diff options
Diffstat (limited to 'media/libopus/silk/float/find_LPC_FLP.c')
| -rw-r--r-- | media/libopus/silk/float/find_LPC_FLP.c | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/media/libopus/silk/float/find_LPC_FLP.c b/media/libopus/silk/float/find_LPC_FLP.c new file mode 100644 index 000000000..fcfe1c368 --- /dev/null +++ b/media/libopus/silk/float/find_LPC_FLP.c @@ -0,0 +1,104 @@ +/*********************************************************************** +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. +***********************************************************************/ + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include "define.h" +#include "main_FLP.h" +#include "tuning_parameters.h" + +/* LPC analysis */ +void silk_find_LPC_FLP( + silk_encoder_state *psEncC, /* I/O Encoder state */ + opus_int16 NLSF_Q15[], /* O NLSFs */ + const silk_float x[], /* I Input signal */ + const silk_float minInvGain /* I Inverse of max prediction gain */ +) +{ + opus_int k, subfr_length; + silk_float a[ MAX_LPC_ORDER ]; + + /* Used only for NLSF interpolation */ + silk_float res_nrg, res_nrg_2nd, res_nrg_interp; + opus_int16 NLSF0_Q15[ MAX_LPC_ORDER ]; + silk_float a_tmp[ MAX_LPC_ORDER ]; + silk_float LPC_res[ MAX_FRAME_LENGTH + MAX_NB_SUBFR * MAX_LPC_ORDER ]; + + subfr_length = psEncC->subfr_length + psEncC->predictLPCOrder; + + /* Default: No interpolation */ + psEncC->indices.NLSFInterpCoef_Q2 = 4; + + /* Burg AR analysis for the full frame */ + res_nrg = silk_burg_modified_FLP( a, x, minInvGain, subfr_length, psEncC->nb_subfr, psEncC->predictLPCOrder ); + + if( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) { + /* Optimal solution for last 10 ms; subtract residual energy here, as that's easier than */ + /* adding it to the residual energy of the first 10 ms in each iteration of the search below */ + res_nrg -= silk_burg_modified_FLP( a_tmp, x + ( MAX_NB_SUBFR / 2 ) * subfr_length, minInvGain, subfr_length, MAX_NB_SUBFR / 2, psEncC->predictLPCOrder ); + + /* Convert to NLSFs */ + silk_A2NLSF_FLP( NLSF_Q15, a_tmp, psEncC->predictLPCOrder ); + + /* Search over interpolation indices to find the one with lowest residual energy */ + res_nrg_2nd = silk_float_MAX; + for( k = 3; k >= 0; k-- ) { + /* Interpolate NLSFs for first half */ + silk_interpolate( NLSF0_Q15, psEncC->prev_NLSFq_Q15, NLSF_Q15, k, psEncC->predictLPCOrder ); + + /* Convert to LPC for residual energy evaluation */ + silk_NLSF2A_FLP( a_tmp, NLSF0_Q15, psEncC->predictLPCOrder ); + + /* Calculate residual energy with LSF interpolation */ + silk_LPC_analysis_filter_FLP( LPC_res, a_tmp, x, 2 * subfr_length, psEncC->predictLPCOrder ); + res_nrg_interp = (silk_float)( + silk_energy_FLP( LPC_res + psEncC->predictLPCOrder, subfr_length - psEncC->predictLPCOrder ) + + silk_energy_FLP( LPC_res + psEncC->predictLPCOrder + subfr_length, subfr_length - psEncC->predictLPCOrder ) ); + + /* Determine whether current interpolated NLSFs are best so far */ + if( res_nrg_interp < res_nrg ) { + /* Interpolation has lower residual energy */ + res_nrg = res_nrg_interp; + psEncC->indices.NLSFInterpCoef_Q2 = (opus_int8)k; + } else if( res_nrg_interp > res_nrg_2nd ) { + /* No reason to continue iterating - residual energies will continue to climb */ + break; + } + res_nrg_2nd = res_nrg_interp; + } + } + + if( psEncC->indices.NLSFInterpCoef_Q2 == 4 ) { + /* NLSF interpolation is currently inactive, calculate NLSFs from full frame AR coefficients */ + silk_A2NLSF_FLP( NLSF_Q15, a, psEncC->predictLPCOrder ); + } + + silk_assert( psEncC->indices.NLSFInterpCoef_Q2 == 4 || + ( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) ); +} |