Line data    Source code

       1             : /***********************************************************************
       2             : Copyright (c) 2006-2011, Skype Limited. All rights reserved.
       3             : Redistribution and use in source and binary forms, with or without
       4             : modification, are permitted provided that the following conditions
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       6             : - Redistributions of source code must retain the above copyright notice,
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       8             : - Redistributions in binary form must reproduce the above copyright
       9             : notice, this list of conditions and the following disclaimer in the
      10             : documentation and/or other materials provided with the distribution.
      11             : - Neither the name of Internet Society, IETF or IETF Trust, nor the
      12             : names of specific contributors, may be used to endorse or promote
      13             : products derived from this software without specific prior written
      14             : permission.
      15             : THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
      16             : AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
      17             : IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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      22             : INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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      24             : ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
      25             : POSSIBILITY OF SUCH DAMAGE.
      26             : ***********************************************************************/
      27             : 
      28             : #ifdef HAVE_CONFIG_H
      29             : #include "config.h"
      30             : #endif
      31             : 
      32             : #include "define.h"
      33             : #include "main_FLP.h"
      34             : #include "tuning_parameters.h"
      35             : 
      36             : /* LPC analysis */
      37           0 : void silk_find_LPC_FLP(
      38             :     silk_encoder_state              *psEncC,                            /* I/O  Encoder state                               */
      39             :     opus_int16                      NLSF_Q15[],                         /* O    NLSFs                                       */
      40             :     const silk_float                x[],                                /* I    Input signal                                */
      41             :     const silk_float                minInvGain                          /* I    Inverse of max prediction gain              */
      42             : )
      43             : {
      44             :     opus_int    k, subfr_length;
      45             :     silk_float  a[ MAX_LPC_ORDER ];
      46             : 
      47             :     /* Used only for NLSF interpolation */
      48             :     silk_float  res_nrg, res_nrg_2nd, res_nrg_interp;
      49             :     opus_int16  NLSF0_Q15[ MAX_LPC_ORDER ];
      50             :     silk_float  a_tmp[ MAX_LPC_ORDER ];
      51             :     silk_float  LPC_res[ MAX_FRAME_LENGTH + MAX_NB_SUBFR * MAX_LPC_ORDER ];
      52             : 
      53           0 :     subfr_length = psEncC->subfr_length + psEncC->predictLPCOrder;
      54             : 
      55             :     /* Default: No interpolation */
      56           0 :     psEncC->indices.NLSFInterpCoef_Q2 = 4;
      57             : 
      58             :     /* Burg AR analysis for the full frame */
      59           0 :     res_nrg = silk_burg_modified_FLP( a, x, minInvGain, subfr_length, psEncC->nb_subfr, psEncC->predictLPCOrder );
      60             : 
      61           0 :     if( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) {
      62             :         /* Optimal solution for last 10 ms; subtract residual energy here, as that's easier than        */
      63             :         /* adding it to the residual energy of the first 10 ms in each iteration of the search below    */
      64           0 :         res_nrg -= silk_burg_modified_FLP( a_tmp, x + ( MAX_NB_SUBFR / 2 ) * subfr_length, minInvGain, subfr_length, MAX_NB_SUBFR / 2, psEncC->predictLPCOrder );
      65             : 
      66             :         /* Convert to NLSFs */
      67           0 :         silk_A2NLSF_FLP( NLSF_Q15, a_tmp, psEncC->predictLPCOrder );
      68             : 
      69             :         /* Search over interpolation indices to find the one with lowest residual energy */
      70           0 :         res_nrg_2nd = silk_float_MAX;
      71           0 :         for( k = 3; k >= 0; k-- ) {
      72             :             /* Interpolate NLSFs for first half */
      73           0 :             silk_interpolate( NLSF0_Q15, psEncC->prev_NLSFq_Q15, NLSF_Q15, k, psEncC->predictLPCOrder );
      74             : 
      75             :             /* Convert to LPC for residual energy evaluation */
      76           0 :             silk_NLSF2A_FLP( a_tmp, NLSF0_Q15, psEncC->predictLPCOrder, psEncC->arch );
      77             : 
      78             :             /* Calculate residual energy with LSF interpolation */
      79           0 :             silk_LPC_analysis_filter_FLP( LPC_res, a_tmp, x, 2 * subfr_length, psEncC->predictLPCOrder );
      80           0 :             res_nrg_interp = (silk_float)(
      81           0 :                 silk_energy_FLP( LPC_res + psEncC->predictLPCOrder,                subfr_length - psEncC->predictLPCOrder ) +
      82           0 :                 silk_energy_FLP( LPC_res + psEncC->predictLPCOrder + subfr_length, subfr_length - psEncC->predictLPCOrder ) );
      83             : 
      84             :             /* Determine whether current interpolated NLSFs are best so far */
      85           0 :             if( res_nrg_interp < res_nrg ) {
      86             :                 /* Interpolation has lower residual energy */
      87           0 :                 res_nrg = res_nrg_interp;
      88           0 :                 psEncC->indices.NLSFInterpCoef_Q2 = (opus_int8)k;
      89           0 :             } else if( res_nrg_interp > res_nrg_2nd ) {
      90             :                 /* No reason to continue iterating - residual energies will continue to climb */
      91           0 :                 break;
      92             :             }
      93           0 :             res_nrg_2nd = res_nrg_interp;
      94             :         }
      95             :     }
      96             : 
      97           0 :     if( psEncC->indices.NLSFInterpCoef_Q2 == 4 ) {
      98             :         /* NLSF interpolation is currently inactive, calculate NLSFs from full frame AR coefficients */
      99           0 :         silk_A2NLSF_FLP( NLSF_Q15, a, psEncC->predictLPCOrder );
     100             :     }
     101             : 
     102           0 :     silk_assert( psEncC->indices.NLSFInterpCoef_Q2 == 4 ||
     103             :         ( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) );
     104           0 : }