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1 <?php |
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2 ///////////////////////////////////////////////////////////////// |
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3 /// getID3() by James Heinrich <info@getid3.org> // |
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4 // available at http://getid3.sourceforge.net // |
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5 // or http://www.getid3.org // |
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6 ///////////////////////////////////////////////////////////////// |
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7 // See readme.txt for more details // |
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8 ///////////////////////////////////////////////////////////////// |
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9 // // |
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10 // module.audio.ac3.php // |
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11 // module for analyzing AC-3 (aka Dolby Digital) audio files // |
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12 // dependencies: NONE // |
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13 // /// |
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14 ///////////////////////////////////////////////////////////////// |
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15 |
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16 |
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17 class getid3_ac3 extends getid3_handler |
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18 { |
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19 private $AC3header = array(); |
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20 private $BSIoffset = 0; |
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21 |
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22 const syncword = "\x0B\x77"; |
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23 |
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24 public function Analyze() { |
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25 $info = &$this->getid3->info; |
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26 |
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27 ///AH |
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28 $info['ac3']['raw']['bsi'] = array(); |
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29 $thisfile_ac3 = &$info['ac3']; |
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30 $thisfile_ac3_raw = &$thisfile_ac3['raw']; |
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31 $thisfile_ac3_raw_bsi = &$thisfile_ac3_raw['bsi']; |
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32 |
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33 |
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34 // http://www.atsc.org/standards/a_52a.pdf |
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35 |
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36 $info['fileformat'] = 'ac3'; |
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37 |
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38 // An AC-3 serial coded audio bit stream is made up of a sequence of synchronization frames |
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39 // Each synchronization frame contains 6 coded audio blocks (AB), each of which represent 256 |
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40 // new audio samples per channel. A synchronization information (SI) header at the beginning |
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41 // of each frame contains information needed to acquire and maintain synchronization. A |
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42 // bit stream information (BSI) header follows SI, and contains parameters describing the coded |
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43 // audio service. The coded audio blocks may be followed by an auxiliary data (Aux) field. At the |
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44 // end of each frame is an error check field that includes a CRC word for error detection. An |
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45 // additional CRC word is located in the SI header, the use of which, by a decoder, is optional. |
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46 // |
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47 // syncinfo() | bsi() | AB0 | AB1 | AB2 | AB3 | AB4 | AB5 | Aux | CRC |
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48 |
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49 // syncinfo() { |
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50 // syncword 16 |
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51 // crc1 16 |
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52 // fscod 2 |
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53 // frmsizecod 6 |
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54 // } /* end of syncinfo */ |
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55 |
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56 $this->fseek($info['avdataoffset']); |
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57 $this->AC3header['syncinfo'] = $this->fread(5); |
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58 |
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59 if (strpos($this->AC3header['syncinfo'], self::syncword) === 0) { |
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60 $thisfile_ac3_raw['synchinfo']['synchword'] = self::syncword; |
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61 $offset = 2; |
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62 } else { |
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63 if (!$this->isDependencyFor('matroska')) { |
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64 unset($info['fileformat'], $info['ac3']); |
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65 return $this->error('Expecting "'.getid3_lib::PrintHexBytes(self::syncword).'" at offset '.$info['avdataoffset'].', found "'.getid3_lib::PrintHexBytes(substr($this->AC3header['syncinfo'], 0, 2)).'"'); |
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66 } |
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67 $offset = 0; |
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68 $this->fseek(-2, SEEK_CUR); |
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69 } |
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70 |
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71 $info['audio']['dataformat'] = 'ac3'; |
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72 $info['audio']['bitrate_mode'] = 'cbr'; |
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73 $info['audio']['lossless'] = false; |
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74 |
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75 $thisfile_ac3_raw['synchinfo']['crc1'] = getid3_lib::LittleEndian2Int(substr($this->AC3header['syncinfo'], $offset, 2)); |
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76 $ac3_synchinfo_fscod_frmsizecod = getid3_lib::LittleEndian2Int(substr($this->AC3header['syncinfo'], ($offset + 2), 1)); |
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77 $thisfile_ac3_raw['synchinfo']['fscod'] = ($ac3_synchinfo_fscod_frmsizecod & 0xC0) >> 6; |
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78 $thisfile_ac3_raw['synchinfo']['frmsizecod'] = ($ac3_synchinfo_fscod_frmsizecod & 0x3F); |
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79 |
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80 $thisfile_ac3['sample_rate'] = self::sampleRateCodeLookup($thisfile_ac3_raw['synchinfo']['fscod']); |
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81 if ($thisfile_ac3_raw['synchinfo']['fscod'] <= 3) { |
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82 $info['audio']['sample_rate'] = $thisfile_ac3['sample_rate']; |
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83 } |
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84 |
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85 $thisfile_ac3['frame_length'] = self::frameSizeLookup($thisfile_ac3_raw['synchinfo']['frmsizecod'], $thisfile_ac3_raw['synchinfo']['fscod']); |
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86 $thisfile_ac3['bitrate'] = self::bitrateLookup($thisfile_ac3_raw['synchinfo']['frmsizecod']); |
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87 $info['audio']['bitrate'] = $thisfile_ac3['bitrate']; |
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88 |
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89 $this->AC3header['bsi'] = getid3_lib::BigEndian2Bin($this->fread(15)); |
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90 $ac3_bsi_offset = 0; |
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91 |
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92 $thisfile_ac3_raw_bsi['bsid'] = $this->readHeaderBSI(5); |
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93 if ($thisfile_ac3_raw_bsi['bsid'] > 8) { |
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94 // Decoders which can decode version 8 will thus be able to decode version numbers less than 8. |
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95 // If this standard is extended by the addition of additional elements or features, a value of bsid greater than 8 will be used. |
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96 // Decoders built to this version of the standard will not be able to decode versions with bsid greater than 8. |
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97 $this->error('Bit stream identification is version '.$thisfile_ac3_raw_bsi['bsid'].', but getID3() only understands up to version 8'); |
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98 unset($info['ac3']); |
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99 return false; |
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100 } |
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101 |
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102 $thisfile_ac3_raw_bsi['bsmod'] = $this->readHeaderBSI(3); |
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103 $thisfile_ac3_raw_bsi['acmod'] = $this->readHeaderBSI(3); |
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104 |
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105 $thisfile_ac3['service_type'] = self::serviceTypeLookup($thisfile_ac3_raw_bsi['bsmod'], $thisfile_ac3_raw_bsi['acmod']); |
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106 $ac3_coding_mode = self::audioCodingModeLookup($thisfile_ac3_raw_bsi['acmod']); |
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107 foreach($ac3_coding_mode as $key => $value) { |
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108 $thisfile_ac3[$key] = $value; |
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109 } |
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110 switch ($thisfile_ac3_raw_bsi['acmod']) { |
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111 case 0: |
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112 case 1: |
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113 $info['audio']['channelmode'] = 'mono'; |
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114 break; |
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115 case 3: |
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116 case 4: |
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117 $info['audio']['channelmode'] = 'stereo'; |
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118 break; |
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119 default: |
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120 $info['audio']['channelmode'] = 'surround'; |
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121 break; |
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122 } |
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123 $info['audio']['channels'] = $thisfile_ac3['num_channels']; |
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124 |
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125 if ($thisfile_ac3_raw_bsi['acmod'] & 0x01) { |
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126 // If the lsb of acmod is a 1, center channel is in use and cmixlev follows in the bit stream. |
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127 $thisfile_ac3_raw_bsi['cmixlev'] = $this->readHeaderBSI(2); |
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128 $thisfile_ac3['center_mix_level'] = self::centerMixLevelLookup($thisfile_ac3_raw_bsi['cmixlev']); |
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129 } |
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130 |
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131 if ($thisfile_ac3_raw_bsi['acmod'] & 0x04) { |
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132 // If the msb of acmod is a 1, surround channels are in use and surmixlev follows in the bit stream. |
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133 $thisfile_ac3_raw_bsi['surmixlev'] = $this->readHeaderBSI(2); |
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134 $thisfile_ac3['surround_mix_level'] = self::surroundMixLevelLookup($thisfile_ac3_raw_bsi['surmixlev']); |
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135 } |
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136 |
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137 if ($thisfile_ac3_raw_bsi['acmod'] == 0x02) { |
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138 // When operating in the two channel mode, this 2-bit code indicates whether or not the program has been encoded in Dolby Surround. |
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139 $thisfile_ac3_raw_bsi['dsurmod'] = $this->readHeaderBSI(2); |
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140 $thisfile_ac3['dolby_surround_mode'] = self::dolbySurroundModeLookup($thisfile_ac3_raw_bsi['dsurmod']); |
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141 } |
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142 |
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143 $thisfile_ac3_raw_bsi['lfeon'] = (bool) $this->readHeaderBSI(1); |
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144 $thisfile_ac3['lfe_enabled'] = $thisfile_ac3_raw_bsi['lfeon']; |
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145 if ($thisfile_ac3_raw_bsi['lfeon']) { |
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146 //$info['audio']['channels']++; |
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147 $info['audio']['channels'] .= '.1'; |
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148 } |
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149 |
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150 $thisfile_ac3['channels_enabled'] = self::channelsEnabledLookup($thisfile_ac3_raw_bsi['acmod'], $thisfile_ac3_raw_bsi['lfeon']); |
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151 |
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152 // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1-31. |
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153 // The value of 0 is reserved. The values of 1 to 31 are interpreted as -1 dB to -31 dB with respect to digital 100 percent. |
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154 $thisfile_ac3_raw_bsi['dialnorm'] = $this->readHeaderBSI(5); |
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155 $thisfile_ac3['dialogue_normalization'] = '-'.$thisfile_ac3_raw_bsi['dialnorm'].'dB'; |
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156 |
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157 $thisfile_ac3_raw_bsi['compre_flag'] = (bool) $this->readHeaderBSI(1); |
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158 if ($thisfile_ac3_raw_bsi['compre_flag']) { |
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159 $thisfile_ac3_raw_bsi['compr'] = $this->readHeaderBSI(8); |
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160 $thisfile_ac3['heavy_compression'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr']); |
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161 } |
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162 |
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163 $thisfile_ac3_raw_bsi['langcode_flag'] = (bool) $this->readHeaderBSI(1); |
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164 if ($thisfile_ac3_raw_bsi['langcode_flag']) { |
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165 $thisfile_ac3_raw_bsi['langcod'] = $this->readHeaderBSI(8); |
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166 } |
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167 |
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168 $thisfile_ac3_raw_bsi['audprodie'] = (bool) $this->readHeaderBSI(1); |
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169 if ($thisfile_ac3_raw_bsi['audprodie']) { |
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170 $thisfile_ac3_raw_bsi['mixlevel'] = $this->readHeaderBSI(5); |
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171 $thisfile_ac3_raw_bsi['roomtyp'] = $this->readHeaderBSI(2); |
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172 |
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173 $thisfile_ac3['mixing_level'] = (80 + $thisfile_ac3_raw_bsi['mixlevel']).'dB'; |
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174 $thisfile_ac3['room_type'] = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp']); |
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175 } |
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176 |
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177 if ($thisfile_ac3_raw_bsi['acmod'] == 0x00) { |
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178 // If acmod is 0, then two completely independent program channels (dual mono) |
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179 // are encoded into the bit stream, and are referenced as Ch1, Ch2. In this case, |
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180 // a number of additional items are present in BSI or audblk to fully describe Ch2. |
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181 |
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182 // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1-31. |
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183 // The value of 0 is reserved. The values of 1 to 31 are interpreted as -1 dB to -31 dB with respect to digital 100 percent. |
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184 $thisfile_ac3_raw_bsi['dialnorm2'] = $this->readHeaderBSI(5); |
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185 $thisfile_ac3['dialogue_normalization2'] = '-'.$thisfile_ac3_raw_bsi['dialnorm2'].'dB'; |
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186 |
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187 $thisfile_ac3_raw_bsi['compre_flag2'] = (bool) $this->readHeaderBSI(1); |
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188 if ($thisfile_ac3_raw_bsi['compre_flag2']) { |
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189 $thisfile_ac3_raw_bsi['compr2'] = $this->readHeaderBSI(8); |
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190 $thisfile_ac3['heavy_compression2'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr2']); |
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191 } |
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192 |
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193 $thisfile_ac3_raw_bsi['langcode_flag2'] = (bool) $this->readHeaderBSI(1); |
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194 if ($thisfile_ac3_raw_bsi['langcode_flag2']) { |
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195 $thisfile_ac3_raw_bsi['langcod2'] = $this->readHeaderBSI(8); |
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196 } |
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197 |
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198 $thisfile_ac3_raw_bsi['audprodie2'] = (bool) $this->readHeaderBSI(1); |
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199 if ($thisfile_ac3_raw_bsi['audprodie2']) { |
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200 $thisfile_ac3_raw_bsi['mixlevel2'] = $this->readHeaderBSI(5); |
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201 $thisfile_ac3_raw_bsi['roomtyp2'] = $this->readHeaderBSI(2); |
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202 |
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203 $thisfile_ac3['mixing_level2'] = (80 + $thisfile_ac3_raw_bsi['mixlevel2']).'dB'; |
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204 $thisfile_ac3['room_type2'] = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp2']); |
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205 } |
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206 |
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207 } |
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208 |
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209 $thisfile_ac3_raw_bsi['copyright'] = (bool) $this->readHeaderBSI(1); |
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210 |
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211 $thisfile_ac3_raw_bsi['original'] = (bool) $this->readHeaderBSI(1); |
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212 |
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213 $thisfile_ac3_raw_bsi['timecode1_flag'] = (bool) $this->readHeaderBSI(1); |
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214 if ($thisfile_ac3_raw_bsi['timecode1_flag']) { |
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215 $thisfile_ac3_raw_bsi['timecode1'] = $this->readHeaderBSI(14); |
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216 } |
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217 |
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218 $thisfile_ac3_raw_bsi['timecode2_flag'] = (bool) $this->readHeaderBSI(1); |
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219 if ($thisfile_ac3_raw_bsi['timecode2_flag']) { |
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220 $thisfile_ac3_raw_bsi['timecode2'] = $this->readHeaderBSI(14); |
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221 } |
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222 |
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223 $thisfile_ac3_raw_bsi['addbsi_flag'] = (bool) $this->readHeaderBSI(1); |
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224 if ($thisfile_ac3_raw_bsi['addbsi_flag']) { |
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225 $thisfile_ac3_raw_bsi['addbsi_length'] = $this->readHeaderBSI(6); |
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226 |
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227 $this->AC3header['bsi'] .= getid3_lib::BigEndian2Bin($this->fread($thisfile_ac3_raw_bsi['addbsi_length'])); |
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228 |
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229 $thisfile_ac3_raw_bsi['addbsi_data'] = substr($this->AC3header['bsi'], $this->BSIoffset, $thisfile_ac3_raw_bsi['addbsi_length'] * 8); |
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230 $this->BSIoffset += $thisfile_ac3_raw_bsi['addbsi_length'] * 8; |
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231 } |
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232 |
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233 return true; |
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234 } |
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235 |
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236 private function readHeaderBSI($length) { |
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237 $data = substr($this->AC3header['bsi'], $this->BSIoffset, $length); |
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238 $this->BSIoffset += $length; |
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239 |
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240 return bindec($data); |
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241 } |
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242 |
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243 public static function sampleRateCodeLookup($fscod) { |
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244 static $sampleRateCodeLookup = array( |
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245 0 => 48000, |
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246 1 => 44100, |
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247 2 => 32000, |
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248 3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute. |
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249 ); |
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250 return (isset($sampleRateCodeLookup[$fscod]) ? $sampleRateCodeLookup[$fscod] : false); |
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251 } |
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252 |
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253 public static function serviceTypeLookup($bsmod, $acmod) { |
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254 static $serviceTypeLookup = array(); |
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255 if (empty($serviceTypeLookup)) { |
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256 for ($i = 0; $i <= 7; $i++) { |
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257 $serviceTypeLookup[0][$i] = 'main audio service: complete main (CM)'; |
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258 $serviceTypeLookup[1][$i] = 'main audio service: music and effects (ME)'; |
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259 $serviceTypeLookup[2][$i] = 'associated service: visually impaired (VI)'; |
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260 $serviceTypeLookup[3][$i] = 'associated service: hearing impaired (HI)'; |
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261 $serviceTypeLookup[4][$i] = 'associated service: dialogue (D)'; |
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262 $serviceTypeLookup[5][$i] = 'associated service: commentary (C)'; |
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263 $serviceTypeLookup[6][$i] = 'associated service: emergency (E)'; |
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264 } |
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265 |
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266 $serviceTypeLookup[7][1] = 'associated service: voice over (VO)'; |
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267 for ($i = 2; $i <= 7; $i++) { |
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268 $serviceTypeLookup[7][$i] = 'main audio service: karaoke'; |
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269 } |
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270 } |
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271 return (isset($serviceTypeLookup[$bsmod][$acmod]) ? $serviceTypeLookup[$bsmod][$acmod] : false); |
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272 } |
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273 |
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274 public static function audioCodingModeLookup($acmod) { |
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275 // array(channel configuration, # channels (not incl LFE), channel order) |
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276 static $audioCodingModeLookup = array ( |
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277 0 => array('channel_config'=>'1+1', 'num_channels'=>2, 'channel_order'=>'Ch1,Ch2'), |
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278 1 => array('channel_config'=>'1/0', 'num_channels'=>1, 'channel_order'=>'C'), |
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279 2 => array('channel_config'=>'2/0', 'num_channels'=>2, 'channel_order'=>'L,R'), |
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280 3 => array('channel_config'=>'3/0', 'num_channels'=>3, 'channel_order'=>'L,C,R'), |
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281 4 => array('channel_config'=>'2/1', 'num_channels'=>3, 'channel_order'=>'L,R,S'), |
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282 5 => array('channel_config'=>'3/1', 'num_channels'=>4, 'channel_order'=>'L,C,R,S'), |
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283 6 => array('channel_config'=>'2/2', 'num_channels'=>4, 'channel_order'=>'L,R,SL,SR'), |
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284 7 => array('channel_config'=>'3/2', 'num_channels'=>5, 'channel_order'=>'L,C,R,SL,SR'), |
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285 ); |
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286 return (isset($audioCodingModeLookup[$acmod]) ? $audioCodingModeLookup[$acmod] : false); |
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287 } |
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288 |
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289 public static function centerMixLevelLookup($cmixlev) { |
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290 static $centerMixLevelLookup; |
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291 if (empty($centerMixLevelLookup)) { |
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292 $centerMixLevelLookup = array( |
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293 0 => pow(2, -3.0 / 6), // 0.707 (-3.0 dB) |
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294 1 => pow(2, -4.5 / 6), // 0.595 (-4.5 dB) |
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295 2 => pow(2, -6.0 / 6), // 0.500 (-6.0 dB) |
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296 3 => 'reserved' |
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297 ); |
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298 } |
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299 return (isset($centerMixLevelLookup[$cmixlev]) ? $centerMixLevelLookup[$cmixlev] : false); |
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300 } |
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301 |
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302 public static function surroundMixLevelLookup($surmixlev) { |
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303 static $surroundMixLevelLookup; |
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304 if (empty($surroundMixLevelLookup)) { |
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305 $surroundMixLevelLookup = array( |
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306 0 => pow(2, -3.0 / 6), |
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307 1 => pow(2, -6.0 / 6), |
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308 2 => 0, |
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309 3 => 'reserved' |
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310 ); |
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311 } |
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312 return (isset($surroundMixLevelLookup[$surmixlev]) ? $surroundMixLevelLookup[$surmixlev] : false); |
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313 } |
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314 |
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315 public static function dolbySurroundModeLookup($dsurmod) { |
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316 static $dolbySurroundModeLookup = array( |
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317 0 => 'not indicated', |
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318 1 => 'Not Dolby Surround encoded', |
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319 2 => 'Dolby Surround encoded', |
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320 3 => 'reserved' |
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321 ); |
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322 return (isset($dolbySurroundModeLookup[$dsurmod]) ? $dolbySurroundModeLookup[$dsurmod] : false); |
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323 } |
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324 |
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325 public static function channelsEnabledLookup($acmod, $lfeon) { |
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326 $lookup = array( |
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327 'ch1'=>(bool) ($acmod == 0), |
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328 'ch2'=>(bool) ($acmod == 0), |
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329 'left'=>(bool) ($acmod > 1), |
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330 'right'=>(bool) ($acmod > 1), |
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331 'center'=>(bool) ($acmod & 0x01), |
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332 'surround_mono'=>false, |
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333 'surround_left'=>false, |
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334 'surround_right'=>false, |
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335 'lfe'=>$lfeon); |
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336 switch ($acmod) { |
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337 case 4: |
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338 case 5: |
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339 $lookup['surround_mono'] = true; |
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340 break; |
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341 case 6: |
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342 case 7: |
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343 $lookup['surround_left'] = true; |
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344 $lookup['surround_right'] = true; |
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345 break; |
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346 } |
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347 return $lookup; |
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348 } |
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349 |
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350 public static function heavyCompression($compre) { |
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351 // The first four bits indicate gain changes in 6.02dB increments which can be |
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352 // implemented with an arithmetic shift operation. The following four bits |
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353 // indicate linear gain changes, and require a 5-bit multiply. |
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354 // We will represent the two 4-bit fields of compr as follows: |
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355 // X0 X1 X2 X3 . Y4 Y5 Y6 Y7 |
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356 // The meaning of the X values is most simply described by considering X to represent a 4-bit |
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357 // signed integer with values from -8 to +7. The gain indicated by X is then (X + 1) * 6.02 dB. The |
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358 // following table shows this in detail. |
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359 |
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360 // Meaning of 4 msb of compr |
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361 // 7 +48.16 dB |
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362 // 6 +42.14 dB |
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363 // 5 +36.12 dB |
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364 // 4 +30.10 dB |
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365 // 3 +24.08 dB |
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366 // 2 +18.06 dB |
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367 // 1 +12.04 dB |
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368 // 0 +6.02 dB |
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369 // -1 0 dB |
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370 // -2 -6.02 dB |
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371 // -3 -12.04 dB |
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372 // -4 -18.06 dB |
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373 // -5 -24.08 dB |
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374 // -6 -30.10 dB |
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375 // -7 -36.12 dB |
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376 // -8 -42.14 dB |
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377 |
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378 $fourbit = str_pad(decbin(($compre & 0xF0) >> 4), 4, '0', STR_PAD_LEFT); |
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379 if ($fourbit{0} == '1') { |
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380 $log_gain = -8 + bindec(substr($fourbit, 1)); |
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381 } else { |
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382 $log_gain = bindec(substr($fourbit, 1)); |
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383 } |
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384 $log_gain = ($log_gain + 1) * getid3_lib::RGADamplitude2dB(2); |
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385 |
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386 // The value of Y is a linear representation of a gain change of up to -6 dB. Y is considered to |
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387 // be an unsigned fractional integer, with a leading value of 1, or: 0.1 Y4 Y5 Y6 Y7 (base 2). Y can |
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388 // represent values between 0.111112 (or 31/32) and 0.100002 (or 1/2). Thus, Y can represent gain |
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389 // changes from -0.28 dB to -6.02 dB. |
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390 |
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391 $lin_gain = (16 + ($compre & 0x0F)) / 32; |
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392 |
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393 // The combination of X and Y values allows compr to indicate gain changes from |
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394 // 48.16 - 0.28 = +47.89 dB, to |
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395 // -42.14 - 6.02 = -48.16 dB. |
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396 |
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397 return $log_gain - $lin_gain; |
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398 } |
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399 |
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400 public static function roomTypeLookup($roomtyp) { |
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401 static $roomTypeLookup = array( |
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402 0 => 'not indicated', |
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403 1 => 'large room, X curve monitor', |
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404 2 => 'small room, flat monitor', |
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405 3 => 'reserved' |
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406 ); |
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407 return (isset($roomTypeLookup[$roomtyp]) ? $roomTypeLookup[$roomtyp] : false); |
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408 } |
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409 |
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410 public static function frameSizeLookup($frmsizecod, $fscod) { |
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411 $padding = (bool) ($frmsizecod % 2); |
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412 $framesizeid = floor($frmsizecod / 2); |
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413 |
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414 static $frameSizeLookup = array(); |
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415 if (empty($frameSizeLookup)) { |
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416 $frameSizeLookup = array ( |
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417 0 => array(128, 138, 192), |
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418 1 => array(40, 160, 174, 240), |
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419 2 => array(48, 192, 208, 288), |
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420 3 => array(56, 224, 242, 336), |
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421 4 => array(64, 256, 278, 384), |
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422 5 => array(80, 320, 348, 480), |
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423 6 => array(96, 384, 416, 576), |
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424 7 => array(112, 448, 486, 672), |
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425 8 => array(128, 512, 556, 768), |
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426 9 => array(160, 640, 696, 960), |
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427 10 => array(192, 768, 834, 1152), |
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428 11 => array(224, 896, 974, 1344), |
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429 12 => array(256, 1024, 1114, 1536), |
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430 13 => array(320, 1280, 1392, 1920), |
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431 14 => array(384, 1536, 1670, 2304), |
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432 15 => array(448, 1792, 1950, 2688), |
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433 16 => array(512, 2048, 2228, 3072), |
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434 17 => array(576, 2304, 2506, 3456), |
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435 18 => array(640, 2560, 2786, 3840) |
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436 ); |
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437 } |
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438 if (($fscod == 1) && $padding) { |
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439 // frame lengths are padded by 1 word (16 bits) at 44100 |
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440 $frameSizeLookup[$frmsizecod] += 2; |
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441 } |
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442 return (isset($frameSizeLookup[$framesizeid][$fscod]) ? $frameSizeLookup[$framesizeid][$fscod] : false); |
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443 } |
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444 |
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445 public static function bitrateLookup($frmsizecod) { |
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446 $framesizeid = floor($frmsizecod / 2); |
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447 |
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448 static $bitrateLookup = array( |
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449 0 => 32000, |
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450 1 => 40000, |
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451 2 => 48000, |
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452 3 => 56000, |
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453 4 => 64000, |
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454 5 => 80000, |
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455 6 => 96000, |
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456 7 => 112000, |
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457 8 => 128000, |
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458 9 => 160000, |
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459 10 => 192000, |
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460 11 => 224000, |
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461 12 => 256000, |
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462 13 => 320000, |
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463 14 => 384000, |
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464 15 => 448000, |
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465 16 => 512000, |
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466 17 => 576000, |
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467 18 => 640000 |
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468 ); |
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469 return (isset($bitrateLookup[$framesizeid]) ? $bitrateLookup[$framesizeid] : false); |
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470 } |
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471 |
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472 |
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473 } |