1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/libopus/silk/NLSF_stabilize.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,142 @@
1.4 +/***********************************************************************
1.5 +Copyright (c) 2006-2011, Skype Limited. All rights reserved.
1.6 +Redistribution and use in source and binary forms, with or without
1.7 +modification, are permitted provided that the following conditions
1.8 +are met:
1.9 +- Redistributions of source code must retain the above copyright notice,
1.10 +this list of conditions and the following disclaimer.
1.11 +- Redistributions in binary form must reproduce the above copyright
1.12 +notice, this list of conditions and the following disclaimer in the
1.13 +documentation and/or other materials provided with the distribution.
1.14 +- Neither the name of Internet Society, IETF or IETF Trust, nor the
1.15 +names of specific contributors, may be used to endorse or promote
1.16 +products derived from this software without specific prior written
1.17 +permission.
1.18 +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
1.19 +AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
1.20 +IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
1.21 +ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
1.22 +LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
1.23 +CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
1.24 +SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
1.25 +INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
1.26 +CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
1.27 +ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
1.28 +POSSIBILITY OF SUCH DAMAGE.
1.29 +***********************************************************************/
1.30 +
1.31 +#ifdef HAVE_CONFIG_H
1.32 +#include "config.h"
1.33 +#endif
1.34 +
1.35 +/* NLSF stabilizer: */
1.36 +/* */
1.37 +/* - Moves NLSFs further apart if they are too close */
1.38 +/* - Moves NLSFs away from borders if they are too close */
1.39 +/* - High effort to achieve a modification with minimum */
1.40 +/* Euclidean distance to input vector */
1.41 +/* - Output are sorted NLSF coefficients */
1.42 +/* */
1.43 +
1.44 +#include "SigProc_FIX.h"
1.45 +
1.46 +/* Constant Definitions */
1.47 +#define MAX_LOOPS 20
1.48 +
1.49 +/* NLSF stabilizer, for a single input data vector */
1.50 +void silk_NLSF_stabilize(
1.51 + opus_int16 *NLSF_Q15, /* I/O Unstable/stabilized normalized LSF vector in Q15 [L] */
1.52 + const opus_int16 *NDeltaMin_Q15, /* I Min distance vector, NDeltaMin_Q15[L] must be >= 1 [L+1] */
1.53 + const opus_int L /* I Number of NLSF parameters in the input vector */
1.54 +)
1.55 +{
1.56 + opus_int i, I=0, k, loops;
1.57 + opus_int16 center_freq_Q15;
1.58 + opus_int32 diff_Q15, min_diff_Q15, min_center_Q15, max_center_Q15;
1.59 +
1.60 + /* This is necessary to ensure an output within range of a opus_int16 */
1.61 + silk_assert( NDeltaMin_Q15[L] >= 1 );
1.62 +
1.63 + for( loops = 0; loops < MAX_LOOPS; loops++ ) {
1.64 + /**************************/
1.65 + /* Find smallest distance */
1.66 + /**************************/
1.67 + /* First element */
1.68 + min_diff_Q15 = NLSF_Q15[0] - NDeltaMin_Q15[0];
1.69 + I = 0;
1.70 + /* Middle elements */
1.71 + for( i = 1; i <= L-1; i++ ) {
1.72 + diff_Q15 = NLSF_Q15[i] - ( NLSF_Q15[i-1] + NDeltaMin_Q15[i] );
1.73 + if( diff_Q15 < min_diff_Q15 ) {
1.74 + min_diff_Q15 = diff_Q15;
1.75 + I = i;
1.76 + }
1.77 + }
1.78 + /* Last element */
1.79 + diff_Q15 = ( 1 << 15 ) - ( NLSF_Q15[L-1] + NDeltaMin_Q15[L] );
1.80 + if( diff_Q15 < min_diff_Q15 ) {
1.81 + min_diff_Q15 = diff_Q15;
1.82 + I = L;
1.83 + }
1.84 +
1.85 + /***************************************************/
1.86 + /* Now check if the smallest distance non-negative */
1.87 + /***************************************************/
1.88 + if( min_diff_Q15 >= 0 ) {
1.89 + return;
1.90 + }
1.91 +
1.92 + if( I == 0 ) {
1.93 + /* Move away from lower limit */
1.94 + NLSF_Q15[0] = NDeltaMin_Q15[0];
1.95 +
1.96 + } else if( I == L) {
1.97 + /* Move away from higher limit */
1.98 + NLSF_Q15[L-1] = ( 1 << 15 ) - NDeltaMin_Q15[L];
1.99 +
1.100 + } else {
1.101 + /* Find the lower extreme for the location of the current center frequency */
1.102 + min_center_Q15 = 0;
1.103 + for( k = 0; k < I; k++ ) {
1.104 + min_center_Q15 += NDeltaMin_Q15[k];
1.105 + }
1.106 + min_center_Q15 += silk_RSHIFT( NDeltaMin_Q15[I], 1 );
1.107 +
1.108 + /* Find the upper extreme for the location of the current center frequency */
1.109 + max_center_Q15 = 1 << 15;
1.110 + for( k = L; k > I; k-- ) {
1.111 + max_center_Q15 -= NDeltaMin_Q15[k];
1.112 + }
1.113 + max_center_Q15 -= silk_RSHIFT( NDeltaMin_Q15[I], 1 );
1.114 +
1.115 + /* Move apart, sorted by value, keeping the same center frequency */
1.116 + center_freq_Q15 = (opus_int16)silk_LIMIT_32( silk_RSHIFT_ROUND( (opus_int32)NLSF_Q15[I-1] + (opus_int32)NLSF_Q15[I], 1 ),
1.117 + min_center_Q15, max_center_Q15 );
1.118 + NLSF_Q15[I-1] = center_freq_Q15 - silk_RSHIFT( NDeltaMin_Q15[I], 1 );
1.119 + NLSF_Q15[I] = NLSF_Q15[I-1] + NDeltaMin_Q15[I];
1.120 + }
1.121 + }
1.122 +
1.123 + /* Safe and simple fall back method, which is less ideal than the above */
1.124 + if( loops == MAX_LOOPS )
1.125 + {
1.126 + /* Insertion sort (fast for already almost sorted arrays): */
1.127 + /* Best case: O(n) for an already sorted array */
1.128 + /* Worst case: O(n^2) for an inversely sorted array */
1.129 + silk_insertion_sort_increasing_all_values_int16( &NLSF_Q15[0], L );
1.130 +
1.131 + /* First NLSF should be no less than NDeltaMin[0] */
1.132 + NLSF_Q15[0] = silk_max_int( NLSF_Q15[0], NDeltaMin_Q15[0] );
1.133 +
1.134 + /* Keep delta_min distance between the NLSFs */
1.135 + for( i = 1; i < L; i++ )
1.136 + NLSF_Q15[i] = silk_max_int( NLSF_Q15[i], NLSF_Q15[i-1] + NDeltaMin_Q15[i] );
1.137 +
1.138 + /* Last NLSF should be no higher than 1 - NDeltaMin[L] */
1.139 + NLSF_Q15[L-1] = silk_min_int( NLSF_Q15[L-1], (1<<15) - NDeltaMin_Q15[L] );
1.140 +
1.141 + /* Keep NDeltaMin distance between the NLSFs */
1.142 + for( i = L-2; i >= 0; i-- )
1.143 + NLSF_Q15[i] = silk_min_int( NLSF_Q15[i], NLSF_Q15[i+1] - NDeltaMin_Q15[i+1] );
1.144 + }
1.145 +}
