diff options
author | markster <markster@f38db490-d61c-443f-a65b-d21fe96a405b> | 2003-04-15 04:36:52 +0000 |
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committer | markster <markster@f38db490-d61c-443f-a65b-d21fe96a405b> | 2003-04-15 04:36:52 +0000 |
commit | 9fa1f6563a431a73d7eb0c8a284e4cf419cbc2fa (patch) | |
tree | 468bcd1944564d1b84b5a9d46b2eb437fe3c73a3 /codecs/ilbc/LPCencode.c | |
parent | 0cc1bf692bcfc7f3f9ffef9d62c6621cd9ab9f4a (diff) |
Add iLBC codec
git-svn-id: http://svn.digium.com/svn/asterisk/trunk@852 f38db490-d61c-443f-a65b-d21fe96a405b
Diffstat (limited to 'codecs/ilbc/LPCencode.c')
-rwxr-xr-x | codecs/ilbc/LPCencode.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/codecs/ilbc/LPCencode.c b/codecs/ilbc/LPCencode.c new file mode 100755 index 000000000..330796d7b --- /dev/null +++ b/codecs/ilbc/LPCencode.c @@ -0,0 +1,184 @@ + +/****************************************************************** + + iLBC Speech Coder ANSI-C Source Code + + LPCencode.c + + Copyright (c) 2001, + Global IP Sound AB. + All rights reserved. + +******************************************************************/ + +#include <string.h> + +#include "iLBC_define.h" +#include "helpfun.h" +#include "lsf.h" +#include "constants.h" + +/*----------------------------------------------------------------* + * lpc analysis (subrutine to LPCencode) + *---------------------------------------------------------------*/ + +void SimpleAnalysis( + float *lsf, /* (o) lsf coefficients */ + float *data, /* (i) new data vector */ + float *lpc_buffer /* (i) buffer containing old data */ +){ + int k, is; + float temp[BLOCKL], lp[LPC_FILTERORDER + 1]; + float lp2[LPC_FILTERORDER + 1]; + float r[LPC_FILTERORDER + 1]; + + memcpy(lpc_buffer+LPC_LOOKBACK,data,BLOCKL*sizeof(float)); + + /* No lookahead, last window is asymmetric */ + + for (k = 0; k < LPC_N; k++) { + + is = LPC_LOOKBACK; + + if (k < (LPC_N - 1)) { + window(temp, lpc_winTbl, lpc_buffer, BLOCKL); + } else { + window(temp, lpc_asymwinTbl, lpc_buffer + is, BLOCKL); + } + + autocorr(r, temp, BLOCKL, 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); + } + memcpy(lpc_buffer, lpc_buffer+BLOCKL, + LPC_LOOKBACK*sizeof(float)); +} + +/*----------------------------------------------------------------* + * lsf interpolator and conversion from lsf to a coefficients + * (subrutine 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 (subrutine 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 FILTERORDER */ +){ + int i, pos, lp_length; + float lp[LPC_FILTERORDER + 1], *lsf2, *lsfdeq2; + + lsf2 = lsf + length; + lsfdeq2 = lsfdeq + length; + lp_length = length + 1; + + /* subframe 1: Interpolation between old and first set of + lsf coefficients */ + + LSFinterpolate2a_enc(lp, lsfdeqold, lsfdeq, + lsf_weightTbl[0], length); + memcpy(syntdenum,lp,lp_length*sizeof(float)); + LSFinterpolate2a_enc(lp, lsfold, lsf, lsf_weightTbl[0], length); + bwexpand(weightdenum, lp, LPC_CHIRP_WEIGHTDENUM, lp_length); + + /* subframe 2 to 6: Interpolation between first and second + set of lsf coefficients */ + + pos = lp_length; + for (i = 1; i < NSUB; i++) { + LSFinterpolate2a_enc(lp, lsfdeq, lsfdeq2, + lsf_weightTbl[i], length); + memcpy(syntdenum + pos,lp,lp_length*sizeof(float)); + + LSFinterpolate2a_enc(lp, lsf, lsf2, + lsf_weightTbl[i], length); + bwexpand(weightdenum + pos, lp, + LPC_CHIRP_WEIGHTDENUM, lp_length); + pos += lp_length; + } + + /* update memory */ + + memcpy(lsfold, lsf2, length*sizeof(float)); + memcpy(lsfdeqold, lsfdeq2, length*sizeof(float)); +} + +/*----------------------------------------------------------------* + * lsf quantizer (subrutine 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 ) */ +){ + /* Quantize first LSF with memoryless split VQ */ + SplitVQ(lsfdeq, index, lsf, lsfCbTbl, LSF_NSPLIT, + dim_lsfCbTbl, size_lsfCbTbl); + + /* 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]; + float lsfdeq[LPC_FILTERORDER * LPC_N]; + int change=0; + + SimpleAnalysis(lsf, data, (*iLBCenc_inst).lpc_buffer); + SimplelsfQ(lsfdeq, lsf_index, lsf); + change=LSF_check(lsfdeq, LPC_FILTERORDER, LPC_N); + SimpleInterpolateLSF(syntdenum, weightdenum, + lsf, lsfdeq, (*iLBCenc_inst).lsfold, + (*iLBCenc_inst).lsfdeqold, LPC_FILTERORDER); +} + + |