Пример #1
0
/* Interpolate two vectors */
void silk_interpolate(
    opus_int16                  xi[ MAX_LPC_ORDER ],            /* O    interpolated vector                         */
    const opus_int16            x0[ MAX_LPC_ORDER ],            /* I    first vector                                */
    const opus_int16            x1[ MAX_LPC_ORDER ],            /* I    second vector                               */
    const opus_int              ifact_Q2,                       /* I    interp. factor, weight on 2nd vector        */
    const opus_int              d                               /* I    number of parameters                        */
)
{
    opus_int i;

    silk_assert( ifact_Q2 >= 0 );
    silk_assert( ifact_Q2 <= 4 );

    for( i = 0; i < d; i++ ) {
        xi[ i ] = (opus_int16)silk_ADD_RSHIFT( x0[ i ], silk_SMULBB( x1[ i ] - x0[ i ], ifact_Q2 ), 2 );
    }
}
Пример #2
0
/* Limit, stabilize, convert and quantize NLSFs */
void silk_process_NLSFs(
    silk_encoder_state          *psEncC,                            /* I/O  Encoder state                               */
    opus_int16                  PredCoef_Q12[ 2 ][ MAX_LPC_ORDER ], /* O    Prediction coefficients                     */
    opus_int16                  pNLSF_Q15[         MAX_LPC_ORDER ], /* I/O  Normalized LSFs (quant out) (0 - (2^15-1))  */
    const opus_int16            prev_NLSFq_Q15[    MAX_LPC_ORDER ]  /* I    Previous Normalized LSFs (0 - (2^15-1))     */
)
{
    opus_int     i, doInterpolate;
    opus_int     NLSF_mu_Q20;
    opus_int32   i_sqr_Q15;
    opus_int16   pNLSF0_temp_Q15[ MAX_LPC_ORDER ];
    opus_int16   pNLSFW_QW[ MAX_LPC_ORDER ];
    opus_int16   pNLSFW0_temp_QW[ MAX_LPC_ORDER ];

    silk_assert(psEncC->speech_activity_Q8 >=   0);
    silk_assert(psEncC->speech_activity_Q8 <= SILK_FIX_CONST(1.0, 8));
    silk_assert(psEncC->useInterpolatedNLSFs == 1 || psEncC->indices.NLSFInterpCoef_Q2 == (1 << 2));

    /***********************/
    /* Calculate mu values */
    /***********************/
    /* NLSF_mu  = 0.003 - 0.0015 * psEnc->speech_activity; */
    NLSF_mu_Q20 = silk_SMLAWB(SILK_FIX_CONST(0.003, 20), SILK_FIX_CONST(-0.001, 28), psEncC->speech_activity_Q8);
    if(psEncC->nb_subfr == 2) {
        /* Multiply by 1.5 for 10 ms packets */
        NLSF_mu_Q20 = silk_ADD_RSHIFT(NLSF_mu_Q20, NLSF_mu_Q20, 1);
    }

    silk_assert(NLSF_mu_Q20 >  0);
    silk_assert(NLSF_mu_Q20 <= SILK_FIX_CONST(0.005, 20));

    /* Calculate NLSF weights */
    silk_NLSF_VQ_weights_laroia(pNLSFW_QW, pNLSF_Q15, psEncC->predictLPCOrder);

    /* Update NLSF weights for interpolated NLSFs */
    doInterpolate = (psEncC->useInterpolatedNLSFs == 1) && (psEncC->indices.NLSFInterpCoef_Q2 < 4);
    if(doInterpolate) {
        /* Calculate the interpolated NLSF vector for the first half */
        silk_interpolate(pNLSF0_temp_Q15, prev_NLSFq_Q15, pNLSF_Q15,
            psEncC->indices.NLSFInterpCoef_Q2, psEncC->predictLPCOrder);

        /* Calculate first half NLSF weights for the interpolated NLSFs */
        silk_NLSF_VQ_weights_laroia(pNLSFW0_temp_QW, pNLSF0_temp_Q15, psEncC->predictLPCOrder);

        /* Update NLSF weights with contribution from first half */
        i_sqr_Q15 = silk_LSHIFT(silk_SMULBB(psEncC->indices.NLSFInterpCoef_Q2, psEncC->indices.NLSFInterpCoef_Q2), 11);
        for(i = 0; i < psEncC->predictLPCOrder; i++) {
            pNLSFW_QW[ i ] = silk_SMLAWB(silk_RSHIFT(pNLSFW_QW[ i ], 1), (opus_int32)pNLSFW0_temp_QW[ i ], i_sqr_Q15);
            silk_assert(pNLSFW_QW[ i ] >= 1);
        }
    }

    silk_NLSF_encode(psEncC->indices.NLSFIndices, pNLSF_Q15, psEncC->psNLSF_CB, pNLSFW_QW,
        NLSF_mu_Q20, psEncC->NLSF_MSVQ_Survivors, psEncC->indices.signalType);

    /* Convert quantized NLSFs back to LPC coefficients */
    silk_NLSF2A(PredCoef_Q12[ 1 ], pNLSF_Q15, psEncC->predictLPCOrder);

    if(doInterpolate) {
        /* Calculate the interpolated, quantized LSF vector for the first half */
        silk_interpolate(pNLSF0_temp_Q15, prev_NLSFq_Q15, pNLSF_Q15,
            psEncC->indices.NLSFInterpCoef_Q2, psEncC->predictLPCOrder);

        /* Convert back to LPC coefficients */
        silk_NLSF2A(PredCoef_Q12[ 0 ], pNLSF0_temp_Q15, psEncC->predictLPCOrder);

    } else {
        /* Copy LPC coefficients for first half from second half */
        silk_memcpy(PredCoef_Q12[ 0 ], PredCoef_Q12[ 1 ], psEncC->predictLPCOrder * sizeof(opus_int16));
    }
}
Пример #3
0
/* If not all roots are found, the a_Q16 coefficients are bandwidth expanded until convergence. */
void silk_A2NLSF(
    opus_int16                  *NLSF,              /* O    Normalized Line Spectral Frequencies in Q15 (0..2^15-1) [d] */
    opus_int32                  *a_Q16,             /* I/O  Monic whitening filter coefficients in Q16 [d]              */
    const opus_int              d                   /* I    Filter order (must be even)                                 */
)
{
    opus_int      i, k, m, dd, root_ix, ffrac;
    opus_int32 xlo, xhi, xmid;
    opus_int32 ylo, yhi, ymid, thr;
    opus_int32 nom, den;
    opus_int32 P[ SILK_MAX_ORDER_LPC / 2 + 1 ];
    opus_int32 Q[ SILK_MAX_ORDER_LPC / 2 + 1 ];
    opus_int32 *PQ[ 2 ];
    opus_int32 *p;

    /* Store pointers to array */
    PQ[ 0 ] = P;
    PQ[ 1 ] = Q;

    dd = silk_RSHIFT( d, 1 );

    silk_A2NLSF_init( a_Q16, P, Q, dd );

    /* Find roots, alternating between P and Q */
    p = P;                          /* Pointer to polynomial */

    xlo = silk_LSFCosTab_FIX_Q12[ 0 ]; /* Q12*/
    ylo = silk_A2NLSF_eval_poly( p, xlo, dd );

    if( ylo < 0 ) {
        /* Set the first NLSF to zero and move on to the next */
        NLSF[ 0 ] = 0;
        p = Q;                      /* Pointer to polynomial */
        ylo = silk_A2NLSF_eval_poly( p, xlo, dd );
        root_ix = 1;                /* Index of current root */
    } else {
        root_ix = 0;                /* Index of current root */
    }
    k = 1;                          /* Loop counter */
    i = 0;                          /* Counter for bandwidth expansions applied */
    thr = 0;
    while( 1 ) {
        /* Evaluate polynomial */
        xhi = silk_LSFCosTab_FIX_Q12[ k ]; /* Q12 */
        yhi = silk_A2NLSF_eval_poly( p, xhi, dd );

        /* Detect zero crossing */
        if( ( ylo <= 0 && yhi >= thr ) || ( ylo >= 0 && yhi <= -thr ) ) {
            if( yhi == 0 ) {
                /* If the root lies exactly at the end of the current       */
                /* interval, look for the next root in the next interval    */
                thr = 1;
            } else {
                thr = 0;
            }
            /* Binary division */
            ffrac = -256;
            for( m = 0; m < BIN_DIV_STEPS_A2NLSF_FIX; m++ ) {
                /* Evaluate polynomial */
                xmid = silk_RSHIFT_ROUND( xlo + xhi, 1 );
                ymid = silk_A2NLSF_eval_poly( p, xmid, dd );

                /* Detect zero crossing */
                if( ( ylo <= 0 && ymid >= 0 ) || ( ylo >= 0 && ymid <= 0 ) ) {
                    /* Reduce frequency */
                    xhi = xmid;
                    yhi = ymid;
                } else {
                    /* Increase frequency */
                    xlo = xmid;
                    ylo = ymid;
                    ffrac = silk_ADD_RSHIFT( ffrac, 128, m );
                }
            }

            /* Interpolate */
            if( silk_abs( ylo ) < 65536 ) {
                /* Avoid dividing by zero */
                den = ylo - yhi;
                nom = silk_LSHIFT( ylo, 8 - BIN_DIV_STEPS_A2NLSF_FIX ) + silk_RSHIFT( den, 1 );
                if( den != 0 ) {
                    ffrac += silk_DIV32( nom, den );
                }
            } else {
                /* No risk of dividing by zero because abs(ylo - yhi) >= abs(ylo) >= 65536 */
                ffrac += silk_DIV32( ylo, silk_RSHIFT( ylo - yhi, 8 - BIN_DIV_STEPS_A2NLSF_FIX ) );
            }
            NLSF[ root_ix ] = (opus_int16)silk_min_32( silk_LSHIFT( (opus_int32)k, 8 ) + ffrac, silk_int16_MAX );

            silk_assert( NLSF[ root_ix ] >= 0 );

            root_ix++;        /* Next root */
            if( root_ix >= d ) {
                /* Found all roots */
                break;
            }
            /* Alternate pointer to polynomial */
            p = PQ[ root_ix & 1 ];

            /* Evaluate polynomial */
            xlo = silk_LSFCosTab_FIX_Q12[ k - 1 ]; /* Q12*/
            ylo = silk_LSHIFT( 1 - ( root_ix & 2 ), 12 );
        } else {
            /* Increment loop counter */
            k++;
            xlo = xhi;
            ylo = yhi;
            thr = 0;

            if( k > LSF_COS_TAB_SZ_FIX ) {
                i++;
                if( i > MAX_ITERATIONS_A2NLSF_FIX ) {
                    /* Set NLSFs to white spectrum and exit */
                    NLSF[ 0 ] = (opus_int16)silk_DIV32_16( 1 << 15, d + 1 );
                    for( k = 1; k < d; k++ ) {
                        NLSF[ k ] = (opus_int16)silk_SMULBB( k + 1, NLSF[ 0 ] );
                    }
                    return;
                }

                /* Error: Apply progressively more bandwidth expansion and run again */
                silk_bwexpander_32( a_Q16, d, 65536 - silk_SMULBB( 10 + i, i ) ); /* 10_Q16 = 0.00015*/

                silk_A2NLSF_init( a_Q16, P, Q, dd );
                p = P;                            /* Pointer to polynomial */
                xlo = silk_LSFCosTab_FIX_Q12[ 0 ]; /* Q12*/
                ylo = silk_A2NLSF_eval_poly( p, xlo, dd );
                if( ylo < 0 ) {
                    /* Set the first NLSF to zero and move on to the next */
                    NLSF[ 0 ] = 0;
                    p = Q;                        /* Pointer to polynomial */
                    ylo = silk_A2NLSF_eval_poly( p, xlo, dd );
                    root_ix = 1;                  /* Index of current root */
                } else {
                    root_ix = 0;                  /* Index of current root */
                }
                k = 1;                            /* Reset loop counter */
            }
        }
    }
}