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annotate src/opus-1.3/silk/LPC_inv_pred_gain.c @ 81:7029a4916348

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Merge build update
author Chris Cannam
date Thu, 31 Oct 2019 13:36:58 +0000
parents 7aeed7906520
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rev   line source
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 "define.h"
Chris@69 34
Chris@69 35 #define QA 24
Chris@69 36 #define A_LIMIT SILK_FIX_CONST( 0.99975, QA )
Chris@69 37
Chris@69 38 #define MUL32_FRAC_Q(a32, b32, Q) ((opus_int32)(silk_RSHIFT_ROUND64(silk_SMULL(a32, b32), Q)))
Chris@69 39
Chris@69 40 /* Compute inverse of LPC prediction gain, and */
Chris@69 41 /* test if LPC coefficients are stable (all poles within unit circle) */
Chris@69 42 static opus_int32 LPC_inverse_pred_gain_QA_c( /* O Returns inverse prediction gain in energy domain, Q30 */
Chris@69 43 opus_int32 A_QA[ SILK_MAX_ORDER_LPC ], /* I Prediction coefficients */
Chris@69 44 const opus_int order /* I Prediction order */
Chris@69 45 )
Chris@69 46 {
Chris@69 47 opus_int k, n, mult2Q;
Chris@69 48 opus_int32 invGain_Q30, rc_Q31, rc_mult1_Q30, rc_mult2, tmp1, tmp2;
Chris@69 49
Chris@69 50 invGain_Q30 = SILK_FIX_CONST( 1, 30 );
Chris@69 51 for( k = order - 1; k > 0; k-- ) {
Chris@69 52 /* Check for stability */
Chris@69 53 if( ( A_QA[ k ] > A_LIMIT ) || ( A_QA[ k ] < -A_LIMIT ) ) {
Chris@69 54 return 0;
Chris@69 55 }
Chris@69 56
Chris@69 57 /* Set RC equal to negated AR coef */
Chris@69 58 rc_Q31 = -silk_LSHIFT( A_QA[ k ], 31 - QA );
Chris@69 59
Chris@69 60 /* rc_mult1_Q30 range: [ 1 : 2^30 ] */
Chris@69 61 rc_mult1_Q30 = silk_SUB32( SILK_FIX_CONST( 1, 30 ), silk_SMMUL( rc_Q31, rc_Q31 ) );
Chris@69 62 silk_assert( rc_mult1_Q30 > ( 1 << 15 ) ); /* reduce A_LIMIT if fails */
Chris@69 63 silk_assert( rc_mult1_Q30 <= ( 1 << 30 ) );
Chris@69 64
Chris@69 65 /* Update inverse gain */
Chris@69 66 /* invGain_Q30 range: [ 0 : 2^30 ] */
Chris@69 67 invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 );
Chris@69 68 silk_assert( invGain_Q30 >= 0 );
Chris@69 69 silk_assert( invGain_Q30 <= ( 1 << 30 ) );
Chris@69 70 if( invGain_Q30 < SILK_FIX_CONST( 1.0f / MAX_PREDICTION_POWER_GAIN, 30 ) ) {
Chris@69 71 return 0;
Chris@69 72 }
Chris@69 73
Chris@69 74 /* rc_mult2 range: [ 2^30 : silk_int32_MAX ] */
Chris@69 75 mult2Q = 32 - silk_CLZ32( silk_abs( rc_mult1_Q30 ) );
Chris@69 76 rc_mult2 = silk_INVERSE32_varQ( rc_mult1_Q30, mult2Q + 30 );
Chris@69 77
Chris@69 78 /* Update AR coefficient */
Chris@69 79 for( n = 0; n < (k + 1) >> 1; n++ ) {
Chris@69 80 opus_int64 tmp64;
Chris@69 81 tmp1 = A_QA[ n ];
Chris@69 82 tmp2 = A_QA[ k - n - 1 ];
Chris@69 83 tmp64 = silk_RSHIFT_ROUND64( silk_SMULL( silk_SUB_SAT32(tmp1,
Chris@69 84 MUL32_FRAC_Q( tmp2, rc_Q31, 31 ) ), rc_mult2 ), mult2Q);
Chris@69 85 if( tmp64 > silk_int32_MAX || tmp64 < silk_int32_MIN ) {
Chris@69 86 return 0;
Chris@69 87 }
Chris@69 88 A_QA[ n ] = ( opus_int32 )tmp64;
Chris@69 89 tmp64 = silk_RSHIFT_ROUND64( silk_SMULL( silk_SUB_SAT32(tmp2,
Chris@69 90 MUL32_FRAC_Q( tmp1, rc_Q31, 31 ) ), rc_mult2), mult2Q);
Chris@69 91 if( tmp64 > silk_int32_MAX || tmp64 < silk_int32_MIN ) {
Chris@69 92 return 0;
Chris@69 93 }
Chris@69 94 A_QA[ k - n - 1 ] = ( opus_int32 )tmp64;
Chris@69 95 }
Chris@69 96 }
Chris@69 97
Chris@69 98 /* Check for stability */
Chris@69 99 if( ( A_QA[ k ] > A_LIMIT ) || ( A_QA[ k ] < -A_LIMIT ) ) {
Chris@69 100 return 0;
Chris@69 101 }
Chris@69 102
Chris@69 103 /* Set RC equal to negated AR coef */
Chris@69 104 rc_Q31 = -silk_LSHIFT( A_QA[ 0 ], 31 - QA );
Chris@69 105
Chris@69 106 /* Range: [ 1 : 2^30 ] */
Chris@69 107 rc_mult1_Q30 = silk_SUB32( SILK_FIX_CONST( 1, 30 ), silk_SMMUL( rc_Q31, rc_Q31 ) );
Chris@69 108
Chris@69 109 /* Update inverse gain */
Chris@69 110 /* Range: [ 0 : 2^30 ] */
Chris@69 111 invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 );
Chris@69 112 silk_assert( invGain_Q30 >= 0 );
Chris@69 113 silk_assert( invGain_Q30 <= ( 1 << 30 ) );
Chris@69 114 if( invGain_Q30 < SILK_FIX_CONST( 1.0f / MAX_PREDICTION_POWER_GAIN, 30 ) ) {
Chris@69 115 return 0;
Chris@69 116 }
Chris@69 117
Chris@69 118 return invGain_Q30;
Chris@69 119 }
Chris@69 120
Chris@69 121 /* For input in Q12 domain */
Chris@69 122 opus_int32 silk_LPC_inverse_pred_gain_c( /* O Returns inverse prediction gain in energy domain, Q30 */
Chris@69 123 const opus_int16 *A_Q12, /* I Prediction coefficients, Q12 [order] */
Chris@69 124 const opus_int order /* I Prediction order */
Chris@69 125 )
Chris@69 126 {
Chris@69 127 opus_int k;
Chris@69 128 opus_int32 Atmp_QA[ SILK_MAX_ORDER_LPC ];
Chris@69 129 opus_int32 DC_resp = 0;
Chris@69 130
Chris@69 131 /* Increase Q domain of the AR coefficients */
Chris@69 132 for( k = 0; k < order; k++ ) {
Chris@69 133 DC_resp += (opus_int32)A_Q12[ k ];
Chris@69 134 Atmp_QA[ k ] = silk_LSHIFT32( (opus_int32)A_Q12[ k ], QA - 12 );
Chris@69 135 }
Chris@69 136 /* If the DC is unstable, we don't even need to do the full calculations */
Chris@69 137 if( DC_resp >= 4096 ) {
Chris@69 138 return 0;
Chris@69 139 }
Chris@69 140 return LPC_inverse_pred_gain_QA_c( Atmp_QA, order );
Chris@69 141 }