Alexandre Lision | 744f742 | 2013-09-25 11:39:37 -0400 | [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. |
Alexandre Lision | 8538238 | 2014-01-27 15:54:16 -0500 | [diff] [blame] | 11 | - Neither the name of Internet Society, IETF or IETF Trust, nor the |
Alexandre Lision | 744f742 | 2013-09-25 11:39:37 -0400 | [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. |
Alexandre Lision | 8538238 | 2014-01-27 15:54:16 -0500 | [diff] [blame] | 15 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
Alexandre Lision | 744f742 | 2013-09-25 11:39:37 -0400 | [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 | /* NLSF stabilizer: */ |
| 33 | /* */ |
| 34 | /* - Moves NLSFs further apart if they are too close */ |
| 35 | /* - Moves NLSFs away from borders if they are too close */ |
| 36 | /* - High effort to achieve a modification with minimum */ |
| 37 | /* Euclidean distance to input vector */ |
| 38 | /* - Output are sorted NLSF coefficients */ |
| 39 | /* */ |
| 40 | |
| 41 | #include "SigProc_FIX.h" |
| 42 | |
| 43 | /* Constant Definitions */ |
| 44 | #define MAX_LOOPS 20 |
| 45 | |
| 46 | /* NLSF stabilizer, for a single input data vector */ |
| 47 | void silk_NLSF_stabilize( |
| 48 | opus_int16 *NLSF_Q15, /* I/O Unstable/stabilized normalized LSF vector in Q15 [L] */ |
| 49 | const opus_int16 *NDeltaMin_Q15, /* I Min distance vector, NDeltaMin_Q15[L] must be >= 1 [L+1] */ |
| 50 | const opus_int L /* I Number of NLSF parameters in the input vector */ |
| 51 | ) |
| 52 | { |
| 53 | opus_int i, I=0, k, loops; |
| 54 | opus_int16 center_freq_Q15; |
| 55 | opus_int32 diff_Q15, min_diff_Q15, min_center_Q15, max_center_Q15; |
| 56 | |
| 57 | /* This is necessary to ensure an output within range of a opus_int16 */ |
| 58 | silk_assert( NDeltaMin_Q15[L] >= 1 ); |
| 59 | |
| 60 | for( loops = 0; loops < MAX_LOOPS; loops++ ) { |
| 61 | /**************************/ |
| 62 | /* Find smallest distance */ |
| 63 | /**************************/ |
| 64 | /* First element */ |
| 65 | min_diff_Q15 = NLSF_Q15[0] - NDeltaMin_Q15[0]; |
| 66 | I = 0; |
| 67 | /* Middle elements */ |
| 68 | for( i = 1; i <= L-1; i++ ) { |
| 69 | diff_Q15 = NLSF_Q15[i] - ( NLSF_Q15[i-1] + NDeltaMin_Q15[i] ); |
| 70 | if( diff_Q15 < min_diff_Q15 ) { |
| 71 | min_diff_Q15 = diff_Q15; |
| 72 | I = i; |
| 73 | } |
| 74 | } |
| 75 | /* Last element */ |
| 76 | diff_Q15 = ( 1 << 15 ) - ( NLSF_Q15[L-1] + NDeltaMin_Q15[L] ); |
| 77 | if( diff_Q15 < min_diff_Q15 ) { |
| 78 | min_diff_Q15 = diff_Q15; |
| 79 | I = L; |
| 80 | } |
| 81 | |
| 82 | /***************************************************/ |
| 83 | /* Now check if the smallest distance non-negative */ |
| 84 | /***************************************************/ |
| 85 | if( min_diff_Q15 >= 0 ) { |
| 86 | return; |
| 87 | } |
| 88 | |
| 89 | if( I == 0 ) { |
| 90 | /* Move away from lower limit */ |
| 91 | NLSF_Q15[0] = NDeltaMin_Q15[0]; |
| 92 | |
| 93 | } else if( I == L) { |
| 94 | /* Move away from higher limit */ |
| 95 | NLSF_Q15[L-1] = ( 1 << 15 ) - NDeltaMin_Q15[L]; |
| 96 | |
| 97 | } else { |
| 98 | /* Find the lower extreme for the location of the current center frequency */ |
| 99 | min_center_Q15 = 0; |
| 100 | for( k = 0; k < I; k++ ) { |
| 101 | min_center_Q15 += NDeltaMin_Q15[k]; |
| 102 | } |
| 103 | min_center_Q15 += silk_RSHIFT( NDeltaMin_Q15[I], 1 ); |
| 104 | |
| 105 | /* Find the upper extreme for the location of the current center frequency */ |
| 106 | max_center_Q15 = 1 << 15; |
| 107 | for( k = L; k > I; k-- ) { |
| 108 | max_center_Q15 -= NDeltaMin_Q15[k]; |
| 109 | } |
| 110 | max_center_Q15 -= silk_RSHIFT( NDeltaMin_Q15[I], 1 ); |
| 111 | |
| 112 | /* Move apart, sorted by value, keeping the same center frequency */ |
| 113 | center_freq_Q15 = (opus_int16)silk_LIMIT_32( silk_RSHIFT_ROUND( (opus_int32)NLSF_Q15[I-1] + (opus_int32)NLSF_Q15[I], 1 ), |
| 114 | min_center_Q15, max_center_Q15 ); |
| 115 | NLSF_Q15[I-1] = center_freq_Q15 - silk_RSHIFT( NDeltaMin_Q15[I], 1 ); |
| 116 | NLSF_Q15[I] = NLSF_Q15[I-1] + NDeltaMin_Q15[I]; |
| 117 | } |
| 118 | } |
| 119 | |
| 120 | /* Safe and simple fall back method, which is less ideal than the above */ |
| 121 | if( loops == MAX_LOOPS ) |
| 122 | { |
| 123 | /* Insertion sort (fast for already almost sorted arrays): */ |
| 124 | /* Best case: O(n) for an already sorted array */ |
| 125 | /* Worst case: O(n^2) for an inversely sorted array */ |
| 126 | silk_insertion_sort_increasing_all_values_int16( &NLSF_Q15[0], L ); |
| 127 | |
| 128 | /* First NLSF should be no less than NDeltaMin[0] */ |
| 129 | NLSF_Q15[0] = silk_max_int( NLSF_Q15[0], NDeltaMin_Q15[0] ); |
| 130 | |
| 131 | /* Keep delta_min distance between the NLSFs */ |
| 132 | for( i = 1; i < L; i++ ) |
| 133 | NLSF_Q15[i] = silk_max_int( NLSF_Q15[i], NLSF_Q15[i-1] + NDeltaMin_Q15[i] ); |
| 134 | |
| 135 | /* Last NLSF should be no higher than 1 - NDeltaMin[L] */ |
| 136 | NLSF_Q15[L-1] = silk_min_int( NLSF_Q15[L-1], (1<<15) - NDeltaMin_Q15[L] ); |
| 137 | |
| 138 | /* Keep NDeltaMin distance between the NLSFs */ |
| 139 | for( i = L-2; i >= 0; i-- ) |
| 140 | NLSF_Q15[i] = silk_min_int( NLSF_Q15[i], NLSF_Q15[i+1] - NDeltaMin_Q15[i+1] ); |
| 141 | } |
| 142 | } |