burg_modified_FLP.c (7955B)
1 /*********************************************************************** 2 Copyright (c) 2006-2011, Skype Limited. All rights reserved. 3 Redistribution and use in source and binary forms, with or without 4 modification, are permitted provided that the following conditions 5 are met: 6 - Redistributions of source code must retain the above copyright notice, 7 this list of conditions and the following disclaimer. 8 - Redistributions in binary form must reproduce the above copyright 9 notice, this list of conditions and the following disclaimer in the 10 documentation and/or other materials provided with the distribution. 11 - Neither the name of Internet Society, IETF or IETF Trust, nor the 12 names of specific contributors, may be used to endorse or promote 13 products derived from this software without specific prior written 14 permission. 15 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 16 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 19 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 20 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 21 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 22 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 23 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 24 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 25 POSSIBILITY OF SUCH DAMAGE. 26 ***********************************************************************/ 27 28 #ifdef HAVE_CONFIG_H 29 #include "config.h" 30 #endif 31 32 #include "SigProc_FLP.h" 33 #include "tuning_parameters.h" 34 #include "define.h" 35 36 #define MAX_FRAME_SIZE 384 /* subfr_length * nb_subfr = ( 0.005 * 16000 + 16 ) * 4 = 384*/ 37 38 /* Compute reflection coefficients from input signal */ 39 silk_float silk_burg_modified_FLP( /* O returns residual energy */ 40 silk_float A[], /* O prediction coefficients (length order) */ 41 const silk_float x[], /* I input signal, length: nb_subfr*(D+L_sub) */ 42 const silk_float minInvGain, /* I minimum inverse prediction gain */ 43 const opus_int subfr_length, /* I input signal subframe length (incl. D preceding samples) */ 44 const opus_int nb_subfr, /* I number of subframes stacked in x */ 45 const opus_int D, /* I order */ 46 int arch 47 ) 48 { 49 opus_int k, n, s, reached_max_gain; 50 double C0, invGain, num, nrg_f, nrg_b, rc, Atmp, tmp1, tmp2; 51 const silk_float *x_ptr; 52 double C_first_row[ SILK_MAX_ORDER_LPC ], C_last_row[ SILK_MAX_ORDER_LPC ]; 53 double CAf[ SILK_MAX_ORDER_LPC + 1 ], CAb[ SILK_MAX_ORDER_LPC + 1 ]; 54 double Af[ SILK_MAX_ORDER_LPC ]; 55 56 celt_assert( subfr_length * nb_subfr <= MAX_FRAME_SIZE ); 57 58 /* Compute autocorrelations, added over subframes */ 59 C0 = silk_energy_FLP( x, nb_subfr * subfr_length ); 60 silk_memset( C_first_row, 0, SILK_MAX_ORDER_LPC * sizeof( double ) ); 61 for( s = 0; s < nb_subfr; s++ ) { 62 x_ptr = x + s * subfr_length; 63 for( n = 1; n < D + 1; n++ ) { 64 C_first_row[ n - 1 ] += silk_inner_product_FLP( x_ptr, x_ptr + n, subfr_length - n, arch ); 65 } 66 } 67 silk_memcpy( C_last_row, C_first_row, SILK_MAX_ORDER_LPC * sizeof( double ) ); 68 69 /* Initialize */ 70 CAb[ 0 ] = CAf[ 0 ] = C0 + FIND_LPC_COND_FAC * C0 + 1e-9f; 71 invGain = 1.0f; 72 reached_max_gain = 0; 73 for( n = 0; n < D; n++ ) { 74 /* Update first row of correlation matrix (without first element) */ 75 /* Update last row of correlation matrix (without last element, stored in reversed order) */ 76 /* Update C * Af */ 77 /* Update C * flipud(Af) (stored in reversed order) */ 78 for( s = 0; s < nb_subfr; s++ ) { 79 x_ptr = x + s * subfr_length; 80 tmp1 = x_ptr[ n ]; 81 tmp2 = x_ptr[ subfr_length - n - 1 ]; 82 for( k = 0; k < n; k++ ) { 83 C_first_row[ k ] -= x_ptr[ n ] * x_ptr[ n - k - 1 ]; 84 C_last_row[ k ] -= x_ptr[ subfr_length - n - 1 ] * x_ptr[ subfr_length - n + k ]; 85 Atmp = Af[ k ]; 86 tmp1 += x_ptr[ n - k - 1 ] * Atmp; 87 tmp2 += x_ptr[ subfr_length - n + k ] * Atmp; 88 } 89 for( k = 0; k <= n; k++ ) { 90 CAf[ k ] -= tmp1 * x_ptr[ n - k ]; 91 CAb[ k ] -= tmp2 * x_ptr[ subfr_length - n + k - 1 ]; 92 } 93 } 94 tmp1 = C_first_row[ n ]; 95 tmp2 = C_last_row[ n ]; 96 for( k = 0; k < n; k++ ) { 97 Atmp = Af[ k ]; 98 tmp1 += C_last_row[ n - k - 1 ] * Atmp; 99 tmp2 += C_first_row[ n - k - 1 ] * Atmp; 100 } 101 CAf[ n + 1 ] = tmp1; 102 CAb[ n + 1 ] = tmp2; 103 104 /* Calculate nominator and denominator for the next order reflection (parcor) coefficient */ 105 num = CAb[ n + 1 ]; 106 nrg_b = CAb[ 0 ]; 107 nrg_f = CAf[ 0 ]; 108 for( k = 0; k < n; k++ ) { 109 Atmp = Af[ k ]; 110 num += CAb[ n - k ] * Atmp; 111 nrg_b += CAb[ k + 1 ] * Atmp; 112 nrg_f += CAf[ k + 1 ] * Atmp; 113 } 114 silk_assert( nrg_f > 0.0 ); 115 silk_assert( nrg_b > 0.0 ); 116 117 /* Calculate the next order reflection (parcor) coefficient */ 118 rc = -2.0 * num / ( nrg_f + nrg_b ); 119 silk_assert( rc > -1.0 && rc < 1.0 ); 120 121 /* Update inverse prediction gain */ 122 tmp1 = invGain * ( 1.0 - rc * rc ); 123 if( tmp1 <= minInvGain ) { 124 /* Max prediction gain exceeded; set reflection coefficient such that max prediction gain is exactly hit */ 125 rc = sqrt( 1.0 - minInvGain / invGain ); 126 if( num > 0 ) { 127 /* Ensure adjusted reflection coefficients has the original sign */ 128 rc = -rc; 129 } 130 invGain = minInvGain; 131 reached_max_gain = 1; 132 } else { 133 invGain = tmp1; 134 } 135 136 /* Update the AR coefficients */ 137 for( k = 0; k < (n + 1) >> 1; k++ ) { 138 tmp1 = Af[ k ]; 139 tmp2 = Af[ n - k - 1 ]; 140 Af[ k ] = tmp1 + rc * tmp2; 141 Af[ n - k - 1 ] = tmp2 + rc * tmp1; 142 } 143 Af[ n ] = rc; 144 145 if( reached_max_gain ) { 146 /* Reached max prediction gain; set remaining coefficients to zero and exit loop */ 147 for( k = n + 1; k < D; k++ ) { 148 Af[ k ] = 0.0; 149 } 150 break; 151 } 152 153 /* Update C * Af and C * Ab */ 154 for( k = 0; k <= n + 1; k++ ) { 155 tmp1 = CAf[ k ]; 156 CAf[ k ] += rc * CAb[ n - k + 1 ]; 157 CAb[ n - k + 1 ] += rc * tmp1; 158 } 159 } 160 161 if( reached_max_gain ) { 162 /* Convert to silk_float */ 163 for( k = 0; k < D; k++ ) { 164 A[ k ] = (silk_float)( -Af[ k ] ); 165 } 166 /* Subtract energy of preceding samples from C0 */ 167 for( s = 0; s < nb_subfr; s++ ) { 168 C0 -= silk_energy_FLP( x + s * subfr_length, D ); 169 } 170 /* Approximate residual energy */ 171 nrg_f = C0 * invGain; 172 } else { 173 /* Compute residual energy and store coefficients as silk_float */ 174 nrg_f = CAf[ 0 ]; 175 tmp1 = 1.0; 176 for( k = 0; k < D; k++ ) { 177 Atmp = Af[ k ]; 178 nrg_f += CAf[ k + 1 ] * Atmp; 179 tmp1 += Atmp * Atmp; 180 A[ k ] = (silk_float)(-Atmp); 181 } 182 nrg_f -= FIND_LPC_COND_FAC * C0 * tmp1; 183 } 184 185 /* Return residual energy */ 186 return (silk_float)nrg_f; 187 }