101 lines
5.3 KiB
C
101 lines
5.3 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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#include "opus/opus_config.h"
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#include "opus/silk/define.h"
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#include "opus/silk/float/main_FLP.h"
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#include "opus/silk/tuning_parameters.h"
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/* LPC analysis */
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void silk_find_LPC_FLP(
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silk_encoder_state *psEncC, /* I/O Encoder state */
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opus_int16 NLSF_Q15[], /* O NLSFs */
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const silk_float x[], /* I Input signal */
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const silk_float minInvGain /* I Inverse of max prediction gain */
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)
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{
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opus_int k, subfr_length;
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silk_float a[ MAX_LPC_ORDER ];
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/* Used only for NLSF interpolation */
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silk_float res_nrg, res_nrg_2nd, res_nrg_interp;
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opus_int16 NLSF0_Q15[ MAX_LPC_ORDER ];
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silk_float a_tmp[ MAX_LPC_ORDER ];
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silk_float LPC_res[ MAX_FRAME_LENGTH + MAX_NB_SUBFR * MAX_LPC_ORDER ];
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subfr_length = psEncC->subfr_length + psEncC->predictLPCOrder;
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/* Default: No interpolation */
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psEncC->indices.NLSFInterpCoef_Q2 = 4;
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/* Burg AR analysis for the full frame */
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res_nrg = silk_burg_modified_FLP( a, x, minInvGain, subfr_length, psEncC->nb_subfr, psEncC->predictLPCOrder );
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if( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) {
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/* Optimal solution for last 10 ms; subtract residual energy here, as that's easier than */
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/* adding it to the residual energy of the first 10 ms in each iteration of the search below */
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res_nrg -= silk_burg_modified_FLP( a_tmp, x + ( MAX_NB_SUBFR / 2 ) * subfr_length, minInvGain, subfr_length, MAX_NB_SUBFR / 2, psEncC->predictLPCOrder );
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/* Convert to NLSFs */
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silk_A2NLSF_FLP( NLSF_Q15, a_tmp, psEncC->predictLPCOrder );
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/* Search over interpolation indices to find the one with lowest residual energy */
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res_nrg_2nd = silk_float_MAX;
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for( k = 3; k >= 0; k-- ) {
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/* Interpolate NLSFs for first half */
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silk_interpolate( NLSF0_Q15, psEncC->prev_NLSFq_Q15, NLSF_Q15, k, psEncC->predictLPCOrder );
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/* Convert to LPC for residual energy evaluation */
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silk_NLSF2A_FLP( a_tmp, NLSF0_Q15, psEncC->predictLPCOrder );
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/* Calculate residual energy with LSF interpolation */
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silk_LPC_analysis_filter_FLP( LPC_res, a_tmp, x, 2 * subfr_length, psEncC->predictLPCOrder );
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res_nrg_interp = (silk_float)(
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silk_energy_FLP( LPC_res + psEncC->predictLPCOrder, subfr_length - psEncC->predictLPCOrder ) +
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silk_energy_FLP( LPC_res + psEncC->predictLPCOrder + subfr_length, subfr_length - psEncC->predictLPCOrder ) );
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/* Determine whether current interpolated NLSFs are best so far */
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if( res_nrg_interp < res_nrg ) {
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/* Interpolation has lower residual energy */
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res_nrg = res_nrg_interp;
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psEncC->indices.NLSFInterpCoef_Q2 = (opus_int8)k;
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} else if( res_nrg_interp > res_nrg_2nd ) {
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/* No reason to continue iterating - residual energies will continue to climb */
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break;
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}
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res_nrg_2nd = res_nrg_interp;
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}
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}
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if( psEncC->indices.NLSFInterpCoef_Q2 == 4 ) {
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/* NLSF interpolation is currently inactive, calculate NLSFs from full frame AR coefficients */
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silk_A2NLSF_FLP( NLSF_Q15, a, psEncC->predictLPCOrder );
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}
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silk_assert( psEncC->indices.NLSFInterpCoef_Q2 == 4 ||
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( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) );
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}
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