73 lines
3.2 KiB
C
73 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.
|
|
***********************************************************************/
|
|
#include "opus/opus_config.h"
|
|
|
|
#include "opus/silk/SigProc_FIX.h"
|
|
#include "opus/silk/float/SigProc_FLP.h"
|
|
|
|
#define RC_THRESHOLD 0.9999f
|
|
|
|
/* compute inverse of LPC prediction gain, and */
|
|
/* test if LPC coefficients are stable (all poles within unit circle) */
|
|
/* this code is based on silk_a2k_FLP() */
|
|
silk_float silk_LPC_inverse_pred_gain_FLP( /* O return inverse prediction gain, energy domain */
|
|
const silk_float *A, /* I prediction coefficients [order] */
|
|
opus_int32 order /* I prediction order */
|
|
)
|
|
{
|
|
opus_int k, n;
|
|
double invGain, rc, rc_mult1, rc_mult2;
|
|
silk_float Atmp[ 2 ][ SILK_MAX_ORDER_LPC ];
|
|
silk_float *Aold, *Anew;
|
|
|
|
Anew = Atmp[ order & 1 ];
|
|
silk_memcpy( Anew, A, order * sizeof(silk_float) );
|
|
|
|
invGain = 1.0;
|
|
for( k = order - 1; k > 0; k-- ) {
|
|
rc = -Anew[ k ];
|
|
if( rc > RC_THRESHOLD || rc < -RC_THRESHOLD ) {
|
|
return 0.0f;
|
|
}
|
|
rc_mult1 = 1.0f - rc * rc;
|
|
rc_mult2 = 1.0f / rc_mult1;
|
|
invGain *= rc_mult1;
|
|
/* swap pointers */
|
|
Aold = Anew;
|
|
Anew = Atmp[ k & 1 ];
|
|
for( n = 0; n < k; n++ ) {
|
|
Anew[ n ] = (silk_float)( ( Aold[ n ] - Aold[ k - n - 1 ] * rc ) * rc_mult2 );
|
|
}
|
|
}
|
|
rc = -Anew[ 0 ];
|
|
if( rc > RC_THRESHOLD || rc < -RC_THRESHOLD ) {
|
|
return 0.0f;
|
|
}
|
|
rc_mult1 = 1.0f - rc * rc;
|
|
invGain *= rc_mult1;
|
|
return (silk_float)invGain;
|
|
}
|