media/libopus/silk/float/LPC_inv_pred_gain_FLP.c@b8a032363ba2 (annotated)
media/libopus/silk/float/LPC_inv_pred_gain_FLP.c
Thu, 22 Jan 2015 13:21:57 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Thu, 22 Jan 2015 13:21:57 +0100
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
- permissions
- -rw-r--r--
Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6
| michael@0 | 1 | /*********************************************************************** |
| michael@0 | 2 | Copyright (c) 2006-2011, Skype Limited. All rights reserved. |
| michael@0 | 3 | Redistribution and use in source and binary forms, with or without |
| michael@0 | 4 | modification, are permitted provided that the following conditions |
| michael@0 | 5 | are met: |
| michael@0 | 6 | - Redistributions of source code must retain the above copyright notice, |
| michael@0 | 7 | this list of conditions and the following disclaimer. |
| michael@0 | 8 | - Redistributions in binary form must reproduce the above copyright |
| michael@0 | 9 | notice, this list of conditions and the following disclaimer in the |
| michael@0 | 10 | documentation and/or other materials provided with the distribution. |
| michael@0 | 11 | - Neither the name of Internet Society, IETF or IETF Trust, nor the |
| michael@0 | 12 | names of specific contributors, may be used to endorse or promote |
| michael@0 | 13 | products derived from this software without specific prior written |
| michael@0 | 14 | permission. |
| michael@0 | 15 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| michael@0 | 16 | AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| michael@0 | 17 | IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| michael@0 | 18 | ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
| michael@0 | 19 | LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| michael@0 | 20 | CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| michael@0 | 21 | SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| michael@0 | 22 | INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| michael@0 | 23 | CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| michael@0 | 24 | ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| michael@0 | 25 | POSSIBILITY OF SUCH DAMAGE. |
| michael@0 | 26 | ***********************************************************************/ |
| michael@0 | 27 | |
| michael@0 | 28 | #ifdef HAVE_CONFIG_H |
| michael@0 | 29 | #include "config.h" |
| michael@0 | 30 | #endif |
| michael@0 | 31 | |
| michael@0 | 32 | #include "SigProc_FIX.h" |
| michael@0 | 33 | #include "SigProc_FLP.h" |
| michael@0 | 34 | |
| michael@0 | 35 | #define RC_THRESHOLD 0.9999f |
| michael@0 | 36 | |
| michael@0 | 37 | /* compute inverse of LPC prediction gain, and */ |
| michael@0 | 38 | /* test if LPC coefficients are stable (all poles within unit circle) */ |
| michael@0 | 39 | /* this code is based on silk_a2k_FLP() */ |
| michael@0 | 40 | silk_float silk_LPC_inverse_pred_gain_FLP( /* O return inverse prediction gain, energy domain */ |
| michael@0 | 41 | const silk_float *A, /* I prediction coefficients [order] */ |
| michael@0 | 42 | opus_int32 order /* I prediction order */ |
| michael@0 | 43 | ) |
| michael@0 | 44 | { |
| michael@0 | 45 | opus_int k, n; |
| michael@0 | 46 | double invGain, rc, rc_mult1, rc_mult2; |
| michael@0 | 47 | silk_float Atmp[ 2 ][ SILK_MAX_ORDER_LPC ]; |
| michael@0 | 48 | silk_float *Aold, *Anew; |
| michael@0 | 49 | |
| michael@0 | 50 | Anew = Atmp[ order & 1 ]; |
| michael@0 | 51 | silk_memcpy( Anew, A, order * sizeof(silk_float) ); |
| michael@0 | 52 | |
| michael@0 | 53 | invGain = 1.0; |
| michael@0 | 54 | for( k = order - 1; k > 0; k-- ) { |
| michael@0 | 55 | rc = -Anew[ k ]; |
| michael@0 | 56 | if( rc > RC_THRESHOLD || rc < -RC_THRESHOLD ) { |
| michael@0 | 57 | return 0.0f; |
| michael@0 | 58 | } |
| michael@0 | 59 | rc_mult1 = 1.0f - rc * rc; |
| michael@0 | 60 | rc_mult2 = 1.0f / rc_mult1; |
| michael@0 | 61 | invGain *= rc_mult1; |
| michael@0 | 62 | /* swap pointers */ |
| michael@0 | 63 | Aold = Anew; |
| michael@0 | 64 | Anew = Atmp[ k & 1 ]; |
| michael@0 | 65 | for( n = 0; n < k; n++ ) { |
| michael@0 | 66 | Anew[ n ] = (silk_float)( ( Aold[ n ] - Aold[ k - n - 1 ] * rc ) * rc_mult2 ); |
| michael@0 | 67 | } |
| michael@0 | 68 | } |
| michael@0 | 69 | rc = -Anew[ 0 ]; |
| michael@0 | 70 | if( rc > RC_THRESHOLD || rc < -RC_THRESHOLD ) { |
| michael@0 | 71 | return 0.0f; |
| michael@0 | 72 | } |
| michael@0 | 73 | rc_mult1 = 1.0f - rc * rc; |
| michael@0 | 74 | invGain *= rc_mult1; |
| michael@0 | 75 | return (silk_float)invGain; |
| michael@0 | 76 | } |
