230 lines
9.3 KiB
C
230 lines
9.3 KiB
C
/*
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* iLBC - a library for the iLBC codec
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*
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* LPCencode.c - The iLBC low bit rate speech codec.
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*
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* Adapted by Steve Underwood <steveu@coppice.org> from the reference
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* iLBC code supplied in RFC3951.
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*
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* Original code Copyright (C) The Internet Society (2004).
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* All changes to produce this version Copyright (C) 2008 by Steve Underwood
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* All Rights Reserved.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*
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* $Id: LPCencode.c,v 1.2 2008/03/06 12:27:37 steveu Exp $
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*/
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/*! \file */
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <inttypes.h>
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#include <string.h>
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#include "ilbc.h"
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#include "helpfun.h"
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#include "lsf.h"
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#include "constants.h"
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#include "LPCencode.h"
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/*----------------------------------------------------------------*
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* lpc analysis (subroutine to LPCencode)
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*---------------------------------------------------------------*/
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static void SimpleAnalysis(float *lsf, /* (o) lsf coefficients */
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float *data, /* (i) new data vector */
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ilbc_encode_state_t *iLBCenc_inst) /* (i/o) the encoder state structure */
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{
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int k;
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int is;
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float temp[ILBC_BLOCK_LEN_MAX];
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float lp[ILBC_LPC_FILTERORDER + 1];
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float lp2[ILBC_LPC_FILTERORDER + 1];
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float r[ILBC_LPC_FILTERORDER + 1];
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is = LPC_LOOKBACK + ILBC_BLOCK_LEN_MAX - iLBCenc_inst->blockl;
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memcpy(iLBCenc_inst->lpc_buffer + is, data, iLBCenc_inst->blockl*sizeof(float));
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/* No lookahead, last window is asymmetric */
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for (k = 0; k < iLBCenc_inst->lpc_n; k++)
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{
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is = LPC_LOOKBACK;
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if (k < (iLBCenc_inst->lpc_n - 1))
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window(temp, lpc_winTbl, iLBCenc_inst->lpc_buffer, ILBC_BLOCK_LEN_MAX);
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else
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window(temp, lpc_asymwinTbl, iLBCenc_inst->lpc_buffer + is, ILBC_BLOCK_LEN_MAX);
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autocorr(r, temp, ILBC_BLOCK_LEN_MAX, ILBC_LPC_FILTERORDER);
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window(r, r, lpc_lagwinTbl, ILBC_LPC_FILTERORDER + 1);
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levdurb(lp, temp, r, ILBC_LPC_FILTERORDER);
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bwexpand(lp2, lp, LPC_CHIRP_SYNTDENUM, ILBC_LPC_FILTERORDER + 1);
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a2lsf(lsf + k*ILBC_LPC_FILTERORDER, lp2);
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}
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is = LPC_LOOKBACK + ILBC_BLOCK_LEN_MAX - iLBCenc_inst->blockl;
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memmove(iLBCenc_inst->lpc_buffer,
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iLBCenc_inst->lpc_buffer + LPC_LOOKBACK + ILBC_BLOCK_LEN_MAX - is,
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is*sizeof(float));
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}
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/*----------------------------------------------------------------*
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* lsf interpolator and conversion from lsf to a coefficients
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* (subroutine to SimpleInterpolateLSF)
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*---------------------------------------------------------------*/
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static void LSFinterpolate2a_enc(float *a, /* (o) lpc coefficients */
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float *lsf1, /* (i) first set of lsf coefficients */
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float *lsf2, /* (i) second set of lsf coefficients */
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float coef, /* (i) weighting coefficient to use between lsf1 and lsf2 */
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long length) /* (i) length of coefficient vectors */
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{
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float lsftmp[ILBC_LPC_FILTERORDER];
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interpolate(lsftmp, lsf1, lsf2, coef, length);
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lsf2a(a, lsftmp);
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}
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/*----------------------------------------------------------------*
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* lsf interpolator (subrutine to LPCencode)
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*---------------------------------------------------------------*/
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static void SimpleInterpolateLSF(float *syntdenum, /* (o) the synthesis filter denominator
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resulting from the quantized
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interpolated lsf */
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float *weightdenum, /* (o) the weighting filter denominator
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resulting from the unquantized
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interpolated lsf */
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float *lsf, /* (i) the unquantized lsf coefficients */
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float *lsfdeq, /* (i) the dequantized lsf coefficients */
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float *lsfold, /* (i) the unquantized lsf coefficients of
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the previous signal frame */
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float *lsfdeqold, /* (i) the dequantized lsf coefficients of
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the previous signal frame */
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int length, /* (i) should equate ILBC_LPC_FILTERORDER */
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ilbc_encode_state_t *iLBCenc_inst) /* (i/o) the encoder state structure */
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{
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int i;
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int pos;
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int lp_length;
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float lp[ILBC_LPC_FILTERORDER + 1];
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float *lsf2;
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float *lsfdeq2;
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lsf2 = lsf + length;
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lsfdeq2 = lsfdeq + length;
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lp_length = length + 1;
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if (iLBCenc_inst->mode == 30)
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{
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/* sub-frame 1: Interpolation between old and first
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set of lsf coefficients */
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LSFinterpolate2a_enc(lp, lsfdeqold, lsfdeq, lsf_weightTbl_30ms[0], length);
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memcpy(syntdenum,lp,lp_length*sizeof(float));
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LSFinterpolate2a_enc(lp, lsfold, lsf, lsf_weightTbl_30ms[0], length);
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bwexpand(weightdenum, lp, LPC_CHIRP_WEIGHTDENUM, lp_length);
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/* sub-frame 2 to 6: Interpolation between first
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and second set of lsf coefficients */
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pos = lp_length;
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for (i = 1; i < iLBCenc_inst->nsub; i++)
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{
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LSFinterpolate2a_enc(lp, lsfdeq, lsfdeq2, lsf_weightTbl_30ms[i], length);
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memcpy(syntdenum + pos,lp,lp_length*sizeof(float));
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LSFinterpolate2a_enc(lp, lsf, lsf2, lsf_weightTbl_30ms[i], length);
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bwexpand(weightdenum + pos, lp, LPC_CHIRP_WEIGHTDENUM, lp_length);
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pos += lp_length;
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}
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}
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else
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{
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pos = 0;
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for (i = 0; i < iLBCenc_inst->nsub; i++)
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{
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LSFinterpolate2a_enc(lp, lsfdeqold, lsfdeq, lsf_weightTbl_20ms[i], length);
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memcpy(syntdenum + pos, lp, lp_length*sizeof(float));
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LSFinterpolate2a_enc(lp, lsfold, lsf, lsf_weightTbl_20ms[i], length);
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bwexpand(weightdenum + pos, lp, LPC_CHIRP_WEIGHTDENUM, lp_length);
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pos += lp_length;
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}
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}
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/* update memory */
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if (iLBCenc_inst->mode == 30)
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{
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memcpy(lsfold, lsf2, length*sizeof(float));
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memcpy(lsfdeqold, lsfdeq2, length*sizeof(float));
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}
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else
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{
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memcpy(lsfold, lsf, length*sizeof(float));
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memcpy(lsfdeqold, lsfdeq, length*sizeof(float));
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}
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}
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/*----------------------------------------------------------------*
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* lsf quantizer (subrutine to LPCencode)
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*---------------------------------------------------------------*/
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static void SimplelsfQ(float *lsfdeq, /* (o) dequantized lsf coefficients (dimension FILTERORDER) */
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int *index, /* (o) quantization index */
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float *lsf, /* (i) the lsf coefficient vector to be quantized (dimension FILTERORDER ) */
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int lpc_n) /* (i) number of lsf sets to quantize */
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{
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/* Quantize first LSF with memoryless split VQ */
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SplitVQ(lsfdeq, index, lsf, lsfCbTbl, LSF_NSPLIT, dim_lsfCbTbl, size_lsfCbTbl);
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if (lpc_n == 2)
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{
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/* Quantize second LSF with memoryless split VQ */
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SplitVQ(lsfdeq + ILBC_LPC_FILTERORDER,
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index + LSF_NSPLIT,
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lsf + ILBC_LPC_FILTERORDER,
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lsfCbTbl,
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LSF_NSPLIT,
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dim_lsfCbTbl,
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size_lsfCbTbl);
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}
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}
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/*----------------------------------------------------------------*
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* lpc encoder
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*---------------------------------------------------------------*/
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void LPCencode(float *syntdenum, /* (i/o) synthesis filter coefficients
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before/after encoding */
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float *weightdenum, /* (i/o) weighting denumerator
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coefficients before/after
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encoding */
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int *lsf_index, /* (o) lsf quantization index */
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float *data, /* (i) lsf coefficients to quantize */
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ilbc_encode_state_t *iLBCenc_inst) /* (i/o) the encoder state structure */
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{
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float lsf[ILBC_LPC_FILTERORDER*LPC_N_MAX];
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float lsfdeq[ILBC_LPC_FILTERORDER*LPC_N_MAX];
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int change = 0;
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SimpleAnalysis(lsf, data, iLBCenc_inst);
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SimplelsfQ(lsfdeq, lsf_index, lsf, iLBCenc_inst->lpc_n);
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change = LSF_check(lsfdeq, ILBC_LPC_FILTERORDER, iLBCenc_inst->lpc_n);
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SimpleInterpolateLSF(syntdenum,
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weightdenum,
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lsf,
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lsfdeq,
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iLBCenc_inst->lsfold,
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iLBCenc_inst->lsfdeqold,
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ILBC_LPC_FILTERORDER,
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iLBCenc_inst);
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}
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