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142 lines
6.2 KiB
142 lines
6.2 KiB
/*********************************************************************** |
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Copyright (c) 2006-2011, Skype Limited. All rights reserved. |
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Redistribution and use in source and binary forms, with or without |
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modification, are permitted provided that the following conditions |
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are met: |
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- Redistributions of source code must retain the above copyright notice, |
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this list of conditions and the following disclaimer. |
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- Redistributions in binary form must reproduce the above copyright |
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notice, this list of conditions and the following disclaimer in the |
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documentation and/or other materials provided with the distribution. |
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- Neither the name of Internet Society, IETF or IETF Trust, nor the |
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names of specific contributors, may be used to endorse or promote |
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products derived from this software without specific prior written |
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permission. |
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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POSSIBILITY OF SUCH DAMAGE. |
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***********************************************************************/ |
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#ifdef HAVE_CONFIG_H |
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#include "config.h" |
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#endif |
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/* NLSF stabilizer: */ |
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/* */ |
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/* - Moves NLSFs further apart if they are too close */ |
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/* - Moves NLSFs away from borders if they are too close */ |
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/* - High effort to achieve a modification with minimum */ |
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/* Euclidean distance to input vector */ |
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/* - Output are sorted NLSF coefficients */ |
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/* */ |
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#include "SigProc_FIX.h" |
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/* Constant Definitions */ |
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#define MAX_LOOPS 20 |
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/* NLSF stabilizer, for a single input data vector */ |
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void silk_NLSF_stabilize( |
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opus_int16 *NLSF_Q15, /* I/O Unstable/stabilized normalized LSF vector in Q15 [L] */ |
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const opus_int16 *NDeltaMin_Q15, /* I Min distance vector, NDeltaMin_Q15[L] must be >= 1 [L+1] */ |
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const opus_int L /* I Number of NLSF parameters in the input vector */ |
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) |
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{ |
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opus_int i, I=0, k, loops; |
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opus_int16 center_freq_Q15; |
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opus_int32 diff_Q15, min_diff_Q15, min_center_Q15, max_center_Q15; |
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/* This is necessary to ensure an output within range of a opus_int16 */ |
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silk_assert( NDeltaMin_Q15[L] >= 1 ); |
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for( loops = 0; loops < MAX_LOOPS; loops++ ) { |
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/**************************/ |
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/* Find smallest distance */ |
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/**************************/ |
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/* First element */ |
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min_diff_Q15 = NLSF_Q15[0] - NDeltaMin_Q15[0]; |
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I = 0; |
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/* Middle elements */ |
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for( i = 1; i <= L-1; i++ ) { |
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diff_Q15 = NLSF_Q15[i] - ( NLSF_Q15[i-1] + NDeltaMin_Q15[i] ); |
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if( diff_Q15 < min_diff_Q15 ) { |
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min_diff_Q15 = diff_Q15; |
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I = i; |
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} |
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} |
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/* Last element */ |
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diff_Q15 = ( 1 << 15 ) - ( NLSF_Q15[L-1] + NDeltaMin_Q15[L] ); |
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if( diff_Q15 < min_diff_Q15 ) { |
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min_diff_Q15 = diff_Q15; |
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I = L; |
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} |
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/***************************************************/ |
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/* Now check if the smallest distance non-negative */ |
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/***************************************************/ |
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if( min_diff_Q15 >= 0 ) { |
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return; |
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} |
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if( I == 0 ) { |
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/* Move away from lower limit */ |
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NLSF_Q15[0] = NDeltaMin_Q15[0]; |
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} else if( I == L) { |
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/* Move away from higher limit */ |
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NLSF_Q15[L-1] = ( 1 << 15 ) - NDeltaMin_Q15[L]; |
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} else { |
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/* Find the lower extreme for the location of the current center frequency */ |
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min_center_Q15 = 0; |
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for( k = 0; k < I; k++ ) { |
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min_center_Q15 += NDeltaMin_Q15[k]; |
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} |
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min_center_Q15 += silk_RSHIFT( NDeltaMin_Q15[I], 1 ); |
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/* Find the upper extreme for the location of the current center frequency */ |
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max_center_Q15 = 1 << 15; |
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for( k = L; k > I; k-- ) { |
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max_center_Q15 -= NDeltaMin_Q15[k]; |
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} |
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max_center_Q15 -= silk_RSHIFT( NDeltaMin_Q15[I], 1 ); |
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/* Move apart, sorted by value, keeping the same center frequency */ |
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center_freq_Q15 = (opus_int16)silk_LIMIT_32( silk_RSHIFT_ROUND( (opus_int32)NLSF_Q15[I-1] + (opus_int32)NLSF_Q15[I], 1 ), |
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min_center_Q15, max_center_Q15 ); |
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NLSF_Q15[I-1] = center_freq_Q15 - silk_RSHIFT( NDeltaMin_Q15[I], 1 ); |
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NLSF_Q15[I] = NLSF_Q15[I-1] + NDeltaMin_Q15[I]; |
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} |
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} |
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/* Safe and simple fall back method, which is less ideal than the above */ |
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if( loops == MAX_LOOPS ) |
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{ |
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/* Insertion sort (fast for already almost sorted arrays): */ |
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/* Best case: O(n) for an already sorted array */ |
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/* Worst case: O(n^2) for an inversely sorted array */ |
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silk_insertion_sort_increasing_all_values_int16( &NLSF_Q15[0], L ); |
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/* First NLSF should be no less than NDeltaMin[0] */ |
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NLSF_Q15[0] = silk_max_int( NLSF_Q15[0], NDeltaMin_Q15[0] ); |
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/* Keep delta_min distance between the NLSFs */ |
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for( i = 1; i < L; i++ ) |
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NLSF_Q15[i] = silk_max_int( NLSF_Q15[i], silk_ADD_SAT16( NLSF_Q15[i-1], NDeltaMin_Q15[i] ) ); |
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/* Last NLSF should be no higher than 1 - NDeltaMin[L] */ |
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NLSF_Q15[L-1] = silk_min_int( NLSF_Q15[L-1], (1<<15) - NDeltaMin_Q15[L] ); |
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/* Keep NDeltaMin distance between the NLSFs */ |
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for( i = L-2; i >= 0; i-- ) |
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NLSF_Q15[i] = silk_min_int( NLSF_Q15[i], NLSF_Q15[i+1] - NDeltaMin_Q15[i+1] ); |
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} |
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}
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