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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 "main_FIX.h"
33 #include "stack_alloc.h"
34 #include "tuning_parameters.h"
35 
36 /* Finds LPC vector from correlations, and converts to NLSF */
silk_find_LPC_FIX(silk_encoder_state * psEncC,opus_int16 NLSF_Q15[],const opus_int16 x[],const opus_int32 minInvGain_Q30)37 void silk_find_LPC_FIX(
38     silk_encoder_state              *psEncC,                                /* I/O  Encoder state                                                               */
39     opus_int16                      NLSF_Q15[],                             /* O    NLSFs                                                                       */
40     const opus_int16                x[],                                    /* I    Input signal                                                                */
41     const opus_int32                minInvGain_Q30                          /* I    Inverse of max prediction gain                                              */
42 )
43 {
44     opus_int     k, subfr_length;
45     opus_int32   a_Q16[ MAX_LPC_ORDER ];
46     opus_int     isInterpLower, shift;
47     opus_int32   res_nrg0, res_nrg1;
48     opus_int     rshift0, rshift1;
49 
50     /* Used only for LSF interpolation */
51     opus_int32   a_tmp_Q16[ MAX_LPC_ORDER ], res_nrg_interp, res_nrg, res_tmp_nrg;
52     opus_int     res_nrg_interp_Q, res_nrg_Q, res_tmp_nrg_Q;
53     opus_int16   a_tmp_Q12[ MAX_LPC_ORDER ];
54     opus_int16   NLSF0_Q15[ MAX_LPC_ORDER ];
55     SAVE_STACK;
56 
57     subfr_length = psEncC->subfr_length + psEncC->predictLPCOrder;
58 
59     /* Default: no interpolation */
60     psEncC->indices.NLSFInterpCoef_Q2 = 4;
61 
62     /* Burg AR analysis for the full frame */
63     silk_burg_modified( &res_nrg, &res_nrg_Q, a_Q16, x, minInvGain_Q30, subfr_length, psEncC->nb_subfr, psEncC->predictLPCOrder, psEncC->arch );
64 
65     if( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) {
66         VARDECL( opus_int16, LPC_res );
67 
68         /* Optimal solution for last 10 ms */
69         silk_burg_modified( &res_tmp_nrg, &res_tmp_nrg_Q, a_tmp_Q16, x + 2 * subfr_length, minInvGain_Q30, subfr_length, 2, psEncC->predictLPCOrder, psEncC->arch );
70 
71         /* subtract residual energy here, as that's easier than adding it to the    */
72         /* residual energy of the first 10 ms in each iteration of the search below */
73         shift = res_tmp_nrg_Q - res_nrg_Q;
74         if( shift >= 0 ) {
75             if( shift < 32 ) {
76                 res_nrg = res_nrg - silk_RSHIFT( res_tmp_nrg, shift );
77             }
78         } else {
79             silk_assert( shift > -32 );
80             res_nrg   = silk_RSHIFT( res_nrg, -shift ) - res_tmp_nrg;
81             res_nrg_Q = res_tmp_nrg_Q;
82         }
83 
84         /* Convert to NLSFs */
85         silk_A2NLSF( NLSF_Q15, a_tmp_Q16, psEncC->predictLPCOrder );
86 
87         ALLOC( LPC_res, 2 * subfr_length, opus_int16 );
88 
89         /* Search over interpolation indices to find the one with lowest residual energy */
90         for( k = 3; k >= 0; k-- ) {
91             /* Interpolate NLSFs for first half */
92             silk_interpolate( NLSF0_Q15, psEncC->prev_NLSFq_Q15, NLSF_Q15, k, psEncC->predictLPCOrder );
93 
94             /* Convert to LPC for residual energy evaluation */
95             silk_NLSF2A( a_tmp_Q12, NLSF0_Q15, psEncC->predictLPCOrder );
96 
97             /* Calculate residual energy with NLSF interpolation */
98             silk_LPC_analysis_filter( LPC_res, x, a_tmp_Q12, 2 * subfr_length, psEncC->predictLPCOrder, psEncC->arch );
99 
100             silk_sum_sqr_shift( &res_nrg0, &rshift0, LPC_res + psEncC->predictLPCOrder,                subfr_length - psEncC->predictLPCOrder );
101             silk_sum_sqr_shift( &res_nrg1, &rshift1, LPC_res + psEncC->predictLPCOrder + subfr_length, subfr_length - psEncC->predictLPCOrder );
102 
103             /* Add subframe energies from first half frame */
104             shift = rshift0 - rshift1;
105             if( shift >= 0 ) {
106                 res_nrg1         = silk_RSHIFT( res_nrg1, shift );
107                 res_nrg_interp_Q = -rshift0;
108             } else {
109                 res_nrg0         = silk_RSHIFT( res_nrg0, -shift );
110                 res_nrg_interp_Q = -rshift1;
111             }
112             res_nrg_interp = silk_ADD32( res_nrg0, res_nrg1 );
113 
114             /* Compare with first half energy without NLSF interpolation, or best interpolated value so far */
115             shift = res_nrg_interp_Q - res_nrg_Q;
116             if( shift >= 0 ) {
117                 if( silk_RSHIFT( res_nrg_interp, shift ) < res_nrg ) {
118                     isInterpLower = silk_TRUE;
119                 } else {
120                     isInterpLower = silk_FALSE;
121                 }
122             } else {
123                 if( -shift < 32 ) {
124                     if( res_nrg_interp < silk_RSHIFT( res_nrg, -shift ) ) {
125                         isInterpLower = silk_TRUE;
126                     } else {
127                         isInterpLower = silk_FALSE;
128                     }
129                 } else {
130                     isInterpLower = silk_FALSE;
131                 }
132             }
133 
134             /* Determine whether current interpolated NLSFs are best so far */
135             if( isInterpLower == silk_TRUE ) {
136                 /* Interpolation has lower residual energy */
137                 res_nrg   = res_nrg_interp;
138                 res_nrg_Q = res_nrg_interp_Q;
139                 psEncC->indices.NLSFInterpCoef_Q2 = (opus_int8)k;
140             }
141         }
142     }
143 
144     if( psEncC->indices.NLSFInterpCoef_Q2 == 4 ) {
145         /* NLSF interpolation is currently inactive, calculate NLSFs from full frame AR coefficients */
146         silk_A2NLSF( NLSF_Q15, a_Q16, psEncC->predictLPCOrder );
147     }
148 
149     silk_assert( psEncC->indices.NLSFInterpCoef_Q2 == 4 || ( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) );
150     RESTORE_STACK;
151 }
152