Line data Source code
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 0 : 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 : )
47 : {
48 : opus_int k, n, s, reached_max_gain;
49 : double C0, invGain, num, nrg_f, nrg_b, rc, Atmp, tmp1, tmp2;
50 : const silk_float *x_ptr;
51 : double C_first_row[ SILK_MAX_ORDER_LPC ], C_last_row[ SILK_MAX_ORDER_LPC ];
52 : double CAf[ SILK_MAX_ORDER_LPC + 1 ], CAb[ SILK_MAX_ORDER_LPC + 1 ];
53 : double Af[ SILK_MAX_ORDER_LPC ];
54 :
55 0 : silk_assert( subfr_length * nb_subfr <= MAX_FRAME_SIZE );
56 :
57 : /* Compute autocorrelations, added over subframes */
58 0 : C0 = silk_energy_FLP( x, nb_subfr * subfr_length );
59 0 : silk_memset( C_first_row, 0, SILK_MAX_ORDER_LPC * sizeof( double ) );
60 0 : for( s = 0; s < nb_subfr; s++ ) {
61 0 : x_ptr = x + s * subfr_length;
62 0 : for( n = 1; n < D + 1; n++ ) {
63 0 : C_first_row[ n - 1 ] += silk_inner_product_FLP( x_ptr, x_ptr + n, subfr_length - n );
64 : }
65 : }
66 0 : silk_memcpy( C_last_row, C_first_row, SILK_MAX_ORDER_LPC * sizeof( double ) );
67 :
68 : /* Initialize */
69 0 : CAb[ 0 ] = CAf[ 0 ] = C0 + FIND_LPC_COND_FAC * C0 + 1e-9f;
70 0 : invGain = 1.0f;
71 0 : reached_max_gain = 0;
72 0 : for( n = 0; n < D; n++ ) {
73 : /* Update first row of correlation matrix (without first element) */
74 : /* Update last row of correlation matrix (without last element, stored in reversed order) */
75 : /* Update C * Af */
76 : /* Update C * flipud(Af) (stored in reversed order) */
77 0 : for( s = 0; s < nb_subfr; s++ ) {
78 0 : x_ptr = x + s * subfr_length;
79 0 : tmp1 = x_ptr[ n ];
80 0 : tmp2 = x_ptr[ subfr_length - n - 1 ];
81 0 : for( k = 0; k < n; k++ ) {
82 0 : C_first_row[ k ] -= x_ptr[ n ] * x_ptr[ n - k - 1 ];
83 0 : C_last_row[ k ] -= x_ptr[ subfr_length - n - 1 ] * x_ptr[ subfr_length - n + k ];
84 0 : Atmp = Af[ k ];
85 0 : tmp1 += x_ptr[ n - k - 1 ] * Atmp;
86 0 : tmp2 += x_ptr[ subfr_length - n + k ] * Atmp;
87 : }
88 0 : for( k = 0; k <= n; k++ ) {
89 0 : CAf[ k ] -= tmp1 * x_ptr[ n - k ];
90 0 : CAb[ k ] -= tmp2 * x_ptr[ subfr_length - n + k - 1 ];
91 : }
92 : }
93 0 : tmp1 = C_first_row[ n ];
94 0 : tmp2 = C_last_row[ n ];
95 0 : for( k = 0; k < n; k++ ) {
96 0 : Atmp = Af[ k ];
97 0 : tmp1 += C_last_row[ n - k - 1 ] * Atmp;
98 0 : tmp2 += C_first_row[ n - k - 1 ] * Atmp;
99 : }
100 0 : CAf[ n + 1 ] = tmp1;
101 0 : CAb[ n + 1 ] = tmp2;
102 :
103 : /* Calculate nominator and denominator for the next order reflection (parcor) coefficient */
104 0 : num = CAb[ n + 1 ];
105 0 : nrg_b = CAb[ 0 ];
106 0 : nrg_f = CAf[ 0 ];
107 0 : for( k = 0; k < n; k++ ) {
108 0 : Atmp = Af[ k ];
109 0 : num += CAb[ n - k ] * Atmp;
110 0 : nrg_b += CAb[ k + 1 ] * Atmp;
111 0 : nrg_f += CAf[ k + 1 ] * Atmp;
112 : }
113 0 : silk_assert( nrg_f > 0.0 );
114 0 : silk_assert( nrg_b > 0.0 );
115 :
116 : /* Calculate the next order reflection (parcor) coefficient */
117 0 : rc = -2.0 * num / ( nrg_f + nrg_b );
118 0 : silk_assert( rc > -1.0 && rc < 1.0 );
119 :
120 : /* Update inverse prediction gain */
121 0 : tmp1 = invGain * ( 1.0 - rc * rc );
122 0 : if( tmp1 <= minInvGain ) {
123 : /* Max prediction gain exceeded; set reflection coefficient such that max prediction gain is exactly hit */
124 0 : rc = sqrt( 1.0 - minInvGain / invGain );
125 0 : if( num > 0 ) {
126 : /* Ensure adjusted reflection coefficients has the original sign */
127 0 : rc = -rc;
128 : }
129 0 : invGain = minInvGain;
130 0 : reached_max_gain = 1;
131 : } else {
132 0 : invGain = tmp1;
133 : }
134 :
135 : /* Update the AR coefficients */
136 0 : for( k = 0; k < (n + 1) >> 1; k++ ) {
137 0 : tmp1 = Af[ k ];
138 0 : tmp2 = Af[ n - k - 1 ];
139 0 : Af[ k ] = tmp1 + rc * tmp2;
140 0 : Af[ n - k - 1 ] = tmp2 + rc * tmp1;
141 : }
142 0 : Af[ n ] = rc;
143 :
144 0 : if( reached_max_gain ) {
145 : /* Reached max prediction gain; set remaining coefficients to zero and exit loop */
146 0 : for( k = n + 1; k < D; k++ ) {
147 0 : Af[ k ] = 0.0;
148 : }
149 0 : break;
150 : }
151 :
152 : /* Update C * Af and C * Ab */
153 0 : for( k = 0; k <= n + 1; k++ ) {
154 0 : tmp1 = CAf[ k ];
155 0 : CAf[ k ] += rc * CAb[ n - k + 1 ];
156 0 : CAb[ n - k + 1 ] += rc * tmp1;
157 : }
158 : }
159 :
160 0 : if( reached_max_gain ) {
161 : /* Convert to silk_float */
162 0 : for( k = 0; k < D; k++ ) {
163 0 : A[ k ] = (silk_float)( -Af[ k ] );
164 : }
165 : /* Subtract energy of preceding samples from C0 */
166 0 : for( s = 0; s < nb_subfr; s++ ) {
167 0 : C0 -= silk_energy_FLP( x + s * subfr_length, D );
168 : }
169 : /* Approximate residual energy */
170 0 : nrg_f = C0 * invGain;
171 : } else {
172 : /* Compute residual energy and store coefficients as silk_float */
173 0 : nrg_f = CAf[ 0 ];
174 0 : tmp1 = 1.0;
175 0 : for( k = 0; k < D; k++ ) {
176 0 : Atmp = Af[ k ];
177 0 : nrg_f += CAf[ k + 1 ] * Atmp;
178 0 : tmp1 += Atmp * Atmp;
179 0 : A[ k ] = (silk_float)(-Atmp);
180 : }
181 0 : nrg_f -= FIND_LPC_COND_FAC * C0 * tmp1;
182 : }
183 :
184 : /* Return residual energy */
185 0 : return (silk_float)nrg_f;
186 : }
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