| /*********************************************************************** |
| Copyright (c) 2006-2011, Skype Limited. All rights reserved. |
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| modification, are permitted provided that the following conditions |
| are met: |
| - Redistributions of source code must retain the above copyright notice, |
| this list of conditions and the following disclaimer. |
| - Redistributions in binary form must reproduce the above copyright |
| notice, this list of conditions and the following disclaimer in the |
| documentation and/or other materials provided with the distribution. |
| - Neither the name of Internet Society, IETF or IETF Trust, nor the |
| names of specific contributors, may be used to endorse or promote |
| products derived from this software without specific prior written |
| permission. |
| THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
| LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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| POSSIBILITY OF SUCH DAMAGE. |
| ***********************************************************************/ |
| |
| #ifdef HAVE_CONFIG_H |
| #include "config.h" |
| #endif |
| |
| #include "SigProc_FLP.h" |
| #include "tuning_parameters.h" |
| #include "define.h" |
| |
| #define MAX_FRAME_SIZE 384 /* subfr_length * nb_subfr = ( 0.005 * 16000 + 16 ) * 4 = 384*/ |
| |
| /* 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 ]; |
| |
| celt_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; |
| } |
