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view e2gallerypro/e2upload/Backend/Assets/getid3/module.audio.ac3.php @ 20:1038db2374ec judyates
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| author | Robert McIntyre <rlm@mit.edu> |
|---|---|
| date | Sun, 08 Sep 2013 00:47:09 -0400 |
| parents | 3f6b44aa6b35 |
| children |
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1 <?php2 // +----------------------------------------------------------------------+3 // | PHP version 5 |4 // +----------------------------------------------------------------------+5 // | Copyright (c) 2002-2006 James Heinrich, Allan Hansen |6 // +----------------------------------------------------------------------+7 // | This source file is subject to version 2 of the GPL license, |8 // | that is bundled with this package in the file license.txt and is |9 // | available through the world-wide-web at the following url: |10 // | http://www.gnu.org/copyleft/gpl.html |11 // +----------------------------------------------------------------------+12 // | getID3() - http://getid3.sourceforge.net or http://www.getid3.org |13 // +----------------------------------------------------------------------+14 // | Authors: James Heinrich <infoุgetid3*org> |15 // | Allan Hansen <ahุartemis*dk> |16 // +----------------------------------------------------------------------+17 // | module.audio.ac3.php |18 // | Module for analyzing AC-3 (aka Dolby Digital) audio files |19 // | dependencies: NONE |20 // +----------------------------------------------------------------------+21 //22 // $Id: module.audio.ac3.php,v 1.3 2006/11/02 10:48:01 ah Exp $26 class getid3_ac3 extends getid3_handler27 {29 public function Analyze() {31 $getid3 = $this->getid3;33 // http://www.atsc.org/standards/a_52a.pdf35 $getid3->info['fileformat'] = 'ac3';36 $getid3->info['audio']['dataformat'] = 'ac3';37 $getid3->info['audio']['bitrate_mode'] = 'cbr';38 $getid3->info['audio']['lossless'] = false;40 $getid3->info['ac3']['raw']['bsi'] = array ();41 $info_ac3 = &$getid3->info['ac3'];42 $info_ac3_raw = &$info_ac3['raw'];43 $info_ac3_raw_bsi = &$info_ac3_raw['bsi'];46 // An AC-3 serial coded audio bit stream is made up of a sequence of synchronization frames47 // Each synchronization frame contains 6 coded audio blocks (AB), each of which represent 25648 // new audio samples per channel. A synchronization information (SI) header at the beginning49 // of each frame contains information needed to acquire and maintain synchronization. A50 // bit stream information (BSI) header follows SI, and contains parameters describing the coded51 // audio service. The coded audio blocks may be followed by an auxiliary data (Aux) field. At the52 // end of each frame is an error check field that includes a CRC word for error detection. An53 // additional CRC word is located in the SI header, the use of which, by a decoder, is optional.54 //55 // syncinfo() | bsi() | AB0 | AB1 | AB2 | AB3 | AB4 | AB5 | Aux | CRC57 $this->fseek($getid3->info['avdataoffset'], SEEK_SET);58 $ac3_header['syncinfo'] = $this->fread(5);59 $info_ac3_raw['synchinfo']['synchword'] = substr($ac3_header['syncinfo'], 0, 2);61 if ($info_ac3_raw['synchinfo']['synchword'] != "\x0B\x77") {62 throw new getid3_exception('Expecting "\x0B\x77" at offset '.$getid3->info['avdataoffset'].', found \x'.strtoupper(dechex($ac3_header['syncinfo']{0})).'\x'.strtoupper(dechex($ac3_header['syncinfo']{1})).' instead');63 }66 // syncinfo() {67 // syncword 1668 // crc1 1669 // fscod 270 // frmsizecod 671 // } /* end of syncinfo */73 $info_ac3_raw['synchinfo']['crc1'] = getid3_lib::LittleEndian2Int(substr($ac3_header['syncinfo'], 2, 2));74 $ac3_synchinfo_fscod_frmsizecod = getid3_lib::LittleEndian2Int(substr($ac3_header['syncinfo'], 4, 1));75 $info_ac3_raw['synchinfo']['fscod'] = ($ac3_synchinfo_fscod_frmsizecod & 0xC0) >> 6;76 $info_ac3_raw['synchinfo']['frmsizecod'] = ($ac3_synchinfo_fscod_frmsizecod & 0x3F);78 $info_ac3['sample_rate'] = getid3_ac3::AC3sampleRateCodeLookup($info_ac3_raw['synchinfo']['fscod']);79 if ($info_ac3_raw['synchinfo']['fscod'] <= 3) {80 $getid3->info['audio']['sample_rate'] = $info_ac3['sample_rate'];81 }83 $info_ac3['frame_length'] = getid3_ac3::AC3frameSizeLookup($info_ac3_raw['synchinfo']['frmsizecod'], $info_ac3_raw['synchinfo']['fscod']);84 $info_ac3['bitrate'] = getid3_ac3::AC3bitrateLookup($info_ac3_raw['synchinfo']['frmsizecod']);85 $getid3->info['audio']['bitrate'] = $info_ac3['bitrate'];87 $ac3_header['bsi'] = getid3_lib::BigEndian2Bin($this->fread(15));89 $info_ac3_raw_bsi['bsid'] = bindec(substr($ac3_header['bsi'], 0, 5));90 if ($info_ac3_raw_bsi['bsid'] > 8) {91 // Decoders which can decode version 8 will thus be able to decode version numbers less than 8.92 // If this standard is extended by the addition of additional elements or features, a value of bsid greater than 8 will be used.93 // Decoders built to this version of the standard will not be able to decode versions with bsid greater than 8.94 throw new getid3_exception('Bit stream identification is version '.$info_ac3_raw_bsi['bsid'].', but getID3() only understands up to version 8');95 }97 $info_ac3_raw_bsi['bsmod'] = bindec(substr($ac3_header['bsi'], 5, 3));98 $info_ac3_raw_bsi['acmod'] = bindec(substr($ac3_header['bsi'], 8, 3));100 $info_ac3['service_type'] = getid3_ac3::AC3serviceTypeLookup($info_ac3_raw_bsi['bsmod'], $info_ac3_raw_bsi['acmod']);101 $ac3_coding_mode = getid3_ac3::AC3audioCodingModeLookup($info_ac3_raw_bsi['acmod']);102 foreach($ac3_coding_mode as $key => $value) {103 $info_ac3[$key] = $value;104 }105 switch ($info_ac3_raw_bsi['acmod']) {106 case 0:107 case 1:108 $getid3->info['audio']['channelmode'] = 'mono';109 break;110 case 3:111 case 4:112 $getid3->info['audio']['channelmode'] = 'stereo';113 break;114 default:115 $getid3->info['audio']['channelmode'] = 'surround';116 break;117 }118 $getid3->info['audio']['channels'] = $info_ac3['num_channels'];120 $offset = 11;122 if ($info_ac3_raw_bsi['acmod'] & 0x01) {123 // If the lsb of acmod is a 1, center channel is in use and cmixlev follows in the bit stream.124 $info_ac3_raw_bsi['cmixlev'] = bindec(substr($ac3_header['bsi'], $offset, 2));125 $info_ac3['center_mix_level'] = getid3_ac3::AC3centerMixLevelLookup($info_ac3_raw_bsi['cmixlev']);126 $offset += 2;127 }129 if ($info_ac3_raw_bsi['acmod'] & 0x04) {130 // If the msb of acmod is a 1, surround channels are in use and surmixlev follows in the bit stream.131 $info_ac3_raw_bsi['surmixlev'] = bindec(substr($ac3_header['bsi'], $offset, 2));132 $info_ac3['surround_mix_level'] = getid3_ac3::AC3surroundMixLevelLookup($info_ac3_raw_bsi['surmixlev']);133 $offset += 2;134 }136 if ($info_ac3_raw_bsi['acmod'] == 0x02) {137 // When operating in the two channel mode, this 2-bit code indicates whether or not the program has been encoded in Dolby Surround.138 $info_ac3_raw_bsi['dsurmod'] = bindec(substr($ac3_header['bsi'], $offset, 2));139 $info_ac3['dolby_surround_mode'] = getid3_ac3::AC3dolbySurroundModeLookup($info_ac3_raw_bsi['dsurmod']);140 $offset += 2;141 }143 $info_ac3_raw_bsi['lfeon'] = $ac3_header['bsi']{$offset++} == '1';144 $info_ac3['lfe_enabled'] = $info_ac3_raw_bsi['lfeon'];145 if ($info_ac3_raw_bsi['lfeon']) {146 $getid3->info['audio']['channels'] .= '.1';147 }149 $info_ac3['channels_enabled'] = getid3_ac3::AC3channelsEnabledLookup($info_ac3_raw_bsi['acmod'], $info_ac3_raw_bsi['lfeon']);151 // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 131.152 // 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.153 $info_ac3_raw_bsi['dialnorm'] = bindec(substr($ac3_header['bsi'], $offset, 5));154 $offset += 5;155 $info_ac3['dialogue_normalization'] = '-'.$info_ac3_raw_bsi['dialnorm'].'dB';157 $info_ac3_raw_bsi['compre_flag'] = $ac3_header['bsi']{$offset++} == '1';158 if ($info_ac3_raw_bsi['compre_flag']) {159 $info_ac3_raw_bsi['compr'] = bindec(substr($ac3_header['bsi'], $offset, 8));160 $offset += 8;162 $info_ac3['heavy_compression'] = getid3_ac3::AC3heavyCompression($info_ac3_raw_bsi['compr']);163 }165 $info_ac3_raw_bsi['langcode_flag'] = $ac3_header['bsi']{$offset++} == '1';166 if ($info_ac3_raw_bsi['langcode_flag']) {167 $info_ac3_raw_bsi['langcod'] = bindec(substr($ac3_header['bsi'], $offset, 8));168 $offset += 8;169 }171 $info_ac3_raw_bsi['audprodie'] = $ac3_header['bsi']{$offset++} == '1';172 if ($info_ac3_raw_bsi['audprodie']) {173 $info_ac3_raw_bsi['mixlevel'] = bindec(substr($ac3_header['bsi'], $offset, 5));174 $offset += 5;176 $info_ac3_raw_bsi['roomtyp'] = bindec(substr($ac3_header['bsi'], $offset, 2));177 $offset += 2;179 $info_ac3['mixing_level'] = (80 + $info_ac3_raw_bsi['mixlevel']).'dB';180 $info_ac3['room_type'] = getid3_ac3::AC3roomTypeLookup($info_ac3_raw_bsi['roomtyp']);181 }183 if ($info_ac3_raw_bsi['acmod'] == 0x00) {184 // If acmod is 0, then two completely independent program channels (dual mono)185 // are encoded into the bit stream, and are referenced as Ch1, Ch2. In this case,186 // a number of additional items are present in BSI or audblk to fully describe Ch2.189 // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 131.190 // 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.191 $info_ac3_raw_bsi['dialnorm2'] = bindec(substr($ac3_header['bsi'], $offset, 5));192 $offset += 5;194 $info_ac3['dialogue_normalization2'] = '-'.$info_ac3_raw_bsi['dialnorm2'].'dB';196 $info_ac3_raw_bsi['compre_flag2'] = $ac3_header['bsi']{$offset++} == '1';197 if ($info_ac3_raw_bsi['compre_flag2']) {198 $info_ac3_raw_bsi['compr2'] = bindec(substr($ac3_header['bsi'], $offset, 8));199 $offset += 8;201 $info_ac3['heavy_compression2'] = getid3_ac3::AC3heavyCompression($info_ac3_raw_bsi['compr2']);202 }204 $info_ac3_raw_bsi['langcode_flag2'] = $ac3_header['bsi']{$offset++} == '1';205 if ($info_ac3_raw_bsi['langcode_flag2']) {206 $info_ac3_raw_bsi['langcod2'] = bindec(substr($ac3_header['bsi'], $offset, 8));207 $offset += 8;208 }210 $info_ac3_raw_bsi['audprodie2'] = $ac3_header['bsi']{$offset++} == '1';211 if ($info_ac3_raw_bsi['audprodie2']) {212 $info_ac3_raw_bsi['mixlevel2'] = bindec(substr($ac3_header['bsi'], $offset, 5));213 $offset += 5;215 $info_ac3_raw_bsi['roomtyp2'] = bindec(substr($ac3_header['bsi'], $offset, 2));216 $offset += 2;218 $info_ac3['mixing_level2'] = (80 + $info_ac3_raw_bsi['mixlevel2']).'dB';219 $info_ac3['room_type2'] = getid3_ac3::AC3roomTypeLookup($info_ac3_raw_bsi['roomtyp2']);220 }222 }224 $info_ac3_raw_bsi['copyright'] = $ac3_header['bsi']{$offset++} == '1';226 $info_ac3_raw_bsi['original'] = $ac3_header['bsi']{$offset++} == '1';228 $info_ac3_raw_bsi['timecode1_flag'] = $ac3_header['bsi']{$offset++} == '1';229 if ($info_ac3_raw_bsi['timecode1_flag']) {230 $info_ac3_raw_bsi['timecode1'] = bindec(substr($ac3_header['bsi'], $offset, 14));231 $offset += 14;232 }234 $info_ac3_raw_bsi['timecode2_flag'] = $ac3_header['bsi']{$offset++} == '1';235 if ($info_ac3_raw_bsi['timecode2_flag']) {236 $info_ac3_raw_bsi['timecode2'] = bindec(substr($ac3_header['bsi'], $offset, 14));237 $offset += 14;238 }240 $info_ac3_raw_bsi['addbsi_flag'] = $ac3_header['bsi']{$offset++} == '1';241 if ($info_ac3_raw_bsi['addbsi_flag']) {242 $info_ac3_raw_bsi['addbsi_length'] = bindec(substr($ac3_header['bsi'], $offset, 6));243 $offset += 6;245 $ac3_header['bsi'] .= getid3_lib::BigEndian2Bin($this->fread($info_ac3_raw_bsi['addbsi_length']));247 $info_ac3_raw_bsi['addbsi_data'] = substr($ac3_header['bsi'], 119, $info_ac3_raw_bsi['addbsi_length'] * 8);248 }250 return true;251 }255 public static function AC3sampleRateCodeLookup($fscod) {257 static $lookup = array (258 0 => 48000,259 1 => 44100,260 2 => 32000,261 3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute.262 );263 return (isset($lookup[$fscod]) ? $lookup[$fscod] : false);264 }268 public static function AC3serviceTypeLookup($bsmod, $acmod) {270 static $lookup = array (271 0 => 'main audio service: complete main (CM)',272 1 => 'main audio service: music and effects (ME)',273 2 => 'associated service: visually impaired (VI)',274 3 => 'associated service: hearing impaired (HI)',275 4 => 'associated service: dialogue (D)',276 5 => 'associated service: commentary (C)',277 6 => 'associated service: emergency (E)',278 7 => 'main audio service: karaoke'279 );281 if ($bsmod == 7 && $acmod == 1) {282 return 'associated service: voice over (VO)';283 }285 return (isset($lookup[$bsmod]) ? $lookup[$bsmod] : false);286 }290 public static function AC3audioCodingModeLookup($acmod) {292 // array (channel configuration, # channels (not incl LFE), channel order)293 static $lookup = array (294 0 => array ('channel_config'=>'1+1', 'num_channels'=>2, 'channel_order'=>'Ch1,Ch2'),295 1 => array ('channel_config'=>'1/0', 'num_channels'=>1, 'channel_order'=>'C'),296 2 => array ('channel_config'=>'2/0', 'num_channels'=>2, 'channel_order'=>'L,R'),297 3 => array ('channel_config'=>'3/0', 'num_channels'=>3, 'channel_order'=>'L,C,R'),298 4 => array ('channel_config'=>'2/1', 'num_channels'=>3, 'channel_order'=>'L,R,S'),299 5 => array ('channel_config'=>'3/1', 'num_channels'=>4, 'channel_order'=>'L,C,R,S'),300 6 => array ('channel_config'=>'2/2', 'num_channels'=>4, 'channel_order'=>'L,R,SL,SR'),301 7 => array ('channel_config'=>'3/2', 'num_channels'=>5, 'channel_order'=>'L,C,R,SL,SR')302 );303 return (isset($lookup[$acmod]) ? $lookup[$acmod] : false);304 }308 public static function AC3centerMixLevelLookup($cmixlev) {310 static $lookup;311 if (!@$lookup) {312 $lookup = array (313 0 => pow(2, -3.0 / 6), // 0.707 (3.0 dB)314 1 => pow(2, -4.5 / 6), // 0.595 (4.5 dB)315 2 => pow(2, -6.0 / 6), // 0.500 (6.0 dB)316 3 => 'reserved'317 );318 }319 return (isset($lookup[$cmixlev]) ? $lookup[$cmixlev] : false);320 }324 public static function AC3surroundMixLevelLookup($surmixlev) {326 static $lookup;327 if (!@$lookup) {328 $lookup = array (329 0 => pow(2, -3.0 / 6),330 1 => pow(2, -6.0 / 6),331 2 => 0,332 3 => 'reserved'333 );334 }335 return (isset($lookup[$surmixlev]) ? $lookup[$surmixlev] : false);336 }340 public static function AC3dolbySurroundModeLookup($dsurmod) {342 static $lookup = array (343 0 => 'not indicated',344 1 => 'Not Dolby Surround encoded',345 2 => 'Dolby Surround encoded',346 3 => 'reserved'347 );348 return (isset($lookup[$dsurmod]) ? $lookup[$dsurmod] : false);349 }353 public static function AC3channelsEnabledLookup($acmod, $lfeon) {355 return array (356 'ch1' => $acmod == 0,357 'ch2' => $acmod == 0,358 'left' => $acmod > 1,359 'right' => $acmod > 1,360 'center' => (bool)($acmod & 0x01),361 'surround_mono' => $acmod == 4 || $acmod == 5,362 'surround_left' => $acmod == 6 || $acmod == 7,363 'surround_right' => $acmod == 6 || $acmod == 7,364 'lfe' => $lfeon365 );366 }370 public static function AC3heavyCompression($compre) {372 // The first four bits indicate gain changes in 6.02dB increments which can be373 // implemented with an arithmetic shift operation. The following four bits374 // indicate linear gain changes, and require a 5-bit multiply.375 // We will represent the two 4-bit fields of compr as follows:376 // X0 X1 X2 X3 . Y4 Y5 Y6 Y7377 // The meaning of the X values is most simply described by considering X to represent a 4-bit378 // signed integer with values from 8 to +7. The gain indicated by X is then (X + 1) * 6.02 dB. The379 // following table shows this in detail.381 // Meaning of 4 msb of compr382 // 7 +48.16 dB383 // 6 +42.14 dB384 // 5 +36.12 dB385 // 4 +30.10 dB386 // 3 +24.08 dB387 // 2 +18.06 dB388 // 1 +12.04 dB389 // 0 +6.02 dB390 // -1 0 dB391 // -2 6.02 dB392 // -3 12.04 dB393 // -4 18.06 dB394 // -5 24.08 dB395 // -6 30.10 dB396 // -7 36.12 dB397 // -8 42.14 dB399 $fourbit = str_pad(decbin(($compre & 0xF0) >> 4), 4, '0', STR_PAD_LEFT);400 if ($fourbit{0} == '1') {401 $log_gain = -8 + bindec(substr($fourbit, 1));402 } else {403 $log_gain = bindec(substr($fourbit, 1));404 }405 $log_gain = ($log_gain + 1) * (20 * log10(2));407 // The value of Y is a linear representation of a gain change of up to 6 dB. Y is considered to408 // be an unsigned fractional integer, with a leading value of 1, or: 0.1 Y4 Y5 Y6 Y7 (base 2). Y can409 // represent values between 0.111112 (or 31/32) and 0.100002 (or 1/2). Thus, Y can represent gain410 // changes from 0.28 dB to 6.02 dB.412 $lin_gain = (16 + ($compre & 0x0F)) / 32;414 // The combination of X and Y values allows compr to indicate gain changes from415 // 48.16 0.28 = +47.89 dB, to416 // 42.14 6.02 = 48.16 dB.418 return $log_gain - $lin_gain;419 }423 public static function AC3roomTypeLookup($roomtyp) {425 static $lookup = array (426 0 => 'not indicated',427 1 => 'large room, X curve monitor',428 2 => 'small room, flat monitor',429 3 => 'reserved'430 );431 return (isset($lookup[$roomtyp]) ? $lookup[$roomtyp] : false);432 }436 public static function AC3frameSizeLookup($frmsizecod, $fscod) {438 $padding = (bool)($frmsizecod % 2);439 $frame_size_id = floor($frmsizecod / 2);441 static $lookup = array (442 0 => array (128, 138, 192),443 1 => array (40, 160, 174, 240),444 2 => array (48, 192, 208, 288),445 3 => array (56, 224, 242, 336),446 4 => array (64, 256, 278, 384),447 5 => array (80, 320, 348, 480),448 6 => array (96, 384, 416, 576),449 7 => array (112, 448, 486, 672),450 8 => array (128, 512, 556, 768),451 9 => array (160, 640, 696, 960),452 10 => array (192, 768, 834, 1152),453 11 => array (224, 896, 974, 1344),454 12 => array (256, 1024, 1114, 1536),455 13 => array (320, 1280, 1392, 1920),456 14 => array (384, 1536, 1670, 2304),457 15 => array (448, 1792, 1950, 2688),458 16 => array (512, 2048, 2228, 3072),459 17 => array (576, 2304, 2506, 3456),460 18 => array (640, 2560, 2786, 3840)461 );462 if (($fscod == 1) && $padding) {463 // frame lengths are padded by 1 word (16 bits) at 44100464 $lookup[$frmsizecod] += 2;465 }466 return (isset($lookup[$frame_size_id][$fscod]) ? $lookup[$frame_size_id][$fscod] : false);467 }471 public static function AC3bitrateLookup($frmsizecod) {473 static $lookup = array (474 0 => 32000,475 1 => 40000,476 2 => 48000,477 3 => 56000,478 4 => 64000,479 5 => 80000,480 6 => 96000,481 7 => 112000,482 8 => 128000,483 9 => 160000,484 10 => 192000,485 11 => 224000,486 12 => 256000,487 13 => 320000,488 14 => 384000,489 15 => 448000,490 16 => 512000,491 17 => 576000,492 18 => 640000493 );494 $frame_size_id = floor($frmsizecod / 2);495 return (isset($lookup[$frame_size_id]) ? $lookup[$frame_size_id] : false);496 }498 }500 ?>