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comparison: media/libopus/silk/float/LPC_inv_pred_gain_FLP.c
media/libopus/silk/float/LPC_inv_pred_gain_FLP.c
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
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| -1:000000000000 | 0:208c39767e9d |
|---|---|
| 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_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 } |
