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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 FrameClassify.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 "iLBC_define.h"
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14
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15 /*---------------------------------------------------------------*
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16 * Classification of subframes to localize start state
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17 *--------------------------------------------------------------*/
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18
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19 int FrameClassify( /* index to the max-energy sub-frame */
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20 iLBC_Enc_Inst_t * iLBCenc_inst,
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21 /* (i/o) the encoder state structure */
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22 float *residual /* (i) lpc residual signal */
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23 )
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24 {
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25 float max_ssqEn, fssqEn[NSUB_MAX], bssqEn[NSUB_MAX], *pp;
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26 int n, l, max_ssqEn_n;
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27 const float ssqEn_win[NSUB_MAX - 1] = { (float) 0.8, (float) 0.9,
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28 (float) 1.0, (float) 0.9, (float) 0.8
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29 };
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30 const float sampEn_win[5] = { (float) 1.0 / (float) 6.0,
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31 (float) 2.0 / (float) 6.0, (float) 3.0 / (float) 6.0,
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32 (float) 4.0 / (float) 6.0, (float) 5.0 / (float) 6.0
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33 };
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34
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35 /* init the front and back energies to zero */
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36
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37 memset(fssqEn, 0, NSUB_MAX * sizeof(float));
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38 memset(bssqEn, 0, NSUB_MAX * sizeof(float));
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39
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40 /* Calculate front of first seqence */
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41
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42 n = 0;
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43 pp = residual;
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44 for (l = 0; l < 5; l++) {
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45 fssqEn[n] += sampEn_win[l] * (*pp) * (*pp);
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46 pp++;
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47 }
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48 for (l = 5; l < SUBL; l++) {
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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
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54 fssqEn[n] += (*pp) * (*pp);
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55 pp++;
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56 }
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57
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58 /* Calculate front and back of all middle sequences */
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59
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60 for (n = 1; n < iLBCenc_inst->nsub - 1; n++) {
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61 pp = residual + n * SUBL;
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62 for (l = 0; l < 5; l++) {
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63 fssqEn[n] += sampEn_win[l] * (*pp) * (*pp);
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64 bssqEn[n] += (*pp) * (*pp);
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65 pp++;
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66 }
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67 for (l = 5; l < SUBL - 5; l++) {
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68 fssqEn[n] += (*pp) * (*pp);
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69 bssqEn[n] += (*pp) * (*pp);
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70 pp++;
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71 }
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72 for (l = SUBL - 5; l < SUBL; l++) {
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73 fssqEn[n] += (*pp) * (*pp);
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74 bssqEn[n] += sampEn_win[SUBL - l - 1] * (*pp) * (*pp);
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75 pp++;
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76 }
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77 }
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78
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79 /* Calculate back of last seqence */
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80
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81 n = iLBCenc_inst->nsub - 1;
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82 pp = residual + n * SUBL;
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83 for (l = 0; l < SUBL - 5; l++) {
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84 bssqEn[n] += (*pp) * (*pp);
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85 pp++;
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86 }
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87 for (l = SUBL - 5; l < SUBL; l++) {
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88 bssqEn[n] += sampEn_win[SUBL - l - 1] * (*pp) * (*pp);
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89 pp++;
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90 }
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91
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92 /* find the index to the weighted 80 sample with
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93 most energy */
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94
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95 if (iLBCenc_inst->mode == 20)
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96 l = 1;
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97 else
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98 l = 0;
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99
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100 max_ssqEn = (fssqEn[0] + bssqEn[1]) * ssqEn_win[l];
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101 max_ssqEn_n = 1;
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102 for (n = 2; n < iLBCenc_inst->nsub; n++) {
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103
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104
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105
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106
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107
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108
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109 l++;
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110 if ((fssqEn[n - 1] + bssqEn[n]) * ssqEn_win[l] > max_ssqEn) {
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111 max_ssqEn = (fssqEn[n - 1] + bssqEn[n]) * ssqEn_win[l];
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112 max_ssqEn_n = n;
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113 }
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114 }
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115
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116 return max_ssqEn_n;
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117 }
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