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