/* Find pitch lags */ void SKP_Silk_find_pitch_lags_FIX( SKP_Silk_encoder_state_FIX *psEnc, /* I/O encoder state */ SKP_Silk_encoder_control_FIX *psEncCtrl, /* I/O encoder control */ SKP_int16 res[], /* O residual */ const SKP_int16 x[] /* I Speech signal */ ) { SKP_int buf_len, i, scale; SKP_int32 thrhld_Q15, res_nrg; const SKP_int16 *x_buf, *x_buf_ptr; SKP_int16 Wsig[ FIND_PITCH_LPC_WIN_MAX ], *Wsig_ptr; SKP_int32 auto_corr[ MAX_FIND_PITCH_LPC_ORDER + 1 ]; SKP_int16 rc_Q15[ MAX_FIND_PITCH_LPC_ORDER ]; SKP_int32 A_Q24[ MAX_FIND_PITCH_LPC_ORDER ]; SKP_int16 A_Q12[ MAX_FIND_PITCH_LPC_ORDER ]; /******************************************/ /* Setup buffer lengths etc based on Fs */ /******************************************/ buf_len = psEnc->sCmn.la_pitch + psEnc->sCmn.frame_length + psEnc->sCmn.ltp_mem_length; /* Safty check */ SKP_assert( buf_len >= psEnc->sCmn.pitch_LPC_win_length ); x_buf = x - psEnc->sCmn.ltp_mem_length; /*************************************/ /* Estimate LPC AR coefficients */ /*************************************/ /* Calculate windowed signal */ /* First LA_LTP samples */ x_buf_ptr = x_buf + buf_len - psEnc->sCmn.pitch_LPC_win_length; Wsig_ptr = Wsig; SKP_Silk_apply_sine_window( Wsig_ptr, x_buf_ptr, 1, psEnc->sCmn.la_pitch ); /* Middle un - windowed samples */ Wsig_ptr += psEnc->sCmn.la_pitch; x_buf_ptr += psEnc->sCmn.la_pitch; SKP_memcpy( Wsig_ptr, x_buf_ptr, ( psEnc->sCmn.pitch_LPC_win_length - SKP_LSHIFT( psEnc->sCmn.la_pitch, 1 ) ) * sizeof( SKP_int16 ) ); /* Last LA_LTP samples */ Wsig_ptr += psEnc->sCmn.pitch_LPC_win_length - SKP_LSHIFT( psEnc->sCmn.la_pitch, 1 ); x_buf_ptr += psEnc->sCmn.pitch_LPC_win_length - SKP_LSHIFT( psEnc->sCmn.la_pitch, 1 ); SKP_Silk_apply_sine_window( Wsig_ptr, x_buf_ptr, 2, psEnc->sCmn.la_pitch ); /* Calculate autocorrelation sequence */ SKP_Silk_autocorr( auto_corr, &scale, Wsig, psEnc->sCmn.pitch_LPC_win_length, psEnc->sCmn.pitchEstimationLPCOrder + 1 ); /* Add white noise, as fraction of energy */ auto_corr[ 0 ] = SKP_SMLAWB( auto_corr[ 0 ], auto_corr[ 0 ], SKP_FIX_CONST( FIND_PITCH_WHITE_NOISE_FRACTION, 16 ) ) + 1; /* Calculate the reflection coefficients using schur */ res_nrg = SKP_Silk_schur( rc_Q15, auto_corr, psEnc->sCmn.pitchEstimationLPCOrder ); /* Prediction gain */ psEncCtrl->predGain_Q16 = SKP_DIV32_varQ( auto_corr[ 0 ], SKP_max_int( res_nrg, 1 ), 16 ); /* Convert reflection coefficients to prediction coefficients */ SKP_Silk_k2a( A_Q24, rc_Q15, psEnc->sCmn.pitchEstimationLPCOrder ); /* Convert From 32 bit Q24 to 16 bit Q12 coefs */ for( i = 0; i < psEnc->sCmn.pitchEstimationLPCOrder; i++ ) { A_Q12[ i ] = ( SKP_int16 )SKP_SAT16( SKP_RSHIFT( A_Q24[ i ], 12 ) ); } /* Do BWE */ SKP_Silk_bwexpander( A_Q12, psEnc->sCmn.pitchEstimationLPCOrder, SKP_FIX_CONST( FIND_PITCH_BANDWITH_EXPANSION, 16 ) ); /*****************************************/ /* LPC analysis filtering */ /*****************************************/ SKP_Silk_LPC_analysis_filter( res, x_buf, A_Q12, buf_len, psEnc->sCmn.pitchEstimationLPCOrder ); if( psEnc->sCmn.indices.signalType != TYPE_NO_VOICE_ACTIVITY && psEnc->sCmn.first_frame_after_reset == 0 ) { /* Threshold for pitch estimator */ thrhld_Q15 = SKP_FIX_CONST( 0.6, 15 ); thrhld_Q15 = SKP_SMLABB( thrhld_Q15, SKP_FIX_CONST( -0.004, 15 ), psEnc->sCmn.pitchEstimationLPCOrder ); thrhld_Q15 = SKP_SMLABB( thrhld_Q15, SKP_FIX_CONST( -0.1, 7 ), psEnc->sCmn.speech_activity_Q8 ); thrhld_Q15 = SKP_SMLABB( thrhld_Q15, SKP_FIX_CONST( -0.15, 15 ), SKP_RSHIFT( psEnc->sCmn.prevSignalType, 1 ) ); thrhld_Q15 = SKP_SMLAWB( thrhld_Q15, SKP_FIX_CONST( -0.1, 16 ), psEnc->sCmn.input_tilt_Q15 ); thrhld_Q15 = SKP_SAT16( thrhld_Q15 ); /*****************************************/ /* Call pitch estimator */ /*****************************************/ if( SKP_Silk_pitch_analysis_core( res, psEncCtrl->pitchL, &psEnc->sCmn.indices.lagIndex, &psEnc->sCmn.indices.contourIndex, &psEnc->LTPCorr_Q15, psEnc->sCmn.prevLag, psEnc->sCmn.pitchEstimationThreshold_Q16, ( SKP_int16 )thrhld_Q15, psEnc->sCmn.fs_kHz, psEnc->sCmn.pitchEstimationComplexity, psEnc->sCmn.nb_subfr ) == 0 ) { psEnc->sCmn.indices.signalType = TYPE_VOICED; } else { psEnc->sCmn.indices.signalType = TYPE_UNVOICED; } } else { SKP_memset( psEncCtrl->pitchL, 0, sizeof( psEncCtrl->pitchL ) ); psEnc->sCmn.indices.lagIndex = 0; psEnc->sCmn.indices.contourIndex = 0; psEnc->LTPCorr_Q15 = 0; } }
/* Finds LPC vector from correlations, and converts to NLSF */ void SKP_Silk_find_LPC_FIX( SKP_int NLSF_Q15[], /* O NLSFs */ SKP_int *interpIndex, /* O NLSF interpolation index, only used for NLSF interpolation */ const SKP_int prev_NLSFq_Q15[], /* I previous NLSFs, only used for NLSF interpolation */ const SKP_int useInterpolatedNLSFs, /* I Flag */ const SKP_int LPC_order, /* I LPC order */ const SKP_int16 x[], /* I Input signal */ const SKP_int subfr_length /* I Input signal subframe length including preceeding samples */ ) { SKP_int k; SKP_int32 a_Q16[ MAX_LPC_ORDER ]; SKP_int isInterpLower, shift; SKP_int16 S[ MAX_LPC_ORDER ]; SKP_int32 res_nrg0, res_nrg1; SKP_int rshift0, rshift1; /* Used only for LSF interpolation */ SKP_int32 a_tmp_Q16[ MAX_LPC_ORDER ], res_nrg_interp, res_nrg, res_tmp_nrg; SKP_int res_nrg_interp_Q, res_nrg_Q, res_tmp_nrg_Q; SKP_int16 a_tmp_Q12[ MAX_LPC_ORDER ]; SKP_int NLSF0_Q15[ MAX_LPC_ORDER ]; SKP_int16 LPC_res[ ( MAX_FRAME_LENGTH + NB_SUBFR * MAX_LPC_ORDER ) / 2 ]; /* Default: no interpolation */ *interpIndex = 4; /* Burg AR analysis for the full frame */ SKP_Silk_burg_modified( &res_nrg, &res_nrg_Q, a_Q16, x, subfr_length, NB_SUBFR, SKP_FIX_CONST( FIND_LPC_COND_FAC, 32 ), LPC_order ); SKP_Silk_bwexpander_32( a_Q16, LPC_order, SKP_FIX_CONST( FIND_LPC_CHIRP, 16 ) ); if( useInterpolatedNLSFs == 1 ) { /* Optimal solution for last 10 ms */ SKP_Silk_burg_modified( &res_tmp_nrg, &res_tmp_nrg_Q, a_tmp_Q16, x + ( NB_SUBFR >> 1 ) * subfr_length, subfr_length, ( NB_SUBFR >> 1 ), SKP_FIX_CONST( FIND_LPC_COND_FAC, 32 ), LPC_order ); SKP_Silk_bwexpander_32( a_tmp_Q16, LPC_order, SKP_FIX_CONST( FIND_LPC_CHIRP, 16 ) ); /* 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 - SKP_RSHIFT( res_tmp_nrg, shift ); } } else { SKP_assert( shift > -32 ); res_nrg = SKP_RSHIFT( res_nrg, -shift ) - res_tmp_nrg; res_nrg_Q = res_tmp_nrg_Q; } /* Convert to NLSFs */ SKP_Silk_A2NLSF( NLSF_Q15, a_tmp_Q16, LPC_order ); /* Search over interpolation indices to find the one with lowest residual energy */ for( k = 3; k >= 0; k-- ) { /* Interpolate NLSFs for first half */ SKP_Silk_interpolate( NLSF0_Q15, prev_NLSFq_Q15, NLSF_Q15, k, LPC_order ); /* Convert to LPC for residual energy evaluation */ SKP_Silk_NLSF2A_stable( a_tmp_Q12, NLSF0_Q15, LPC_order ); /* Calculate residual energy with NLSF interpolation */ SKP_memset( S, 0, LPC_order * sizeof( SKP_int16 ) ); SKP_Silk_LPC_analysis_filter( x, a_tmp_Q12, S, LPC_res, 2 * subfr_length, LPC_order ); SKP_Silk_sum_sqr_shift( &res_nrg0, &rshift0, LPC_res + LPC_order, subfr_length - LPC_order ); SKP_Silk_sum_sqr_shift( &res_nrg1, &rshift1, LPC_res + LPC_order + subfr_length, subfr_length - LPC_order ); /* Add subframe energies from first half frame */ shift = rshift0 - rshift1; if( shift >= 0 ) { res_nrg1 = SKP_RSHIFT( res_nrg1, shift ); res_nrg_interp_Q = -rshift0; } else { res_nrg0 = SKP_RSHIFT( res_nrg0, -shift ); res_nrg_interp_Q = -rshift1; } res_nrg_interp = SKP_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( SKP_RSHIFT( res_nrg_interp, shift ) < res_nrg ) { isInterpLower = SKP_TRUE; } else { isInterpLower = SKP_FALSE; } } else { if( -shift < 32 ) { if( res_nrg_interp < SKP_RSHIFT( res_nrg, -shift ) ) { isInterpLower = SKP_TRUE; } else { isInterpLower = SKP_FALSE; } } else { isInterpLower = SKP_FALSE; } } /* Determine whether current interpolated NLSFs are best so far */ if( isInterpLower == SKP_TRUE ) { /* Interpolation has lower residual energy */ res_nrg = res_nrg_interp; res_nrg_Q = res_nrg_interp_Q; *interpIndex = k; } } }