void SKP_Silk_find_pitch_lags_FLP(
SKP_Silk_encoder_state_FLP *psEnc, /* I/O Encoder state FLP */
SKP_Silk_encoder_control_FLP *psEncCtrl, /* I/O Encoder control FLP */
SKP_float res[], /* O Residual */
const SKP_float x[] /* I Speech signal */
)
{
SKP_Silk_predict_state_FLP *psPredSt = &psEnc->sPred;
SKP_int buf_len;
SKP_float thrhld, res_nrg;
const SKP_float *x_buf_ptr, *x_buf;
SKP_float auto_corr[ MAX_FIND_PITCH_LPC_ORDER + 1 ];
SKP_float A[ MAX_FIND_PITCH_LPC_ORDER ];
SKP_float refl_coef[ MAX_FIND_PITCH_LPC_ORDER ];
SKP_float Wsig[ FIND_PITCH_LPC_WIN_MAX ];
SKP_float *Wsig_ptr;
/******************************************/
/* Setup buffer lengths etc based on Fs */
/******************************************/
buf_len = 2 * psEnc->sCmn.frame_length + psEnc->sCmn.la_pitch;
/* Safty check */
SKP_assert( buf_len >= psPredSt->pitch_LPC_win_length );
x_buf = x - psEnc->sCmn.frame_length;
/******************************************/
/* Estimate LPC AR coeficients */
/******************************************/
/* Calculate windowed signal */
/* First LA_LTP samples */
x_buf_ptr = x_buf + buf_len - psPredSt->pitch_LPC_win_length;
Wsig_ptr = Wsig;
SKP_Silk_apply_sine_window_FLP( Wsig_ptr, x_buf_ptr, 1, psEnc->sCmn.la_pitch );
/* Middle non-windowed samples */
Wsig_ptr += psEnc->sCmn.la_pitch;
x_buf_ptr += psEnc->sCmn.la_pitch;
SKP_memcpy( Wsig_ptr, x_buf_ptr, ( psPredSt->pitch_LPC_win_length - ( psEnc->sCmn.la_pitch << 1 ) ) * sizeof( SKP_float ) );
/* Last LA_LTP samples */
Wsig_ptr += psPredSt->pitch_LPC_win_length - ( psEnc->sCmn.la_pitch << 1 );
x_buf_ptr += psPredSt->pitch_LPC_win_length - ( psEnc->sCmn.la_pitch << 1 );
SKP_Silk_apply_sine_window_FLP( Wsig_ptr, x_buf_ptr, 2, psEnc->sCmn.la_pitch );
/* Calculate autocorrelation sequence */
SKP_Silk_autocorrelation_FLP( auto_corr, Wsig, psPredSt->pitch_LPC_win_length, psEnc->sCmn.pitchEstimationLPCOrder + 1 );
/* Add white noise, as a fraction of the energy */
auto_corr[ 0 ] += auto_corr[ 0 ] * FIND_PITCH_WHITE_NOISE_FRACTION;
/* Calculate the reflection coefficients using Schur */
res_nrg = SKP_Silk_schur_FLP( refl_coef, auto_corr, psEnc->sCmn.pitchEstimationLPCOrder );
/* Prediction gain */
psEncCtrl->predGain = auto_corr[ 0 ] / SKP_max_float( res_nrg, 1.0f );
/* Convert reflection coefficients to prediction coefficients */
SKP_Silk_k2a_FLP( A, refl_coef, psEnc->sCmn.pitchEstimationLPCOrder );
/* Bandwidth expansion */
SKP_Silk_bwexpander_FLP( A, psEnc->sCmn.pitchEstimationLPCOrder, FIND_PITCH_BANDWITH_EXPANSION );
/*****************************************/
/* LPC analysis filtering */
/*****************************************/
SKP_Silk_LPC_analysis_filter_FLP( res, A, x_buf, buf_len, psEnc->sCmn.pitchEstimationLPCOrder );
SKP_memset( res, 0, psEnc->sCmn.pitchEstimationLPCOrder * sizeof( SKP_float ) );
/* Threshold for pitch estimator */
thrhld = 0.45f;
thrhld -= 0.004f * psEnc->sCmn.pitchEstimationLPCOrder;
thrhld -= 0.1f * psEnc->speech_activity;
thrhld += 0.15f * psEnc->sCmn.prev_sigtype;
thrhld -= 0.1f * psEncCtrl->input_tilt;
/*****************************************/
/* Call Pitch estimator */
/*****************************************/
psEncCtrl->sCmn.sigtype = SKP_Silk_pitch_analysis_core_FLP( res, psEncCtrl->sCmn.pitchL, &psEncCtrl->sCmn.lagIndex,
&psEncCtrl->sCmn.contourIndex, &psEnc->LTPCorr, psEnc->sCmn.prevLag, psEnc->sCmn.pitchEstimationThreshold_Q16 / 65536.0f,
thrhld, psEnc->sCmn.fs_kHz, psEnc->sCmn.pitchEstimationComplexity );
}
void SKP_Silk_find_LPC_FLP(
SKP_float NLSF[], /* O NLSFs */
SKP_int *interpIndex, /* O NLSF interp. index for NLSF interp. */
const SKP_float prev_NLSFq[], /* I Previous NLSFs, for NLSF interpolation */
const SKP_int useInterpNLSFs, /* I Flag */
const SKP_int LPC_order, /* I LPC order */
const SKP_float x[], /* I Input signal */
const SKP_int subfr_length /* I Subframe length incl preceeding samples */
)
{
SKP_int k;
SKP_float a[ MAX_LPC_ORDER ];
/* Used only for NLSF interpolation */
double res_nrg, res_nrg_2nd, res_nrg_interp;
SKP_float a_tmp[ MAX_LPC_ORDER ], NLSF0[ MAX_LPC_ORDER ];
SKP_float LPC_res[ ( MAX_FRAME_LENGTH + NB_SUBFR * MAX_LPC_ORDER ) / 2 ];
/* Default: No interpolation */
*interpIndex = 4;
/* Burg AR analysis for the full frame */
res_nrg = SKP_Silk_burg_modified_FLP( a, x, subfr_length, NB_SUBFR, FIND_LPC_COND_FAC, LPC_order );
SKP_Silk_bwexpander_FLP( a, LPC_order, FIND_LPC_CHIRP );
if( useInterpNLSFs == 1 ) {
/* 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 -= SKP_Silk_burg_modified_FLP( a_tmp, x + ( NB_SUBFR / 2 ) * subfr_length,
subfr_length, NB_SUBFR / 2, FIND_LPC_COND_FAC, LPC_order );
SKP_Silk_bwexpander_FLP( a_tmp, LPC_order, FIND_LPC_CHIRP );
/* Convert to NLSFs */
SKP_Silk_A2NLSF_FLP( NLSF, a_tmp, LPC_order );
/* Search over interpolation indices to find the one with lowest residual energy */
res_nrg_2nd = SKP_float_MAX;
for( k = 3; k >= 0; k-- ) {
/* Interpolate NLSFs for first half */
SKP_Silk_interpolate_wrapper_FLP( NLSF0, prev_NLSFq, NLSF, 0.25f * k, LPC_order );
/* Convert to LPC for residual energy evaluation */
SKP_Silk_NLSF2A_stable_FLP( a_tmp, NLSF0, LPC_order );
/* Calculate residual energy with LSF interpolation */
SKP_Silk_LPC_analysis_filter_FLP( LPC_res, a_tmp, x, 2 * subfr_length, LPC_order );
res_nrg_interp =
SKP_Silk_energy_FLP( LPC_res + LPC_order, subfr_length - LPC_order ) +
SKP_Silk_energy_FLP( LPC_res + LPC_order + subfr_length, subfr_length - LPC_order );
/* 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;
*interpIndex = 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( *interpIndex == 4 ) {
/* NLSF interpolation is currently inactive, calculate NLSFs from full frame AR coefficients */
SKP_Silk_A2NLSF_FLP( NLSF, a, LPC_order );
}
}
