diff options
Diffstat (limited to 'third_party/ilbc/LPCdecode.c')
-rw-r--r-- | third_party/ilbc/LPCdecode.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/third_party/ilbc/LPCdecode.c b/third_party/ilbc/LPCdecode.c new file mode 100644 index 00000000..81bab904 --- /dev/null +++ b/third_party/ilbc/LPCdecode.c @@ -0,0 +1,158 @@ + + /****************************************************************** + + iLBC Speech Coder ANSI-C Source Code + + LPC_decode.c + + Copyright (C) The Internet Society (2004). + All Rights Reserved. + + ******************************************************************/ + + #include <math.h> + #include <string.h> + + #include "helpfun.h" + #include "lsf.h" + #include "iLBC_define.h" + #include "constants.h" + + /*---------------------------------------------------------------* + * interpolation of lsf coefficients for the decoder + *--------------------------------------------------------------*/ + + void LSFinterpolate2a_dec( + float *a, /* (o) lpc coefficients for a sub-frame */ + float *lsf1, /* (i) first lsf coefficient vector */ + float *lsf2, /* (i) second lsf coefficient vector */ + float coef, /* (i) interpolation weight */ + int length /* (i) length of lsf vectors */ + ){ + float lsftmp[LPC_FILTERORDER]; + + interpolate(lsftmp, lsf1, lsf2, coef, length); + lsf2a(a, lsftmp); + } + + /*---------------------------------------------------------------* + * obtain dequantized lsf coefficients from quantization index + *--------------------------------------------------------------*/ + + void SimplelsfDEQ( + float *lsfdeq, /* (o) dequantized lsf coefficients */ + int *index, /* (i) quantization index */ + int lpc_n /* (i) number of LPCs */ + ){ + int i, j, pos, cb_pos; + + + + + + /* decode first LSF */ + + pos = 0; + cb_pos = 0; + for (i = 0; i < LSF_NSPLIT; i++) { + for (j = 0; j < dim_lsfCbTbl[i]; j++) { + lsfdeq[pos + j] = lsfCbTbl[cb_pos + + (long)(index[i])*dim_lsfCbTbl[i] + j]; + } + pos += dim_lsfCbTbl[i]; + cb_pos += size_lsfCbTbl[i]*dim_lsfCbTbl[i]; + } + + if (lpc_n>1) { + + /* decode last LSF */ + + pos = 0; + cb_pos = 0; + for (i = 0; i < LSF_NSPLIT; i++) { + for (j = 0; j < dim_lsfCbTbl[i]; j++) { + lsfdeq[LPC_FILTERORDER + pos + j] = + lsfCbTbl[cb_pos + + (long)(index[LSF_NSPLIT + i])* + dim_lsfCbTbl[i] + j]; + } + pos += dim_lsfCbTbl[i]; + cb_pos += size_lsfCbTbl[i]*dim_lsfCbTbl[i]; + } + } + } + + /*----------------------------------------------------------------* + * obtain synthesis and weighting filters form lsf coefficients + *---------------------------------------------------------------*/ + + void DecoderInterpolateLSF( + float *syntdenum, /* (o) synthesis filter coefficients */ + float *weightdenum, /* (o) weighting denumerator + coefficients */ + float *lsfdeq, /* (i) dequantized lsf coefficients */ + int length, /* (i) length of lsf coefficient vector */ + iLBC_Dec_Inst_t *iLBCdec_inst + /* (i) the decoder state structure */ + ){ + int i, pos, lp_length; + float lp[LPC_FILTERORDER + 1], *lsfdeq2; + + + + + + + lsfdeq2 = lsfdeq + length; + lp_length = length + 1; + + if (iLBCdec_inst->mode==30) { + /* sub-frame 1: Interpolation between old and first */ + + LSFinterpolate2a_dec(lp, iLBCdec_inst->lsfdeqold, lsfdeq, + lsf_weightTbl_30ms[0], length); + memcpy(syntdenum,lp,lp_length*sizeof(float)); + bwexpand(weightdenum, lp, LPC_CHIRP_WEIGHTDENUM, + lp_length); + + /* sub-frames 2 to 6: interpolation between first + and last LSF */ + + pos = lp_length; + for (i = 1; i < 6; i++) { + LSFinterpolate2a_dec(lp, lsfdeq, lsfdeq2, + lsf_weightTbl_30ms[i], length); + memcpy(syntdenum + pos,lp,lp_length*sizeof(float)); + bwexpand(weightdenum + pos, lp, + LPC_CHIRP_WEIGHTDENUM, lp_length); + pos += lp_length; + } + } + else { + pos = 0; + for (i = 0; i < iLBCdec_inst->nsub; i++) { + LSFinterpolate2a_dec(lp, iLBCdec_inst->lsfdeqold, + lsfdeq, lsf_weightTbl_20ms[i], length); + memcpy(syntdenum+pos,lp,lp_length*sizeof(float)); + bwexpand(weightdenum+pos, lp, LPC_CHIRP_WEIGHTDENUM, + lp_length); + pos += lp_length; + } + } + + /* update memory */ + + if (iLBCdec_inst->mode==30) + memcpy(iLBCdec_inst->lsfdeqold, lsfdeq2, + length*sizeof(float)); + else + memcpy(iLBCdec_inst->lsfdeqold, lsfdeq, + length*sizeof(float)); + + } + + + + + + |