/****************************************************************** iLBC Speech Coder ANSI-C Source Code LPCencode.c Copyright (C) The Internet Society (2004). All Rights Reserved. ******************************************************************/ #include #include "iLBC_define.h" #include "helpfun.h" #include "lsf.h" #include "constants.h" /*----------------------------------------------------------------* * lpc analysis (subroutine to LPCencode) *---------------------------------------------------------------*/ void SimpleAnalysis( float *lsf, /* (o) lsf coefficients */ float *data, /* (i) new data vector */ iLBC_Enc_Inst_t *iLBCenc_inst /* (i/o) the encoder state structure */ ){ int k, is; float temp[BLOCKL_MAX], lp[LPC_FILTERORDER + 1]; float lp2[LPC_FILTERORDER + 1]; float r[LPC_FILTERORDER + 1]; is=LPC_LOOKBACK+BLOCKL_MAX-iLBCenc_inst->blockl; memcpy(iLBCenc_inst->lpc_buffer+is,data, iLBCenc_inst->blockl*sizeof(float)); /* No lookahead, last window is asymmetric */ for (k = 0; k < iLBCenc_inst->lpc_n; k++) { is = LPC_LOOKBACK; if (k < (iLBCenc_inst->lpc_n - 1)) { window(temp, lpc_winTbl, iLBCenc_inst->lpc_buffer, BLOCKL_MAX); } else { window(temp, lpc_asymwinTbl, iLBCenc_inst->lpc_buffer + is, BLOCKL_MAX); } autocorr(r, temp, BLOCKL_MAX, LPC_FILTERORDER); window(r, r, lpc_lagwinTbl, LPC_FILTERORDER + 1); levdurb(lp, temp, r, LPC_FILTERORDER); bwexpand(lp2, lp, LPC_CHIRP_SYNTDENUM, LPC_FILTERORDER+1); a2lsf(lsf + k*LPC_FILTERORDER, lp2); } is=LPC_LOOKBACK+BLOCKL_MAX-iLBCenc_inst->blockl; memmove(iLBCenc_inst->lpc_buffer, iLBCenc_inst->lpc_buffer+LPC_LOOKBACK+BLOCKL_MAX-is, is*sizeof(float)); } /*----------------------------------------------------------------* * lsf interpolator and conversion from lsf to a coefficients * (subroutine to SimpleInterpolateLSF) *---------------------------------------------------------------*/ void LSFinterpolate2a_enc( float *a, /* (o) lpc coefficients */ float *lsf1,/* (i) first set of lsf coefficients */ float *lsf2,/* (i) second set of lsf coefficients */ float coef, /* (i) weighting coefficient to use between lsf1 and lsf2 */ long length /* (i) length of coefficient vectors */ ){ float lsftmp[LPC_FILTERORDER]; interpolate(lsftmp, lsf1, lsf2, coef, length); lsf2a(a, lsftmp); } /*----------------------------------------------------------------* * lsf interpolator (subroutine to LPCencode) *---------------------------------------------------------------*/ void SimpleInterpolateLSF( float *syntdenum, /* (o) the synthesis filter denominator resulting from the quantized interpolated lsf */ float *weightdenum, /* (o) the weighting filter denominator resulting from the unquantized interpolated lsf */ float *lsf, /* (i) the unquantized lsf coefficients */ float *lsfdeq, /* (i) the dequantized lsf coefficients */ float *lsfold, /* (i) the unquantized lsf coefficients of the previous signal frame */ float *lsfdeqold, /* (i) the dequantized lsf coefficients of the previous signal frame */ int length, /* (i) should equate LPC_FILTERORDER */ iLBC_Enc_Inst_t *iLBCenc_inst /* (i/o) the encoder state structure */ ){ int i, pos, lp_length; float lp[LPC_FILTERORDER + 1], *lsf2, *lsfdeq2; lsf2 = lsf + length; lsfdeq2 = lsfdeq + length; lp_length = length + 1; if (iLBCenc_inst->mode==30) { /* sub-frame 1: Interpolation between old and first set of lsf coefficients */ LSFinterpolate2a_enc(lp, lsfdeqold, lsfdeq, lsf_weightTbl_30ms[0], length); memcpy(syntdenum,lp,lp_length*sizeof(float)); LSFinterpolate2a_enc(lp, lsfold, lsf, lsf_weightTbl_30ms[0], length); bwexpand(weightdenum, lp, LPC_CHIRP_WEIGHTDENUM, lp_length); /* sub-frame 2 to 6: Interpolation between first and second set of lsf coefficients */ pos = lp_length; for (i = 1; i < iLBCenc_inst->nsub; i++) { LSFinterpolate2a_enc(lp, lsfdeq, lsfdeq2, lsf_weightTbl_30ms[i], length); memcpy(syntdenum + pos,lp,lp_length*sizeof(float)); LSFinterpolate2a_enc(lp, lsf, lsf2, lsf_weightTbl_30ms[i], length); bwexpand(weightdenum + pos, lp, LPC_CHIRP_WEIGHTDENUM, lp_length); pos += lp_length; } } else { pos = 0; for (i = 0; i < iLBCenc_inst->nsub; i++) { LSFinterpolate2a_enc(lp, lsfdeqold, lsfdeq, lsf_weightTbl_20ms[i], length); memcpy(syntdenum+pos,lp,lp_length*sizeof(float)); LSFinterpolate2a_enc(lp, lsfold, lsf, lsf_weightTbl_20ms[i], length); bwexpand(weightdenum+pos, lp, LPC_CHIRP_WEIGHTDENUM, lp_length); pos += lp_length; } } /* update memory */ if (iLBCenc_inst->mode==30) { memcpy(lsfold, lsf2, length*sizeof(float)); memcpy(lsfdeqold, lsfdeq2, length*sizeof(float)); } else { memcpy(lsfold, lsf, length*sizeof(float)); memcpy(lsfdeqold, lsfdeq, length*sizeof(float)); } } /*----------------------------------------------------------------* * lsf quantizer (subroutine to LPCencode) *---------------------------------------------------------------*/ void SimplelsfQ( float *lsfdeq, /* (o) dequantized lsf coefficients (dimension FILTERORDER) */ int *index, /* (o) quantization index */ float *lsf, /* (i) the lsf coefficient vector to be quantized (dimension FILTERORDER ) */ int lpc_n /* (i) number of lsf sets to quantize */ ){ /* Quantize first LSF with memoryless split VQ */ SplitVQ(lsfdeq, index, lsf, lsfCbTbl, LSF_NSPLIT, dim_lsfCbTbl, size_lsfCbTbl); if (lpc_n==2) { /* Quantize second LSF with memoryless split VQ */ SplitVQ(lsfdeq + LPC_FILTERORDER, index + LSF_NSPLIT, lsf + LPC_FILTERORDER, lsfCbTbl, LSF_NSPLIT, dim_lsfCbTbl, size_lsfCbTbl); } } /*----------------------------------------------------------------* * lpc encoder *---------------------------------------------------------------*/ void LPCencode( float *syntdenum, /* (i/o) synthesis filter coefficients before/after encoding */ float *weightdenum, /* (i/o) weighting denumerator coefficients before/after encoding */ int *lsf_index, /* (o) lsf quantization index */ float *data, /* (i) lsf coefficients to quantize */ iLBC_Enc_Inst_t *iLBCenc_inst /* (i/o) the encoder state structure */ ){ float lsf[LPC_FILTERORDER * LPC_N_MAX]; float lsfdeq[LPC_FILTERORDER * LPC_N_MAX]; SimpleAnalysis(lsf, data, iLBCenc_inst); SimplelsfQ(lsfdeq, lsf_index, lsf, iLBCenc_inst->lpc_n); LSF_check(lsfdeq, LPC_FILTERORDER, iLBCenc_inst->lpc_n); SimpleInterpolateLSF(syntdenum, weightdenum, lsf, lsfdeq, iLBCenc_inst->lsfold, iLBCenc_inst->lsfdeqold, LPC_FILTERORDER, iLBCenc_inst); }