += LTP_shp_buf[ ( idx - HARM_SHAPE_FIR_TAPS / 2 + 1) & LTP_MASK ] * HarmShapeFIR[ 2 ];
        } else {
            n_LTP = 0;
        }

        n_Tilt = sLF_AR_shp * Tilt;
        n_LF   = sLF_AR_shp * LF_AR_shp + sLF_MA_shp * LF_MA_shp;

        sLF_AR_shp = st_res[ i ] - n_Tilt;
        sLF_MA_shp = sLF_AR_shp - n_LF;

        LTP_shp_buf_idx = ( LTP_shp_buf_idx - 1 ) & LTP_MASK;
        LTP_shp_buf[ LTP_shp_buf_idx ] = sLF_MA_shp;

        xw[ i ] = sLF_MA_shp - n_LTP;
    }
    /* Copy temp variable back to state */
    P->sLF_AR_shp       = sLF_AR_shp;
    P->sLF_MA_shp       = sLF_MA_shp;
    P->sLTP_shp_buf_idx = LTP_shp_buf_idx;
}