## ffmpeg / libavcodec / acelp_pitch_delay.c @ 2912e87a

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1 | e500315b | Vladimir Voroshilov | ```
/*
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2 | ```
* gain code, gain pitch and pitch delay decoding
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3 | ```
*
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4 | ```
* Copyright (c) 2008 Vladimir Voroshilov
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5 | ```
*
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6 | 2912e87a | Mans Rullgard | ```
* This file is part of Libav.
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7 | e500315b | Vladimir Voroshilov | ```
*
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8 | 2912e87a | Mans Rullgard | ```
* Libav is free software; you can redistribute it and/or
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9 | e500315b | Vladimir Voroshilov | ```
* modify it under the terms of the GNU Lesser General Public
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10 | ```
* License as published by the Free Software Foundation; either
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11 | ```
* version 2.1 of the License, or (at your option) any later version.
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12 | ```
*
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13 | 2912e87a | Mans Rullgard | ```
* Libav is distributed in the hope that it will be useful,
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14 | e500315b | Vladimir Voroshilov | ```
* but WITHOUT ANY WARRANTY; without even the implied warranty of
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15 | ```
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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16 | ```
* Lesser General Public License for more details.
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17 | ```
*
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18 | ```
* You should have received a copy of the GNU Lesser General Public
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19 | 2912e87a | Mans Rullgard | ```
* License along with Libav; if not, write to the Free Software
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20 | e500315b | Vladimir Voroshilov | ```
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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21 | ```
*/
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22 | |||

23 | #include "avcodec.h" |
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24 | 27513162 | Aurelien Jacobs | #include "dsputil.h" |

25 | e500315b | Vladimir Voroshilov | #include "acelp_pitch_delay.h" |

26 | 60c25a4b | Kenan Gillet | #include "celp_math.h" |

27 | e500315b | Vladimir Voroshilov | |

28 | int ff_acelp_decode_8bit_to_1st_delay3(int ac_index) |
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29 | { |
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30 | ```
ac_index += 58;
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31 | if(ac_index > 254) |
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32 | ac_index = 3 * ac_index - 510; |
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33 | ```
return ac_index;
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34 | } |
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35 | |||

36 | ```
int ff_acelp_decode_4bit_to_2nd_delay3(
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37 | ```
int ac_index,
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38 | ```
int pitch_delay_min)
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39 | { |
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40 | if(ac_index < 4) |
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41 | return 3 * (ac_index + pitch_delay_min); |
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42 | else if(ac_index < 12) |
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43 | return 3 * pitch_delay_min + ac_index + 6; |
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44 | ```
else
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45 | return 3 * (ac_index + pitch_delay_min) - 18; |
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46 | } |
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47 | |||

48 | ```
int ff_acelp_decode_5_6_bit_to_2nd_delay3(
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49 | ```
int ac_index,
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50 | ```
int pitch_delay_min)
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51 | { |
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52 | return 3 * pitch_delay_min + ac_index - 2; |
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53 | } |
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54 | |||

55 | int ff_acelp_decode_9bit_to_1st_delay6(int ac_index) |
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56 | { |
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57 | if(ac_index < 463) |
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58 | return ac_index + 105; |
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59 | ```
else
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60 | return 6 * (ac_index - 368); |
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61 | } |
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62 | ```
int ff_acelp_decode_6bit_to_2nd_delay6(
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63 | ```
int ac_index,
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64 | ```
int pitch_delay_min)
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65 | { |
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66 | return 6 * pitch_delay_min + ac_index - 3; |
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67 | } |
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68 | |||

69 | ```
void ff_acelp_update_past_gain(
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70 | int16_t* quant_energy, |
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71 | ```
int gain_corr_factor,
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72 | ```
int log2_ma_pred_order,
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73 | ```
int erasure)
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74 | { |
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75 | ```
int i;
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76 | int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10) |
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77 | |||

78 | for(i=(1 << log2_ma_pred_order) - 1; i>0; i--) |
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79 | { |
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80 | ```
avg_gain += quant_energy[i-1];
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81 | ```
quant_energy[i] = quant_energy[i-1];
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82 | } |
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83 | |||

84 | ```
if(erasure)
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85 | quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10) |
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86 | ```
else
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87 | quant_energy[0] = (6165 * ((ff_log2(gain_corr_factor) >> 2) - (13 << 13))) >> 13; |
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88 | } |
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89 | |||

90 | int16_t ff_acelp_decode_gain_code( |
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91 | 27513162 | Aurelien Jacobs | DSPContext *dsp, |

92 | e500315b | Vladimir Voroshilov | ```
int gain_corr_factor,
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93 | ```
const int16_t* fc_v,
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94 | ```
int mr_energy,
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95 | ```
const int16_t* quant_energy,
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96 | ```
const int16_t* ma_prediction_coeff,
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97 | ```
int subframe_size,
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98 | ```
int ma_pred_order)
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99 | { |
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100 | ```
int i;
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101 | |||

102 | ```
mr_energy <<= 10;
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103 | |||

104 | for(i=0; i<ma_pred_order; i++) |
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105 | mr_energy += quant_energy[i] * ma_prediction_coeff[i]; |
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106 | |||

107 | ```
#ifdef G729_BITEXACT
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108 | 27513162 | Aurelien Jacobs | mr_energy += (((-6165LL * ff_log2(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0))) >> 3) & ~0x3ff); |

109 | e500315b | Vladimir Voroshilov | |

110 | mr_energy = (5439 * (mr_energy >> 15)) >> 8; // (0.15) = (0.15) * (7.23) |
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111 | |||

112 | ```
return bidir_sal(
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113 | ((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1), |
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114 | (mr_energy >> 15) - 25 |
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115 | ); |
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116 | ```
#else
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117 | mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) / |
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118 | 27513162 | Aurelien Jacobs | ```
sqrt(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0));
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119 | e500315b | Vladimir Voroshilov | return mr_energy >> 12; |

120 | ```
#endif
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121 | } |
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122 | 083c5a48 | Vitor Sessak | |

123 | float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy, |
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124 | float *prediction_error, float energy_mean, |
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125 | const float *pred_table) |
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126 | { |
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127 | ```
// Equations 66-69:
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128 | ```
// ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector)
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129 | ```
// Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)).
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130 | ```
float val = fixed_gain_factor *
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131 | e4a35244 | Måns Rullgård | exp2f(M_LOG2_10 * 0.05 * |

132 | 083c5a48 | Vitor Sessak | ```
(ff_dot_productf(pred_table, prediction_error, 4) +
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133 | energy_mean)) / |
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134 | sqrtf(fixed_mean_energy); |
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135 | |||

136 | ```
// update quantified prediction error energy history
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137 | memmove(&prediction_error[0], &prediction_error[1], |
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138 | 3 * sizeof(prediction_error[0])); |
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139 | prediction_error[3] = 20.0 * log10f(fixed_gain_factor); |
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140 | |||

141 | ```
return val;
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142 | } |
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143 | b2bf3cfe | Vitor Sessak | |

144 | void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index, |
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145 | const int prev_lag_int, const int subframe, |
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146 | int third_as_first, int resolution) |
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147 | { |
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148 | ```
/* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */
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149 | if (subframe == 0 || (subframe == 2 && third_as_first)) { |
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150 | |||

151 | if (pitch_index < 197) |
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152 | ```
pitch_index += 59;
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153 | ```
else
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154 | pitch_index = 3 * pitch_index - 335; |
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155 | |||

156 | ```
} else {
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157 | if (resolution == 4) { |
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158 | int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN, |
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159 | ```
PITCH_DELAY_MAX - 9);
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160 | |||

161 | ```
// decoding with 4-bit resolution
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162 | if (pitch_index < 4) { |
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163 | ```
// integer only precision for [search_range_min, search_range_min+3]
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164 | pitch_index = 3 * (pitch_index + search_range_min) + 1; |
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165 | } else if (pitch_index < 12) { |
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166 | ```
// 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3]
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167 | pitch_index += 3 * search_range_min + 7; |
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168 | ```
} else {
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169 | ```
// integer only precision for [search_range_min+6, search_range_min+9]
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170 | pitch_index = 3 * (pitch_index + search_range_min - 6) + 1; |
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171 | } |
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172 | ```
} else {
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173 | ```
// decoding with 5 or 6 bit resolution, 1/3 fractional precision
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174 | pitch_index--; |
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175 | |||

176 | if (resolution == 5) { |
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177 | pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN, |
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178 | ```
PITCH_DELAY_MAX - 19);
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179 | ```
} else
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180 | pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN, |
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181 | ```
PITCH_DELAY_MAX - 9);
``` |
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182 | } |
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183 | } |
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184 | *lag_int = pitch_index * 10923 >> 15; |
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185 | *lag_frac = pitch_index - 3 * *lag_int - 1; |
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186 | } |