d9a291f641
Took the opportunity to undo the Godot changed made to the opus source. The opus module should eventually be built in its own environment to avoid polluting others with too many include dirs and defines. TODO: Fix the platform/ stuff for opus.
81 lines
3.2 KiB
C
81 lines
3.2 KiB
C
/***********************************************************************
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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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#include "SigProc_FLP.h"
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/* Solve the normal equations using the Levinson-Durbin recursion */
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silk_float silk_levinsondurbin_FLP( /* O prediction error energy */
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silk_float A[], /* O prediction coefficients [order] */
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const silk_float corr[], /* I input auto-correlations [order + 1] */
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const opus_int order /* I prediction order */
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)
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{
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opus_int i, mHalf, m;
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silk_float min_nrg, nrg, t, km, Atmp1, Atmp2;
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min_nrg = 1e-12f * corr[ 0 ] + 1e-9f;
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nrg = corr[ 0 ];
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nrg = silk_max_float(min_nrg, nrg);
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A[ 0 ] = corr[ 1 ] / nrg;
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nrg -= A[ 0 ] * corr[ 1 ];
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nrg = silk_max_float(min_nrg, nrg);
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for( m = 1; m < order; m++ )
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{
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t = corr[ m + 1 ];
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for( i = 0; i < m; i++ ) {
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t -= A[ i ] * corr[ m - i ];
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}
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/* reflection coefficient */
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km = t / nrg;
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/* residual energy */
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nrg -= km * t;
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nrg = silk_max_float(min_nrg, nrg);
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mHalf = m >> 1;
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for( i = 0; i < mHalf; i++ ) {
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Atmp1 = A[ i ];
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Atmp2 = A[ m - i - 1 ];
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A[ m - i - 1 ] -= km * Atmp1;
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A[ i ] -= km * Atmp2;
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}
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if( m & 1 ) {
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A[ mHalf ] -= km * A[ mHalf ];
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}
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A[ m ] = km;
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}
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/* return the residual energy */
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return nrg;
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}
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