/* Calculates correlation matrix X'*X */ void silk_corrMatrix_FLP(const silk_float * x, /* I x vector [ L+order-1 ] used to create X */ const int L, /* I Length of vectors */ const int Order, /* I Max lag for correlation */ silk_float * XX /* O X'*X correlation matrix [order x order] */ ) { int j, lag; double energy; const silk_float *ptr1, *ptr2; ptr1 = &x[Order - 1]; /* First sample of column 0 of X */ energy = silk_energy_FLP(ptr1, L); /* X[:,0]'*X[:,0] */ matrix_ptr(XX, 0, 0, Order) = (silk_float) energy; for (j = 1; j < Order; j++) { /* Calculate X[:,j]'*X[:,j] */ energy += ptr1[-j] * ptr1[-j] - ptr1[L - j] * ptr1[L - j]; matrix_ptr(XX, j, j, Order) = (silk_float) energy; } ptr2 = &x[Order - 2]; /* First sample of column 1 of X */ for (lag = 1; lag < Order; lag++) { /* Calculate X[:,0]'*X[:,lag] */ energy = silk_inner_product_FLP(ptr1, ptr2, L); matrix_ptr(XX, lag, 0, Order) = (silk_float) energy; matrix_ptr(XX, 0, lag, Order) = (silk_float) energy; /* Calculate X[:,j]'*X[:,j + lag] */ for (j = 1; j < (Order - lag); j++) { energy += ptr1[-j] * ptr2[-j] - ptr1[L - j] * ptr2[L - j]; matrix_ptr(XX, lag + j, j, Order) = (silk_float) energy; matrix_ptr(XX, j, lag + j, Order) = (silk_float) energy; } ptr2--; /* Next column of X */ } }
/* compute autocorrelation */ void silk_autocorrelation_FLP( SKP_float *results, /* O result (length correlationCount) */ const SKP_float *inputData, /* I input data to correlate */ SKP_int inputDataSize, /* I length of input */ SKP_int correlationCount /* I number of correlation taps to compute */ ) { SKP_int i; if ( correlationCount > inputDataSize ) { correlationCount = inputDataSize; } for( i = 0; i < correlationCount; i++ ) { results[ i ] = (SKP_float)silk_inner_product_FLP( inputData, inputData + i, inputDataSize - i ); } }
/* Calculates correlation vector X'*t */ void silk_corrVector_FLP(const silk_float * x, /* I x vector [L+order-1] used to create X */ const silk_float * t, /* I Target vector [L] */ const int L, /* I Length of vecors */ const int Order, /* I Max lag for correlation */ silk_float * Xt /* O X'*t correlation vector [order] */ ) { int lag; const silk_float *ptr1; ptr1 = &x[Order - 1]; /* Points to first sample of column 0 of X: X[:,0] */ for (lag = 0; lag < Order; lag++) { /* Calculate X[:,lag]'*t */ Xt[lag] = (silk_float) silk_inner_product_FLP(ptr1, t, L); ptr1--; /* Next column of X */ } }
/* Compute reflection coefficients from input signal */ silk_float silk_burg_modified_FLP( /* O returns residual energy */ silk_float A[], /* O prediction coefficients (length order) */ const silk_float x[], /* I input signal, length: nb_subfr*(D+L_sub) */ const silk_float minInvGain, /* I minimum inverse prediction gain */ const opus_int subfr_length, /* I input signal subframe length (incl. D preceding samples) */ const opus_int nb_subfr, /* I number of subframes stacked in x */ const opus_int D /* I order */ ) { opus_int k, n, s, reached_max_gain; double C0, invGain, num, nrg_f, nrg_b, rc, Atmp, tmp1, tmp2; const silk_float *x_ptr; double C_first_row[ SILK_MAX_ORDER_LPC ], C_last_row[ SILK_MAX_ORDER_LPC ]; double CAf[ SILK_MAX_ORDER_LPC + 1 ], CAb[ SILK_MAX_ORDER_LPC + 1 ]; double Af[ SILK_MAX_ORDER_LPC ]; silk_assert( subfr_length * nb_subfr <= MAX_FRAME_SIZE ); /* Compute autocorrelations, added over subframes */ C0 = silk_energy_FLP( x, nb_subfr * subfr_length ); silk_memset( C_first_row, 0, SILK_MAX_ORDER_LPC * sizeof( double ) ); for( s = 0; s < nb_subfr; s++ ) { x_ptr = x + s * subfr_length; for( n = 1; n < D + 1; n++ ) { C_first_row[ n - 1 ] += silk_inner_product_FLP( x_ptr, x_ptr + n, subfr_length - n ); } } silk_memcpy( C_last_row, C_first_row, SILK_MAX_ORDER_LPC * sizeof( double ) ); /* Initialize */ CAb[ 0 ] = CAf[ 0 ] = C0 + FIND_LPC_COND_FAC * C0 + 1e-9f; invGain = 1.0f; reached_max_gain = 0; for( n = 0; n < D; n++ ) { /* Update first row of correlation matrix (without first element) */ /* Update last row of correlation matrix (without last element, stored in reversed order) */ /* Update C * Af */ /* Update C * flipud(Af) (stored in reversed order) */ for( s = 0; s < nb_subfr; s++ ) { x_ptr = x + s * subfr_length; tmp1 = x_ptr[ n ]; tmp2 = x_ptr[ subfr_length - n - 1 ]; for( k = 0; k < n; k++ ) { C_first_row[ k ] -= x_ptr[ n ] * x_ptr[ n - k - 1 ]; C_last_row[ k ] -= x_ptr[ subfr_length - n - 1 ] * x_ptr[ subfr_length - n + k ]; Atmp = Af[ k ]; tmp1 += x_ptr[ n - k - 1 ] * Atmp; tmp2 += x_ptr[ subfr_length - n + k ] * Atmp; } for( k = 0; k <= n; k++ ) { CAf[ k ] -= tmp1 * x_ptr[ n - k ]; CAb[ k ] -= tmp2 * x_ptr[ subfr_length - n + k - 1 ]; } } tmp1 = C_first_row[ n ]; tmp2 = C_last_row[ n ]; for( k = 0; k < n; k++ ) { Atmp = Af[ k ]; tmp1 += C_last_row[ n - k - 1 ] * Atmp; tmp2 += C_first_row[ n - k - 1 ] * Atmp; } CAf[ n + 1 ] = tmp1; CAb[ n + 1 ] = tmp2; /* Calculate nominator and denominator for the next order reflection (parcor) coefficient */ num = CAb[ n + 1 ]; nrg_b = CAb[ 0 ]; nrg_f = CAf[ 0 ]; for( k = 0; k < n; k++ ) { Atmp = Af[ k ]; num += CAb[ n - k ] * Atmp; nrg_b += CAb[ k + 1 ] * Atmp; nrg_f += CAf[ k + 1 ] * Atmp; } silk_assert( nrg_f > 0.0 ); silk_assert( nrg_b > 0.0 ); /* Calculate the next order reflection (parcor) coefficient */ rc = -2.0 * num / ( nrg_f + nrg_b ); silk_assert( rc > -1.0 && rc < 1.0 ); /* Update inverse prediction gain */ tmp1 = invGain * ( 1.0 - rc * rc ); if( tmp1 <= minInvGain ) { /* Max prediction gain exceeded; set reflection coefficient such that max prediction gain is exactly hit */ rc = sqrt( 1.0 - minInvGain / invGain ); if( num > 0 ) { /* Ensure adjusted reflection coefficients has the original sign */ rc = -rc; } invGain = minInvGain; reached_max_gain = 1; } else { invGain = tmp1; } /* Update the AR coefficients */ for( k = 0; k < (n + 1) >> 1; k++ ) { tmp1 = Af[ k ]; tmp2 = Af[ n - k - 1 ]; Af[ k ] = tmp1 + rc * tmp2; Af[ n - k - 1 ] = tmp2 + rc * tmp1; } Af[ n ] = rc; if( reached_max_gain ) { /* Reached max prediction gain; set remaining coefficients to zero and exit loop */ for( k = n + 1; k < D; k++ ) { Af[ k ] = 0.0; } break; } /* Update C * Af and C * Ab */ for( k = 0; k <= n + 1; k++ ) { tmp1 = CAf[ k ]; CAf[ k ] += rc * CAb[ n - k + 1 ]; CAb[ n - k + 1 ] += rc * tmp1; } } if( reached_max_gain ) { /* Convert to silk_float */ for( k = 0; k < D; k++ ) { A[ k ] = (silk_float)( -Af[ k ] ); } /* Subtract energy of preceding samples from C0 */ for( s = 0; s < nb_subfr; s++ ) { C0 -= silk_energy_FLP( x + s * subfr_length, D ); } /* Approximate residual energy */ nrg_f = C0 * invGain; } else { /* Compute residual energy and store coefficients as silk_float */ nrg_f = CAf[ 0 ]; tmp1 = 1.0; for( k = 0; k < D; k++ ) { Atmp = Af[ k ]; nrg_f += CAf[ k + 1 ] * Atmp; tmp1 += Atmp * Atmp; A[ k ] = (silk_float)(-Atmp); } nrg_f -= FIND_LPC_COND_FAC * C0 * tmp1; } /* Return residual energy */ return (silk_float)nrg_f; }
/* Compute reflection coefficients from input signal */ silk_float silk_burg_modified_FLP( /* O returns residual energy */ silk_float A[], /* O prediction coefficients (length order) */ const silk_float x[], /* I input signal, length: nb_subfr*(D+L_sub) */ const opus_int subfr_length, /* I input signal subframe length (incl. D preceeding samples) */ const opus_int nb_subfr, /* I number of subframes stacked in x */ const silk_float WhiteNoiseFrac, /* I fraction added to zero-lag autocorrelation */ const opus_int D /* I order */ ) { opus_int k, n, s; double C0, num, nrg_f, nrg_b, rc, Atmp, tmp1, tmp2; const silk_float *x_ptr; double C_first_row[ SILK_MAX_ORDER_LPC ], C_last_row[ SILK_MAX_ORDER_LPC ]; double CAf[ SILK_MAX_ORDER_LPC + 1 ], CAb[ SILK_MAX_ORDER_LPC + 1 ]; double Af[ SILK_MAX_ORDER_LPC ]; silk_assert( subfr_length * nb_subfr <= MAX_FRAME_SIZE ); silk_assert( nb_subfr <= MAX_NB_SUBFR ); /* Compute autocorrelations, added over subframes */ C0 = silk_energy_FLP( x, nb_subfr * subfr_length ); silk_memset( C_first_row, 0, SILK_MAX_ORDER_LPC * sizeof( double ) ); for( s = 0; s < nb_subfr; s++ ) { x_ptr = x + s * subfr_length; for( n = 1; n < D + 1; n++ ) { C_first_row[ n - 1 ] += silk_inner_product_FLP( x_ptr, x_ptr + n, subfr_length - n ); } } silk_memcpy( C_last_row, C_first_row, SILK_MAX_ORDER_LPC * sizeof( double ) ); /* Initialize */ CAb[ 0 ] = CAf[ 0 ] = C0 + WhiteNoiseFrac * C0 + 1e-9f; for( n = 0; n < D; n++ ) { /* Update first row of correlation matrix (without first element) */ /* Update last row of correlation matrix (without last element, stored in reversed order) */ /* Update C * Af */ /* Update C * flipud(Af) (stored in reversed order) */ for( s = 0; s < nb_subfr; s++ ) { x_ptr = x + s * subfr_length; tmp1 = x_ptr[ n ]; tmp2 = x_ptr[ subfr_length - n - 1 ]; for( k = 0; k < n; k++ ) { C_first_row[ k ] -= x_ptr[ n ] * x_ptr[ n - k - 1 ]; C_last_row[ k ] -= x_ptr[ subfr_length - n - 1 ] * x_ptr[ subfr_length - n + k ]; Atmp = Af[ k ]; tmp1 += x_ptr[ n - k - 1 ] * Atmp; tmp2 += x_ptr[ subfr_length - n + k ] * Atmp; } for( k = 0; k <= n; k++ ) { CAf[ k ] -= tmp1 * x_ptr[ n - k ]; CAb[ k ] -= tmp2 * x_ptr[ subfr_length - n + k - 1 ]; } } tmp1 = C_first_row[ n ]; tmp2 = C_last_row[ n ]; for( k = 0; k < n; k++ ) { Atmp = Af[ k ]; tmp1 += C_last_row[ n - k - 1 ] * Atmp; tmp2 += C_first_row[ n - k - 1 ] * Atmp; } CAf[ n + 1 ] = tmp1; CAb[ n + 1 ] = tmp2; /* Calculate nominator and denominator for the next order reflection (parcor) coefficient */ num = CAb[ n + 1 ]; nrg_b = CAb[ 0 ]; nrg_f = CAf[ 0 ]; for( k = 0; k < n; k++ ) { Atmp = Af[ k ]; num += CAb[ n - k ] * Atmp; nrg_b += CAb[ k + 1 ] * Atmp; nrg_f += CAf[ k + 1 ] * Atmp; } silk_assert( nrg_f > 0.0 ); silk_assert( nrg_b > 0.0 ); /* Calculate the next order reflection (parcor) coefficient */ rc = -2.0 * num / ( nrg_f + nrg_b ); silk_assert( rc > -1.0 && rc < 1.0 ); /* Update the AR coefficients */ for( k = 0; k < (n + 1) >> 1; k++ ) { tmp1 = Af[ k ]; tmp2 = Af[ n - k - 1 ]; Af[ k ] = tmp1 + rc * tmp2; Af[ n - k - 1 ] = tmp2 + rc * tmp1; } Af[ n ] = rc; /* Update C * Af and C * Ab */ for( k = 0; k <= n + 1; k++ ) { tmp1 = CAf[ k ]; CAf[ k ] += rc * CAb[ n - k + 1 ]; CAb[ n - k + 1 ] += rc * tmp1; } } /* Return residual energy */ nrg_f = CAf[ 0 ]; tmp1 = 1.0; for( k = 0; k < D; k++ ) { Atmp = Af[ k ]; nrg_f += CAf[ k + 1 ] * Atmp; tmp1 += Atmp * Atmp; A[ k ] = (silk_float)(-Atmp); } nrg_f -= WhiteNoiseFrac * C0 * tmp1; return (silk_float)nrg_f; }