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1 <?php 2 ///////////////////////////////////////////////////////////////// 3 /// getID3() by James Heinrich <info@getid3.org> // 4 // available at http://getid3.sourceforge.net // 5 // or http://www.getid3.org // 6 ///////////////////////////////////////////////////////////////// 7 // See readme.txt for more details // 8 ///////////////////////////////////////////////////////////////// 9 // // 10 // module.audio.ac3.php // 11 // module for analyzing AC-3 (aka Dolby Digital) audio files // 12 // dependencies: NONE // 13 // /// 14 ///////////////////////////////////////////////////////////////// 15 16 17 class getid3_ac3 extends getid3_handler 18 { 19 private $AC3header = array(); 20 private $BSIoffset = 0; 21 22 const syncword = "\x0B\x77"; 23 24 public function Analyze() { 25 $info = &$this->getid3->info; 26 27 ///AH 28 $info['ac3']['raw']['bsi'] = array(); 29 $thisfile_ac3 = &$info['ac3']; 30 $thisfile_ac3_raw = &$thisfile_ac3['raw']; 31 $thisfile_ac3_raw_bsi = &$thisfile_ac3_raw['bsi']; 32 33 34 // http://www.atsc.org/standards/a_52a.pdf 35 36 $info['fileformat'] = 'ac3'; 37 38 // An AC-3 serial coded audio bit stream is made up of a sequence of synchronization frames 39 // Each synchronization frame contains 6 coded audio blocks (AB), each of which represent 256 40 // new audio samples per channel. A synchronization information (SI) header at the beginning 41 // of each frame contains information needed to acquire and maintain synchronization. A 42 // bit stream information (BSI) header follows SI, and contains parameters describing the coded 43 // audio service. The coded audio blocks may be followed by an auxiliary data (Aux) field. At the 44 // end of each frame is an error check field that includes a CRC word for error detection. An 45 // additional CRC word is located in the SI header, the use of which, by a decoder, is optional. 46 // 47 // syncinfo() | bsi() | AB0 | AB1 | AB2 | AB3 | AB4 | AB5 | Aux | CRC 48 49 // syncinfo() { 50 // syncword 16 51 // crc1 16 52 // fscod 2 53 // frmsizecod 6 54 // } /* end of syncinfo */ 55 56 $this->fseek($info['avdataoffset']); 57 $this->AC3header['syncinfo'] = $this->fread(5); 58 59 if (strpos($this->AC3header['syncinfo'], self::syncword) === 0) { 60 $thisfile_ac3_raw['synchinfo']['synchword'] = self::syncword; 61 $offset = 2; 62 } else { 63 if (!$this->isDependencyFor('matroska')) { 64 unset($info['fileformat'], $info['ac3']); 65 return $this->error('Expecting "'.getid3_lib::PrintHexBytes(self::syncword).'" at offset '.$info['avdataoffset'].', found "'.getid3_lib::PrintHexBytes(substr($this->AC3header['syncinfo'], 0, 2)).'"'); 66 } 67 $offset = 0; 68 $this->fseek(-2, SEEK_CUR); 69 } 70 71 $info['audio']['dataformat'] = 'ac3'; 72 $info['audio']['bitrate_mode'] = 'cbr'; 73 $info['audio']['lossless'] = false; 74 75 $thisfile_ac3_raw['synchinfo']['crc1'] = getid3_lib::LittleEndian2Int(substr($this->AC3header['syncinfo'], $offset, 2)); 76 $ac3_synchinfo_fscod_frmsizecod = getid3_lib::LittleEndian2Int(substr($this->AC3header['syncinfo'], ($offset + 2), 1)); 77 $thisfile_ac3_raw['synchinfo']['fscod'] = ($ac3_synchinfo_fscod_frmsizecod & 0xC0) >> 6; 78 $thisfile_ac3_raw['synchinfo']['frmsizecod'] = ($ac3_synchinfo_fscod_frmsizecod & 0x3F); 79 80 $thisfile_ac3['sample_rate'] = self::sampleRateCodeLookup($thisfile_ac3_raw['synchinfo']['fscod']); 81 if ($thisfile_ac3_raw['synchinfo']['fscod'] <= 3) { 82 $info['audio']['sample_rate'] = $thisfile_ac3['sample_rate']; 83 } 84 85 $thisfile_ac3['frame_length'] = self::frameSizeLookup($thisfile_ac3_raw['synchinfo']['frmsizecod'], $thisfile_ac3_raw['synchinfo']['fscod']); 86 $thisfile_ac3['bitrate'] = self::bitrateLookup($thisfile_ac3_raw['synchinfo']['frmsizecod']); 87 $info['audio']['bitrate'] = $thisfile_ac3['bitrate']; 88 89 $this->AC3header['bsi'] = getid3_lib::BigEndian2Bin($this->fread(15)); 90 $ac3_bsi_offset = 0; 91 92 $thisfile_ac3_raw_bsi['bsid'] = $this->readHeaderBSI(5); 93 if ($thisfile_ac3_raw_bsi['bsid'] > 8) { 94 // Decoders which can decode version 8 will thus be able to decode version numbers less than 8. 95 // If this standard is extended by the addition of additional elements or features, a value of bsid greater than 8 will be used. 96 // Decoders built to this version of the standard will not be able to decode versions with bsid greater than 8. 97 $this->error('Bit stream identification is version '.$thisfile_ac3_raw_bsi['bsid'].', but getID3() only understands up to version 8'); 98 unset($info['ac3']); 99 return false; 100 } 101 102 $thisfile_ac3_raw_bsi['bsmod'] = $this->readHeaderBSI(3); 103 $thisfile_ac3_raw_bsi['acmod'] = $this->readHeaderBSI(3); 104 105 $thisfile_ac3['service_type'] = self::serviceTypeLookup($thisfile_ac3_raw_bsi['bsmod'], $thisfile_ac3_raw_bsi['acmod']); 106 $ac3_coding_mode = self::audioCodingModeLookup($thisfile_ac3_raw_bsi['acmod']); 107 foreach($ac3_coding_mode as $key => $value) { 108 $thisfile_ac3[$key] = $value; 109 } 110 switch ($thisfile_ac3_raw_bsi['acmod']) { 111 case 0: 112 case 1: 113 $info['audio']['channelmode'] = 'mono'; 114 break; 115 case 3: 116 case 4: 117 $info['audio']['channelmode'] = 'stereo'; 118 break; 119 default: 120 $info['audio']['channelmode'] = 'surround'; 121 break; 122 } 123 $info['audio']['channels'] = $thisfile_ac3['num_channels']; 124 125 if ($thisfile_ac3_raw_bsi['acmod'] & 0x01) { 126 // If the lsb of acmod is a 1, center channel is in use and cmixlev follows in the bit stream. 127 $thisfile_ac3_raw_bsi['cmixlev'] = $this->readHeaderBSI(2); 128 $thisfile_ac3['center_mix_level'] = self::centerMixLevelLookup($thisfile_ac3_raw_bsi['cmixlev']); 129 } 130 131 if ($thisfile_ac3_raw_bsi['acmod'] & 0x04) { 132 // If the msb of acmod is a 1, surround channels are in use and surmixlev follows in the bit stream. 133 $thisfile_ac3_raw_bsi['surmixlev'] = $this->readHeaderBSI(2); 134 $thisfile_ac3['surround_mix_level'] = self::surroundMixLevelLookup($thisfile_ac3_raw_bsi['surmixlev']); 135 } 136 137 if ($thisfile_ac3_raw_bsi['acmod'] == 0x02) { 138 // When operating in the two channel mode, this 2-bit code indicates whether or not the program has been encoded in Dolby Surround. 139 $thisfile_ac3_raw_bsi['dsurmod'] = $this->readHeaderBSI(2); 140 $thisfile_ac3['dolby_surround_mode'] = self::dolbySurroundModeLookup($thisfile_ac3_raw_bsi['dsurmod']); 141 } 142 143 $thisfile_ac3_raw_bsi['lfeon'] = (bool) $this->readHeaderBSI(1); 144 $thisfile_ac3['lfe_enabled'] = $thisfile_ac3_raw_bsi['lfeon']; 145 if ($thisfile_ac3_raw_bsi['lfeon']) { 146 //$info['audio']['channels']++; 147 $info['audio']['channels'] .= '.1'; 148 } 149 150 $thisfile_ac3['channels_enabled'] = self::channelsEnabledLookup($thisfile_ac3_raw_bsi['acmod'], $thisfile_ac3_raw_bsi['lfeon']); 151 152 // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1-31. 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. 154 $thisfile_ac3_raw_bsi['dialnorm'] = $this->readHeaderBSI(5); 155 $thisfile_ac3['dialogue_normalization'] = '-'.$thisfile_ac3_raw_bsi['dialnorm'].'dB'; 156 157 $thisfile_ac3_raw_bsi['compre_flag'] = (bool) $this->readHeaderBSI(1); 158 if ($thisfile_ac3_raw_bsi['compre_flag']) { 159 $thisfile_ac3_raw_bsi['compr'] = $this->readHeaderBSI(8); 160 $thisfile_ac3['heavy_compression'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr']); 161 } 162 163 $thisfile_ac3_raw_bsi['langcode_flag'] = (bool) $this->readHeaderBSI(1); 164 if ($thisfile_ac3_raw_bsi['langcode_flag']) { 165 $thisfile_ac3_raw_bsi['langcod'] = $this->readHeaderBSI(8); 166 } 167 168 $thisfile_ac3_raw_bsi['audprodie'] = (bool) $this->readHeaderBSI(1); 169 if ($thisfile_ac3_raw_bsi['audprodie']) { 170 $thisfile_ac3_raw_bsi['mixlevel'] = $this->readHeaderBSI(5); 171 $thisfile_ac3_raw_bsi['roomtyp'] = $this->readHeaderBSI(2); 172 173 $thisfile_ac3['mixing_level'] = (80 + $thisfile_ac3_raw_bsi['mixlevel']).'dB'; 174 $thisfile_ac3['room_type'] = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp']); 175 } 176 177 if ($thisfile_ac3_raw_bsi['acmod'] == 0x00) { 178 // If acmod is 0, then two completely independent program channels (dual mono) 179 // are encoded into the bit stream, and are referenced as Ch1, Ch2. In this case, 180 // a number of additional items are present in BSI or audblk to fully describe Ch2. 181 182 // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1-31. 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. 184 $thisfile_ac3_raw_bsi['dialnorm2'] = $this->readHeaderBSI(5); 185 $thisfile_ac3['dialogue_normalization2'] = '-'.$thisfile_ac3_raw_bsi['dialnorm2'].'dB'; 186 187 $thisfile_ac3_raw_bsi['compre_flag2'] = (bool) $this->readHeaderBSI(1); 188 if ($thisfile_ac3_raw_bsi['compre_flag2']) { 189 $thisfile_ac3_raw_bsi['compr2'] = $this->readHeaderBSI(8); 190 $thisfile_ac3['heavy_compression2'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr2']); 191 } 192 193 $thisfile_ac3_raw_bsi['langcode_flag2'] = (bool) $this->readHeaderBSI(1); 194 if ($thisfile_ac3_raw_bsi['langcode_flag2']) { 195 $thisfile_ac3_raw_bsi['langcod2'] = $this->readHeaderBSI(8); 196 } 197 198 $thisfile_ac3_raw_bsi['audprodie2'] = (bool) $this->readHeaderBSI(1); 199 if ($thisfile_ac3_raw_bsi['audprodie2']) { 200 $thisfile_ac3_raw_bsi['mixlevel2'] = $this->readHeaderBSI(5); 201 $thisfile_ac3_raw_bsi['roomtyp2'] = $this->readHeaderBSI(2); 202 203 $thisfile_ac3['mixing_level2'] = (80 + $thisfile_ac3_raw_bsi['mixlevel2']).'dB'; 204 $thisfile_ac3['room_type2'] = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp2']); 205 } 206 207 } 208 209 $thisfile_ac3_raw_bsi['copyright'] = (bool) $this->readHeaderBSI(1); 210 211 $thisfile_ac3_raw_bsi['original'] = (bool) $this->readHeaderBSI(1); 212 213 $thisfile_ac3_raw_bsi['timecode1_flag'] = (bool) $this->readHeaderBSI(1); 214 if ($thisfile_ac3_raw_bsi['timecode1_flag']) { 215 $thisfile_ac3_raw_bsi['timecode1'] = $this->readHeaderBSI(14); 216 } 217 218 $thisfile_ac3_raw_bsi['timecode2_flag'] = (bool) $this->readHeaderBSI(1); 219 if ($thisfile_ac3_raw_bsi['timecode2_flag']) { 220 $thisfile_ac3_raw_bsi['timecode2'] = $this->readHeaderBSI(14); 221 } 222 223 $thisfile_ac3_raw_bsi['addbsi_flag'] = (bool) $this->readHeaderBSI(1); 224 if ($thisfile_ac3_raw_bsi['addbsi_flag']) { 225 $thisfile_ac3_raw_bsi['addbsi_length'] = $this->readHeaderBSI(6); 226 227 $this->AC3header['bsi'] .= getid3_lib::BigEndian2Bin($this->fread($thisfile_ac3_raw_bsi['addbsi_length'])); 228 229 $thisfile_ac3_raw_bsi['addbsi_data'] = substr($this->AC3header['bsi'], $this->BSIoffset, $thisfile_ac3_raw_bsi['addbsi_length'] * 8); 230 $this->BSIoffset += $thisfile_ac3_raw_bsi['addbsi_length'] * 8; 231 } 232 233 return true; 234 } 235 236 private function readHeaderBSI($length) { 237 $data = substr($this->AC3header['bsi'], $this->BSIoffset, $length); 238 $this->BSIoffset += $length; 239 240 return bindec($data); 241 } 242 243 public static function sampleRateCodeLookup($fscod) { 244 static $sampleRateCodeLookup = array( 245 0 => 48000, 246 1 => 44100, 247 2 => 32000, 248 3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute. 249 ); 250 return (isset($sampleRateCodeLookup[$fscod]) ? $sampleRateCodeLookup[$fscod] : false); 251 } 252 253 public static function serviceTypeLookup($bsmod, $acmod) { 254 static $serviceTypeLookup = array(); 255 if (empty($serviceTypeLookup)) { 256 for ($i = 0; $i <= 7; $i++) { 257 $serviceTypeLookup[0][$i] = 'main audio service: complete main (CM)'; 258 $serviceTypeLookup[1][$i] = 'main audio service: music and effects (ME)'; 259 $serviceTypeLookup[2][$i] = 'associated service: visually impaired (VI)'; 260 $serviceTypeLookup[3][$i] = 'associated service: hearing impaired (HI)'; 261 $serviceTypeLookup[4][$i] = 'associated service: dialogue (D)'; 262 $serviceTypeLookup[5][$i] = 'associated service: commentary (C)'; 263 $serviceTypeLookup[6][$i] = 'associated service: emergency (E)'; 264 } 265 266 $serviceTypeLookup[7][1] = 'associated service: voice over (VO)'; 267 for ($i = 2; $i <= 7; $i++) { 268 $serviceTypeLookup[7][$i] = 'main audio service: karaoke'; 269 } 270 } 271 return (isset($serviceTypeLookup[$bsmod][$acmod]) ? $serviceTypeLookup[$bsmod][$acmod] : false); 272 } 273 274 public static function audioCodingModeLookup($acmod) { 275 // array(channel configuration, # channels (not incl LFE), channel order) 276 static $audioCodingModeLookup = array ( 277 0 => array('channel_config'=>'1+1', 'num_channels'=>2, 'channel_order'=>'Ch1,Ch2'), 278 1 => array('channel_config'=>'1/0', 'num_channels'=>1, 'channel_order'=>'C'), 279 2 => array('channel_config'=>'2/0', 'num_channels'=>2, 'channel_order'=>'L,R'), 280 3 => array('channel_config'=>'3/0', 'num_channels'=>3, 'channel_order'=>'L,C,R'), 281 4 => array('channel_config'=>'2/1', 'num_channels'=>3, 'channel_order'=>'L,R,S'), 282 5 => array('channel_config'=>'3/1', 'num_channels'=>4, 'channel_order'=>'L,C,R,S'), 283 6 => array('channel_config'=>'2/2', 'num_channels'=>4, 'channel_order'=>'L,R,SL,SR'), 284 7 => array('channel_config'=>'3/2', 'num_channels'=>5, 'channel_order'=>'L,C,R,SL,SR'), 285 ); 286 return (isset($audioCodingModeLookup[$acmod]) ? $audioCodingModeLookup[$acmod] : false); 287 } 288 289 public static function centerMixLevelLookup($cmixlev) { 290 static $centerMixLevelLookup; 291 if (empty($centerMixLevelLookup)) { 292 $centerMixLevelLookup = array( 293 0 => pow(2, -3.0 / 6), // 0.707 (-3.0 dB) 294 1 => pow(2, -4.5 / 6), // 0.595 (-4.5 dB) 295 2 => pow(2, -6.0 / 6), // 0.500 (-6.0 dB) 296 3 => 'reserved' 297 ); 298 } 299 return (isset($centerMixLevelLookup[$cmixlev]) ? $centerMixLevelLookup[$cmixlev] : false); 300 } 301 302 public static function surroundMixLevelLookup($surmixlev) { 303 static $surroundMixLevelLookup; 304 if (empty($surroundMixLevelLookup)) { 305 $surroundMixLevelLookup = array( 306 0 => pow(2, -3.0 / 6), 307 1 => pow(2, -6.0 / 6), 308 2 => 0, 309 3 => 'reserved' 310 ); 311 } 312 return (isset($surroundMixLevelLookup[$surmixlev]) ? $surroundMixLevelLookup[$surmixlev] : false); 313 } 314 315 public static function dolbySurroundModeLookup($dsurmod) { 316 static $dolbySurroundModeLookup = array( 317 0 => 'not indicated', 318 1 => 'Not Dolby Surround encoded', 319 2 => 'Dolby Surround encoded', 320 3 => 'reserved' 321 ); 322 return (isset($dolbySurroundModeLookup[$dsurmod]) ? $dolbySurroundModeLookup[$dsurmod] : false); 323 } 324 325 public static function channelsEnabledLookup($acmod, $lfeon) { 326 $lookup = array( 327 'ch1'=>(bool) ($acmod == 0), 328 'ch2'=>(bool) ($acmod == 0), 329 'left'=>(bool) ($acmod > 1), 330 'right'=>(bool) ($acmod > 1), 331 'center'=>(bool) ($acmod & 0x01), 332 'surround_mono'=>false, 333 'surround_left'=>false, 334 'surround_right'=>false, 335 'lfe'=>$lfeon); 336 switch ($acmod) { 337 case 4: 338 case 5: 339 $lookup['surround_mono'] = true; 340 break; 341 case 6: 342 case 7: 343 $lookup['surround_left'] = true; 344 $lookup['surround_right'] = true; 345 break; 346 } 347 return $lookup; 348 } 349 350 public static function heavyCompression($compre) { 351 // The first four bits indicate gain changes in 6.02dB increments which can be 352 // implemented with an arithmetic shift operation. The following four bits 353 // indicate linear gain changes, and require a 5-bit multiply. 354 // We will represent the two 4-bit fields of compr as follows: 355 // X0 X1 X2 X3 . Y4 Y5 Y6 Y7 356 // The meaning of the X values is most simply described by considering X to represent a 4-bit 357 // signed integer with values from -8 to +7. The gain indicated by X is then (X + 1) * 6.02 dB. The 358 // following table shows this in detail. 359 360 // Meaning of 4 msb of compr 361 // 7 +48.16 dB 362 // 6 +42.14 dB 363 // 5 +36.12 dB 364 // 4 +30.10 dB 365 // 3 +24.08 dB 366 // 2 +18.06 dB 367 // 1 +12.04 dB 368 // 0 +6.02 dB 369 // -1 0 dB 370 // -2 -6.02 dB 371 // -3 -12.04 dB 372 // -4 -18.06 dB 373 // -5 -24.08 dB 374 // -6 -30.10 dB 375 // -7 -36.12 dB 376 // -8 -42.14 dB 377 378 $fourbit = str_pad(decbin(($compre & 0xF0) >> 4), 4, '0', STR_PAD_LEFT); 379 if ($fourbit{0} == '1') { 380 $log_gain = -8 + bindec(substr($fourbit, 1)); 381 } else { 382 $log_gain = bindec(substr($fourbit, 1)); 383 } 384 $log_gain = ($log_gain + 1) * getid3_lib::RGADamplitude2dB(2); 385 386 // The value of Y is a linear representation of a gain change of up to -6 dB. Y is considered to 387 // be an unsigned fractional integer, with a leading value of 1, or: 0.1 Y4 Y5 Y6 Y7 (base 2). Y can 388 // represent values between 0.111112 (or 31/32) and 0.100002 (or 1/2). Thus, Y can represent gain 389 // changes from -0.28 dB to -6.02 dB. 390 391 $lin_gain = (16 + ($compre & 0x0F)) / 32; 392 393 // The combination of X and Y values allows compr to indicate gain changes from 394 // 48.16 - 0.28 = +47.89 dB, to 395 // -42.14 - 6.02 = -48.16 dB. 396 397 return $log_gain - $lin_gain; 398 } 399 400 public static function roomTypeLookup($roomtyp) { 401 static $roomTypeLookup = array( 402 0 => 'not indicated', 403 1 => 'large room, X curve monitor', 404 2 => 'small room, flat monitor', 405 3 => 'reserved' 406 ); 407 return (isset($roomTypeLookup[$roomtyp]) ? $roomTypeLookup[$roomtyp] : false); 408 } 409 410 public static function frameSizeLookup($frmsizecod, $fscod) { 411 $padding = (bool) ($frmsizecod % 2); 412 $framesizeid = floor($frmsizecod / 2); 413 414 static $frameSizeLookup = array(); 415 if (empty($frameSizeLookup)) { 416 $frameSizeLookup = array ( 417 0 => array(128, 138, 192), 418 1 => array(40, 160, 174, 240), 419 2 => array(48, 192, 208, 288), 420 3 => array(56, 224, 242, 336), 421 4 => array(64, 256, 278, 384), 422 5 => array(80, 320, 348, 480), 423 6 => array(96, 384, 416, 576), 424 7 => array(112, 448, 486, 672), 425 8 => array(128, 512, 556, 768), 426 9 => array(160, 640, 696, 960), 427 10 => array(192, 768, 834, 1152), 428 11 => array(224, 896, 974, 1344), 429 12 => array(256, 1024, 1114, 1536), 430 13 => array(320, 1280, 1392, 1920), 431 14 => array(384, 1536, 1670, 2304), 432 15 => array(448, 1792, 1950, 2688), 433 16 => array(512, 2048, 2228, 3072), 434 17 => array(576, 2304, 2506, 3456), 435 18 => array(640, 2560, 2786, 3840) 436 ); 437 } 438 if (($fscod == 1) && $padding) { 439 // frame lengths are padded by 1 word (16 bits) at 44100 440 $frameSizeLookup[$frmsizecod] += 2; 441 } 442 return (isset($frameSizeLookup[$framesizeid][$fscod]) ? $frameSizeLookup[$framesizeid][$fscod] : false); 443 } 444 445 public static function bitrateLookup($frmsizecod) { 446 $framesizeid = floor($frmsizecod / 2); 447 448 static $bitrateLookup = array( 449 0 => 32000, 450 1 => 40000, 451 2 => 48000, 452 3 => 56000, 453 4 => 64000, 454 5 => 80000, 455 6 => 96000, 456 7 => 112000, 457 8 => 128000, 458 9 => 160000, 459 10 => 192000, 460 11 => 224000, 461 12 => 256000, 462 13 => 320000, 463 14 => 384000, 464 15 => 448000, 465 16 => 512000, 466 17 => 576000, 467 18 => 640000 468 ); 469 return (isset($bitrateLookup[$framesizeid]) ? $bitrateLookup[$framesizeid] : false); 470 } 471 472 473 }
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| Generated: Tue Mar 25 01:41:18 2014 | WordPress honlapkészítés: online1.hu |