/* Convert input to a linear scale */
SKP_int32 silk_log2lin( const SKP_int32 inLog_Q7 ) /* I: Input on log scale */
{
SKP_int32 out, frac_Q7;
if( inLog_Q7 < 0 ) {
return 0;
}
out = SKP_LSHIFT( 1, SKP_RSHIFT( inLog_Q7, 7 ) );
frac_Q7 = inLog_Q7 & 0x7F;
if( inLog_Q7 < 2048 ) {
/* Piece-wise parabolic approximation */
out = SKP_ADD_RSHIFT( out, SKP_MUL( out, SKP_SMLAWB( frac_Q7, SKP_MUL( frac_Q7, 128 - frac_Q7 ), -174 ) ), 7 );
} else {
/* Piece-wise parabolic approximation */
out = SKP_MLA( out, SKP_RSHIFT( out, 7 ), SKP_SMLAWB( frac_Q7, SKP_MUL( frac_Q7, 128 - frac_Q7 ), -174 ) );
}
return out;
}
/* 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 ];
SKP_assert( psEncC->speech_activity_Q8 >= 0 );
SKP_assert( psEncC->speech_activity_Q8 <= SILK_FIX_CONST( 1.0, 8 ) );
/***********************/
/* Calculate mu values */
/***********************/
/* NLSF_mu = 0.003 - 0.0015 * psEnc->speech_activity; */
NLSF_mu_Q20 = SKP_SMLAWB( SILK_FIX_CONST( 0.0025, 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 = SKP_ADD_RSHIFT( NLSF_mu_Q20, NLSF_mu_Q20, 1 );
}
SKP_assert( NLSF_mu_Q20 > 0 );
SKP_assert( NLSF_mu_Q20 <= SILK_FIX_CONST( 0.0045, 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 = SKP_LSHIFT( SKP_SMULBB( psEncC->indices.NLSFInterpCoef_Q2, psEncC->indices.NLSFInterpCoef_Q2 ), 11 );
for( i = 0; i < psEncC->predictLPCOrder; i++ ) {
pNLSFW_QW[ i ] = SKP_SMLAWB( SKP_RSHIFT( pNLSFW_QW[ i ], 1 ), pNLSFW0_temp_QW[ i ], i_sqr_Q15 );
SKP_assert( pNLSFW_QW[ i ] <= SKP_int16_MAX );
SKP_assert( pNLSFW_QW[ i ] >= 1 );
}
}
TIC(NLSF_encode)
silk_NLSF_encode( psEncC->indices.NLSFIndices, pNLSF_Q15, psEncC->psNLSF_CB, pNLSFW_QW,
NLSF_mu_Q20, psEncC->NLSF_MSVQ_Survivors, psEncC->indices.signalType );
TOC(NLSF_encode)
/* 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 */
SKP_memcpy( PredCoef_Q12[ 0 ], PredCoef_Q12[ 1 ], psEncC->predictLPCOrder * sizeof( opus_int16 ) );
}
}
