Tristan Matthews | 0a329cc | 2013-07-17 13:20:14 -0400 | [diff] [blame] | 1 | |
| 2 | /****************************************************************** |
| 3 | |
| 4 | iLBC Speech Coder ANSI-C Source Code |
| 5 | |
| 6 | LPC_decode.c |
| 7 | |
| 8 | Copyright (C) The Internet Society (2004). |
| 9 | All Rights Reserved. |
| 10 | |
| 11 | ******************************************************************/ |
| 12 | |
| 13 | #include <math.h> |
| 14 | #include <string.h> |
| 15 | |
| 16 | #include "helpfun.h" |
| 17 | #include "lsf.h" |
| 18 | #include "iLBC_define.h" |
| 19 | #include "constants.h" |
| 20 | |
| 21 | /*---------------------------------------------------------------* |
| 22 | * interpolation of lsf coefficients for the decoder |
| 23 | *--------------------------------------------------------------*/ |
| 24 | |
| 25 | void LSFinterpolate2a_dec( |
| 26 | float *a, /* (o) lpc coefficients for a sub-frame */ |
| 27 | float *lsf1, /* (i) first lsf coefficient vector */ |
| 28 | float *lsf2, /* (i) second lsf coefficient vector */ |
| 29 | float coef, /* (i) interpolation weight */ |
| 30 | int length /* (i) length of lsf vectors */ |
| 31 | ){ |
| 32 | float lsftmp[LPC_FILTERORDER]; |
| 33 | |
| 34 | interpolate(lsftmp, lsf1, lsf2, coef, length); |
| 35 | lsf2a(a, lsftmp); |
| 36 | } |
| 37 | |
| 38 | /*---------------------------------------------------------------* |
| 39 | * obtain dequantized lsf coefficients from quantization index |
| 40 | *--------------------------------------------------------------*/ |
| 41 | |
| 42 | void SimplelsfDEQ( |
| 43 | float *lsfdeq, /* (o) dequantized lsf coefficients */ |
| 44 | int *index, /* (i) quantization index */ |
| 45 | int lpc_n /* (i) number of LPCs */ |
| 46 | ){ |
| 47 | int i, j, pos, cb_pos; |
| 48 | |
| 49 | |
| 50 | |
| 51 | |
| 52 | |
| 53 | /* decode first LSF */ |
| 54 | |
| 55 | pos = 0; |
| 56 | cb_pos = 0; |
| 57 | for (i = 0; i < LSF_NSPLIT; i++) { |
| 58 | for (j = 0; j < dim_lsfCbTbl[i]; j++) { |
| 59 | lsfdeq[pos + j] = lsfCbTbl[cb_pos + |
| 60 | (long)(index[i])*dim_lsfCbTbl[i] + j]; |
| 61 | } |
| 62 | pos += dim_lsfCbTbl[i]; |
| 63 | cb_pos += size_lsfCbTbl[i]*dim_lsfCbTbl[i]; |
| 64 | } |
| 65 | |
| 66 | if (lpc_n>1) { |
| 67 | |
| 68 | /* decode last LSF */ |
| 69 | |
| 70 | pos = 0; |
| 71 | cb_pos = 0; |
| 72 | for (i = 0; i < LSF_NSPLIT; i++) { |
| 73 | for (j = 0; j < dim_lsfCbTbl[i]; j++) { |
| 74 | lsfdeq[LPC_FILTERORDER + pos + j] = |
| 75 | lsfCbTbl[cb_pos + |
| 76 | (long)(index[LSF_NSPLIT + i])* |
| 77 | dim_lsfCbTbl[i] + j]; |
| 78 | } |
| 79 | pos += dim_lsfCbTbl[i]; |
| 80 | cb_pos += size_lsfCbTbl[i]*dim_lsfCbTbl[i]; |
| 81 | } |
| 82 | } |
| 83 | } |
| 84 | |
| 85 | /*----------------------------------------------------------------* |
| 86 | * obtain synthesis and weighting filters form lsf coefficients |
| 87 | *---------------------------------------------------------------*/ |
| 88 | |
| 89 | void DecoderInterpolateLSF( |
| 90 | float *syntdenum, /* (o) synthesis filter coefficients */ |
| 91 | float *weightdenum, /* (o) weighting denumerator |
| 92 | coefficients */ |
| 93 | float *lsfdeq, /* (i) dequantized lsf coefficients */ |
| 94 | int length, /* (i) length of lsf coefficient vector */ |
| 95 | iLBC_Dec_Inst_t *iLBCdec_inst |
| 96 | /* (i) the decoder state structure */ |
| 97 | ){ |
| 98 | int i, pos, lp_length; |
| 99 | float lp[LPC_FILTERORDER + 1], *lsfdeq2; |
| 100 | |
| 101 | |
| 102 | |
| 103 | |
| 104 | |
| 105 | |
| 106 | lsfdeq2 = lsfdeq + length; |
| 107 | lp_length = length + 1; |
| 108 | |
| 109 | if (iLBCdec_inst->mode==30) { |
| 110 | /* sub-frame 1: Interpolation between old and first */ |
| 111 | |
| 112 | LSFinterpolate2a_dec(lp, iLBCdec_inst->lsfdeqold, lsfdeq, |
| 113 | lsf_weightTbl_30ms[0], length); |
| 114 | memcpy(syntdenum,lp,lp_length*sizeof(float)); |
| 115 | bwexpand(weightdenum, lp, LPC_CHIRP_WEIGHTDENUM, |
| 116 | lp_length); |
| 117 | |
| 118 | /* sub-frames 2 to 6: interpolation between first |
| 119 | and last LSF */ |
| 120 | |
| 121 | pos = lp_length; |
| 122 | for (i = 1; i < 6; i++) { |
| 123 | LSFinterpolate2a_dec(lp, lsfdeq, lsfdeq2, |
| 124 | lsf_weightTbl_30ms[i], length); |
| 125 | memcpy(syntdenum + pos,lp,lp_length*sizeof(float)); |
| 126 | bwexpand(weightdenum + pos, lp, |
| 127 | LPC_CHIRP_WEIGHTDENUM, lp_length); |
| 128 | pos += lp_length; |
| 129 | } |
| 130 | } |
| 131 | else { |
| 132 | pos = 0; |
| 133 | for (i = 0; i < iLBCdec_inst->nsub; i++) { |
| 134 | LSFinterpolate2a_dec(lp, iLBCdec_inst->lsfdeqold, |
| 135 | lsfdeq, lsf_weightTbl_20ms[i], length); |
| 136 | memcpy(syntdenum+pos,lp,lp_length*sizeof(float)); |
| 137 | bwexpand(weightdenum+pos, lp, LPC_CHIRP_WEIGHTDENUM, |
| 138 | lp_length); |
| 139 | pos += lp_length; |
| 140 | } |
| 141 | } |
| 142 | |
| 143 | /* update memory */ |
| 144 | |
| 145 | if (iLBCdec_inst->mode==30) |
| 146 | memcpy(iLBCdec_inst->lsfdeqold, lsfdeq2, |
| 147 | length*sizeof(float)); |
| 148 | else |
| 149 | memcpy(iLBCdec_inst->lsfdeqold, lsfdeq, |
| 150 | length*sizeof(float)); |
| 151 | |
| 152 | } |
| 153 | |
| 154 | |
| 155 | |
| 156 | |
| 157 | |
| 158 | |