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Diffstat (limited to 'trunk/codecs/ilbc/LPCencode.c')
| -rw-r--r-- | trunk/codecs/ilbc/LPCencode.c | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/trunk/codecs/ilbc/LPCencode.c b/trunk/codecs/ilbc/LPCencode.c new file mode 100644 index 000000000..4d5fcff21 --- /dev/null +++ b/trunk/codecs/ilbc/LPCencode.c @@ -0,0 +1,228 @@ + +/****************************************************************** + + iLBC Speech Coder ANSI-C Source Code + + LPCencode.c + + Copyright (C) The Internet Society (2004). + All Rights Reserved. + +******************************************************************/ + +#include <string.h> + + + +#include "iLBC_define.h" +#include "LPCencode.h" +#include "helpfun.h" +#include "lsf.h" +#include "constants.h" + +/*----------------------------------------------------------------* + * lpc analysis (subrutine to LPCencode) + *---------------------------------------------------------------*/ + +static 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 + * (subrutine to SimpleInterpolateLSF) + *---------------------------------------------------------------*/ + +static 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 (subrutine to LPCencode) + *---------------------------------------------------------------*/ + +static 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 (subrutine to LPCencode) + *---------------------------------------------------------------*/ + +static 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]; + int change=0; + + SimpleAnalysis(lsf, data, iLBCenc_inst); + SimplelsfQ(lsfdeq, lsf_index, lsf, iLBCenc_inst->lpc_n); + change=LSF_check(lsfdeq, LPC_FILTERORDER, iLBCenc_inst->lpc_n); + SimpleInterpolateLSF(syntdenum, weightdenum, + lsf, lsfdeq, iLBCenc_inst->lsfold, + iLBCenc_inst->lsfdeqold, LPC_FILTERORDER, iLBCenc_inst); +} + + + |