239 lines
8.1 KiB
C
239 lines
8.1 KiB
C
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/******************************************************************
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iLBC Speech Coder ANSI-C Source Code
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LPCencode.c
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Copyright (C) The Internet Society (2004).
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All Rights Reserved.
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******************************************************************/
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#include <string.h>
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#include "iLBC_define.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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/*----------------------------------------------------------------*
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* lpc analysis (subroutine to LPCencode)
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*---------------------------------------------------------------*/
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void SimpleAnalysis(
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float *lsf, /* (o) lsf coefficients */
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float *data, /* (i) new data vector */
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iLBC_Enc_Inst_t *iLBCenc_inst
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/* (i/o) the encoder state structure */
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){
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int k, is;
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float temp[BLOCKL_MAX], lp[LPC_FILTERORDER + 1];
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float lp2[LPC_FILTERORDER + 1];
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float r[LPC_FILTERORDER + 1];
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is=LPC_LOOKBACK+BLOCKL_MAX-iLBCenc_inst->blockl;
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memcpy(iLBCenc_inst->lpc_buffer+is,data,
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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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is = LPC_LOOKBACK;
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if (k < (iLBCenc_inst->lpc_n - 1)) {
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window(temp, lpc_winTbl,
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iLBCenc_inst->lpc_buffer, BLOCKL_MAX);
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} else {
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window(temp, lpc_asymwinTbl,
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iLBCenc_inst->lpc_buffer + is, BLOCKL_MAX);
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}
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autocorr(r, temp, BLOCKL_MAX, LPC_FILTERORDER);
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window(r, r, lpc_lagwinTbl, LPC_FILTERORDER + 1);
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levdurb(lp, temp, r, LPC_FILTERORDER);
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bwexpand(lp2, lp, LPC_CHIRP_SYNTDENUM, LPC_FILTERORDER+1);
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a2lsf(lsf + k*LPC_FILTERORDER, lp2);
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}
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is=LPC_LOOKBACK+BLOCKL_MAX-iLBCenc_inst->blockl;
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memmove(iLBCenc_inst->lpc_buffer,
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iLBCenc_inst->lpc_buffer+LPC_LOOKBACK+BLOCKL_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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void LSFinterpolate2a_enc(
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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
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lsf1 and lsf2 */
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long length /* (i) length of coefficient vectors */
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){
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float lsftmp[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 (subroutine to LPCencode)
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*---------------------------------------------------------------*/
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void SimpleInterpolateLSF(
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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 LPC_FILTERORDER */
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iLBC_Enc_Inst_t *iLBCenc_inst
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/* (i/o) the encoder state structure */
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){
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int i, pos, lp_length;
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float lp[LPC_FILTERORDER + 1], *lsf2, *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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/* 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,
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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,
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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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LSFinterpolate2a_enc(lp, lsfdeq, lsfdeq2,
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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,
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lsf_weightTbl_30ms[i], length);
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bwexpand(weightdenum + pos, lp,
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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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pos = 0;
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for (i = 0; i < iLBCenc_inst->nsub; i++) {
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LSFinterpolate2a_enc(lp, lsfdeqold, lsfdeq,
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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,
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lsf_weightTbl_20ms[i], length);
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bwexpand(weightdenum+pos, lp,
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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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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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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 (subroutine to LPCencode)
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*---------------------------------------------------------------*/
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void SimplelsfQ(
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float *lsfdeq, /* (o) dequantized lsf coefficients
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(dimension FILTERORDER) */
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int *index, /* (o) quantization index */
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float *lsf, /* (i) the lsf coefficient vector to be
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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,
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dim_lsfCbTbl, size_lsfCbTbl);
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if (lpc_n==2) {
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/* Quantize second LSF with memoryless split VQ */
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SplitVQ(lsfdeq + LPC_FILTERORDER, index + LSF_NSPLIT,
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lsf + LPC_FILTERORDER, lsfCbTbl, LSF_NSPLIT,
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dim_lsfCbTbl, 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(
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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_Enc_Inst_t *iLBCenc_inst
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/* (i/o) the encoder state structure */
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){
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float lsf[LPC_FILTERORDER * LPC_N_MAX];
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float lsfdeq[LPC_FILTERORDER * LPC_N_MAX];
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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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LSF_check(lsfdeq, LPC_FILTERORDER, iLBCenc_inst->lpc_n);
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SimpleInterpolateLSF(syntdenum, weightdenum,
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lsf, lsfdeq, iLBCenc_inst->lsfold,
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iLBCenc_inst->lsfdeqold, LPC_FILTERORDER, iLBCenc_inst);
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}
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