sergeyu@chromium.org | 885f2ff | 2012-10-17 22:31:52 +0000 | [diff] [blame] | 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. |
tlegrand@chromium.org | e3ea049 | 2013-10-23 09:13:50 +0000 | [diff] [blame] | 11 | - Neither the name of Internet Society, IETF or IETF Trust, nor the |
sergeyu@chromium.org | 885f2ff | 2012-10-17 22:31:52 +0000 | [diff] [blame] | 12 | names of specific contributors, may be used to endorse or promote |
| 13 | products derived from this software without specific prior written |
| 14 | permission. |
tlegrand@chromium.org | e3ea049 | 2013-10-23 09:13:50 +0000 | [diff] [blame] | 15 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
sergeyu@chromium.org | 885f2ff | 2012-10-17 22:31:52 +0000 | [diff] [blame] | 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_FIX.h" |
| 33 | #include "SigProc_FLP.h" |
| 34 | |
| 35 | #define RC_THRESHOLD 0.9999f |
| 36 | |
| 37 | /* compute inverse of LPC prediction gain, and */ |
| 38 | /* test if LPC coefficients are stable (all poles within unit circle) */ |
| 39 | /* this code is based on silk_a2k_FLP() */ |
| 40 | silk_float silk_LPC_inverse_pred_gain_FLP( /* O return inverse prediction gain, energy domain */ |
| 41 | const silk_float *A, /* I prediction coefficients [order] */ |
| 42 | opus_int32 order /* I prediction order */ |
| 43 | ) |
| 44 | { |
| 45 | opus_int k, n; |
| 46 | double invGain, rc, rc_mult1, rc_mult2; |
| 47 | silk_float Atmp[ 2 ][ SILK_MAX_ORDER_LPC ]; |
| 48 | silk_float *Aold, *Anew; |
| 49 | |
| 50 | Anew = Atmp[ order & 1 ]; |
| 51 | silk_memcpy( Anew, A, order * sizeof(silk_float) ); |
| 52 | |
| 53 | invGain = 1.0; |
| 54 | for( k = order - 1; k > 0; k-- ) { |
| 55 | rc = -Anew[ k ]; |
| 56 | if( rc > RC_THRESHOLD || rc < -RC_THRESHOLD ) { |
| 57 | return 0.0f; |
| 58 | } |
| 59 | rc_mult1 = 1.0f - rc * rc; |
| 60 | rc_mult2 = 1.0f / rc_mult1; |
| 61 | invGain *= rc_mult1; |
| 62 | /* swap pointers */ |
| 63 | Aold = Anew; |
| 64 | Anew = Atmp[ k & 1 ]; |
| 65 | for( n = 0; n < k; n++ ) { |
| 66 | Anew[ n ] = (silk_float)( ( Aold[ n ] - Aold[ k - n - 1 ] * rc ) * rc_mult2 ); |
| 67 | } |
| 68 | } |
| 69 | rc = -Anew[ 0 ]; |
| 70 | if( rc > RC_THRESHOLD || rc < -RC_THRESHOLD ) { |
| 71 | return 0.0f; |
| 72 | } |
| 73 | rc_mult1 = 1.0f - rc * rc; |
| 74 | invGain *= rc_mult1; |
| 75 | return (silk_float)invGain; |
| 76 | } |