1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/libopus/silk/float/LPC_inv_pred_gain_FLP.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,76 @@
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 +#include "SigProc_FIX.h"
1.36 +#include "SigProc_FLP.h"
1.37 +
1.38 +#define RC_THRESHOLD 0.9999f
1.39 +
1.40 +/* compute inverse of LPC prediction gain, and */
1.41 +/* test if LPC coefficients are stable (all poles within unit circle) */
1.42 +/* this code is based on silk_a2k_FLP() */
1.43 +silk_float silk_LPC_inverse_pred_gain_FLP( /* O return inverse prediction gain, energy domain */
1.44 + const silk_float *A, /* I prediction coefficients [order] */
1.45 + opus_int32 order /* I prediction order */
1.46 +)
1.47 +{
1.48 + opus_int k, n;
1.49 + double invGain, rc, rc_mult1, rc_mult2;
1.50 + silk_float Atmp[ 2 ][ SILK_MAX_ORDER_LPC ];
1.51 + silk_float *Aold, *Anew;
1.52 +
1.53 + Anew = Atmp[ order & 1 ];
1.54 + silk_memcpy( Anew, A, order * sizeof(silk_float) );
1.55 +
1.56 + invGain = 1.0;
1.57 + for( k = order - 1; k > 0; k-- ) {
1.58 + rc = -Anew[ k ];
1.59 + if( rc > RC_THRESHOLD || rc < -RC_THRESHOLD ) {
1.60 + return 0.0f;
1.61 + }
1.62 + rc_mult1 = 1.0f - rc * rc;
1.63 + rc_mult2 = 1.0f / rc_mult1;
1.64 + invGain *= rc_mult1;
1.65 + /* swap pointers */
1.66 + Aold = Anew;
1.67 + Anew = Atmp[ k & 1 ];
1.68 + for( n = 0; n < k; n++ ) {
1.69 + Anew[ n ] = (silk_float)( ( Aold[ n ] - Aold[ k - n - 1 ] * rc ) * rc_mult2 );
1.70 + }
1.71 + }
1.72 + rc = -Anew[ 0 ];
1.73 + if( rc > RC_THRESHOLD || rc < -RC_THRESHOLD ) {
1.74 + return 0.0f;
1.75 + }
1.76 + rc_mult1 = 1.0f - rc * rc;
1.77 + invGain *= rc_mult1;
1.78 + return (silk_float)invGain;
1.79 +}
