mirror of
https://github.com/Relintai/pandemonium_engine.git
synced 2024-12-27 06:07:14 +01:00
82 lines
3.2 KiB
C
82 lines
3.2 KiB
C
|
/***********************************************************************
|
||
|
|
Copyright (c) 2006-2011, Skype Limited. All rights reserved.
|
||
|
|
Redistribution and use in source and binary forms, with or without
|
||
|
|
modification, are permitted provided that the following conditions
|
||
|
|
are met:
|
||
|
|
- Redistributions of source code must retain the above copyright notice,
|
||
|
|
this list of conditions and the following disclaimer.
|
||
|
|
- Redistributions in binary form must reproduce the above copyright
|
||
|
|
notice, this list of conditions and the following disclaimer in the
|
||
|
|
documentation and/or other materials provided with the distribution.
|
||
|
|
- Neither the name of Internet Society, IETF or IETF Trust, nor the
|
||
|
|
names of specific contributors, may be used to endorse or promote
|
||
|
|
products derived from this software without specific prior written
|
||
|
|
permission.
|
||
|
|
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
||
|
|
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||
|
|
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
||
|
|
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
||
|
|
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
||
|
|
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
||
|
|
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
||
|
|
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
||
|
|
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
||
|
|
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
||
|
|
POSSIBILITY OF SUCH DAMAGE.
|
||
|
|
***********************************************************************/
|
||
|
|
|
||
|
|
#ifdef HAVE_CONFIG_H
|
||
|
|
#include "config.h"
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#include "SigProc_FLP.h"
|
||
|
|
|
||
|
|
/* Solve the normal equations using the Levinson-Durbin recursion */
|
||
|
|
silk_float silk_levinsondurbin_FLP( /* O prediction error energy */
|
||
|
|
silk_float A[], /* O prediction coefficients [order] */
|
||
|
|
const silk_float corr[], /* I input auto-correlations [order + 1] */
|
||
|
|
const opus_int order /* I prediction order */
|
||
|
|
)
|
||
|
|
{
|
||
|
|
opus_int i, mHalf, m;
|
||
|
|
silk_float min_nrg, nrg, t, km, Atmp1, Atmp2;
|
||
|
|
|
||
|
|
min_nrg = 1e-12f * corr[ 0 ] + 1e-9f;
|
||
|
|
nrg = corr[ 0 ];
|
||
|
|
nrg = silk_max_float(min_nrg, nrg);
|
||
|
|
A[ 0 ] = corr[ 1 ] / nrg;
|
||
|
|
nrg -= A[ 0 ] * corr[ 1 ];
|
||
|
|
nrg = silk_max_float(min_nrg, nrg);
|
||
|
|
|
||
|
|
for( m = 1; m < order; m++ )
|
||
|
|
{
|
||
|
|
t = corr[ m + 1 ];
|
||
|
|
for( i = 0; i < m; i++ ) {
|
||
|
|
t -= A[ i ] * corr[ m - i ];
|
||
|
|
}
|
||
|
|
|
||
|
|
/* reflection coefficient */
|
||
|
|
km = t / nrg;
|
||
|
|
|
||
|
|
/* residual energy */
|
||
|
|
nrg -= km * t;
|
||
|
|
nrg = silk_max_float(min_nrg, nrg);
|
||
|
|
|
||
|
|
mHalf = m >> 1;
|
||
|
|
for( i = 0; i < mHalf; i++ ) {
|
||
|
|
Atmp1 = A[ i ];
|
||
|
|
Atmp2 = A[ m - i - 1 ];
|
||
|
|
A[ m - i - 1 ] -= km * Atmp1;
|
||
|
|
A[ i ] -= km * Atmp2;
|
||
|
|
}
|
||
|
|
if( m & 1 ) {
|
||
|
|
A[ mHalf ] -= km * A[ mHalf ];
|
||
|
|
}
|
||
|
|
A[ m ] = km;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* return the residual energy */
|
||
|
|
return nrg;
|
||
|
|
}
|
||
|
|
|