/* LPC analysis */
void silk_find_LPC_FLP(
silk_encoder_state *psEncC, /* I/O Encoder state */
opus_int16 NLSF_Q15[], /* O NLSFs */
const silk_float x[], /* I Input signal */
const silk_float minInvGain /* I Inverse of max prediction gain */
)
{
opus_int k, subfr_length;
silk_float a[ MAX_LPC_ORDER ];
/* Used only for NLSF interpolation */
silk_float res_nrg, res_nrg_2nd, res_nrg_interp;
opus_int16 NLSF0_Q15[ MAX_LPC_ORDER ];
silk_float a_tmp[ MAX_LPC_ORDER ];
silk_float LPC_res[ MAX_FRAME_LENGTH + MAX_NB_SUBFR * MAX_LPC_ORDER ];
subfr_length = psEncC->subfr_length + psEncC->predictLPCOrder;
/* Default: No interpolation */
psEncC->indices.NLSFInterpCoef_Q2 = 4;
/* Burg AR analysis for the full frame */
res_nrg = silk_burg_modified_FLP( a, x, minInvGain, subfr_length, psEncC->nb_subfr, psEncC->predictLPCOrder );
if( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) {
/* Optimal solution for last 10 ms; subtract residual energy here, as that's easier than */
/* adding it to the residual energy of the first 10 ms in each iteration of the search below */
res_nrg -= silk_burg_modified_FLP( a_tmp, x + ( MAX_NB_SUBFR / 2 ) * subfr_length, minInvGain, subfr_length, MAX_NB_SUBFR / 2, psEncC->predictLPCOrder );
/* Convert to NLSFs */
silk_A2NLSF_FLP( NLSF_Q15, a_tmp, psEncC->predictLPCOrder );
/* Search over interpolation indices to find the one with lowest residual energy */
res_nrg_2nd = silk_float_MAX;
for( k = 3; k >= 0; k-- ) {
/* Interpolate NLSFs for first half */
silk_interpolate( NLSF0_Q15, psEncC->prev_NLSFq_Q15, NLSF_Q15, k, psEncC->predictLPCOrder );
/* Convert to LPC for residual energy evaluation */
silk_NLSF2A_FLP( a_tmp, NLSF0_Q15, psEncC->predictLPCOrder );
/* Calculate residual energy with LSF interpolation */
silk_LPC_analysis_filter_FLP( LPC_res, a_tmp, x, 2 * subfr_length, psEncC->predictLPCOrder );
res_nrg_interp = (silk_float)(
silk_energy_FLP( LPC_res + psEncC->predictLPCOrder, subfr_length - psEncC->predictLPCOrder ) +
silk_energy_FLP( LPC_res + psEncC->predictLPCOrder + subfr_length, subfr_length - psEncC->predictLPCOrder ) );
/* Determine whether current interpolated NLSFs are best so far */
if( res_nrg_interp < res_nrg ) {
/* Interpolation has lower residual energy */
res_nrg = res_nrg_interp;
psEncC->indices.NLSFInterpCoef_Q2 = (opus_int8)k;
} else if( res_nrg_interp > res_nrg_2nd ) {
/* No reason to continue iterating - residual energies will continue to climb */
break;
}
res_nrg_2nd = res_nrg_interp;
}
}
if( psEncC->indices.NLSFInterpCoef_Q2 == 4 ) {
/* NLSF interpolation is currently inactive, calculate NLSFs from full frame AR coefficients */
silk_A2NLSF_FLP( NLSF_Q15, a, psEncC->predictLPCOrder );
}
silk_assert( psEncC->indices.NLSFInterpCoef_Q2 == 4 ||
( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) );
}
/* 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));
}
}
/* Finds LPC vector from correlations, and converts to NLSF */
void silk_find_LPC_FIX(
silk_encoder_state *psEncC, /* I/O Encoder state */
opus_int16 NLSF_Q15[], /* O NLSFs */
const opus_int16 x[], /* I Input signal */
const opus_int32 minInvGain_Q30 /* I Inverse of max prediction gain */
)
{
opus_int k, subfr_length;
opus_int32 a_Q16[ MAX_LPC_ORDER ];
opus_int isInterpLower, shift;
opus_int32 res_nrg0, res_nrg1;
opus_int rshift0, rshift1;
/* Used only for LSF interpolation */
opus_int32 a_tmp_Q16[ MAX_LPC_ORDER ], res_nrg_interp, res_nrg, res_tmp_nrg;
opus_int res_nrg_interp_Q, res_nrg_Q, res_tmp_nrg_Q;
opus_int16 a_tmp_Q12[ MAX_LPC_ORDER ];
opus_int16 NLSF0_Q15[ MAX_LPC_ORDER ];
SAVE_STACK;
subfr_length = psEncC->subfr_length + psEncC->predictLPCOrder;
/* Default: no interpolation */
psEncC->indices.NLSFInterpCoef_Q2 = 4;
/* Burg AR analysis for the full frame */
silk_burg_modified( &res_nrg, &res_nrg_Q, a_Q16, x, minInvGain_Q30, subfr_length, psEncC->nb_subfr, psEncC->predictLPCOrder, psEncC->arch );
if( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) {
VARDECL( opus_int16, LPC_res );
/* Optimal solution for last 10 ms */
silk_burg_modified( &res_tmp_nrg, &res_tmp_nrg_Q, a_tmp_Q16, x + 2 * subfr_length, minInvGain_Q30, subfr_length, 2, psEncC->predictLPCOrder, psEncC->arch );
/* subtract residual energy here, as that's easier than adding it to the */
/* residual energy of the first 10 ms in each iteration of the search below */
shift = res_tmp_nrg_Q - res_nrg_Q;
if( shift >= 0 ) {
if( shift < 32 ) {
res_nrg = res_nrg - silk_RSHIFT( res_tmp_nrg, shift );
}
} else {
silk_assert( shift > -32 );
res_nrg = silk_RSHIFT( res_nrg, -shift ) - res_tmp_nrg;
res_nrg_Q = res_tmp_nrg_Q;
}
/* Convert to NLSFs */
silk_A2NLSF( NLSF_Q15, a_tmp_Q16, psEncC->predictLPCOrder );
ALLOC( LPC_res, 2 * subfr_length, opus_int16 );
/* Search over interpolation indices to find the one with lowest residual energy */
for( k = 3; k >= 0; k-- ) {
/* Interpolate NLSFs for first half */
silk_interpolate( NLSF0_Q15, psEncC->prev_NLSFq_Q15, NLSF_Q15, k, psEncC->predictLPCOrder );
/* Convert to LPC for residual energy evaluation */
silk_NLSF2A( a_tmp_Q12, NLSF0_Q15, psEncC->predictLPCOrder );
/* Calculate residual energy with NLSF interpolation */
silk_LPC_analysis_filter( LPC_res, x, a_tmp_Q12, 2 * subfr_length, psEncC->predictLPCOrder );
silk_sum_sqr_shift( &res_nrg0, &rshift0, LPC_res + psEncC->predictLPCOrder, subfr_length - psEncC->predictLPCOrder );
silk_sum_sqr_shift( &res_nrg1, &rshift1, LPC_res + psEncC->predictLPCOrder + subfr_length, subfr_length - psEncC->predictLPCOrder );
/* Add subframe energies from first half frame */
shift = rshift0 - rshift1;
if( shift >= 0 ) {
res_nrg1 = silk_RSHIFT( res_nrg1, shift );
res_nrg_interp_Q = -rshift0;
} else {
res_nrg0 = silk_RSHIFT( res_nrg0, -shift );
res_nrg_interp_Q = -rshift1;
}
res_nrg_interp = silk_ADD32( res_nrg0, res_nrg1 );
/* Compare with first half energy without NLSF interpolation, or best interpolated value so far */
shift = res_nrg_interp_Q - res_nrg_Q;
if( shift >= 0 ) {
if( silk_RSHIFT( res_nrg_interp, shift ) < res_nrg ) {
isInterpLower = silk_TRUE;
} else {
isInterpLower = silk_FALSE;
}
} else {
if( -shift < 32 ) {
if( res_nrg_interp < silk_RSHIFT( res_nrg, -shift ) ) {
isInterpLower = silk_TRUE;
} else {
isInterpLower = silk_FALSE;
}
} else {
isInterpLower = silk_FALSE;
}
}
/* Determine whether current interpolated NLSFs are best so far */
if( isInterpLower == silk_TRUE ) {
/* Interpolation has lower residual energy */
res_nrg = res_nrg_interp;
res_nrg_Q = res_nrg_interp_Q;
psEncC->indices.NLSFInterpCoef_Q2 = (opus_int8)k;
}
}
}
if( psEncC->indices.NLSFInterpCoef_Q2 == 4 ) {
/* NLSF interpolation is currently inactive, calculate NLSFs from full frame AR coefficients */
silk_A2NLSF( NLSF_Q15, a_Q16, psEncC->predictLPCOrder );
}
silk_assert( psEncC->indices.NLSFInterpCoef_Q2 == 4 || ( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) );
RESTORE_STACK;
}
