## ffmpeg / libavcodec / ac3enc.c @ 1c2a8c7f

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1 | de6d9b64 | Fabrice Bellard | ```
/*
``` |
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2 | ```
* The simplest AC3 encoder
``` |
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3 | ```
* Copyright (c) 2000 Gerard Lantau.
``` |
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4 | ```
*
``` |
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5 | ```
* This program is free software; you can redistribute it and/or modify
``` |
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6 | ```
* it under the terms of the GNU General Public License as published by
``` |
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7 | ```
* the Free Software Foundation; either version 2 of the License, or
``` |
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8 | ```
* (at your option) any later version.
``` |
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9 | ```
*
``` |
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10 | ```
* This program is distributed in the hope that it will be useful,
``` |
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11 | ```
* but WITHOUT ANY WARRANTY; without even the implied warranty of
``` |
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12 | ```
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
``` |
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13 | ```
* GNU General Public License for more details.
``` |
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14 | ```
*
``` |
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15 | ```
* You should have received a copy of the GNU General Public License
``` |
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16 | ```
* along with this program; if not, write to the Free Software
``` |
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17 | ```
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
``` |
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18 | ```
*/
``` |
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19 | 1a565432 | Fabrice Bellard | ```
//#define DEBUG
``` |

20 | ```
//#define DEBUG_BITALLOC
``` |
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21 | de6d9b64 | Fabrice Bellard | #include "avcodec.h" |

22 | 1a565432 | Fabrice Bellard | #include <math.h> |

23 | de6d9b64 | Fabrice Bellard | |

24 | #include "ac3enc.h" |
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25 | #include "ac3tab.h" |
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26 | |||

27 | |||

28 | #define MDCT_NBITS 9 |
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29 | #define N (1 << MDCT_NBITS) |
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30 | #define NB_BLOCKS 6 /* number of PCM blocks inside an AC3 frame */ |
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31 | |||

32 | ```
/* new exponents are sent if their Norm 1 exceed this number */
``` |
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33 | #define EXP_DIFF_THRESHOLD 1000 |
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34 | |||

35 | ```
/* exponent encoding strategy */
``` |
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36 | #define EXP_REUSE 0 |
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37 | #define EXP_NEW 1 |
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38 | |||

39 | #define EXP_D15 1 |
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40 | #define EXP_D25 2 |
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41 | #define EXP_D45 3 |
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42 | |||

43 | static void fft_init(int ln); |
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44 | static void ac3_crc_init(void); |
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45 | |||

46 | static inline INT16 fix15(float a) |
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47 | { |
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48 | ```
int v;
``` |
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49 | v = (int)(a * (float)(1 << 15)); |
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50 | if (v < -32767) |
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51 | ```
v = -32767;
``` |
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52 | else if (v > 32767) |
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53 | ```
v = 32767;
``` |
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54 | ```
return v;
``` |
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55 | } |
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56 | |||

57 | static inline int calc_lowcomp1(int a, int b0, int b1) |
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58 | { |
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59 | if ((b0 + 256) == b1) { |
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60 | ```
a = 384 ;
``` |
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61 | } else if (b0 > b1) { |
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62 | ```
a = a - 64;
``` |
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63 | if (a < 0) a=0; |
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64 | } |
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65 | ```
return a;
``` |
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66 | } |
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67 | |||

68 | static inline int calc_lowcomp(int a, int b0, int b1, int bin) |
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69 | { |
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70 | if (bin < 7) { |
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71 | if ((b0 + 256) == b1) { |
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72 | ```
a = 384 ;
``` |
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73 | } else if (b0 > b1) { |
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74 | ```
a = a - 64;
``` |
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75 | if (a < 0) a=0; |
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76 | } |
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77 | } else if (bin < 20) { |
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78 | if ((b0 + 256) == b1) { |
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79 | ```
a = 320 ;
``` |
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80 | } else if (b0 > b1) { |
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81 | ```
a= a - 64;
``` |
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82 | if (a < 0) a=0; |
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83 | } |
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84 | ```
} else {
``` |
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85 | ```
a = a - 128;
``` |
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86 | if (a < 0) a=0; |
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87 | } |
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88 | ```
return a;
``` |
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89 | } |
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90 | |||

91 | ```
/* AC3 bit allocation. The algorithm is the one described in the AC3
``` |
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92 | ```
spec with some optimizations because of our simplified encoding
``` |
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93 | ```
assumptions. */
``` |
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94 | ```
void parametric_bit_allocation(AC3EncodeContext *s, UINT8 *bap,
``` |
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95 | INT8 *exp, int start, int end, |
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96 | 30b68f33 | Zdenek Kabelac | int snroffset, int fgain, int is_lfe) |

97 | de6d9b64 | Fabrice Bellard | { |

98 | ```
int bin,i,j,k,end1,v,v1,bndstrt,bndend,lowcomp,begin;
``` |
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99 | ```
int fastleak,slowleak,address,tmp;
``` |
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100 | INT16 psd[256]; /* scaled exponents */ |
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101 | INT16 bndpsd[50]; /* interpolated exponents */ |
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102 | INT16 excite[50]; /* excitation */ |
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103 | INT16 mask[50]; /* masking value */ |
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104 | |||

105 | ```
/* exponent mapping to PSD */
``` |
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106 | ```
for(bin=start;bin<end;bin++) {
``` |
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107 | psd[bin]=(3072 - (exp[bin] << 7)); |
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108 | } |
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109 | |||

110 | ```
/* PSD integration */
``` |
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111 | j=start; |
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112 | k=masktab[start]; |
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113 | ```
do {
``` |
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114 | v=psd[j]; |
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115 | j++; |
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116 | ```
end1=bndtab[k+1];
``` |
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117 | ```
if (end1 > end) end1=end;
``` |
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118 | ```
for(i=j;i<end1;i++) {
``` |
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119 | ```
int c,adr;
``` |
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120 | ```
/* logadd */
``` |
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121 | v1=psd[j]; |
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122 | c=v-v1; |
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123 | if (c >= 0) { |
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124 | ```
adr=c >> 1;
``` |
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125 | if (adr > 255) adr=255; |
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126 | v=v + latab[adr]; |
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127 | ```
} else {
``` |
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128 | ```
adr=(-c) >> 1;
``` |
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129 | if (adr > 255) adr=255; |
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130 | v=v1 + latab[adr]; |
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131 | } |
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132 | j++; |
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133 | } |
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134 | bndpsd[k]=v; |
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135 | k++; |
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136 | ```
} while (end > bndtab[k]);
``` |
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137 | |||

138 | ```
/* excitation function */
``` |
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139 | bndstrt = masktab[start]; |
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140 | bndend = masktab[end-1] + 1; |
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141 | |||

142 | ```
lowcomp = 0;
``` |
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143 | lowcomp = calc_lowcomp1(lowcomp, bndpsd[0], bndpsd[1]) ; |
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144 | excite[0] = bndpsd[0] - fgain - lowcomp ; |
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145 | lowcomp = calc_lowcomp1(lowcomp, bndpsd[1], bndpsd[2]) ; |
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146 | excite[1] = bndpsd[1] - fgain - lowcomp ; |
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147 | ```
begin = 7 ;
``` |
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148 | for (bin = 2; bin < 7; bin++) { |
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149 | 30b68f33 | Zdenek Kabelac | if (!(is_lfe && bin == 6)) |

150 | ```
lowcomp = calc_lowcomp1(lowcomp, bndpsd[bin], bndpsd[bin+1]) ;
``` |
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151 | de6d9b64 | Fabrice Bellard | fastleak = bndpsd[bin] - fgain ; |

152 | slowleak = bndpsd[bin] - s->sgain ; |
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153 | excite[bin] = fastleak - lowcomp ; |
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154 | 30b68f33 | Zdenek Kabelac | if (!(is_lfe && bin == 6)) { |

155 | if (bndpsd[bin] <= bndpsd[bin+1]) { |
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156 | ```
begin = bin + 1 ;
``` |
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157 | ```
break ;
``` |
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158 | } |
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159 | } |
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160 | de6d9b64 | Fabrice Bellard | } |

161 | |||

162 | end1=bndend; |
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163 | if (end1 > 22) end1=22; |
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164 | |||

165 | ```
for (bin = begin; bin < end1; bin++) {
``` |
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166 | 30b68f33 | Zdenek Kabelac | if (!(is_lfe && bin == 6)) |

167 | ```
lowcomp = calc_lowcomp(lowcomp, bndpsd[bin], bndpsd[bin+1], bin) ;
``` |
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168 | de6d9b64 | Fabrice Bellard | |

169 | fastleak -= s->fdecay ; |
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170 | v = bndpsd[bin] - fgain; |
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171 | ```
if (fastleak < v) fastleak = v;
``` |
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172 | |||

173 | slowleak -= s->sdecay ; |
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174 | v = bndpsd[bin] - s->sgain; |
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175 | ```
if (slowleak < v) slowleak = v;
``` |
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176 | |||

177 | v=fastleak - lowcomp; |
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178 | ```
if (slowleak > v) v=slowleak;
``` |
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179 | |||

180 | excite[bin] = v; |
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181 | } |
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182 | |||

183 | for (bin = 22; bin < bndend; bin++) { |
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184 | fastleak -= s->fdecay ; |
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185 | v = bndpsd[bin] - fgain; |
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186 | ```
if (fastleak < v) fastleak = v;
``` |
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187 | slowleak -= s->sdecay ; |
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188 | v = bndpsd[bin] - s->sgain; |
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189 | ```
if (slowleak < v) slowleak = v;
``` |
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190 | |||

191 | v=fastleak; |
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192 | ```
if (slowleak > v) v = slowleak;
``` |
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193 | excite[bin] = v; |
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194 | } |
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195 | |||

196 | ```
/* compute masking curve */
``` |
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197 | |||

198 | ```
for (bin = bndstrt; bin < bndend; bin++) {
``` |
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199 | v1 = excite[bin]; |
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200 | tmp = s->dbknee - bndpsd[bin]; |
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201 | if (tmp > 0) { |
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202 | ```
v1 += tmp >> 2;
``` |
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203 | } |
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204 | v=hth[bin >> s->halfratecod][s->fscod]; |
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205 | ```
if (v1 > v) v=v1;
``` |
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206 | mask[bin] = v; |
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207 | } |
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208 | |||

209 | ```
/* compute bit allocation */
``` |
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210 | |||

211 | i = start ; |
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212 | j = masktab[start] ; |
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213 | ```
do {
``` |
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214 | v=mask[j]; |
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215 | v -= snroffset ; |
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216 | v -= s->floor ; |
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217 | if (v < 0) v = 0; |
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218 | ```
v &= 0x1fe0 ;
``` |
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219 | v += s->floor ; |
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220 | |||

221 | end1=bndtab[j] + bndsz[j]; |
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222 | ```
if (end1 > end) end1=end;
``` |
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223 | |||

224 | ```
for (k = i; k < end1; k++) {
``` |
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225 | ```
address = (psd[i] - v) >> 5 ;
``` |
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226 | if (address < 0) address=0; |
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227 | else if (address > 63) address=63; |
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228 | bap[i] = baptab[address]; |
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229 | i++; |
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230 | } |
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231 | ```
} while (end > bndtab[j++]) ;
``` |
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232 | } |
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233 | |||

234 | typedef struct IComplex { |
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235 | ```
short re,im;
``` |
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236 | } IComplex; |
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237 | |||

238 | static void fft_init(int ln) |
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239 | { |
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240 | ```
int i, j, m, n;
``` |
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241 | ```
float alpha;
``` |
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242 | |||

243 | ```
n = 1 << ln;
``` |
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244 | |||

245 | for(i=0;i<(n/2);i++) { |
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246 | alpha = 2 * M_PI * (float)i / (float)n; |
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247 | costab[i] = fix15(cos(alpha)); |
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248 | sintab[i] = fix15(sin(alpha)); |
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249 | } |
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250 | |||

251 | for(i=0;i<n;i++) { |
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252 | ```
m=0;
``` |
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253 | for(j=0;j<ln;j++) { |
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254 | m |= ((i >> j) & 1) << (ln-j-1); |
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255 | } |
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256 | fft_rev[i]=m; |
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257 | } |
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258 | } |
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259 | |||

260 | ```
/* butter fly op */
``` |
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261 | ```
#define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \
``` |
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262 | {\ |
||

263 | ```
int ax, ay, bx, by;\
``` |
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264 | bx=pre1;\ |
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265 | by=pim1;\ |
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266 | ax=qre1;\ |
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267 | ay=qim1;\ |
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268 | ```
pre = (bx + ax) >> 1;\
``` |
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269 | ```
pim = (by + ay) >> 1;\
``` |
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270 | ```
qre = (bx - ax) >> 1;\
``` |
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271 | ```
qim = (by - ay) >> 1;\
``` |
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272 | } |
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273 | |||

274 | ```
#define MUL16(a,b) ((a) * (b))
``` |
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275 | |||

276 | ```
#define CMUL(pre, pim, are, aim, bre, bim) \
``` |
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277 | {\ |
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278 | ```
pre = (MUL16(are, bre) - MUL16(aim, bim)) >> 15;\
``` |
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279 | ```
pim = (MUL16(are, bim) + MUL16(bre, aim)) >> 15;\
``` |
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280 | } |
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281 | |||

282 | |||

283 | ```
/* do a 2^n point complex fft on 2^ln points. */
``` |
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284 | static void fft(IComplex *z, int ln) |
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285 | { |
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286 | ```
int j, l, np, np2;
``` |
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287 | ```
int nblocks, nloops;
``` |
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288 | ```
register IComplex *p,*q;
``` |
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289 | ```
int tmp_re, tmp_im;
``` |
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290 | |||

291 | ```
np = 1 << ln;
``` |
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292 | |||

293 | ```
/* reverse */
``` |
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294 | for(j=0;j<np;j++) { |
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295 | ```
int k;
``` |
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296 | IComplex tmp; |
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297 | k = fft_rev[j]; |
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298 | ```
if (k < j) {
``` |
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299 | tmp = z[k]; |
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300 | z[k] = z[j]; |
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301 | z[j] = tmp; |
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302 | } |
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303 | } |
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304 | |||

305 | ```
/* pass 0 */
``` |
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306 | |||

307 | ```
p=&z[0];
``` |
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308 | ```
j=(np >> 1);
``` |
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309 | ```
do {
``` |
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310 | BF(p[0].re, p[0].im, p[1].re, p[1].im, |
||

311 | p[0].re, p[0].im, p[1].re, p[1].im); |
||

312 | ```
p+=2;
``` |
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313 | } while (--j != 0); |
||

314 | |||

315 | ```
/* pass 1 */
``` |
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316 | |||

317 | ```
p=&z[0];
``` |
||

318 | ```
j=np >> 2;
``` |
||

319 | ```
do {
``` |
||

320 | BF(p[0].re, p[0].im, p[2].re, p[2].im, |
||

321 | p[0].re, p[0].im, p[2].re, p[2].im); |
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322 | BF(p[1].re, p[1].im, p[3].re, p[3].im, |
||

323 | p[1].re, p[1].im, p[3].im, -p[3].re); |
||

324 | ```
p+=4;
``` |
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325 | } while (--j != 0); |
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326 | |||

327 | ```
/* pass 2 .. ln-1 */
``` |
||

328 | |||

329 | ```
nblocks = np >> 3;
``` |
||

330 | nloops = 1 << 2; |
||

331 | ```
np2 = np >> 1;
``` |
||

332 | ```
do {
``` |
||

333 | p = z; |
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334 | q = z + nloops; |
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335 | for (j = 0; j < nblocks; ++j) { |
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336 | |||

337 | BF(p->re, p->im, q->re, q->im, |
||

338 | p->re, p->im, q->re, q->im); |
||

339 | |||

340 | p++; |
||

341 | q++; |
||

342 | ```
for(l = nblocks; l < np2; l += nblocks) {
``` |
||

343 | CMUL(tmp_re, tmp_im, costab[l], -sintab[l], q->re, q->im); |
||

344 | BF(p->re, p->im, q->re, q->im, |
||

345 | p->re, p->im, tmp_re, tmp_im); |
||

346 | p++; |
||

347 | q++; |
||

348 | } |
||

349 | p += nloops; |
||

350 | q += nloops; |
||

351 | } |
||

352 | ```
nblocks = nblocks >> 1;
``` |
||

353 | ```
nloops = nloops << 1;
``` |
||

354 | } while (nblocks != 0); |
||

355 | } |
||

356 | |||

357 | ```
/* do a 512 point mdct */
``` |
||

358 | static void mdct512(INT32 *out, INT16 *in) |
||

359 | { |
||

360 | ```
int i, re, im, re1, im1;
``` |
||

361 | INT16 rot[N]; |
||

362 | ```
IComplex x[N/4];
``` |
||

363 | |||

364 | ```
/* shift to simplify computations */
``` |
||

365 | for(i=0;i<N/4;i++) |
||

366 | rot[i] = -in[i + 3*N/4]; |
||

367 | for(i=N/4;i<N;i++) |
||

368 | ```
rot[i] = in[i - N/4];
``` |
||

369 | |||

370 | ```
/* pre rotation */
``` |
||

371 | for(i=0;i<N/4;i++) { |
||

372 | re = ((int)rot[2*i] - (int)rot[N-1-2*i]) >> 1; |
||

373 | im = -((int)rot[N/2+2*i] - (int)rot[N/2-1-2*i]) >> 1; |
||

374 | CMUL(x[i].re, x[i].im, re, im, -xcos1[i], xsin1[i]); |
||

375 | } |
||

376 | |||

377 | ```
fft(x, MDCT_NBITS - 2);
``` |
||

378 | |||

379 | ```
/* post rotation */
``` |
||

380 | for(i=0;i<N/4;i++) { |
||

381 | re = x[i].re; |
||

382 | im = x[i].im; |
||

383 | CMUL(re1, im1, re, im, xsin1[i], xcos1[i]); |
||

384 | ```
out[2*i] = im1;
``` |
||

385 | out[N/2-1-2*i] = re1; |
||

386 | } |
||

387 | } |
||

388 | |||

389 | ```
/* XXX: use another norm ? */
``` |
||

390 | static int calc_exp_diff(UINT8 *exp1, UINT8 *exp2, int n) |
||

391 | { |
||

392 | ```
int sum, i;
``` |
||

393 | ```
sum = 0;
``` |
||

394 | for(i=0;i<n;i++) { |
||

395 | sum += abs(exp1[i] - exp2[i]); |
||

396 | } |
||

397 | ```
return sum;
``` |
||

398 | } |
||

399 | |||

400 | static void compute_exp_strategy(UINT8 exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS], |
||

401 | ```
UINT8 exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
``` |
||

402 | 30b68f33 | Zdenek Kabelac | int ch, int is_lfe) |

403 | de6d9b64 | Fabrice Bellard | { |

404 | ```
int i, j;
``` |
||

405 | ```
int exp_diff;
``` |
||

406 | |||

407 | ```
/* estimate if the exponent variation & decide if they should be
``` |
||

408 | ```
reused in the next frame */
``` |
||

409 | ```
exp_strategy[0][ch] = EXP_NEW;
``` |
||

410 | for(i=1;i<NB_BLOCKS;i++) { |
||

411 | exp_diff = calc_exp_diff(exp[i][ch], exp[i-1][ch], N/2); |
||

412 | ```
#ifdef DEBUG
``` |
||

413 | ```
printf("exp_diff=%d\n", exp_diff);
``` |
||

414 | ```
#endif
``` |
||

415 | ```
if (exp_diff > EXP_DIFF_THRESHOLD)
``` |
||

416 | exp_strategy[i][ch] = EXP_NEW; |
||

417 | ```
else
``` |
||

418 | exp_strategy[i][ch] = EXP_REUSE; |
||

419 | } |
||

420 | 30b68f33 | Zdenek Kabelac | ```
if (is_lfe)
``` |

421 | ```
return;
``` |
||

422 | |||

423 | de6d9b64 | Fabrice Bellard | ```
/* now select the encoding strategy type : if exponents are often
``` |

424 | ```
recoded, we use a coarse encoding */
``` |
||

425 | ```
i = 0;
``` |
||

426 | ```
while (i < NB_BLOCKS) {
``` |
||

427 | ```
j = i + 1;
``` |
||

428 | ```
while (j < NB_BLOCKS && exp_strategy[j][ch] == EXP_REUSE)
``` |
||

429 | j++; |
||

430 | ```
switch(j - i) {
``` |
||

431 | case 1: |
||

432 | exp_strategy[i][ch] = EXP_D45; |
||

433 | ```
break;
``` |
||

434 | case 2: |
||

435 | case 3: |
||

436 | exp_strategy[i][ch] = EXP_D25; |
||

437 | ```
break;
``` |
||

438 | ```
default:
``` |
||

439 | exp_strategy[i][ch] = EXP_D15; |
||

440 | ```
break;
``` |
||

441 | } |
||

442 | 30b68f33 | Zdenek Kabelac | i = j; |

443 | de6d9b64 | Fabrice Bellard | } |

444 | } |
||

445 | |||

446 | ```
/* set exp[i] to min(exp[i], exp1[i]) */
``` |
||

447 | static void exponent_min(UINT8 exp[N/2], UINT8 exp1[N/2], int n) |
||

448 | { |
||

449 | ```
int i;
``` |
||

450 | |||

451 | for(i=0;i<n;i++) { |
||

452 | ```
if (exp1[i] < exp[i])
``` |
||

453 | exp[i] = exp1[i]; |
||

454 | } |
||

455 | } |
||

456 | |||

457 | ```
/* update the exponents so that they are the ones the decoder will
``` |
||

458 | ```
decode. Return the number of bits used to code the exponents */
``` |
||

459 | static int encode_exp(UINT8 encoded_exp[N/2], |
||

460 | ```
UINT8 exp[N/2],
``` |
||

461 | ```
int nb_exps,
``` |
||

462 | ```
int exp_strategy)
``` |
||

463 | { |
||

464 | ```
int group_size, nb_groups, i, j, k, recurse, exp_min, delta;
``` |
||

465 | ```
UINT8 exp1[N/2];
``` |
||

466 | |||

467 | ```
switch(exp_strategy) {
``` |
||

468 | ```
case EXP_D15:
``` |
||

469 | ```
group_size = 1;
``` |
||

470 | ```
break;
``` |
||

471 | ```
case EXP_D25:
``` |
||

472 | ```
group_size = 2;
``` |
||

473 | ```
break;
``` |
||

474 | ```
default:
``` |
||

475 | ```
case EXP_D45:
``` |
||

476 | ```
group_size = 4;
``` |
||

477 | ```
break;
``` |
||

478 | } |
||

479 | nb_groups = ((nb_exps + (group_size * 3) - 4) / (3 * group_size)) * 3; |
||

480 | |||

481 | ```
/* for each group, compute the minimum exponent */
``` |
||

482 | exp1[0] = exp[0]; /* DC exponent is handled separately */ |
||

483 | ```
k = 1;
``` |
||

484 | for(i=1;i<=nb_groups;i++) { |
||

485 | exp_min = exp[k]; |
||

486 | assert(exp_min >= 0 && exp_min <= 24); |
||

487 | for(j=1;j<group_size;j++) { |
||

488 | ```
if (exp[k+j] < exp_min)
``` |
||

489 | exp_min = exp[k+j]; |
||

490 | } |
||

491 | exp1[i] = exp_min; |
||

492 | k += group_size; |
||

493 | } |
||

494 | |||

495 | ```
/* constraint for DC exponent */
``` |
||

496 | if (exp1[0] > 15) |
||

497 | exp1[0] = 15; |
||

498 | |||

499 | ```
/* Iterate until the delta constraints between each groups are
``` |
||

500 | ```
satisfyed. I'm sure it is possible to find a better algorithm,
``` |
||

501 | ```
but I am lazy */
``` |
||

502 | ```
do {
``` |
||

503 | ```
recurse = 0;
``` |
||

504 | for(i=1;i<=nb_groups;i++) { |
||

505 | ```
delta = exp1[i] - exp1[i-1];
``` |
||

506 | if (delta > 2) { |
||

507 | ```
/* if delta too big, we encode a smaller exponent */
``` |
||

508 | exp1[i] = exp1[i-1] + 2; |
||

509 | } else if (delta < -2) { |
||

510 | ```
/* if delta is too small, we must decrease the previous
``` |
||

511 | ```
exponent, which means we must recurse */
``` |
||

512 | ```
recurse = 1;
``` |
||

513 | exp1[i-1] = exp1[i] + 2; |
||

514 | } |
||

515 | } |
||

516 | ```
} while (recurse);
``` |
||

517 | |||

518 | ```
/* now we have the exponent values the decoder will see */
``` |
||

519 | encoded_exp[0] = exp1[0]; |
||

520 | ```
k = 1;
``` |
||

521 | for(i=1;i<=nb_groups;i++) { |
||

522 | for(j=0;j<group_size;j++) { |
||

523 | encoded_exp[k+j] = exp1[i]; |
||

524 | } |
||

525 | k += group_size; |
||

526 | } |
||

527 | |||

528 | ```
#if defined(DEBUG)
``` |
||

529 | ```
printf("exponents: strategy=%d\n", exp_strategy);
``` |
||

530 | for(i=0;i<=nb_groups * group_size;i++) { |
||

531 | ```
printf("%d ", encoded_exp[i]);
``` |
||

532 | } |
||

533 | ```
printf("\n");
``` |
||

534 | ```
#endif
``` |
||

535 | |||

536 | return 4 + (nb_groups / 3) * 7; |
||

537 | } |
||

538 | |||

539 | ```
/* return the size in bits taken by the mantissa */
``` |
||

540 | int compute_mantissa_size(AC3EncodeContext *s, UINT8 *m, int nb_coefs) |
||

541 | { |
||

542 | ```
int bits, mant, i;
``` |
||

543 | |||

544 | ```
bits = 0;
``` |
||

545 | for(i=0;i<nb_coefs;i++) { |
||

546 | mant = m[i]; |
||

547 | ```
switch(mant) {
``` |
||

548 | case 0: |
||

549 | ```
/* nothing */
``` |
||

550 | ```
break;
``` |
||

551 | case 1: |
||

552 | ```
/* 3 mantissa in 5 bits */
``` |
||

553 | if (s->mant1_cnt == 0) |
||

554 | ```
bits += 5;
``` |
||

555 | if (++s->mant1_cnt == 3) |
||

556 | ```
s->mant1_cnt = 0;
``` |
||

557 | ```
break;
``` |
||

558 | case 2: |
||

559 | ```
/* 3 mantissa in 7 bits */
``` |
||

560 | if (s->mant2_cnt == 0) |
||

561 | ```
bits += 7;
``` |
||

562 | if (++s->mant2_cnt == 3) |
||

563 | ```
s->mant2_cnt = 0;
``` |
||

564 | ```
break;
``` |
||

565 | case 3: |
||

566 | ```
bits += 3;
``` |
||

567 | ```
break;
``` |
||

568 | case 4: |
||

569 | ```
/* 2 mantissa in 7 bits */
``` |
||

570 | if (s->mant4_cnt == 0) |
||

571 | ```
bits += 7;
``` |
||

572 | if (++s->mant4_cnt == 2) |
||

573 | ```
s->mant4_cnt = 0;
``` |
||

574 | ```
break;
``` |
||

575 | case 14: |
||

576 | ```
bits += 14;
``` |
||

577 | ```
break;
``` |
||

578 | case 15: |
||

579 | ```
bits += 16;
``` |
||

580 | ```
break;
``` |
||

581 | ```
default:
``` |
||

582 | ```
bits += mant - 1;
``` |
||

583 | ```
break;
``` |
||

584 | } |
||

585 | } |
||

586 | ```
return bits;
``` |
||

587 | } |
||

588 | |||

589 | |||

590 | static int bit_alloc(AC3EncodeContext *s, |
||

591 | ```
UINT8 bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
``` |
||

592 | ```
UINT8 encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
``` |
||

593 | UINT8 exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS], |
||

594 | int frame_bits, int csnroffst, int fsnroffst) |
||

595 | { |
||

596 | ```
int i, ch;
``` |
||

597 | |||

598 | ```
/* compute size */
``` |
||

599 | for(i=0;i<NB_BLOCKS;i++) { |
||

600 | ```
s->mant1_cnt = 0;
``` |
||

601 | ```
s->mant2_cnt = 0;
``` |
||

602 | ```
s->mant4_cnt = 0;
``` |
||

603 | 30b68f33 | Zdenek Kabelac | for(ch=0;ch<s->nb_all_channels;ch++) { |

604 | 98be975d | Fabrice Bellard | parametric_bit_allocation(s, bap[i][ch], (INT8 *)encoded_exp[i][ch], |

605 | de6d9b64 | Fabrice Bellard | ```
0, s->nb_coefs[ch],
``` |

606 | (((csnroffst-15) << 4) + |
||

607 | ```
fsnroffst) << 2,
``` |
||

608 | 30b68f33 | Zdenek Kabelac | fgaintab[s->fgaincod[ch]], |

609 | ch == s->lfe_channel); |
||

610 | de6d9b64 | Fabrice Bellard | frame_bits += compute_mantissa_size(s, bap[i][ch], |

611 | s->nb_coefs[ch]); |
||

612 | } |
||

613 | } |
||

614 | ```
#if 0
``` |
||

615 | ```
printf("csnr=%d fsnr=%d frame_bits=%d diff=%d\n",
``` |
||

616 | ```
csnroffst, fsnroffst, frame_bits,
``` |
||

617 | ```
16 * s->frame_size - ((frame_bits + 7) & ~7));
``` |
||

618 | ```
#endif
``` |
||

619 | return 16 * s->frame_size - frame_bits; |
||

620 | } |
||

621 | |||

622 | #define SNR_INC1 4 |
||

623 | |||

624 | static int compute_bit_allocation(AC3EncodeContext *s, |
||

625 | ```
UINT8 bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
``` |
||

626 | ```
UINT8 encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
``` |
||

627 | UINT8 exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS], |
||

628 | ```
int frame_bits)
``` |
||

629 | { |
||

630 | ```
int i, ch;
``` |
||

631 | ```
int csnroffst, fsnroffst;
``` |
||

632 | ```
UINT8 bap1[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
``` |
||

633 | 30b68f33 | Zdenek Kabelac | static int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 }; |

634 | de6d9b64 | Fabrice Bellard | |

635 | ```
/* init default parameters */
``` |
||

636 | ```
s->sdecaycod = 2;
``` |
||

637 | ```
s->fdecaycod = 1;
``` |
||

638 | ```
s->sgaincod = 1;
``` |
||

639 | ```
s->dbkneecod = 2;
``` |
||

640 | ```
s->floorcod = 4;
``` |
||

641 | 30b68f33 | Zdenek Kabelac | for(ch=0;ch<s->nb_all_channels;ch++) |

642 | de6d9b64 | Fabrice Bellard | ```
s->fgaincod[ch] = 4;
``` |

643 | |||

644 | ```
/* compute real values */
``` |
||

645 | s->sdecay = sdecaytab[s->sdecaycod] >> s->halfratecod; |
||

646 | s->fdecay = fdecaytab[s->fdecaycod] >> s->halfratecod; |
||

647 | s->sgain = sgaintab[s->sgaincod]; |
||

648 | s->dbknee = dbkneetab[s->dbkneecod]; |
||

649 | s->floor = floortab[s->floorcod]; |
||

650 | |||

651 | ```
/* header size */
``` |
||

652 | ```
frame_bits += 65;
``` |
||

653 | 30b68f33 | Zdenek Kabelac | ```
// if (s->acmod == 2)
``` |

654 | ```
// frame_bits += 2;
``` |
||

655 | frame_bits += frame_bits_inc[s->acmod]; |
||

656 | de6d9b64 | Fabrice Bellard | |

657 | ```
/* audio blocks */
``` |
||

658 | for(i=0;i<NB_BLOCKS;i++) { |
||

659 | 30b68f33 | Zdenek Kabelac | frame_bits += s->nb_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */ |

660 | de6d9b64 | Fabrice Bellard | if (s->acmod == 2) |

661 | 30b68f33 | Zdenek Kabelac | ```
frame_bits++; /* rematstr */
``` |

662 | frame_bits += 2 * s->nb_channels; /* chexpstr[2] * c */ |
||

663 | ```
if (s->lfe)
``` |
||

664 | ```
frame_bits++; /* lfeexpstr */
``` |
||

665 | de6d9b64 | Fabrice Bellard | for(ch=0;ch<s->nb_channels;ch++) { |

666 | ```
if (exp_strategy[i][ch] != EXP_REUSE)
``` |
||

667 | 30b68f33 | Zdenek Kabelac | frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */ |

668 | de6d9b64 | Fabrice Bellard | } |

669 | ```
frame_bits++; /* baie */
``` |
||

670 | ```
frame_bits++; /* snr */
``` |
||

671 | frame_bits += 2; /* delta / skip */ |
||

672 | } |
||

673 | ```
frame_bits++; /* cplinu for block 0 */
``` |
||

674 | ```
/* bit alloc info */
``` |
||

675 | 30b68f33 | Zdenek Kabelac | ```
/* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
``` |

676 | ```
/* csnroffset[6] */
``` |
||

677 | ```
/* (fsnoffset[4] + fgaincod[4]) * c */
``` |
||

678 | frame_bits += 2*4 + 3 + 6 + s->nb_all_channels * (4 + 3); |
||

679 | de6d9b64 | Fabrice Bellard | |

680 | ```
/* CRC */
``` |
||

681 | ```
frame_bits += 16;
``` |
||

682 | |||

683 | ```
/* now the big work begins : do the bit allocation. Modify the snr
``` |
||

684 | ```
offset until we can pack everything in the requested frame size */
``` |
||

685 | |||

686 | csnroffst = s->csnroffst; |
||

687 | while (csnroffst >= 0 && |
||

688 | 30b68f33 | Zdenek Kabelac | bit_alloc(s, bap, encoded_exp, exp_strategy, frame_bits, csnroffst, 0) < 0) |

689 | csnroffst -= SNR_INC1; |
||

690 | de6d9b64 | Fabrice Bellard | if (csnroffst < 0) { |

691 | 30b68f33 | Zdenek Kabelac | ```
fprintf(stderr, "Yack, Error !!!\n");
``` |

692 | return -1; |
||

693 | de6d9b64 | Fabrice Bellard | } |

694 | while ((csnroffst + SNR_INC1) <= 63 && |
||

695 | bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits, |
||

696 | csnroffst + SNR_INC1, 0) >= 0) { |
||

697 | csnroffst += SNR_INC1; |
||

698 | ```
memcpy(bap, bap1, sizeof(bap1));
``` |
||

699 | } |
||

700 | while ((csnroffst + 1) <= 63 && |
||

701 | bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits, csnroffst + 1, 0) >= 0) { |
||

702 | csnroffst++; |
||

703 | ```
memcpy(bap, bap1, sizeof(bap1));
``` |
||

704 | } |
||

705 | |||

706 | ```
fsnroffst = 0;
``` |
||

707 | while ((fsnroffst + SNR_INC1) <= 15 && |
||

708 | bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits, |
||

709 | ```
csnroffst, fsnroffst + SNR_INC1) >= 0) {
``` |
||

710 | fsnroffst += SNR_INC1; |
||

711 | ```
memcpy(bap, bap1, sizeof(bap1));
``` |
||

712 | } |
||

713 | while ((fsnroffst + 1) <= 15 && |
||

714 | bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits, |
||

715 | csnroffst, fsnroffst + 1) >= 0) { |
||

716 | fsnroffst++; |
||

717 | ```
memcpy(bap, bap1, sizeof(bap1));
``` |
||

718 | } |
||

719 | |||

720 | s->csnroffst = csnroffst; |
||

721 | 30b68f33 | Zdenek Kabelac | for(ch=0;ch<s->nb_all_channels;ch++) |

722 | de6d9b64 | Fabrice Bellard | s->fsnroffst[ch] = fsnroffst; |

723 | ```
#if defined(DEBUG_BITALLOC)
``` |
||

724 | { |
||

725 | ```
int j;
``` |
||

726 | |||

727 | for(i=0;i<6;i++) { |
||

728 | 30b68f33 | Zdenek Kabelac | for(ch=0;ch<s->nb_all_channels;ch++) { |

729 | de6d9b64 | Fabrice Bellard | ```
printf("Block #%d Ch%d:\n", i, ch);
``` |

730 | ```
printf("bap=");
``` |
||

731 | for(j=0;j<s->nb_coefs[ch];j++) { |
||

732 | ```
printf("%d ",bap[i][ch][j]);
``` |
||

733 | } |
||

734 | ```
printf("\n");
``` |
||

735 | } |
||

736 | } |
||

737 | } |
||

738 | ```
#endif
``` |
||

739 | return 0; |
||

740 | } |
||

741 | |||

742 | static int AC3_encode_init(AVCodecContext *avctx) |
||

743 | { |
||

744 | ```
int freq = avctx->sample_rate;
``` |
||

745 | ```
int bitrate = avctx->bit_rate;
``` |
||

746 | ```
int channels = avctx->channels;
``` |
||

747 | AC3EncodeContext *s = avctx->priv_data; |
||

748 | ```
int i, j, k, l, ch, v;
``` |
||

749 | ```
float alpha;
``` |
||

750 | static unsigned short freqs[3] = { 48000, 44100, 32000 }; |
||

751 | 30b68f33 | Zdenek Kabelac | static int acmod_defs[6] = { |

752 | 0x01, /* C */ |
||

753 | 0x02, /* L R */ |
||

754 | 0x03, /* L C R */ |
||

755 | 0x06, /* L R SL SR */ |
||

756 | 0x07, /* L C R SL SR */ |
||

757 | 0x07, /* L C R SL SR (+LFE) */ |
||

758 | }; |
||

759 | de6d9b64 | Fabrice Bellard | |

760 | avctx->frame_size = AC3_FRAME_SIZE; |
||

761 | avctx->key_frame = 1; /* always key frame */ |
||

762 | |||

763 | ```
/* number of channels */
``` |
||

764 | 30b68f33 | Zdenek Kabelac | if (channels < 1 || channels > 6) |

765 | return -1; |
||

766 | ```
s->acmod = acmod_defs[channels - 1];
``` |
||

767 | s->lfe = (channels == 6) ? 1 : 0; |
||

768 | s->nb_all_channels = channels; |
||

769 | s->nb_channels = channels > 5 ? 5 : channels; |
||

770 | s->lfe_channel = s->lfe ? 5 : -1; |
||

771 | de6d9b64 | Fabrice Bellard | |

772 | ```
/* frequency */
``` |
||

773 | for(i=0;i<3;i++) { |
||

774 | for(j=0;j<3;j++) |
||

775 | ```
if ((freqs[j] >> i) == freq)
``` |
||

776 | ```
goto found;
``` |
||

777 | } |
||

778 | return -1; |
||

779 | ```
found:
``` |
||

780 | s->sample_rate = freq; |
||

781 | s->halfratecod = i; |
||

782 | s->fscod = j; |
||

783 | ```
s->bsid = 8 + s->halfratecod;
``` |
||

784 | s->bsmod = 0; /* complete main audio service */ |
||

785 | |||

786 | ```
/* bitrate & frame size */
``` |
||

787 | ```
bitrate /= 1000;
``` |
||

788 | for(i=0;i<19;i++) { |
||

789 | ```
if ((bitratetab[i] >> s->halfratecod) == bitrate)
``` |
||

790 | ```
break;
``` |
||

791 | } |
||

792 | if (i == 19) |
||

793 | return -1; |
||

794 | s->bit_rate = bitrate; |
||

795 | ```
s->frmsizecod = i << 1;
``` |
||

796 | s->frame_size_min = (bitrate * 1000 * AC3_FRAME_SIZE) / (freq * 16); |
||

797 | ```
/* for now we do not handle fractional sizes */
``` |
||

798 | s->frame_size = s->frame_size_min; |
||

799 | |||

800 | ```
/* bit allocation init */
``` |
||

801 | for(ch=0;ch<s->nb_channels;ch++) { |
||

802 | ```
/* bandwidth for each channel */
``` |
||

803 | ```
/* XXX: should compute the bandwidth according to the frame
``` |
||

804 | ```
size, so that we avoid anoying high freq artefacts */
``` |
||

805 | s->chbwcod[ch] = 50; /* sample bandwidth as mpeg audio layer 2 table 0 */ |
||

806 | s->nb_coefs[ch] = ((s->chbwcod[ch] + 12) * 3) + 37; |
||

807 | } |
||

808 | 30b68f33 | Zdenek Kabelac | ```
if (s->lfe) {
``` |

809 | s->nb_coefs[s->lfe_channel] = 7; /* fixed */ |
||

810 | } |
||

811 | de6d9b64 | Fabrice Bellard | ```
/* initial snr offset */
``` |

812 | ```
s->csnroffst = 40;
``` |
||

813 | |||

814 | ```
/* compute bndtab and masktab from bandsz */
``` |
||

815 | ```
k = 0;
``` |
||

816 | ```
l = 0;
``` |
||

817 | for(i=0;i<50;i++) { |
||

818 | bndtab[i] = l; |
||

819 | v = bndsz[i]; |
||

820 | for(j=0;j<v;j++) masktab[k++]=i; |
||

821 | l += v; |
||

822 | } |
||

823 | bndtab[50] = 0; |
||

824 | |||

825 | ```
/* mdct init */
``` |
||

826 | ```
fft_init(MDCT_NBITS - 2);
``` |
||

827 | for(i=0;i<N/4;i++) { |
||

828 | alpha = 2 * M_PI * (i + 1.0 / 8.0) / (float)N; |
||

829 | xcos1[i] = fix15(-cos(alpha)); |
||

830 | xsin1[i] = fix15(-sin(alpha)); |
||

831 | } |
||

832 | |||

833 | ac3_crc_init(); |
||

834 | |||

835 | return 0; |
||

836 | } |
||

837 | |||

838 | ```
/* output the AC3 frame header */
``` |
||

839 | static void output_frame_header(AC3EncodeContext *s, unsigned char *frame) |
||

840 | { |
||

841 | init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE, NULL, NULL); |
||

842 | |||

843 | put_bits(&s->pb, 16, 0x0b77); /* frame header */ |
||

844 | put_bits(&s->pb, 16, 0); /* crc1: will be filled later */ |
||

845 | ```
put_bits(&s->pb, 2, s->fscod);
``` |
||

846 | ```
put_bits(&s->pb, 6, s->frmsizecod + (s->frame_size - s->frame_size_min));
``` |
||

847 | ```
put_bits(&s->pb, 5, s->bsid);
``` |
||

848 | ```
put_bits(&s->pb, 3, s->bsmod);
``` |
||

849 | ```
put_bits(&s->pb, 3, s->acmod);
``` |
||

850 | 30b68f33 | Zdenek Kabelac | if ((s->acmod & 0x01) && s->acmod != 0x01) |

851 | put_bits(&s->pb, 2, 1); /* XXX -4.5 dB */ |
||

852 | if (s->acmod & 0x04) |
||

853 | put_bits(&s->pb, 2, 1); /* XXX -6 dB */ |
||

854 | if (s->acmod == 0x02) |
||

855 | de6d9b64 | Fabrice Bellard | put_bits(&s->pb, 2, 0); /* surround not indicated */ |

856 | 30b68f33 | Zdenek Kabelac | put_bits(&s->pb, 1, s->lfe); /* LFE */ |

857 | de6d9b64 | Fabrice Bellard | put_bits(&s->pb, 5, 31); /* dialog norm: -31 db */ |

858 | put_bits(&s->pb, 1, 0); /* no compression control word */ |
||

859 | put_bits(&s->pb, 1, 0); /* no lang code */ |
||

860 | put_bits(&s->pb, 1, 0); /* no audio production info */ |
||

861 | put_bits(&s->pb, 1, 0); /* no copyright */ |
||

862 | put_bits(&s->pb, 1, 1); /* original bitstream */ |
||

863 | put_bits(&s->pb, 1, 0); /* no time code 1 */ |
||

864 | put_bits(&s->pb, 1, 0); /* no time code 2 */ |
||

865 | put_bits(&s->pb, 1, 0); /* no addtional bit stream info */ |
||

866 | } |
||

867 | |||

868 | ```
/* symetric quantization on 'levels' levels */
``` |
||

869 | static inline int sym_quant(int c, int e, int levels) |
||

870 | { |
||

871 | ```
int v;
``` |
||

872 | |||

873 | if (c >= 0) { |
||

874 | 8d67072f | Fabrice Bellard | ```
v = (levels * (c << e)) >> 24;
``` |

875 | v = (v + 1) >> 1; |
||

876 | de6d9b64 | Fabrice Bellard | ```
v = (levels >> 1) + v;
``` |

877 | ```
} else {
``` |
||

878 | 8d67072f | Fabrice Bellard | ```
v = (levels * ((-c) << e)) >> 24;
``` |

879 | v = (v + 1) >> 1; |
||

880 | de6d9b64 | Fabrice Bellard | ```
v = (levels >> 1) - v;
``` |

881 | } |
||

882 | ```
assert (v >= 0 && v < levels);
``` |
||

883 | ```
return v;
``` |
||

884 | } |
||

885 | |||

886 | ```
/* asymetric quantization on 2^qbits levels */
``` |
||

887 | static inline int asym_quant(int c, int e, int qbits) |
||

888 | { |
||

889 | ```
int lshift, m, v;
``` |
||

890 | |||

891 | ```
lshift = e + qbits - 24;
``` |
||

892 | if (lshift >= 0) |
||

893 | v = c << lshift; |
||

894 | ```
else
``` |
||

895 | v = c >> (-lshift); |
||

896 | ```
/* rounding */
``` |
||

897 | v = (v + 1) >> 1; |
||

898 | m = (1 << (qbits-1)); |
||

899 | ```
if (v >= m)
``` |
||

900 | ```
v = m - 1;
``` |
||

901 | assert(v >= -m); |
||

902 | return v & ((1 << qbits)-1); |
||

903 | } |
||

904 | |||

905 | ```
/* Output one audio block. There are NB_BLOCKS audio blocks in one AC3
``` |
||

906 | ```
frame */
``` |
||

907 | static void output_audio_block(AC3EncodeContext *s, |
||

908 | UINT8 exp_strategy[AC3_MAX_CHANNELS], |
||

909 | ```
UINT8 encoded_exp[AC3_MAX_CHANNELS][N/2],
``` |
||

910 | ```
UINT8 bap[AC3_MAX_CHANNELS][N/2],
``` |
||

911 | ```
INT32 mdct_coefs[AC3_MAX_CHANNELS][N/2],
``` |
||

912 | INT8 global_exp[AC3_MAX_CHANNELS], |
||

913 | ```
int block_num)
``` |
||

914 | { |
||

915 | ```
int ch, nb_groups, group_size, i, baie;
``` |
||

916 | UINT8 *p; |
||

917 | ```
UINT16 qmant[AC3_MAX_CHANNELS][N/2];
``` |
||

918 | ```
int exp0, exp1;
``` |
||

919 | ```
int mant1_cnt, mant2_cnt, mant4_cnt;
``` |
||

920 | UINT16 *qmant1_ptr, *qmant2_ptr, *qmant4_ptr; |
||

921 | ```
int delta0, delta1, delta2;
``` |
||

922 | |||

923 | for(ch=0;ch<s->nb_channels;ch++) |
||

924 | put_bits(&s->pb, 1, 0); /* 512 point MDCT */ |
||

925 | for(ch=0;ch<s->nb_channels;ch++) |
||

926 | put_bits(&s->pb, 1, 1); /* no dither */ |
||

927 | put_bits(&s->pb, 1, 0); /* no dynamic range */ |
||

928 | if (block_num == 0) { |
||

929 | ```
/* for block 0, even if no coupling, we must say it. This is a
``` |
||

930 | ```
waste of bit :-) */
``` |
||

931 | put_bits(&s->pb, 1, 1); /* coupling strategy present */ |
||

932 | put_bits(&s->pb, 1, 0); /* no coupling strategy */ |
||

933 | ```
} else {
``` |
||

934 | put_bits(&s->pb, 1, 0); /* no new coupling strategy */ |
||

935 | } |
||

936 | |||

937 | if (s->acmod == 2) { |
||

938 | put_bits(&s->pb, 1, 0); /* no matrixing (but should be used in the future) */ |
||

939 | } |
||

940 | |||

941 | ```
#if defined(DEBUG)
``` |
||

942 | { |
||

943 | static int count = 0; |
||

944 | ```
printf("Block #%d (%d)\n", block_num, count++);
``` |
||

945 | } |
||

946 | ```
#endif
``` |
||

947 | ```
/* exponent strategy */
``` |
||

948 | for(ch=0;ch<s->nb_channels;ch++) { |
||

949 | ```
put_bits(&s->pb, 2, exp_strategy[ch]);
``` |
||

950 | } |
||

951 | |||

952 | 30b68f33 | Zdenek Kabelac | ```
if (s->lfe) {
``` |

953 | ```
put_bits(&s->pb, 1, exp_strategy[s->lfe_channel]);
``` |
||

954 | } |
||

955 | |||

956 | de6d9b64 | Fabrice Bellard | for(ch=0;ch<s->nb_channels;ch++) { |

957 | ```
if (exp_strategy[ch] != EXP_REUSE)
``` |
||

958 | ```
put_bits(&s->pb, 6, s->chbwcod[ch]);
``` |
||

959 | } |
||

960 | |||

961 | ```
/* exponents */
``` |
||

962 | 30b68f33 | Zdenek Kabelac | for (ch = 0; ch < s->nb_all_channels; ch++) { |

963 | de6d9b64 | Fabrice Bellard | ```
switch(exp_strategy[ch]) {
``` |

964 | ```
case EXP_REUSE:
``` |
||

965 | ```
continue;
``` |
||

966 | ```
case EXP_D15:
``` |
||

967 | ```
group_size = 1;
``` |
||

968 | ```
break;
``` |
||

969 | ```
case EXP_D25:
``` |
||

970 | ```
group_size = 2;
``` |
||

971 | ```
break;
``` |
||

972 | ```
default:
``` |
||

973 | ```
case EXP_D45:
``` |
||

974 | ```
group_size = 4;
``` |
||

975 | ```
break;
``` |
||

976 | } |
||

977 | 30b68f33 | Zdenek Kabelac | nb_groups = (s->nb_coefs[ch] + (group_size * 3) - 4) / (3 * group_size); |

978 | de6d9b64 | Fabrice Bellard | p = encoded_exp[ch]; |

979 | |||

980 | ```
/* first exponent */
``` |
||

981 | exp1 = *p++; |
||

982 | ```
put_bits(&s->pb, 4, exp1);
``` |
||

983 | |||

984 | ```
/* next ones are delta encoded */
``` |
||

985 | for(i=0;i<nb_groups;i++) { |
||

986 | ```
/* merge three delta in one code */
``` |
||

987 | exp0 = exp1; |
||

988 | ```
exp1 = p[0];
``` |
||

989 | p += group_size; |
||

990 | ```
delta0 = exp1 - exp0 + 2;
``` |
||

991 | |||

992 | exp0 = exp1; |
||

993 | ```
exp1 = p[0];
``` |
||

994 | p += group_size; |
||

995 | ```
delta1 = exp1 - exp0 + 2;
``` |
||

996 | |||

997 | exp0 = exp1; |
||

998 | ```
exp1 = p[0];
``` |
||

999 | p += group_size; |
||

1000 | ```
delta2 = exp1 - exp0 + 2;
``` |
||

1001 | |||

1002 | put_bits(&s->pb, 7, ((delta0 * 5 + delta1) * 5) + delta2); |
||

1003 | } |
||

1004 | |||

1005 | 30b68f33 | Zdenek Kabelac | ```
if (ch != s->lfe_channel)
``` |

1006 | put_bits(&s->pb, 2, 0); /* no gain range info */ |
||

1007 | de6d9b64 | Fabrice Bellard | } |

1008 | |||

1009 | ```
/* bit allocation info */
``` |
||

1010 | ```
baie = (block_num == 0);
``` |
||

1011 | ```
put_bits(&s->pb, 1, baie);
``` |
||

1012 | ```
if (baie) {
``` |
||

1013 | ```
put_bits(&s->pb, 2, s->sdecaycod);
``` |
||

1014 | ```
put_bits(&s->pb, 2, s->fdecaycod);
``` |
||

1015 | ```
put_bits(&s->pb, 2, s->sgaincod);
``` |
||

1016 | ```
put_bits(&s->pb, 2, s->dbkneecod);
``` |
||

1017 | ```
put_bits(&s->pb, 3, s->floorcod);
``` |
||

1018 | } |
||

1019 | |||

1020 | ```
/* snr offset */
``` |
||

1021 | put_bits(&s->pb, 1, baie); /* always present with bai */ |
||

1022 | ```
if (baie) {
``` |
||

1023 | ```
put_bits(&s->pb, 6, s->csnroffst);
``` |
||

1024 | 30b68f33 | Zdenek Kabelac | for(ch=0;ch<s->nb_all_channels;ch++) { |

1025 | de6d9b64 | Fabrice Bellard | ```
put_bits(&s->pb, 4, s->fsnroffst[ch]);
``` |

1026 | ```
put_bits(&s->pb, 3, s->fgaincod[ch]);
``` |
||

1027 | } |
||

1028 | } |
||

1029 | |||

1030 | put_bits(&s->pb, 1, 0); /* no delta bit allocation */ |
||

1031 | put_bits(&s->pb, 1, 0); /* no data to skip */ |
||

1032 | |||

1033 | ```
/* mantissa encoding : we use two passes to handle the grouping. A
``` |
||

1034 | ```
one pass method may be faster, but it would necessitate to
``` |
||

1035 | ```
modify the output stream. */
``` |
||

1036 | |||

1037 | ```
/* first pass: quantize */
``` |
||

1038 | ```
mant1_cnt = mant2_cnt = mant4_cnt = 0;
``` |
||

1039 | ```
qmant1_ptr = qmant2_ptr = qmant4_ptr = NULL;
``` |
||

1040 | |||

1041 | 30b68f33 | Zdenek Kabelac | for (ch = 0; ch < s->nb_all_channels; ch++) { |

1042 | de6d9b64 | Fabrice Bellard | ```
int b, c, e, v;
``` |

1043 | |||

1044 | for(i=0;i<s->nb_coefs[ch];i++) { |
||

1045 | c = mdct_coefs[ch][i]; |
||

1046 | e = encoded_exp[ch][i] - global_exp[ch]; |
||

1047 | b = bap[ch][i]; |
||

1048 | ```
switch(b) {
``` |
||

1049 | case 0: |
||

1050 | ```
v = 0;
``` |
||

1051 | ```
break;
``` |
||

1052 | case 1: |
||

1053 | ```
v = sym_quant(c, e, 3);
``` |
||

1054 | ```
switch(mant1_cnt) {
``` |
||

1055 | case 0: |
||

1056 | qmant1_ptr = &qmant[ch][i]; |
||

1057 | ```
v = 9 * v;
``` |
||

1058 | ```
mant1_cnt = 1;
``` |
||

1059 | ```
break;
``` |
||

1060 | case 1: |
||

1061 | ```
*qmant1_ptr += 3 * v;
``` |
||

1062 | ```
mant1_cnt = 2;
``` |
||

1063 | ```
v = 128;
``` |
||

1064 | ```
break;
``` |
||

1065 | ```
default:
``` |
||

1066 | *qmant1_ptr += v; |
||

1067 | ```
mant1_cnt = 0;
``` |
||

1068 | ```
v = 128;
``` |
||

1069 | ```
break;
``` |
||

1070 | } |
||

1071 | ```
break;
``` |
||

1072 | case 2: |
||

1073 | ```
v = sym_quant(c, e, 5);
``` |
||

1074 | ```
switch(mant2_cnt) {
``` |
||

1075 | case 0: |
||

1076 | qmant2_ptr = &qmant[ch][i]; |
||

1077 | ```
v = 25 * v;
``` |
||

1078 | ```
mant2_cnt = 1;
``` |
||

1079 | ```
break;
``` |
||

1080 | case 1: |
||

1081 | ```
*qmant2_ptr += 5 * v;
``` |
||

1082 | ```
mant2_cnt = 2;
``` |
||

1083 | ```
v = 128;
``` |
||

1084 | ```
break;
``` |
||

1085 | ```
default:
``` |
||

1086 | *qmant2_ptr += v; |
||

1087 | ```
mant2_cnt = 0;
``` |
||

1088 | ```
v = 128;
``` |
||

1089 | ```
break;
``` |
||

1090 | } |
||

1091 | ```
break;
``` |
||

1092 | case 3: |
||

1093 | ```
v = sym_quant(c, e, 7);
``` |
||

1094 | ```
break;
``` |
||

1095 | case 4: |
||

1096 | ```
v = sym_quant(c, e, 11);
``` |
||

1097 | ```
switch(mant4_cnt) {
``` |
||

1098 | case 0: |
||

1099 | qmant4_ptr = &qmant[ch][i]; |
||

1100 | ```
v = 11 * v;
``` |
||

1101 | ```
mant4_cnt = 1;
``` |
||

1102 | ```
break;
``` |
||

1103 | ```
default:
``` |
||

1104 | *qmant4_ptr += v; |
||

1105 | ```
mant4_cnt = 0;
``` |
||

1106 | ```
v = 128;
``` |
||

1107 | ```
break;
``` |
||

1108 | } |
||

1109 | ```
break;
``` |
||

1110 | case 5: |
||

1111 | ```
v = sym_quant(c, e, 15);
``` |
||

1112 | ```
break;
``` |
||

1113 | case 14: |
||

1114 | ```
v = asym_quant(c, e, 14);
``` |
||

1115 | ```
break;
``` |
||

1116 | case 15: |
||

1117 | ```
v = asym_quant(c, e, 16);
``` |
||

1118 | ```
break;
``` |
||

1119 | ```
default:
``` |
||

1120 | ```
v = asym_quant(c, e, b - 1);
``` |
||

1121 | ```
break;
``` |
||

1122 | } |
||

1123 | qmant[ch][i] = v; |
||

1124 | } |
||

1125 | } |
||

1126 | |||

1127 | ```
/* second pass : output the values */
``` |
||

1128 | 30b68f33 | Zdenek Kabelac | for (ch = 0; ch < s->nb_all_channels; ch++) { |

1129 | de6d9b64 | Fabrice Bellard | ```
int b, q;
``` |

1130 | |||

1131 | for(i=0;i<s->nb_coefs[ch];i++) { |
||

1132 | q = qmant[ch][i]; |
||

1133 | b = bap[ch][i]; |
||

1134 | ```
switch(b) {
``` |
||

1135 | case 0: |
||

1136 | ```
break;
``` |
||

1137 | case 1: |
||

1138 | if (q != 128) |
||

1139 | ```
put_bits(&s->pb, 5, q);
``` |
||

1140 | ```
break;
``` |
||

1141 | case 2: |
||

1142 | if (q != 128) |
||

1143 | ```
put_bits(&s->pb, 7, q);
``` |
||

1144 | ```
break;
``` |
||

1145 | case 3: |
||

1146 | ```
put_bits(&s->pb, 3, q);
``` |
||

1147 | ```
break;
``` |
||

1148 | case 4: |
||

1149 | if (q != 128) |
||

1150 | ```
put_bits(&s->pb, 7, q);
``` |
||

1151 | ```
break;
``` |
||

1152 | case 14: |
||

1153 | ```
put_bits(&s->pb, 14, q);
``` |
||

1154 | ```
break;
``` |
||

1155 | case 15: |
||

1156 | ```
put_bits(&s->pb, 16, q);
``` |
||

1157 | ```
break;
``` |
||

1158 | ```
default:
``` |
||

1159 | ```
put_bits(&s->pb, b - 1, q);
``` |
||

1160 | ```
break;
``` |
||

1161 | } |
||

1162 | } |
||

1163 | } |
||

1164 | } |
||

1165 | |||

1166 | ```
/* compute the ac3 crc */
``` |
||

1167 | |||

1168 | #define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16)) |
||

1169 | |||

1170 | static void ac3_crc_init(void) |
||

1171 | { |
||

1172 | unsigned int c, n, k; |
||

1173 | |||

1174 | for(n=0;n<256;n++) { |
||

1175 | ```
c = n << 8;
``` |
||

1176 | for (k = 0; k < 8; k++) { |
||

1177 | if (c & (1 << 15)) |
||

1178 | c = ((c << 1) & 0xffff) ^ (CRC16_POLY & 0xffff); |
||

1179 | ```
else
``` |
||

1180 | ```
c = c << 1;
``` |
||

1181 | } |
||

1182 | crc_table[n] = c; |
||

1183 | } |
||

1184 | } |
||

1185 | |||

1186 | static unsigned int ac3_crc(UINT8 *data, int n, unsigned int crc) |
||

1187 | { |
||

1188 | ```
int i;
``` |
||

1189 | for(i=0;i<n;i++) { |
||

1190 | crc = (crc_table[data[i] ^ (crc >> 8)] ^ (crc << 8)) & 0xffff; |
||

1191 | } |
||

1192 | ```
return crc;
``` |
||

1193 | } |
||

1194 | |||

1195 | static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly) |
||

1196 | { |
||

1197 | unsigned int c; |
||

1198 | |||

1199 | ```
c = 0;
``` |
||

1200 | ```
while (a) {
``` |
||

1201 | if (a & 1) |
||

1202 | c ^= b; |
||

1203 | ```
a = a >> 1;
``` |
||

1204 | ```
b = b << 1;
``` |
||

1205 | if (b & (1 << 16)) |
||

1206 | b ^= poly; |
||

1207 | } |
||

1208 | ```
return c;
``` |
||

1209 | } |
||

1210 | |||

1211 | static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly) |
||

1212 | { |
||

1213 | unsigned int r; |
||

1214 | ```
r = 1;
``` |
||

1215 | ```
while (n) {
``` |
||

1216 | if (n & 1) |
||

1217 | r = mul_poly(r, a, poly); |
||

1218 | a = mul_poly(a, a, poly); |
||

1219 | ```
n >>= 1;
``` |
||

1220 | } |
||

1221 | ```
return r;
``` |
||

1222 | } |
||

1223 | |||

1224 | |||

1225 | ```
/* compute log2(max(abs(tab[]))) */
``` |
||

1226 | static int log2_tab(INT16 *tab, int n) |
||

1227 | { |
||

1228 | ```
int i, v;
``` |
||

1229 | |||

1230 | ```
v = 0;
``` |
||

1231 | for(i=0;i<n;i++) { |
||

1232 | v |= abs(tab[i]); |
||

1233 | } |
||

1234 | 34763c15 | Fabrice Bellard | ```
return av_log2(v);
``` |

1235 | de6d9b64 | Fabrice Bellard | } |

1236 | |||

1237 | static void lshift_tab(INT16 *tab, int n, int lshift) |
||

1238 | { |
||

1239 | ```
int i;
``` |
||

1240 | |||

1241 | if (lshift > 0) { |
||

1242 | for(i=0;i<n;i++) { |
||

1243 | tab[i] <<= lshift; |
||

1244 | } |
||

1245 | } else if (lshift < 0) { |
||

1246 | lshift = -lshift; |
||

1247 | for(i=0;i<n;i++) { |
||

1248 | tab[i] >>= lshift; |
||

1249 | } |
||

1250 | } |
||

1251 | } |
||

1252 | |||

1253 | ```
/* fill the end of the frame and compute the two crcs */
``` |
||

1254 | static int output_frame_end(AC3EncodeContext *s) |
||

1255 | { |
||

1256 | ```
int frame_size, frame_size_58, n, crc1, crc2, crc_inv;
``` |
||

1257 | UINT8 *frame; |
||

1258 | |||

1259 | ```
frame_size = s->frame_size; /* frame size in words */
``` |
||

1260 | ```
/* align to 8 bits */
``` |
||

1261 | flush_put_bits(&s->pb); |
||

1262 | ```
/* add zero bytes to reach the frame size */
``` |
||

1263 | frame = s->pb.buf; |
||

1264 | 17592475 | Michael Niedermayer | n = 2 * s->frame_size - (pbBufPtr(&s->pb) - frame) - 2; |

1265 | de6d9b64 | Fabrice Bellard | ```
assert(n >= 0);
``` |

1266 | 17592475 | Michael Niedermayer | ```
memset(pbBufPtr(&s->pb), 0, n);
``` |

1267 | de6d9b64 | Fabrice Bellard | |

1268 | ```
/* Now we must compute both crcs : this is not so easy for crc1
``` |
||

1269 | ```
because it is at the beginning of the data... */
``` |
||

1270 | frame_size_58 = (frame_size >> 1) + (frame_size >> 3); |
||

1271 | crc1 = ac3_crc(frame + 4, (2 * frame_size_58) - 4, 0); |
||

1272 | ```
/* XXX: could precompute crc_inv */
``` |
||

1273 | crc_inv = pow_poly((CRC16_POLY >> 1), (16 * frame_size_58) - 16, CRC16_POLY); |
||

1274 | crc1 = mul_poly(crc_inv, crc1, CRC16_POLY); |
||

1275 | frame[2] = crc1 >> 8; |
||

1276 | ```
frame[3] = crc1;
``` |
||

1277 | |||

1278 | crc2 = ac3_crc(frame + 2 * frame_size_58, (frame_size - frame_size_58) * 2 - 2, 0); |
||

1279 | frame[2*frame_size - 2] = crc2 >> 8; |
||

1280 | frame[2*frame_size - 1] = crc2; |
||

1281 | |||

1282 | ```
// printf("n=%d frame_size=%d\n", n, frame_size);
``` |
||

1283 | return frame_size * 2; |
||

1284 | } |
||

1285 | |||

1286 | ```
int AC3_encode_frame(AVCodecContext *avctx,
``` |
||

1287 | unsigned char *frame, int buf_size, void *data) |
||

1288 | { |
||

1289 | AC3EncodeContext *s = avctx->priv_data; |
||

1290 | ```
short *samples = data;
``` |
||

1291 | ```
int i, j, k, v, ch;
``` |
||

1292 | INT16 input_samples[N]; |
||

1293 | ```
INT32 mdct_coef[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
``` |
||

1294 | ```
UINT8 exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
``` |
||

1295 | UINT8 exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS]; |
||

1296 | ```
UINT8 encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
``` |
||

1297 | ```
UINT8 bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
``` |
||

1298 | INT8 exp_samples[NB_BLOCKS][AC3_MAX_CHANNELS]; |
||

1299 | ```
int frame_bits;
``` |
||

1300 | |||

1301 | ```
frame_bits = 0;
``` |
||

1302 | 30b68f33 | Zdenek Kabelac | for(ch=0;ch<s->nb_all_channels;ch++) { |

1303 | de6d9b64 | Fabrice Bellard | ```
/* fixed mdct to the six sub blocks & exponent computation */
``` |

1304 | for(i=0;i<NB_BLOCKS;i++) { |
||

1305 | INT16 *sptr; |
||

1306 | ```
int sinc;
``` |
||

1307 | |||

1308 | ```
/* compute input samples */
``` |
||

1309 | memcpy(input_samples, s->last_samples[ch], N/2 * sizeof(INT16)); |
||

1310 | 30b68f33 | Zdenek Kabelac | sinc = s->nb_all_channels; |

1311 | de6d9b64 | Fabrice Bellard | ```
sptr = samples + (sinc * (N/2) * i) + ch;
``` |

1312 | for(j=0;j<N/2;j++) { |
||

1313 | v = *sptr; |
||

1314 | ```
input_samples[j + N/2] = v;
``` |
||

1315 | s->last_samples[ch][j] = v; |
||

1316 | sptr += sinc; |
||

1317 | } |
||

1318 | |||

1319 | ```
/* apply the MDCT window */
``` |
||

1320 | for(j=0;j<N/2;j++) { |
||

1321 | input_samples[j] = MUL16(input_samples[j], |
||

1322 | ```
ac3_window[j]) >> 15;
``` |
||

1323 | input_samples[N-j-1] = MUL16(input_samples[N-j-1], |
||

1324 | ```
ac3_window[j]) >> 15;
``` |
||

1325 | } |
||

1326 | |||

1327 | ```
/* Normalize the samples to use the maximum available
``` |
||

1328 | ```
precision */
``` |
||

1329 | ```
v = 14 - log2_tab(input_samples, N);
``` |
||

1330 | if (v < 0) |
||

1331 | ```
v = 0;
``` |
||

1332 | ```
exp_samples[i][ch] = v - 8;
``` |
||

1333 | lshift_tab(input_samples, N, v); |
||

1334 | |||

1335 | ```
/* do the MDCT */
``` |
||

1336 | mdct512(mdct_coef[i][ch], input_samples); |
||

1337 | |||

1338 | ```
/* compute "exponents". We take into account the
``` |
||

1339 | ```
normalization there */
``` |
||

1340 | for(j=0;j<N/2;j++) { |
||

1341 | ```
int e;
``` |
||

1342 | v = abs(mdct_coef[i][ch][j]); |
||

1343 | if (v == 0) |
||

1344 | ```
e = 24;
``` |
||

1345 | ```
else {
``` |
||

1346 | 34763c15 | Fabrice Bellard | ```
e = 23 - av_log2(v) + exp_samples[i][ch];
``` |

1347 | de6d9b64 | Fabrice Bellard | if (e >= 24) { |

1348 | ```
e = 24;
``` |
||

1349 | ```
mdct_coef[i][ch][j] = 0;
``` |
||

1350 | } |
||

1351 | } |
||

1352 | exp[i][ch][j] = e; |
||

1353 | } |
||

1354 | } |
||

1355 | |||

1356 | 30b68f33 | Zdenek Kabelac | compute_exp_strategy(exp_strategy, exp, ch, ch == s->lfe_channel); |

1357 | de6d9b64 | Fabrice Bellard | |

1358 | ```
/* compute the exponents as the decoder will see them. The
``` |
||

1359 | ```
EXP_REUSE case must be handled carefully : we select the
``` |
||

1360 | ```
min of the exponents */
``` |
||

1361 | ```
i = 0;
``` |
||

1362 | ```
while (i < NB_BLOCKS) {
``` |
||

1363 | ```
j = i + 1;
``` |
||

1364 | ```
while (j < NB_BLOCKS && exp_strategy[j][ch] == EXP_REUSE) {
``` |
||

1365 | exponent_min(exp[i][ch], exp[j][ch], s->nb_coefs[ch]); |
||

1366 | j++; |
||

1367 | } |
||

1368 | frame_bits += encode_exp(encoded_exp[i][ch], |
||

1369 | exp[i][ch], s->nb_coefs[ch], |
||

1370 | exp_strategy[i][ch]); |
||

1371 | ```
/* copy encoded exponents for reuse case */
``` |
||

1372 | for(k=i+1;k<j;k++) { |
||

1373 | memcpy(encoded_exp[k][ch], encoded_exp[i][ch], |
||

1374 | ```
s->nb_coefs[ch] * sizeof(UINT8));
``` |
||

1375 | } |
||

1376 | i = j; |
||

1377 | } |
||

1378 | } |
||

1379 | |||

1380 | compute_bit_allocation(s, bap, encoded_exp, exp_strategy, frame_bits); |
||

1381 | ```
/* everything is known... let's output the frame */
``` |
||

1382 | output_frame_header(s, frame); |
||

1383 | |||

1384 | for(i=0;i<NB_BLOCKS;i++) { |
||

1385 | output_audio_block(s, exp_strategy[i], encoded_exp[i], |
||

1386 | bap[i], mdct_coef[i], exp_samples[i], i); |
||

1387 | } |
||

1388 | ```
return output_frame_end(s);
``` |
||

1389 | } |
||

1390 | |||

1391 | ```
#if 0
``` |
||

1392 | ```
/*************************************************************************/
``` |
||

1393 | ```
/* TEST */
``` |
||

1394 | |||

1395 | ```
#define FN (N/4)
``` |
||

1396 | |||

1397 | ```
void fft_test(void)
``` |
||

1398 | ```
{
``` |
||

1399 | ```
IComplex in[FN], in1[FN];
``` |
||

1400 | ```
int k, n, i;
``` |
||

1401 | ```
float sum_re, sum_im, a;
``` |
||

1402 | |||

1403 | ```
/* FFT test */
``` |
||

1404 | |||

1405 | ```
for(i=0;i<FN;i++) {
``` |
||

1406 | ```
in[i].re = random() % 65535 - 32767;
``` |
||

1407 | ```
in[i].im = random() % 65535 - 32767;
``` |
||

1408 | ```
in1[i] = in[i];
``` |
||

1409 | ```
}
``` |
||

1410 | ```
fft(in, 7);
``` |
||

1411 | |||

1412 | ```
/* do it by hand */
``` |
||

1413 | ```
for(k=0;k<FN;k++) {
``` |
||

1414 | ```
sum_re = 0;
``` |
||

1415 | ```
sum_im = 0;
``` |
||

1416 | ```
for(n=0;n<FN;n++) {
``` |
||

1417 | ```
a = -2 * M_PI * (n * k) / FN;
``` |
||

1418 | ```
sum_re += in1[n].re * cos(a) - in1[n].im * sin(a);
``` |
||

1419 | ```
sum_im += in1[n].re * sin(a) + in1[n].im * cos(a);
``` |
||

1420 | ```
}
``` |
||

1421 | ```
printf("%3d: %6d,%6d %6.0f,%6.0f\n",
``` |
||

1422 | ```
k, in[k].re, in[k].im, sum_re / FN, sum_im / FN);
``` |
||

1423 | ```
}
``` |
||

1424 | ```
}
``` |
||

1425 | |||

1426 | ```
void mdct_test(void)
``` |
||

1427 | ```
{
``` |
||

1428 | ```
INT16 input[N];
``` |
||

1429 | ```
INT32 output[N/2];
``` |
||

1430 | ```
float input1[N];
``` |
||

1431 | ```
float output1[N/2];
``` |
||

1432 | ```
float s, a, err, e, emax;
``` |
||

1433 | ```
int i, k, n;
``` |
||

1434 | |||

1435 | ```
for(i=0;i<N;i++) {
``` |
||

1436 | ```
input[i] = (random() % 65535 - 32767) * 9 / 10;
``` |
||

1437 | ```
input1[i] = input[i];
``` |
||

1438 | ```
}
``` |
||

1439 | |||

1440 | ```
mdct512(output, input);
``` |
||

1441 | ```
``` |
||

1442 | ```
/* do it by hand */
``` |
||

1443 | ```
for(k=0;k<N/2;k++) {
``` |
||

1444 | ```
s = 0;
``` |
||

1445 | ```
for(n=0;n<N;n++) {
``` |
||

1446 | ```
a = (2*M_PI*(2*n+1+N/2)*(2*k+1) / (4 * N));
``` |
||

1447 | ```
s += input1[n] * cos(a);
``` |
||

1448 | ```
}
``` |
||

1449 | ```
output1[k] = -2 * s / N;
``` |
||

1450 | ```
}
``` |
||

1451 | ```
``` |
||

1452 | ```
err = 0;
``` |
||

1453 | ```
emax = 0;
``` |
||

1454 | ```
for(i=0;i<N/2;i++) {
``` |
||

1455 | ```
printf("%3d: %7d %7.0f\n", i, output[i], output1[i]);
``` |
||

1456 | ```
e = output[i] - output1[i];
``` |
||

1457 | ```
if (e > emax)
``` |
||

1458 | ```
emax = e;
``` |
||

1459 | ```
err += e * e;
``` |
||

1460 | ```
}
``` |
||

1461 | ```
printf("err2=%f emax=%f\n", err / (N/2), emax);
``` |
||

1462 | ```
}
``` |
||

1463 | |||

1464 | ```
void test_ac3(void)
``` |
||

1465 | ```
{
``` |
||

1466 | ```
AC3EncodeContext ctx;
``` |
||

1467 | ```
unsigned char frame[AC3_MAX_CODED_FRAME_SIZE];
``` |
||

1468 | ```
short samples[AC3_FRAME_SIZE];
``` |
||

1469 | ```
int ret, i;
``` |
||

1470 | ```
``` |
||

1471 | ```
AC3_encode_init(&ctx, 44100, 64000, 1);
``` |
||

1472 | |||

1473 | ```
fft_test();
``` |
||

1474 | ```
mdct_test();
``` |
||

1475 | |||

1476 | ```
for(i=0;i<AC3_FRAME_SIZE;i++)
``` |
||

1477 | ```
samples[i] = (int)(sin(2*M_PI*i*1000.0/44100) * 10000);
``` |
||

1478 | ```
ret = AC3_encode_frame(&ctx, frame, samples);
``` |
||

1479 | ```
printf("ret=%d\n", ret);
``` |
||

1480 | ```
}
``` |
||

1481 | ```
#endif
``` |
||

1482 | |||

1483 | AVCodec ac3_encoder = { |
||

1484 | ```
"ac3",
``` |
||

1485 | CODEC_TYPE_AUDIO, |
||

1486 | CODEC_ID_AC3, |
||

1487 | ```
sizeof(AC3EncodeContext),
``` |
||

1488 | AC3_encode_init, |
||

1489 | AC3_encode_frame, |
||

1490 | ```
NULL,
``` |
||

1491 | }; |