|
Chris@69
|
1 /***********************************************************************
|
|
Chris@69
|
2 Copyright (c) 2006-2011, Skype Limited. All rights reserved.
|
|
Chris@69
|
3 Redistribution and use in source and binary forms, with or without
|
|
Chris@69
|
4 modification, are permitted provided that the following conditions
|
|
Chris@69
|
5 are met:
|
|
Chris@69
|
6 - Redistributions of source code must retain the above copyright notice,
|
|
Chris@69
|
7 this list of conditions and the following disclaimer.
|
|
Chris@69
|
8 - Redistributions in binary form must reproduce the above copyright
|
|
Chris@69
|
9 notice, this list of conditions and the following disclaimer in the
|
|
Chris@69
|
10 documentation and/or other materials provided with the distribution.
|
|
Chris@69
|
11 - Neither the name of Internet Society, IETF or IETF Trust, nor the
|
|
Chris@69
|
12 names of specific contributors, may be used to endorse or promote
|
|
Chris@69
|
13 products derived from this software without specific prior written
|
|
Chris@69
|
14 permission.
|
|
Chris@69
|
15 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
Chris@69
|
16 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
Chris@69
|
17 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
Chris@69
|
18 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
|
Chris@69
|
19 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
Chris@69
|
20 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
Chris@69
|
21 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
Chris@69
|
22 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
Chris@69
|
23 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
Chris@69
|
24 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
Chris@69
|
25 POSSIBILITY OF SUCH DAMAGE.
|
|
Chris@69
|
26 ***********************************************************************/
|
|
Chris@69
|
27
|
|
Chris@69
|
28 #ifdef HAVE_CONFIG_H
|
|
Chris@69
|
29 #include "config.h"
|
|
Chris@69
|
30 #endif
|
|
Chris@69
|
31
|
|
Chris@69
|
32 #include "SigProc_FIX.h"
|
|
Chris@69
|
33 #include "SigProc_FLP.h"
|
|
Chris@69
|
34 #include "define.h"
|
|
Chris@69
|
35
|
|
Chris@69
|
36 /* compute inverse of LPC prediction gain, and */
|
|
Chris@69
|
37 /* test if LPC coefficients are stable (all poles within unit circle) */
|
|
Chris@69
|
38 /* this code is based on silk_a2k_FLP() */
|
|
Chris@69
|
39 silk_float silk_LPC_inverse_pred_gain_FLP( /* O return inverse prediction gain, energy domain */
|
|
Chris@69
|
40 const silk_float *A, /* I prediction coefficients [order] */
|
|
Chris@69
|
41 opus_int32 order /* I prediction order */
|
|
Chris@69
|
42 )
|
|
Chris@69
|
43 {
|
|
Chris@69
|
44 opus_int k, n;
|
|
Chris@69
|
45 double invGain, rc, rc_mult1, rc_mult2, tmp1, tmp2;
|
|
Chris@69
|
46 silk_float Atmp[ SILK_MAX_ORDER_LPC ];
|
|
Chris@69
|
47
|
|
Chris@69
|
48 silk_memcpy( Atmp, A, order * sizeof(silk_float) );
|
|
Chris@69
|
49
|
|
Chris@69
|
50 invGain = 1.0;
|
|
Chris@69
|
51 for( k = order - 1; k > 0; k-- ) {
|
|
Chris@69
|
52 rc = -Atmp[ k ];
|
|
Chris@69
|
53 rc_mult1 = 1.0f - rc * rc;
|
|
Chris@69
|
54 invGain *= rc_mult1;
|
|
Chris@69
|
55 if( invGain * MAX_PREDICTION_POWER_GAIN < 1.0f ) {
|
|
Chris@69
|
56 return 0.0f;
|
|
Chris@69
|
57 }
|
|
Chris@69
|
58 rc_mult2 = 1.0f / rc_mult1;
|
|
Chris@69
|
59 for( n = 0; n < (k + 1) >> 1; n++ ) {
|
|
Chris@69
|
60 tmp1 = Atmp[ n ];
|
|
Chris@69
|
61 tmp2 = Atmp[ k - n - 1 ];
|
|
Chris@69
|
62 Atmp[ n ] = (silk_float)( ( tmp1 - tmp2 * rc ) * rc_mult2 );
|
|
Chris@69
|
63 Atmp[ k - n - 1 ] = (silk_float)( ( tmp2 - tmp1 * rc ) * rc_mult2 );
|
|
Chris@69
|
64 }
|
|
Chris@69
|
65 }
|
|
Chris@69
|
66 rc = -Atmp[ 0 ];
|
|
Chris@69
|
67 rc_mult1 = 1.0f - rc * rc;
|
|
Chris@69
|
68 invGain *= rc_mult1;
|
|
Chris@69
|
69 if( invGain * MAX_PREDICTION_POWER_GAIN < 1.0f ) {
|
|
Chris@69
|
70 return 0.0f;
|
|
Chris@69
|
71 }
|
|
Chris@69
|
72 return (silk_float)invGain;
|
|
Chris@69
|
73 }
|
