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1 <?php 2 3 ///////////////////////////////////////////////////////////////// 4 /// getID3() by James Heinrich <info@getid3.org> // 5 // available at https://github.com/JamesHeinrich/getID3 // 6 // or https://www.getid3.org // 7 // or http://getid3.sourceforge.net // 8 // see readme.txt for more details // 9 ///////////////////////////////////////////////////////////////// 10 // // 11 // module.audio.ac3.php // 12 // module for analyzing AC-3 (aka Dolby Digital) audio files // 13 // dependencies: NONE // 14 // /// 15 ///////////////////////////////////////////////////////////////// 16 17 if (!defined('GETID3_INCLUDEPATH')) { // prevent path-exposing attacks that access modules directly on public webservers 18 exit; 19 } 20 21 class getid3_ac3 extends getid3_handler 22 { 23 /** 24 * @var array 25 */ 26 private $AC3header = array(); 27 28 /** 29 * @var int 30 */ 31 private $BSIoffset = 0; 32 33 const syncword = 0x0B77; 34 35 /** 36 * @return bool 37 */ 38 public function Analyze() { 39 $info = &$this->getid3->info; 40 41 ///AH 42 $info['ac3']['raw']['bsi'] = array(); 43 $thisfile_ac3 = &$info['ac3']; 44 $thisfile_ac3_raw = &$thisfile_ac3['raw']; 45 $thisfile_ac3_raw_bsi = &$thisfile_ac3_raw['bsi']; 46 47 48 // http://www.atsc.org/standards/a_52a.pdf 49 50 $info['fileformat'] = 'ac3'; 51 52 // An AC-3 serial coded audio bit stream is made up of a sequence of synchronization frames 53 // Each synchronization frame contains 6 coded audio blocks (AB), each of which represent 256 54 // new audio samples per channel. A synchronization information (SI) header at the beginning 55 // of each frame contains information needed to acquire and maintain synchronization. A 56 // bit stream information (BSI) header follows SI, and contains parameters describing the coded 57 // audio service. The coded audio blocks may be followed by an auxiliary data (Aux) field. At the 58 // end of each frame is an error check field that includes a CRC word for error detection. An 59 // additional CRC word is located in the SI header, the use of which, by a decoder, is optional. 60 // 61 // syncinfo() | bsi() | AB0 | AB1 | AB2 | AB3 | AB4 | AB5 | Aux | CRC 62 63 // syncinfo() { 64 // syncword 16 65 // crc1 16 66 // fscod 2 67 // frmsizecod 6 68 // } /* end of syncinfo */ 69 70 $this->fseek($info['avdataoffset']); 71 $tempAC3header = $this->fread(100); // should be enough to cover all data, there are some variable-length fields...? 72 $this->AC3header['syncinfo'] = getid3_lib::BigEndian2Int(substr($tempAC3header, 0, 2)); 73 $this->AC3header['bsi'] = getid3_lib::BigEndian2Bin(substr($tempAC3header, 2)); 74 $thisfile_ac3_raw_bsi['bsid'] = (getid3_lib::LittleEndian2Int(substr($tempAC3header, 5, 1)) & 0xF8) >> 3; // AC3 and E-AC3 put the "bsid" version identifier in the same place, but unfortnately the 4 bytes between the syncword and the version identifier are interpreted differently, so grab it here so the following code structure can make sense 75 unset($tempAC3header); 76 77 if ($this->AC3header['syncinfo'] !== self::syncword) { 78 if (!$this->isDependencyFor('matroska')) { 79 unset($info['fileformat'], $info['ac3']); 80 return $this->error('Expecting "'.dechex(self::syncword).'" at offset '.$info['avdataoffset'].', found "'.dechex($this->AC3header['syncinfo']).'"'); 81 } 82 } 83 84 $info['audio']['dataformat'] = 'ac3'; 85 $info['audio']['bitrate_mode'] = 'cbr'; 86 $info['audio']['lossless'] = false; 87 88 if ($thisfile_ac3_raw_bsi['bsid'] <= 8) { 89 90 $thisfile_ac3_raw_bsi['crc1'] = getid3_lib::Bin2Dec($this->readHeaderBSI(16)); 91 $thisfile_ac3_raw_bsi['fscod'] = $this->readHeaderBSI(2); // 5.4.1.3 92 $thisfile_ac3_raw_bsi['frmsizecod'] = $this->readHeaderBSI(6); // 5.4.1.4 93 if ($thisfile_ac3_raw_bsi['frmsizecod'] > 37) { // binary: 100101 - see Table 5.18 Frame Size Code Table (1 word = 16 bits) 94 $this->warning('Unexpected ac3.bsi.frmsizecod value: '.$thisfile_ac3_raw_bsi['frmsizecod'].', bitrate not set correctly'); 95 } 96 97 $thisfile_ac3_raw_bsi['bsid'] = $this->readHeaderBSI(5); // we already know this from pre-parsing the version identifier, but re-read it to let the bitstream flow as intended 98 $thisfile_ac3_raw_bsi['bsmod'] = $this->readHeaderBSI(3); 99 $thisfile_ac3_raw_bsi['acmod'] = $this->readHeaderBSI(3); 100 101 if ($thisfile_ac3_raw_bsi['acmod'] & 0x01) { 102 // If the lsb of acmod is a 1, center channel is in use and cmixlev follows in the bit stream. 103 $thisfile_ac3_raw_bsi['cmixlev'] = $this->readHeaderBSI(2); 104 $thisfile_ac3['center_mix_level'] = self::centerMixLevelLookup($thisfile_ac3_raw_bsi['cmixlev']); 105 } 106 107 if ($thisfile_ac3_raw_bsi['acmod'] & 0x04) { 108 // If the msb of acmod is a 1, surround channels are in use and surmixlev follows in the bit stream. 109 $thisfile_ac3_raw_bsi['surmixlev'] = $this->readHeaderBSI(2); 110 $thisfile_ac3['surround_mix_level'] = self::surroundMixLevelLookup($thisfile_ac3_raw_bsi['surmixlev']); 111 } 112 113 if ($thisfile_ac3_raw_bsi['acmod'] == 0x02) { 114 // When operating in the two channel mode, this 2-bit code indicates whether or not the program has been encoded in Dolby Surround. 115 $thisfile_ac3_raw_bsi['dsurmod'] = $this->readHeaderBSI(2); 116 $thisfile_ac3['dolby_surround_mode'] = self::dolbySurroundModeLookup($thisfile_ac3_raw_bsi['dsurmod']); 117 } 118 119 $thisfile_ac3_raw_bsi['flags']['lfeon'] = (bool) $this->readHeaderBSI(1); 120 121 // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1-31. 122 // 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. 123 $thisfile_ac3_raw_bsi['dialnorm'] = $this->readHeaderBSI(5); // 5.4.2.8 dialnorm: Dialogue Normalization, 5 Bits 124 125 $thisfile_ac3_raw_bsi['flags']['compr'] = (bool) $this->readHeaderBSI(1); // 5.4.2.9 compre: Compression Gain Word Exists, 1 Bit 126 if ($thisfile_ac3_raw_bsi['flags']['compr']) { 127 $thisfile_ac3_raw_bsi['compr'] = $this->readHeaderBSI(8); // 5.4.2.10 compr: Compression Gain Word, 8 Bits 128 $thisfile_ac3['heavy_compression'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr']); 129 } 130 131 $thisfile_ac3_raw_bsi['flags']['langcod'] = (bool) $this->readHeaderBSI(1); // 5.4.2.11 langcode: Language Code Exists, 1 Bit 132 if ($thisfile_ac3_raw_bsi['flags']['langcod']) { 133 $thisfile_ac3_raw_bsi['langcod'] = $this->readHeaderBSI(8); // 5.4.2.12 langcod: Language Code, 8 Bits 134 } 135 136 $thisfile_ac3_raw_bsi['flags']['audprodinfo'] = (bool) $this->readHeaderBSI(1); // 5.4.2.13 audprodie: Audio Production Information Exists, 1 Bit 137 if ($thisfile_ac3_raw_bsi['flags']['audprodinfo']) { 138 $thisfile_ac3_raw_bsi['mixlevel'] = $this->readHeaderBSI(5); // 5.4.2.14 mixlevel: Mixing Level, 5 Bits 139 $thisfile_ac3_raw_bsi['roomtyp'] = $this->readHeaderBSI(2); // 5.4.2.15 roomtyp: Room Type, 2 Bits 140 141 $thisfile_ac3['mixing_level'] = (80 + $thisfile_ac3_raw_bsi['mixlevel']).'dB'; 142 $thisfile_ac3['room_type'] = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp']); 143 } 144 145 146 $thisfile_ac3_raw_bsi['dialnorm2'] = $this->readHeaderBSI(5); // 5.4.2.16 dialnorm2: Dialogue Normalization, ch2, 5 Bits 147 $thisfile_ac3['dialogue_normalization2'] = '-'.$thisfile_ac3_raw_bsi['dialnorm2'].'dB'; // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1-31. 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. 148 149 $thisfile_ac3_raw_bsi['flags']['compr2'] = (bool) $this->readHeaderBSI(1); // 5.4.2.17 compr2e: Compression Gain Word Exists, ch2, 1 Bit 150 if ($thisfile_ac3_raw_bsi['flags']['compr2']) { 151 $thisfile_ac3_raw_bsi['compr2'] = $this->readHeaderBSI(8); // 5.4.2.18 compr2: Compression Gain Word, ch2, 8 Bits 152 $thisfile_ac3['heavy_compression2'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr2']); 153 } 154 155 $thisfile_ac3_raw_bsi['flags']['langcod2'] = (bool) $this->readHeaderBSI(1); // 5.4.2.19 langcod2e: Language Code Exists, ch2, 1 Bit 156 if ($thisfile_ac3_raw_bsi['flags']['langcod2']) { 157 $thisfile_ac3_raw_bsi['langcod2'] = $this->readHeaderBSI(8); // 5.4.2.20 langcod2: Language Code, ch2, 8 Bits 158 } 159 160 $thisfile_ac3_raw_bsi['flags']['audprodinfo2'] = (bool) $this->readHeaderBSI(1); // 5.4.2.21 audprodi2e: Audio Production Information Exists, ch2, 1 Bit 161 if ($thisfile_ac3_raw_bsi['flags']['audprodinfo2']) { 162 $thisfile_ac3_raw_bsi['mixlevel2'] = $this->readHeaderBSI(5); // 5.4.2.22 mixlevel2: Mixing Level, ch2, 5 Bits 163 $thisfile_ac3_raw_bsi['roomtyp2'] = $this->readHeaderBSI(2); // 5.4.2.23 roomtyp2: Room Type, ch2, 2 Bits 164 165 $thisfile_ac3['mixing_level2'] = (80 + $thisfile_ac3_raw_bsi['mixlevel2']).'dB'; 166 $thisfile_ac3['room_type2'] = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp2']); 167 } 168 169 $thisfile_ac3_raw_bsi['copyright'] = (bool) $this->readHeaderBSI(1); // 5.4.2.24 copyrightb: Copyright Bit, 1 Bit 170 171 $thisfile_ac3_raw_bsi['original'] = (bool) $this->readHeaderBSI(1); // 5.4.2.25 origbs: Original Bit Stream, 1 Bit 172 173 $thisfile_ac3_raw_bsi['flags']['timecod1'] = $this->readHeaderBSI(2); // 5.4.2.26 timecod1e, timcode2e: Time Code (first and second) Halves Exist, 2 Bits 174 if ($thisfile_ac3_raw_bsi['flags']['timecod1'] & 0x01) { 175 $thisfile_ac3_raw_bsi['timecod1'] = $this->readHeaderBSI(14); // 5.4.2.27 timecod1: Time code first half, 14 bits 176 $thisfile_ac3['timecode1'] = 0; 177 $thisfile_ac3['timecode1'] += (($thisfile_ac3_raw_bsi['timecod1'] & 0x3E00) >> 9) * 3600; // The first 5 bits of this 14-bit field represent the time in hours, with valid values of 0�23 178 $thisfile_ac3['timecode1'] += (($thisfile_ac3_raw_bsi['timecod1'] & 0x01F8) >> 3) * 60; // The next 6 bits represent the time in minutes, with valid values of 0�59 179 $thisfile_ac3['timecode1'] += (($thisfile_ac3_raw_bsi['timecod1'] & 0x0003) >> 0) * 8; // The final 3 bits represents the time in 8 second increments, with valid values of 0�7 (representing 0, 8, 16, ... 56 seconds) 180 } 181 if ($thisfile_ac3_raw_bsi['flags']['timecod1'] & 0x02) { 182 $thisfile_ac3_raw_bsi['timecod2'] = $this->readHeaderBSI(14); // 5.4.2.28 timecod2: Time code second half, 14 bits 183 $thisfile_ac3['timecode2'] = 0; 184 $thisfile_ac3['timecode2'] += (($thisfile_ac3_raw_bsi['timecod2'] & 0x3800) >> 11) * 1; // The first 3 bits of this 14-bit field represent the time in seconds, with valid values from 0�7 (representing 0-7 seconds) 185 $thisfile_ac3['timecode2'] += (($thisfile_ac3_raw_bsi['timecod2'] & 0x07C0) >> 6) * (1 / 30); // The next 5 bits represents the time in frames, with valid values from 0�29 (one frame = 1/30th of a second) 186 $thisfile_ac3['timecode2'] += (($thisfile_ac3_raw_bsi['timecod2'] & 0x003F) >> 0) * ((1 / 30) / 60); // The final 6 bits represents fractions of 1/64 of a frame, with valid values from 0�63 187 } 188 189 $thisfile_ac3_raw_bsi['flags']['addbsi'] = (bool) $this->readHeaderBSI(1); 190 if ($thisfile_ac3_raw_bsi['flags']['addbsi']) { 191 $thisfile_ac3_raw_bsi['addbsi_length'] = $this->readHeaderBSI(6) + 1; // This 6-bit code, which exists only if addbside is a 1, indicates the length in bytes of additional bit stream information. The valid range of addbsil is 0�63, indicating 1�64 additional bytes, respectively. 192 193 $this->AC3header['bsi'] .= getid3_lib::BigEndian2Bin($this->fread($thisfile_ac3_raw_bsi['addbsi_length'])); 194 195 $thisfile_ac3_raw_bsi['addbsi_data'] = substr($this->AC3header['bsi'], $this->BSIoffset, $thisfile_ac3_raw_bsi['addbsi_length'] * 8); 196 $this->BSIoffset += $thisfile_ac3_raw_bsi['addbsi_length'] * 8; 197 } 198 199 200 } elseif ($thisfile_ac3_raw_bsi['bsid'] <= 16) { // E-AC3 201 202 203 $this->error('E-AC3 parsing is incomplete and experimental in this version of getID3 ('.$this->getid3->version().'). Notably the bitrate calculations are wrong -- value might (or not) be correct, but it is not calculated correctly. Email info@getid3.org if you know how to calculate EAC3 bitrate correctly.'); 204 $info['audio']['dataformat'] = 'eac3'; 205 206 $thisfile_ac3_raw_bsi['strmtyp'] = $this->readHeaderBSI(2); 207 $thisfile_ac3_raw_bsi['substreamid'] = $this->readHeaderBSI(3); 208 $thisfile_ac3_raw_bsi['frmsiz'] = $this->readHeaderBSI(11); 209 $thisfile_ac3_raw_bsi['fscod'] = $this->readHeaderBSI(2); 210 if ($thisfile_ac3_raw_bsi['fscod'] == 3) { 211 $thisfile_ac3_raw_bsi['fscod2'] = $this->readHeaderBSI(2); 212 $thisfile_ac3_raw_bsi['numblkscod'] = 3; // six blocks per syncframe 213 } else { 214 $thisfile_ac3_raw_bsi['numblkscod'] = $this->readHeaderBSI(2); 215 } 216 $thisfile_ac3['bsi']['blocks_per_sync_frame'] = self::blocksPerSyncFrame($thisfile_ac3_raw_bsi['numblkscod']); 217 $thisfile_ac3_raw_bsi['acmod'] = $this->readHeaderBSI(3); 218 $thisfile_ac3_raw_bsi['flags']['lfeon'] = (bool) $this->readHeaderBSI(1); 219 $thisfile_ac3_raw_bsi['bsid'] = $this->readHeaderBSI(5); // we already know this from pre-parsing the version identifier, but re-read it to let the bitstream flow as intended 220 $thisfile_ac3_raw_bsi['dialnorm'] = $this->readHeaderBSI(5); 221 $thisfile_ac3_raw_bsi['flags']['compr'] = (bool) $this->readHeaderBSI(1); 222 if ($thisfile_ac3_raw_bsi['flags']['compr']) { 223 $thisfile_ac3_raw_bsi['compr'] = $this->readHeaderBSI(8); 224 } 225 if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value) 226 $thisfile_ac3_raw_bsi['dialnorm2'] = $this->readHeaderBSI(5); 227 $thisfile_ac3_raw_bsi['flags']['compr2'] = (bool) $this->readHeaderBSI(1); 228 if ($thisfile_ac3_raw_bsi['flags']['compr2']) { 229 $thisfile_ac3_raw_bsi['compr2'] = $this->readHeaderBSI(8); 230 } 231 } 232 if ($thisfile_ac3_raw_bsi['strmtyp'] == 1) { // if dependent stream 233 $thisfile_ac3_raw_bsi['flags']['chanmap'] = (bool) $this->readHeaderBSI(1); 234 if ($thisfile_ac3_raw_bsi['flags']['chanmap']) { 235 $thisfile_ac3_raw_bsi['chanmap'] = $this->readHeaderBSI(8); 236 } 237 } 238 $thisfile_ac3_raw_bsi['flags']['mixmdat'] = (bool) $this->readHeaderBSI(1); 239 if ($thisfile_ac3_raw_bsi['flags']['mixmdat']) { // Mixing metadata 240 if ($thisfile_ac3_raw_bsi['acmod'] > 2) { // if more than 2 channels 241 $thisfile_ac3_raw_bsi['dmixmod'] = $this->readHeaderBSI(2); 242 } 243 if (($thisfile_ac3_raw_bsi['acmod'] & 0x01) && ($thisfile_ac3_raw_bsi['acmod'] > 2)) { // if three front channels exist 244 $thisfile_ac3_raw_bsi['ltrtcmixlev'] = $this->readHeaderBSI(3); 245 $thisfile_ac3_raw_bsi['lorocmixlev'] = $this->readHeaderBSI(3); 246 } 247 if ($thisfile_ac3_raw_bsi['acmod'] & 0x04) { // if a surround channel exists 248 $thisfile_ac3_raw_bsi['ltrtsurmixlev'] = $this->readHeaderBSI(3); 249 $thisfile_ac3_raw_bsi['lorosurmixlev'] = $this->readHeaderBSI(3); 250 } 251 if ($thisfile_ac3_raw_bsi['flags']['lfeon']) { // if the LFE channel exists 252 $thisfile_ac3_raw_bsi['flags']['lfemixlevcod'] = (bool) $this->readHeaderBSI(1); 253 if ($thisfile_ac3_raw_bsi['flags']['lfemixlevcod']) { 254 $thisfile_ac3_raw_bsi['lfemixlevcod'] = $this->readHeaderBSI(5); 255 } 256 } 257 if ($thisfile_ac3_raw_bsi['strmtyp'] == 0) { // if independent stream 258 $thisfile_ac3_raw_bsi['flags']['pgmscl'] = (bool) $this->readHeaderBSI(1); 259 if ($thisfile_ac3_raw_bsi['flags']['pgmscl']) { 260 $thisfile_ac3_raw_bsi['pgmscl'] = $this->readHeaderBSI(6); 261 } 262 if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value) 263 $thisfile_ac3_raw_bsi['flags']['pgmscl2'] = (bool) $this->readHeaderBSI(1); 264 if ($thisfile_ac3_raw_bsi['flags']['pgmscl2']) { 265 $thisfile_ac3_raw_bsi['pgmscl2'] = $this->readHeaderBSI(6); 266 } 267 } 268 $thisfile_ac3_raw_bsi['flags']['extpgmscl'] = (bool) $this->readHeaderBSI(1); 269 if ($thisfile_ac3_raw_bsi['flags']['extpgmscl']) { 270 $thisfile_ac3_raw_bsi['extpgmscl'] = $this->readHeaderBSI(6); 271 } 272 $thisfile_ac3_raw_bsi['mixdef'] = $this->readHeaderBSI(2); 273 if ($thisfile_ac3_raw_bsi['mixdef'] == 1) { // mixing option 2 274 $thisfile_ac3_raw_bsi['premixcmpsel'] = (bool) $this->readHeaderBSI(1); 275 $thisfile_ac3_raw_bsi['drcsrc'] = (bool) $this->readHeaderBSI(1); 276 $thisfile_ac3_raw_bsi['premixcmpscl'] = $this->readHeaderBSI(3); 277 } elseif ($thisfile_ac3_raw_bsi['mixdef'] == 2) { // mixing option 3 278 $thisfile_ac3_raw_bsi['mixdata'] = $this->readHeaderBSI(12); 279 } elseif ($thisfile_ac3_raw_bsi['mixdef'] == 3) { // mixing option 4 280 $mixdefbitsread = 0; 281 $thisfile_ac3_raw_bsi['mixdeflen'] = $this->readHeaderBSI(5); $mixdefbitsread += 5; 282 $thisfile_ac3_raw_bsi['flags']['mixdata2'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1; 283 if ($thisfile_ac3_raw_bsi['flags']['mixdata2']) { 284 $thisfile_ac3_raw_bsi['premixcmpsel'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1; 285 $thisfile_ac3_raw_bsi['drcsrc'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1; 286 $thisfile_ac3_raw_bsi['premixcmpscl'] = $this->readHeaderBSI(3); $mixdefbitsread += 3; 287 $thisfile_ac3_raw_bsi['flags']['extpgmlscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1; 288 if ($thisfile_ac3_raw_bsi['flags']['extpgmlscl']) { 289 $thisfile_ac3_raw_bsi['extpgmlscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4; 290 } 291 $thisfile_ac3_raw_bsi['flags']['extpgmcscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1; 292 if ($thisfile_ac3_raw_bsi['flags']['extpgmcscl']) { 293 $thisfile_ac3_raw_bsi['extpgmcscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4; 294 } 295 $thisfile_ac3_raw_bsi['flags']['extpgmrscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1; 296 if ($thisfile_ac3_raw_bsi['flags']['extpgmrscl']) { 297 $thisfile_ac3_raw_bsi['extpgmrscl'] = $this->readHeaderBSI(4); 298 } 299 $thisfile_ac3_raw_bsi['flags']['extpgmlsscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1; 300 if ($thisfile_ac3_raw_bsi['flags']['extpgmlsscl']) { 301 $thisfile_ac3_raw_bsi['extpgmlsscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4; 302 } 303 $thisfile_ac3_raw_bsi['flags']['extpgmrsscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1; 304 if ($thisfile_ac3_raw_bsi['flags']['extpgmrsscl']) { 305 $thisfile_ac3_raw_bsi['extpgmrsscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4; 306 } 307 $thisfile_ac3_raw_bsi['flags']['extpgmlfescl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1; 308 if ($thisfile_ac3_raw_bsi['flags']['extpgmlfescl']) { 309 $thisfile_ac3_raw_bsi['extpgmlfescl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4; 310 } 311 $thisfile_ac3_raw_bsi['flags']['dmixscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1; 312 if ($thisfile_ac3_raw_bsi['flags']['dmixscl']) { 313 $thisfile_ac3_raw_bsi['dmixscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4; 314 } 315 $thisfile_ac3_raw_bsi['flags']['addch'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1; 316 if ($thisfile_ac3_raw_bsi['flags']['addch']) { 317 $thisfile_ac3_raw_bsi['flags']['extpgmaux1scl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1; 318 if ($thisfile_ac3_raw_bsi['flags']['extpgmaux1scl']) { 319 $thisfile_ac3_raw_bsi['extpgmaux1scl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4; 320 } 321 $thisfile_ac3_raw_bsi['flags']['extpgmaux2scl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1; 322 if ($thisfile_ac3_raw_bsi['flags']['extpgmaux2scl']) { 323 $thisfile_ac3_raw_bsi['extpgmaux2scl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4; 324 } 325 } 326 } 327 $thisfile_ac3_raw_bsi['flags']['mixdata3'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1; 328 if ($thisfile_ac3_raw_bsi['flags']['mixdata3']) { 329 $thisfile_ac3_raw_bsi['spchdat'] = $this->readHeaderBSI(5); $mixdefbitsread += 5; 330 $thisfile_ac3_raw_bsi['flags']['addspchdat'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1; 331 if ($thisfile_ac3_raw_bsi['flags']['addspchdat']) { 332 $thisfile_ac3_raw_bsi['spchdat1'] = $this->readHeaderBSI(5); $mixdefbitsread += 5; 333 $thisfile_ac3_raw_bsi['spchan1att'] = $this->readHeaderBSI(2); $mixdefbitsread += 2; 334 $thisfile_ac3_raw_bsi['flags']['addspchdat1'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1; 335 if ($thisfile_ac3_raw_bsi['flags']['addspchdat1']) { 336 $thisfile_ac3_raw_bsi['spchdat2'] = $this->readHeaderBSI(5); $mixdefbitsread += 5; 337 $thisfile_ac3_raw_bsi['spchan2att'] = $this->readHeaderBSI(3); $mixdefbitsread += 3; 338 } 339 } 340 } 341 $mixdata_bits = (8 * ($thisfile_ac3_raw_bsi['mixdeflen'] + 2)) - $mixdefbitsread; 342 $mixdata_fill = (($mixdata_bits % 8) ? 8 - ($mixdata_bits % 8) : 0); 343 $thisfile_ac3_raw_bsi['mixdata'] = $this->readHeaderBSI($mixdata_bits); 344 $thisfile_ac3_raw_bsi['mixdatafill'] = $this->readHeaderBSI($mixdata_fill); 345 unset($mixdefbitsread, $mixdata_bits, $mixdata_fill); 346 } 347 if ($thisfile_ac3_raw_bsi['acmod'] < 2) { // if mono or dual mono source 348 $thisfile_ac3_raw_bsi['flags']['paninfo'] = (bool) $this->readHeaderBSI(1); 349 if ($thisfile_ac3_raw_bsi['flags']['paninfo']) { 350 $thisfile_ac3_raw_bsi['panmean'] = $this->readHeaderBSI(8); 351 $thisfile_ac3_raw_bsi['paninfo'] = $this->readHeaderBSI(6); 352 } 353 if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value) 354 $thisfile_ac3_raw_bsi['flags']['paninfo2'] = (bool) $this->readHeaderBSI(1); 355 if ($thisfile_ac3_raw_bsi['flags']['paninfo2']) { 356 $thisfile_ac3_raw_bsi['panmean2'] = $this->readHeaderBSI(8); 357 $thisfile_ac3_raw_bsi['paninfo2'] = $this->readHeaderBSI(6); 358 } 359 } 360 } 361 $thisfile_ac3_raw_bsi['flags']['frmmixcfginfo'] = (bool) $this->readHeaderBSI(1); 362 if ($thisfile_ac3_raw_bsi['flags']['frmmixcfginfo']) { // mixing configuration information 363 if ($thisfile_ac3_raw_bsi['numblkscod'] == 0) { 364 $thisfile_ac3_raw_bsi['blkmixcfginfo'][0] = $this->readHeaderBSI(5); 365 } else { 366 for ($blk = 0; $blk < $thisfile_ac3_raw_bsi['numblkscod']; $blk++) { 367 $thisfile_ac3_raw_bsi['flags']['blkmixcfginfo'.$blk] = (bool) $this->readHeaderBSI(1); 368 if ($thisfile_ac3_raw_bsi['flags']['blkmixcfginfo'.$blk]) { // mixing configuration information 369 $thisfile_ac3_raw_bsi['blkmixcfginfo'][$blk] = $this->readHeaderBSI(5); 370 } 371 } 372 } 373 } 374 } 375 } 376 $thisfile_ac3_raw_bsi['flags']['infomdat'] = (bool) $this->readHeaderBSI(1); 377 if ($thisfile_ac3_raw_bsi['flags']['infomdat']) { // Informational metadata 378 $thisfile_ac3_raw_bsi['bsmod'] = $this->readHeaderBSI(3); 379 $thisfile_ac3_raw_bsi['flags']['copyrightb'] = (bool) $this->readHeaderBSI(1); 380 $thisfile_ac3_raw_bsi['flags']['origbs'] = (bool) $this->readHeaderBSI(1); 381 if ($thisfile_ac3_raw_bsi['acmod'] == 2) { // if in 2/0 mode 382 $thisfile_ac3_raw_bsi['dsurmod'] = $this->readHeaderBSI(2); 383 $thisfile_ac3_raw_bsi['dheadphonmod'] = $this->readHeaderBSI(2); 384 } 385 if ($thisfile_ac3_raw_bsi['acmod'] >= 6) { // if both surround channels exist 386 $thisfile_ac3_raw_bsi['dsurexmod'] = $this->readHeaderBSI(2); 387 } 388 $thisfile_ac3_raw_bsi['flags']['audprodi'] = (bool) $this->readHeaderBSI(1); 389 if ($thisfile_ac3_raw_bsi['flags']['audprodi']) { 390 $thisfile_ac3_raw_bsi['mixlevel'] = $this->readHeaderBSI(5); 391 $thisfile_ac3_raw_bsi['roomtyp'] = $this->readHeaderBSI(2); 392 $thisfile_ac3_raw_bsi['flags']['adconvtyp'] = (bool) $this->readHeaderBSI(1); 393 } 394 if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value) 395 $thisfile_ac3_raw_bsi['flags']['audprodi2'] = (bool) $this->readHeaderBSI(1); 396 if ($thisfile_ac3_raw_bsi['flags']['audprodi2']) { 397 $thisfile_ac3_raw_bsi['mixlevel2'] = $this->readHeaderBSI(5); 398 $thisfile_ac3_raw_bsi['roomtyp2'] = $this->readHeaderBSI(2); 399 $thisfile_ac3_raw_bsi['flags']['adconvtyp2'] = (bool) $this->readHeaderBSI(1); 400 } 401 } 402 if ($thisfile_ac3_raw_bsi['fscod'] < 3) { // if not half sample rate 403 $thisfile_ac3_raw_bsi['flags']['sourcefscod'] = (bool) $this->readHeaderBSI(1); 404 } 405 } 406 if (($thisfile_ac3_raw_bsi['strmtyp'] == 0) && ($thisfile_ac3_raw_bsi['numblkscod'] != 3)) { // if both surround channels exist 407 $thisfile_ac3_raw_bsi['flags']['convsync'] = (bool) $this->readHeaderBSI(1); 408 } 409 if ($thisfile_ac3_raw_bsi['strmtyp'] == 2) { // if bit stream converted from AC-3 410 if ($thisfile_ac3_raw_bsi['numblkscod'] != 3) { // 6 blocks per syncframe 411 $thisfile_ac3_raw_bsi['flags']['blkid'] = 1; 412 } else { 413 $thisfile_ac3_raw_bsi['flags']['blkid'] = (bool) $this->readHeaderBSI(1); 414 } 415 if ($thisfile_ac3_raw_bsi['flags']['blkid']) { 416 $thisfile_ac3_raw_bsi['frmsizecod'] = $this->readHeaderBSI(6); 417 } 418 } 419 $thisfile_ac3_raw_bsi['flags']['addbsi'] = (bool) $this->readHeaderBSI(1); 420 if ($thisfile_ac3_raw_bsi['flags']['addbsi']) { 421 $thisfile_ac3_raw_bsi['addbsil'] = $this->readHeaderBSI(6); 422 $thisfile_ac3_raw_bsi['addbsi'] = $this->readHeaderBSI(($thisfile_ac3_raw_bsi['addbsil'] + 1) * 8); 423 } 424 425 } else { 426 427 $this->error('Bit stream identification is version '.$thisfile_ac3_raw_bsi['bsid'].', but getID3() only understands up to version 16. Please submit a support ticket with a sample file.'); 428 unset($info['ac3']); 429 return false; 430 431 } 432 433 if (isset($thisfile_ac3_raw_bsi['fscod2'])) { 434 $thisfile_ac3['sample_rate'] = self::sampleRateCodeLookup2($thisfile_ac3_raw_bsi['fscod2']); 435 } else { 436 $thisfile_ac3['sample_rate'] = self::sampleRateCodeLookup($thisfile_ac3_raw_bsi['fscod']); 437 } 438 if ($thisfile_ac3_raw_bsi['fscod'] <= 3) { 439 $info['audio']['sample_rate'] = $thisfile_ac3['sample_rate']; 440 } else { 441 $this->warning('Unexpected ac3.bsi.fscod value: '.$thisfile_ac3_raw_bsi['fscod']); 442 } 443 if (isset($thisfile_ac3_raw_bsi['frmsizecod'])) { 444 $thisfile_ac3['frame_length'] = self::frameSizeLookup($thisfile_ac3_raw_bsi['frmsizecod'], $thisfile_ac3_raw_bsi['fscod']); 445 $thisfile_ac3['bitrate'] = self::bitrateLookup($thisfile_ac3_raw_bsi['frmsizecod']); 446 } elseif (!empty($thisfile_ac3_raw_bsi['frmsiz'])) { 447 // this isn't right, but it's (usually) close, roughly 5% less than it should be. 448 // but WHERE is the actual bitrate value stored in EAC3?? email info@getid3.org if you know! 449 $thisfile_ac3['bitrate'] = ($thisfile_ac3_raw_bsi['frmsiz'] + 1) * 16 * 30; // The frmsiz field shall contain a value one less than the overall size of the coded syncframe in 16-bit words. That is, this field may assume a value ranging from 0 to 2047, and these values correspond to syncframe sizes ranging from 1 to 2048. 450 // kludge-fix to make it approximately the expected value, still not "right": 451 $thisfile_ac3['bitrate'] = round(($thisfile_ac3['bitrate'] * 1.05) / 16000) * 16000; 452 } 453 $info['audio']['bitrate'] = $thisfile_ac3['bitrate']; 454 455 if (isset($thisfile_ac3_raw_bsi['bsmod']) && isset($thisfile_ac3_raw_bsi['acmod'])) { 456 $thisfile_ac3['service_type'] = self::serviceTypeLookup($thisfile_ac3_raw_bsi['bsmod'], $thisfile_ac3_raw_bsi['acmod']); 457 } 458 $ac3_coding_mode = self::audioCodingModeLookup($thisfile_ac3_raw_bsi['acmod']); 459 foreach($ac3_coding_mode as $key => $value) { 460 $thisfile_ac3[$key] = $value; 461 } 462 switch ($thisfile_ac3_raw_bsi['acmod']) { 463 case 0: 464 case 1: 465 $info['audio']['channelmode'] = 'mono'; 466 break; 467 case 3: 468 case 4: 469 $info['audio']['channelmode'] = 'stereo'; 470 break; 471 default: 472 $info['audio']['channelmode'] = 'surround'; 473 break; 474 } 475 $info['audio']['channels'] = $thisfile_ac3['num_channels']; 476 477 $thisfile_ac3['lfe_enabled'] = $thisfile_ac3_raw_bsi['flags']['lfeon']; 478 if ($thisfile_ac3_raw_bsi['flags']['lfeon']) { 479 $info['audio']['channels'] .= '.1'; 480 } 481 482 $thisfile_ac3['channels_enabled'] = self::channelsEnabledLookup($thisfile_ac3_raw_bsi['acmod'], $thisfile_ac3_raw_bsi['flags']['lfeon']); 483 $thisfile_ac3['dialogue_normalization'] = '-'.$thisfile_ac3_raw_bsi['dialnorm'].'dB'; 484 485 return true; 486 } 487 488 /** 489 * @param int $length 490 * 491 * @return int 492 */ 493 private function readHeaderBSI($length) { 494 $data = substr($this->AC3header['bsi'], $this->BSIoffset, $length); 495 $this->BSIoffset += $length; 496 497 return bindec($data); 498 } 499 500 /** 501 * @param int $fscod 502 * 503 * @return int|string|false 504 */ 505 public static function sampleRateCodeLookup($fscod) { 506 static $sampleRateCodeLookup = array( 507 0 => 48000, 508 1 => 44100, 509 2 => 32000, 510 3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute. 511 ); 512 return (isset($sampleRateCodeLookup[$fscod]) ? $sampleRateCodeLookup[$fscod] : false); 513 } 514 515 /** 516 * @param int $fscod2 517 * 518 * @return int|string|false 519 */ 520 public static function sampleRateCodeLookup2($fscod2) { 521 static $sampleRateCodeLookup2 = array( 522 0 => 24000, 523 1 => 22050, 524 2 => 16000, 525 3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute. 526 ); 527 return (isset($sampleRateCodeLookup2[$fscod2]) ? $sampleRateCodeLookup2[$fscod2] : false); 528 } 529 530 /** 531 * @param int $bsmod 532 * @param int $acmod 533 * 534 * @return string|false 535 */ 536 public static function serviceTypeLookup($bsmod, $acmod) { 537 static $serviceTypeLookup = array(); 538 if (empty($serviceTypeLookup)) { 539 for ($i = 0; $i <= 7; $i++) { 540 $serviceTypeLookup[0][$i] = 'main audio service: complete main (CM)'; 541 $serviceTypeLookup[1][$i] = 'main audio service: music and effects (ME)'; 542 $serviceTypeLookup[2][$i] = 'associated service: visually impaired (VI)'; 543 $serviceTypeLookup[3][$i] = 'associated service: hearing impaired (HI)'; 544 $serviceTypeLookup[4][$i] = 'associated service: dialogue (D)'; 545 $serviceTypeLookup[5][$i] = 'associated service: commentary (C)'; 546 $serviceTypeLookup[6][$i] = 'associated service: emergency (E)'; 547 } 548 549 $serviceTypeLookup[7][1] = 'associated service: voice over (VO)'; 550 for ($i = 2; $i <= 7; $i++) { 551 $serviceTypeLookup[7][$i] = 'main audio service: karaoke'; 552 } 553 } 554 return (isset($serviceTypeLookup[$bsmod][$acmod]) ? $serviceTypeLookup[$bsmod][$acmod] : false); 555 } 556 557 /** 558 * @param int $acmod 559 * 560 * @return array|false 561 */ 562 public static function audioCodingModeLookup($acmod) { 563 // array(channel configuration, # channels (not incl LFE), channel order) 564 static $audioCodingModeLookup = array ( 565 0 => array('channel_config'=>'1+1', 'num_channels'=>2, 'channel_order'=>'Ch1,Ch2'), 566 1 => array('channel_config'=>'1/0', 'num_channels'=>1, 'channel_order'=>'C'), 567 2 => array('channel_config'=>'2/0', 'num_channels'=>2, 'channel_order'=>'L,R'), 568 3 => array('channel_config'=>'3/0', 'num_channels'=>3, 'channel_order'=>'L,C,R'), 569 4 => array('channel_config'=>'2/1', 'num_channels'=>3, 'channel_order'=>'L,R,S'), 570 5 => array('channel_config'=>'3/1', 'num_channels'=>4, 'channel_order'=>'L,C,R,S'), 571 6 => array('channel_config'=>'2/2', 'num_channels'=>4, 'channel_order'=>'L,R,SL,SR'), 572 7 => array('channel_config'=>'3/2', 'num_channels'=>5, 'channel_order'=>'L,C,R,SL,SR'), 573 ); 574 return (isset($audioCodingModeLookup[$acmod]) ? $audioCodingModeLookup[$acmod] : false); 575 } 576 577 /** 578 * @param int $cmixlev 579 * 580 * @return int|float|string|false 581 */ 582 public static function centerMixLevelLookup($cmixlev) { 583 static $centerMixLevelLookup; 584 if (empty($centerMixLevelLookup)) { 585 $centerMixLevelLookup = array( 586 0 => pow(2, -3.0 / 6), // 0.707 (-3.0 dB) 587 1 => pow(2, -4.5 / 6), // 0.595 (-4.5 dB) 588 2 => pow(2, -6.0 / 6), // 0.500 (-6.0 dB) 589 3 => 'reserved' 590 ); 591 } 592 return (isset($centerMixLevelLookup[$cmixlev]) ? $centerMixLevelLookup[$cmixlev] : false); 593 } 594 595 /** 596 * @param int $surmixlev 597 * 598 * @return int|float|string|false 599 */ 600 public static function surroundMixLevelLookup($surmixlev) { 601 static $surroundMixLevelLookup; 602 if (empty($surroundMixLevelLookup)) { 603 $surroundMixLevelLookup = array( 604 0 => pow(2, -3.0 / 6), 605 1 => pow(2, -6.0 / 6), 606 2 => 0, 607 3 => 'reserved' 608 ); 609 } 610 return (isset($surroundMixLevelLookup[$surmixlev]) ? $surroundMixLevelLookup[$surmixlev] : false); 611 } 612 613 /** 614 * @param int $dsurmod 615 * 616 * @return string|false 617 */ 618 public static function dolbySurroundModeLookup($dsurmod) { 619 static $dolbySurroundModeLookup = array( 620 0 => 'not indicated', 621 1 => 'Not Dolby Surround encoded', 622 2 => 'Dolby Surround encoded', 623 3 => 'reserved' 624 ); 625 return (isset($dolbySurroundModeLookup[$dsurmod]) ? $dolbySurroundModeLookup[$dsurmod] : false); 626 } 627 628 /** 629 * @param int $acmod 630 * @param bool $lfeon 631 * 632 * @return array 633 */ 634 public static function channelsEnabledLookup($acmod, $lfeon) { 635 $lookup = array( 636 'ch1'=>($acmod == 0), 637 'ch2'=>($acmod == 0), 638 'left'=>($acmod > 1), 639 'right'=>($acmod > 1), 640 'center'=>(bool) ($acmod & 0x01), 641 'surround_mono'=>false, 642 'surround_left'=>false, 643 'surround_right'=>false, 644 'lfe'=>$lfeon); 645 switch ($acmod) { 646 case 4: 647 case 5: 648 $lookup['surround_mono'] = true; 649 break; 650 case 6: 651 case 7: 652 $lookup['surround_left'] = true; 653 $lookup['surround_right'] = true; 654 break; 655 } 656 return $lookup; 657 } 658 659 /** 660 * @param int $compre 661 * 662 * @return float|int 663 */ 664 public static function heavyCompression($compre) { 665 // The first four bits indicate gain changes in 6.02dB increments which can be 666 // implemented with an arithmetic shift operation. The following four bits 667 // indicate linear gain changes, and require a 5-bit multiply. 668 // We will represent the two 4-bit fields of compr as follows: 669 // X0 X1 X2 X3 . Y4 Y5 Y6 Y7 670 // The meaning of the X values is most simply described by considering X to represent a 4-bit 671 // signed integer with values from -8 to +7. The gain indicated by X is then (X + 1) * 6.02 dB. The 672 // following table shows this in detail. 673 674 // Meaning of 4 msb of compr 675 // 7 +48.16 dB 676 // 6 +42.14 dB 677 // 5 +36.12 dB 678 // 4 +30.10 dB 679 // 3 +24.08 dB 680 // 2 +18.06 dB 681 // 1 +12.04 dB 682 // 0 +6.02 dB 683 // -1 0 dB 684 // -2 -6.02 dB 685 // -3 -12.04 dB 686 // -4 -18.06 dB 687 // -5 -24.08 dB 688 // -6 -30.10 dB 689 // -7 -36.12 dB 690 // -8 -42.14 dB 691 692 $fourbit = str_pad(decbin(($compre & 0xF0) >> 4), 4, '0', STR_PAD_LEFT); 693 if ($fourbit[0] == '1') { 694 $log_gain = -8 + bindec(substr($fourbit, 1)); 695 } else { 696 $log_gain = bindec(substr($fourbit, 1)); 697 } 698 $log_gain = ($log_gain + 1) * getid3_lib::RGADamplitude2dB(2); 699 700 // The value of Y is a linear representation of a gain change of up to -6 dB. Y is considered to 701 // be an unsigned fractional integer, with a leading value of 1, or: 0.1 Y4 Y5 Y6 Y7 (base 2). Y can 702 // represent values between 0.111112 (or 31/32) and 0.100002 (or 1/2). Thus, Y can represent gain 703 // changes from -0.28 dB to -6.02 dB. 704 705 $lin_gain = (16 + ($compre & 0x0F)) / 32; 706 707 // The combination of X and Y values allows compr to indicate gain changes from 708 // 48.16 - 0.28 = +47.89 dB, to 709 // -42.14 - 6.02 = -48.16 dB. 710 711 return $log_gain - $lin_gain; 712 } 713 714 /** 715 * @param int $roomtyp 716 * 717 * @return string|false 718 */ 719 public static function roomTypeLookup($roomtyp) { 720 static $roomTypeLookup = array( 721 0 => 'not indicated', 722 1 => 'large room, X curve monitor', 723 2 => 'small room, flat monitor', 724 3 => 'reserved' 725 ); 726 return (isset($roomTypeLookup[$roomtyp]) ? $roomTypeLookup[$roomtyp] : false); 727 } 728 729 /** 730 * @param int $frmsizecod 731 * @param int $fscod 732 * 733 * @return int|false 734 */ 735 public static function frameSizeLookup($frmsizecod, $fscod) { 736 // LSB is whether padding is used or not 737 $padding = (bool) ($frmsizecod & 0x01); 738 $framesizeid = ($frmsizecod & 0x3E) >> 1; 739 740 static $frameSizeLookup = array(); 741 if (empty($frameSizeLookup)) { 742 $frameSizeLookup = array ( 743 0 => array( 128, 138, 192), // 32 kbps 744 1 => array( 160, 174, 240), // 40 kbps 745 2 => array( 192, 208, 288), // 48 kbps 746 3 => array( 224, 242, 336), // 56 kbps 747 4 => array( 256, 278, 384), // 64 kbps 748 5 => array( 320, 348, 480), // 80 kbps 749 6 => array( 384, 416, 576), // 96 kbps 750 7 => array( 448, 486, 672), // 112 kbps 751 8 => array( 512, 556, 768), // 128 kbps 752 9 => array( 640, 696, 960), // 160 kbps 753 10 => array( 768, 834, 1152), // 192 kbps 754 11 => array( 896, 974, 1344), // 224 kbps 755 12 => array(1024, 1114, 1536), // 256 kbps 756 13 => array(1280, 1392, 1920), // 320 kbps 757 14 => array(1536, 1670, 2304), // 384 kbps 758 15 => array(1792, 1950, 2688), // 448 kbps 759 16 => array(2048, 2228, 3072), // 512 kbps 760 17 => array(2304, 2506, 3456), // 576 kbps 761 18 => array(2560, 2786, 3840) // 640 kbps 762 ); 763 } 764 $paddingBytes = 0; 765 if (($fscod == 1) && $padding) { 766 // frame lengths are padded by 1 word (16 bits) at 44100 767 // (fscode==1) means 44100Hz (see sampleRateCodeLookup) 768 $paddingBytes = 2; 769 } 770 return (isset($frameSizeLookup[$framesizeid][$fscod]) ? $frameSizeLookup[$framesizeid][$fscod] + $paddingBytes : false); 771 } 772 773 /** 774 * @param int $frmsizecod 775 * 776 * @return int|false 777 */ 778 public static function bitrateLookup($frmsizecod) { 779 // LSB is whether padding is used or not 780 $padding = (bool) ($frmsizecod & 0x01); 781 $framesizeid = ($frmsizecod & 0x3E) >> 1; 782 783 static $bitrateLookup = array( 784 0 => 32000, 785 1 => 40000, 786 2 => 48000, 787 3 => 56000, 788 4 => 64000, 789 5 => 80000, 790 6 => 96000, 791 7 => 112000, 792 8 => 128000, 793 9 => 160000, 794 10 => 192000, 795 11 => 224000, 796 12 => 256000, 797 13 => 320000, 798 14 => 384000, 799 15 => 448000, 800 16 => 512000, 801 17 => 576000, 802 18 => 640000, 803 ); 804 return (isset($bitrateLookup[$framesizeid]) ? $bitrateLookup[$framesizeid] : false); 805 } 806 807 /** 808 * @param int $numblkscod 809 * 810 * @return int|false 811 */ 812 public static function blocksPerSyncFrame($numblkscod) { 813 static $blocksPerSyncFrameLookup = array( 814 0 => 1, 815 1 => 2, 816 2 => 3, 817 3 => 6, 818 ); 819 return (isset($blocksPerSyncFrameLookup[$numblkscod]) ? $blocksPerSyncFrameLookup[$numblkscod] : false); 820 } 821 822 823 }
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