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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 doCPLC.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 #include <stdio.h>
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16
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17
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18
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19
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20
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21 #include "iLBC_define.h"
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22
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23 /*----------------------------------------------------------------*
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24 * Compute cross correlation and pitch gain for pitch prediction
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25 * of last subframe at given lag.
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26 *---------------------------------------------------------------*/
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27
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28 void compCorr(float *cc, /* (o) cross correlation coefficient */
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29 float *gc, /* (o) gain */
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30 float *pm, float *buffer, /* (i) signal buffer */
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31 int lag, /* (i) pitch lag */
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32 int bLen, /* (i) length of buffer */
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33 int sRange /* (i) correlation search length */
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34 )
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35 {
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36 int i;
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37 float ftmp1, ftmp2, ftmp3;
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38
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39 /* Guard against getting outside buffer */
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40 if ((bLen - sRange - lag) < 0) {
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41 sRange = bLen - lag;
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42 }
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43
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44 ftmp1 = 0.0;
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45 ftmp2 = 0.0;
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46 ftmp3 = 0.0;
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47 for (i = 0; i < sRange; i++) {
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48 ftmp1 += buffer[bLen - sRange + i] *
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49 buffer[bLen - sRange + i - lag];
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50 ftmp2 += buffer[bLen - sRange + i - lag] *
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51 buffer[bLen - sRange + i - lag];
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52 ftmp3 += buffer[bLen - sRange + i] * buffer[bLen - sRange + i];
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53 }
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54
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55 if (ftmp2 > 0.0) {
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56 *cc = ftmp1 * ftmp1 / ftmp2;
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57 *gc = (float) fabs(ftmp1 / ftmp2);
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58 *pm = (float) fabs(ftmp1) /
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59 ((float) sqrt(ftmp2) * (float) sqrt(ftmp3));
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60 } else {
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61 *cc = 0.0;
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62 *gc = 0.0;
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63 *pm = 0.0;
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64 }
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65 }
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66
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67
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68
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69
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70
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71 /*----------------------------------------------------------------*
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72 * Packet loss concealment routine. Conceals a residual signal
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73 * and LP parameters. If no packet loss, update state.
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74 *---------------------------------------------------------------*/
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75
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76 void doThePLC(float *PLCresidual, /* (o) concealed residual */
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77 float *PLClpc, /* (o) concealed LP parameters */
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78 int PLI, /* (i) packet loss indicator
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79 0 - no PL, 1 = PL */
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80 float *decresidual, /* (i) decoded residual */
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81 float *lpc, /* (i) decoded LPC (only used for no PL) */
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82 int inlag, /* (i) pitch lag */
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83 iLBC_Dec_Inst_t * iLBCdec_inst
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84 /* (i/o) decoder instance */
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85 )
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86 {
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87 int lag = 20, randlag;
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88 float gain, maxcc;
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89 float use_gain;
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90 float gain_comp, maxcc_comp, per, max_per;
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91 int i, pick, use_lag;
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92 float ftmp, randvec[BLOCKL_MAX], pitchfact, energy;
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93
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94 /* Packet Loss */
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95
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96 if (PLI == 1) {
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97
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98 iLBCdec_inst->consPLICount += 1;
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99
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100 /* if previous frame not lost,
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101 determine pitch pred. gain */
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102
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103 if (iLBCdec_inst->prevPLI != 1) {
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104
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105 /* Search around the previous lag to find the
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106 best pitch period */
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107
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108 lag = inlag - 3;
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109 compCorr(&maxcc, &gain, &max_per,
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110 iLBCdec_inst->prevResidual, lag, iLBCdec_inst->blockl, 60);
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111 for (i = inlag - 2; i <= inlag + 3; i++) {
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112 compCorr(&maxcc_comp, &gain_comp, &per,
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113 iLBCdec_inst->prevResidual, i, iLBCdec_inst->blockl, 60);
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114
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115 if (maxcc_comp > maxcc) {
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116 maxcc = maxcc_comp;
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117
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118
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119
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120
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121
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122 gain = gain_comp;
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123 lag = i;
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124 max_per = per;
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125 }
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126 }
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127
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128 }
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129
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130 /* previous frame lost, use recorded lag and periodicity */
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131
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132 else {
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133 lag = iLBCdec_inst->prevLag;
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134 max_per = iLBCdec_inst->per;
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135 }
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136
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137 /* downscaling */
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138
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139 use_gain = 1.0;
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140 if (iLBCdec_inst->consPLICount * iLBCdec_inst->blockl > 320)
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141 use_gain = (float) 0.9;
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142 else if (iLBCdec_inst->consPLICount *
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143 iLBCdec_inst->blockl > 2 * 320)
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144 use_gain = (float) 0.7;
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145 else if (iLBCdec_inst->consPLICount *
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146 iLBCdec_inst->blockl > 3 * 320)
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147 use_gain = (float) 0.5;
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148 else if (iLBCdec_inst->consPLICount *
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149 iLBCdec_inst->blockl > 4 * 320)
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150 use_gain = (float) 0.0;
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151
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152 /* mix noise and pitch repeatition */
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153 ftmp = (float) sqrt(max_per);
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154 if (ftmp > (float) 0.7)
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155 pitchfact = (float) 1.0;
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156 else if (ftmp > (float) 0.4)
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157 pitchfact = (ftmp - (float) 0.4) / ((float) 0.7 - (float) 0.4);
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158 else
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159 pitchfact = 0.0;
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160
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161
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162 /* avoid repetition of same pitch cycle */
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163 use_lag = lag;
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164 if (lag < 80) {
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165 use_lag = 2 * lag;
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166 }
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167
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168 /* compute concealed residual */
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169
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170
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171
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172
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173
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174
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175 energy = 0.0;
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176 for (i = 0; i < iLBCdec_inst->blockl; i++) {
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177
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178 /* noise component */
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179
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180 iLBCdec_inst->seed = (iLBCdec_inst->seed * 69069L + 1) &
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181 (0x80000000L - 1);
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182 randlag = 50 + ((signed long) iLBCdec_inst->seed) % 70;
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183 pick = i - randlag;
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184
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185 if (pick < 0) {
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186 randvec[i] =
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187 iLBCdec_inst->prevResidual[iLBCdec_inst->blockl + pick];
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188 } else {
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189 randvec[i] = randvec[pick];
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190 }
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191
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192 /* pitch repeatition component */
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193 pick = i - use_lag;
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194
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195 if (pick < 0) {
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196 PLCresidual[i] =
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197 iLBCdec_inst->prevResidual[iLBCdec_inst->blockl + pick];
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198 } else {
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199 PLCresidual[i] = PLCresidual[pick];
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200 }
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201
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202 /* mix random and periodicity component */
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203
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204 if (i < 80)
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205 PLCresidual[i] = use_gain * (pitchfact *
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206 PLCresidual[i] + ((float) 1.0 - pitchfact) * randvec[i]);
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207 else if (i < 160)
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208 PLCresidual[i] = (float) 0.95 *use_gain * (pitchfact *
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209 PLCresidual[i] + ((float) 1.0 - pitchfact) * randvec[i]);
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210 else
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211 PLCresidual[i] = (float) 0.9 *use_gain * (pitchfact *
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212 PLCresidual[i] + ((float) 1.0 - pitchfact) * randvec[i]);
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213
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214 energy += PLCresidual[i] * PLCresidual[i];
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215 }
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216
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217 /* less than 30 dB, use only noise */
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218
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219
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220
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221
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222
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223
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224 if (sqrt(energy / (float) iLBCdec_inst->blockl) < 30.0) {
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225 gain = 0.0;
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226 for (i = 0; i < iLBCdec_inst->blockl; i++) {
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227 PLCresidual[i] = randvec[i];
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228 }
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229 }
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230
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231 /* use old LPC */
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232
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233 memcpy(PLClpc, iLBCdec_inst->prevLpc,
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234 (LPC_FILTERORDER + 1) * sizeof(float));
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235
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236 }
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237
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238 /* no packet loss, copy input */
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239
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240 else {
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241 memcpy(PLCresidual, decresidual,
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242 iLBCdec_inst->blockl * sizeof(float));
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243 memcpy(PLClpc, lpc, (LPC_FILTERORDER + 1) * sizeof(float));
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244 iLBCdec_inst->consPLICount = 0;
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245 }
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246
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247 /* update state */
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248
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249 if (PLI) {
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250 iLBCdec_inst->prevLag = lag;
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251 iLBCdec_inst->per = max_per;
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252 }
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253
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254 iLBCdec_inst->prevPLI = PLI;
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255 memcpy(iLBCdec_inst->prevLpc, PLClpc,
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256 (LPC_FILTERORDER + 1) * sizeof(float));
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257 memcpy(iLBCdec_inst->prevResidual, PLCresidual,
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258 iLBCdec_inst->blockl * sizeof(float));
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259 }
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