152 lines
7.4 KiB
C
152 lines
7.4 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, (subject to the limitations in the disclaimer below)
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are permitted provided that the following conditions 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 Skype Limited, nor the names of specific
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contributors, may be used to endorse or promote products derived from
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this software without specific prior written permission.
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NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
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BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
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BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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***********************************************************************/
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#include "SKP_Silk_main_FIX.h"
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#include "SKP_Silk_tuning_parameters.h"
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/* Finds LPC vector from correlations, and converts to NLSF */
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void SKP_Silk_find_LPC_FIX(
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SKP_int NLSF_Q15[], /* O NLSFs */
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SKP_int *interpIndex, /* O NLSF interpolation index, only used for NLSF interpolation */
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const SKP_int prev_NLSFq_Q15[], /* I previous NLSFs, only used for NLSF interpolation */
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const SKP_int useInterpolatedNLSFs, /* I Flag */
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const SKP_int LPC_order, /* I LPC order */
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const SKP_int16 x[], /* I Input signal */
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const SKP_int subfr_length /* I Input signal subframe length including preceeding samples */
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)
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{
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SKP_int k;
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SKP_int32 a_Q16[ MAX_LPC_ORDER ];
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SKP_int isInterpLower, shift;
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SKP_int16 S[ MAX_LPC_ORDER ];
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SKP_int32 res_nrg0, res_nrg1;
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SKP_int rshift0, rshift1;
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/* Used only for LSF interpolation */
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SKP_int32 a_tmp_Q16[ MAX_LPC_ORDER ], res_nrg_interp, res_nrg, res_tmp_nrg, res_nrg_2nd;
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SKP_int res_nrg_interp_Q, res_nrg_Q, res_tmp_nrg_Q, res_nrg_2nd_Q;
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SKP_int16 a_tmp_Q12[ MAX_LPC_ORDER ];
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SKP_int NLSF0_Q15[ MAX_LPC_ORDER ];
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SKP_int16 LPC_res[ ( MAX_FRAME_LENGTH + NB_SUBFR * MAX_LPC_ORDER ) / 2 ];
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/* Default: no interpolation */
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*interpIndex = 4;
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/* Burg AR analysis for the full frame */
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SKP_Silk_burg_modified( &res_nrg, &res_nrg_Q, a_Q16, x, subfr_length, NB_SUBFR, SKP_FIX_CONST( FIND_LPC_COND_FAC, 32 ), LPC_order );
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SKP_Silk_bwexpander_32( a_Q16, LPC_order, SKP_FIX_CONST( FIND_LPC_CHIRP, 16 ) );
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if( useInterpolatedNLSFs == 1 ) {
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/* Optimal solution for last 10 ms */
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SKP_Silk_burg_modified( &res_tmp_nrg, &res_tmp_nrg_Q, a_tmp_Q16, x + ( NB_SUBFR >> 1 ) * subfr_length,
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subfr_length, ( NB_SUBFR >> 1 ), SKP_FIX_CONST( FIND_LPC_COND_FAC, 32 ), LPC_order );
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SKP_Silk_bwexpander_32( a_tmp_Q16, LPC_order, SKP_FIX_CONST( FIND_LPC_CHIRP, 16 ) );
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/* subtract residual energy here, as that's easier than adding it to the */
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/* residual energy of the first 10 ms in each iteration of the search below */
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shift = res_tmp_nrg_Q - res_nrg_Q;
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if( shift >= 0 ) {
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if( shift < 32 ) {
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res_nrg = res_nrg - SKP_RSHIFT( res_tmp_nrg, shift );
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}
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} else {
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SKP_assert( shift > -32 );
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res_nrg = SKP_RSHIFT( res_nrg, -shift ) - res_tmp_nrg;
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res_nrg_Q = res_tmp_nrg_Q;
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}
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/* Convert to NLSFs */
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SKP_Silk_A2NLSF( NLSF_Q15, a_tmp_Q16, LPC_order );
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/* Search over interpolation indices to find the one with lowest residual energy */
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res_nrg_2nd = SKP_int32_MAX;
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for( k = 3; k >= 0; k-- ) {
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/* Interpolate NLSFs for first half */
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SKP_Silk_interpolate( NLSF0_Q15, prev_NLSFq_Q15, NLSF_Q15, k, LPC_order );
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/* Convert to LPC for residual energy evaluation */
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SKP_Silk_NLSF2A_stable( a_tmp_Q12, NLSF0_Q15, LPC_order );
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/* Calculate residual energy with NLSF interpolation */
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SKP_memset( S, 0, LPC_order * sizeof( SKP_int16 ) );
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SKP_Silk_LPC_analysis_filter( x, a_tmp_Q12, S, LPC_res, 2 * subfr_length, LPC_order );
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SKP_Silk_sum_sqr_shift( &res_nrg0, &rshift0, LPC_res + LPC_order, subfr_length - LPC_order );
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SKP_Silk_sum_sqr_shift( &res_nrg1, &rshift1, LPC_res + LPC_order + subfr_length, subfr_length - LPC_order );
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/* Add subframe energies from first half frame */
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shift = rshift0 - rshift1;
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if( shift >= 0 ) {
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res_nrg1 = SKP_RSHIFT( res_nrg1, shift );
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res_nrg_interp_Q = -rshift0;
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} else {
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res_nrg0 = SKP_RSHIFT( res_nrg0, -shift );
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res_nrg_interp_Q = -rshift1;
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}
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res_nrg_interp = SKP_ADD32( res_nrg0, res_nrg1 );
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/* Compare with first half energy without NLSF interpolation, or best interpolated value so far */
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shift = res_nrg_interp_Q - res_nrg_Q;
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if( shift >= 0 ) {
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if( SKP_RSHIFT( res_nrg_interp, shift ) < res_nrg ) {
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isInterpLower = SKP_TRUE;
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} else {
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isInterpLower = SKP_FALSE;
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}
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} else {
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if( -shift < 32 ) {
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if( res_nrg_interp < SKP_RSHIFT( res_nrg, -shift ) ) {
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isInterpLower = SKP_TRUE;
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} else {
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isInterpLower = SKP_FALSE;
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}
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} else {
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isInterpLower = SKP_FALSE;
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}
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}
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/* Determine whether current interpolated NLSFs are best so far */
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if( isInterpLower == SKP_TRUE ) {
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/* Interpolation has lower residual energy */
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res_nrg = res_nrg_interp;
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res_nrg_Q = res_nrg_interp_Q;
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*interpIndex = k;
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}
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res_nrg_2nd = res_nrg_interp;
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res_nrg_2nd_Q = res_nrg_interp_Q;
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}
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}
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if( *interpIndex == 4 ) {
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/* NLSF interpolation is currently inactive, calculate NLSFs from full frame AR coefficients */
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SKP_Silk_A2NLSF( NLSF_Q15, a_Q16, LPC_order );
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}
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}
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