Mercurial > judyates

     1 <?php

     2 // +----------------------------------------------------------------------+

     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 <infoØgetid3*org>                            |

    15 // |          Allan Hansen <ahØartemis*dk>                                |

    16 // +----------------------------------------------------------------------+

    17 // | module.audio.aac_adts.php                                            |

    18 // | Module for analyzing AAC files with ADTS header.                     |

    19 // | dependencies: NONE                                                   |

    20 // +----------------------------------------------------------------------+

    21 //

    22 // $Id: module.audio.aac_adts.php,v 1.4 2006/11/02 10:48:01 ah Exp $

    23 

    24         

    25         

    26 class getid3_aac_adts extends getid3_handler

    27 {

    28 

    29     public $option_max_frames_to_scan   = 1000000;

    30     public $option_return_extended_info = false;

    31     

    32 

    33     private $decbin_cache;

    34     private $bitrate_cache;

    35     

    36 

    37 

    38     public function __construct(getID3 $getid3) {

    39         

    40         parent::__construct($getid3);

    41     

    42         // Populate bindec_cache

    43         for ($i = 0; $i < 256; $i++) {

    44                 $this->decbin_cache[chr($i)] = str_pad(decbin($i), 8, '0', STR_PAD_LEFT);

    45         }

    46         

    47         // Init cache

    48         $this->bitrate_cache = array ();

    49         

    50         // Fast scanning?

    51         if (!$getid3->option_accurate_results) {

    52             $this->option_max_frames_to_scan = 200;

    53             $getid3->warning('option_accurate_results set to false - bitrate and playing time are not accurate.');

    54         }

    55     }

    56     

    57         

    58 

    59     public function Analyze() {

    60         

    61         $getid3 = $this->getid3;

    62 

    63         // based loosely on code from AACfile by Jurgen Faul  <jfaulØgmx.de>

    64         // http://jfaul.de/atl  or  http://j-faul.virtualave.net/atl/atl.html

    65 

    66 

    67         // http://faac.sourceforge.net/wiki/index.php?page=ADTS

    68 

    69         // * ADTS Fixed Header: these don't change from frame to frame

    70         // syncword                                       12    always: '111111111111'

    71         // ID                                              1    0: MPEG-4, 1: MPEG-2

    72         // layer                                           2    always: '00'

    73         // protection_absent                               1

    74         // profile                                         2

    75         // sampling_frequency_index                        4

    76         // private_bit                                     1

    77         // channel_configuration                           3

    78         // original/copy                                   1

    79         // home                                            1

    80         // emphasis                                        2    only if ID == 0 (ie MPEG-4)

    81 

    82         // * ADTS Variable Header: these can change from frame to frame

    83         // copyright_identification_bit                    1

    84         // copyright_identification_start                  1

    85         // aac_frame_length                               13    length of the frame including header (in bytes)

    86         // adts_buffer_fullness                           11    0x7FF indicates VBR

    87         // no_raw_data_blocks_in_frame                     2

    88 

    89         // * ADTS Error check

    90         // crc_check                                      16    only if protection_absent == 0

    91 

    92         $getid3->info['aac']['header'] = array () ;

    93         $info_aac        = &$getid3->info['aac'];

    94         $info_aac_header = & $info_aac['header'];

    95 

    96         $byte_offset  = $frame_number = 0;

    97 

    98         while (true) {

    99             

   100             // Breaks out when end-of-file encountered, or invalid data found,

   101             // or MaxFramesToScan frames have been scanned

   102 

   103             fseek($getid3->fp, $byte_offset, SEEK_SET);

   104 

   105             // First get substring

   106             $sub_string = fread($getid3->fp, 10);

   107             $sub_string_length = strlen($sub_string);

   108             if ($sub_string_length != 10) {

   109                 throw new getid3_exception('Failed to read 10 bytes at offset '.(ftell($getid3->fp) - $sub_string_length).' (only read '.$sub_string_length.' bytes)');

   110             }

   111 

   112             // Initialise $aac_header_bitstream

   113             $aac_header_bitstream = '';

   114 

   115             // Loop thru substring chars

   116             for ($i = 0; $i < 10; $i++) {

   117                 $aac_header_bitstream .= $this->decbin_cache[$sub_string[$i]];

   118             }

   119             

   120             $sync_test  = bindec(substr($aac_header_bitstream, 0, 12));

   121             $bit_offset = 12;

   122             

   123             if ($sync_test != 0x0FFF) {

   124                 throw new getid3_exception('Synch pattern (0x0FFF) not found at offset '.(ftell($getid3->fp) - 10).' (found 0x0'.strtoupper(dechex($sync_test)).' instead)');

   125             }

   126 

   127             // Only gather info once - this takes time to do 1000 times!

   128             if ($frame_number > 0) {

   129 

   130                 // MPEG-4: 20,  // MPEG-2: 18

   131                 $bit_offset += $aac_header_bitstream[$bit_offset] ? 18 : 20;

   132             } 

   133         

   134             // Gather info for first frame only - this takes time to do 1000 times!

   135             else {

   136 

   137                 $info_aac['header_type']             = 'ADTS';

   138                 $info_aac_header['synch']            = $sync_test;

   139                 $getid3->info['fileformat']          = 'aac';

   140                 $getid3->info['audio']['dataformat'] = 'aac';

   141 

   142                 $info_aac_header['mpeg_version']     = $aac_header_bitstream{$bit_offset++} == '0' ? 4 : 2;

   143                 $info_aac_header['layer']            = bindec(substr($aac_header_bitstream, $bit_offset, 2));

   144                 $bit_offset += 2;

   145                 

   146                 if ($info_aac_header['layer'] != 0) {

   147                     throw new getid3_exception('Layer error - expected 0x00, found 0x'.dechex($info_aac_header['layer']).' instead');

   148                 }

   149                 

   150                 $info_aac_header['crc_present'] = $aac_header_bitstream{$bit_offset++} == '0' ? true : false;

   151                 

   152                 $info_aac_header['profile_id'] = bindec(substr($aac_header_bitstream, $bit_offset, 2));

   153                 $bit_offset += 2;

   154                 

   155                 $info_aac_header['profile_text'] = getid3_aac_adts::AACprofileLookup($info_aac_header['profile_id'], $info_aac_header['mpeg_version']);

   156 

   157                 $info_aac_header['sample_frequency_index'] = bindec(substr($aac_header_bitstream, $bit_offset, 4));

   158                 $bit_offset += 4;

   159                 

   160                 $info_aac_header['sample_frequency'] = getid3_aac_adts::AACsampleRateLookup($info_aac_header['sample_frequency_index']);

   161                 

   162                 $getid3->info['audio']['sample_rate'] = $info_aac_header['sample_frequency'];

   163 

   164                 $info_aac_header['private'] = $aac_header_bitstream{$bit_offset++} == 1;

   165                 

   166                 $info_aac_header['channel_configuration'] = $getid3->info['audio']['channels'] = bindec(substr($aac_header_bitstream, $bit_offset, 3));

   167                 $bit_offset += 3;

   168                 

   169                 $info_aac_header['original'] = $aac_header_bitstream{$bit_offset++} == 1;

   170                 $info_aac_header['home']     = $aac_header_bitstream{$bit_offset++} == 1;

   171 

   172                 if ($info_aac_header['mpeg_version'] == 4) {

   173                     $info_aac_header['emphasis']  = bindec(substr($aac_header_bitstream, $bit_offset, 2));

   174                     $bit_offset += 2;

   175                 }

   176 

   177                 if ($this->option_return_extended_info) {

   178 

   179                     $info_aac[$frame_number]['copyright_id_bit']   = $aac_header_bitstream{$bit_offset++} == 1;

   180                     $info_aac[$frame_number]['copyright_id_start'] = $aac_header_bitstream{$bit_offset++} == 1;

   181 

   182                 }  else {

   183                     $bit_offset += 2;

   184                 }

   185             }

   186 

   187             $frame_length = bindec(substr($aac_header_bitstream, $bit_offset, 13));

   188 

   189             if (!isset($this->bitrate_cache[$frame_length])) {

   190                 $this->bitrate_cache[$frame_length] = ($info_aac_header['sample_frequency'] / 1024) * $frame_length * 8;

   191             }

   192             @$info_aac['bitrate_distribution'][$this->bitrate_cache[$frame_length]]++;

   193 

   194             $info_aac[$frame_number]['aac_frame_length']     = $frame_length;

   195             $bit_offset += 13;

   196             

   197             $info_aac[$frame_number]['adts_buffer_fullness'] = bindec(substr($aac_header_bitstream, $bit_offset, 11));

   198             $bit_offset += 11;

   199             

   200             $getid3->info['audio']['bitrate_mode'] = ($info_aac[$frame_number]['adts_buffer_fullness'] == 0x07FF) ? 'vbr' : 'cbr';

   201             

   202             $info_aac[$frame_number]['num_raw_data_blocks']  = bindec(substr($aac_header_bitstream, $bit_offset, 2));

   203             $bit_offset += 2;

   204 

   205             if ($info_aac_header['crc_present']) {

   206                 $bit_offset += 16;

   207             }

   208 

   209             if (!$this->option_return_extended_info) {

   210                 unset($info_aac[$frame_number]);

   211             }

   212 

   213             $byte_offset += $frame_length;

   214             if ((++$frame_number < $this->option_max_frames_to_scan) && (($byte_offset + 10) < $getid3->info['avdataend'])) {

   215 

   216                 // keep scanning

   217 

   218             } else {

   219 

   220                 $info_aac['frames']    = $frame_number;

   221                 $getid3->info['playtime_seconds'] = ($getid3->info['avdataend'] / $byte_offset) * (($frame_number * 1024) / $info_aac_header['sample_frequency']);  // (1 / % of file scanned) * (samples / (samples/sec)) = seconds

   222                 $getid3->info['audio']['bitrate'] = (($getid3->info['avdataend'] - $getid3->info['avdataoffset']) * 8) / $getid3->info['playtime_seconds'];

   223                 ksort($info_aac['bitrate_distribution']);

   224 

   225                 $getid3->info['audio']['encoder_options'] = $info_aac['header_type'].' '.$info_aac_header['profile_text'];

   226 

   227                 return true;

   228             }

   229         }

   230     }

   231 

   232     

   233     

   234     public static function AACsampleRateLookup($samplerate_id) {

   235         

   236         static $lookup = array (

   237             0  => 96000,

   238             1  => 88200,

   239             2  => 64000,

   240             3  => 48000,

   241             4  => 44100,

   242             5  => 32000,

   243             6  => 24000,

   244             7  => 22050,

   245             8  => 16000,

   246             9  => 12000,

   247             10 => 11025,

   248             11 => 8000,

   249             12 => 0,

   250             13 => 0,

   251             14 => 0,

   252             15 => 0

   253         );

   254         return (isset($lookup[$samplerate_id]) ? $lookup[$samplerate_id] : 'invalid');

   255     }

   256 

   257 

   258 

   259     public static function AACprofileLookup($profile_id, $mpeg_version) {

   260         

   261         static $lookup = array (

   262             2 => array ( 

   263                 0 => 'Main profile',

   264                 1 => 'Low Complexity profile (LC)',

   265                 2 => 'Scalable Sample Rate profile (SSR)',

   266                 3 => '(reserved)'

   267             ),            

   268             4 => array (

   269                 0 => 'AAC_MAIN',

   270                 1 => 'AAC_LC',

   271                 2 => 'AAC_SSR',

   272                 3 => 'AAC_LTP'

   273             )

   274         );

   275         return (isset($lookup[$mpeg_version][$profile_id]) ? $lookup[$mpeg_version][$profile_id] : 'invalid');

   276     }

   277 

   278 

   279 }

   280 

   281 

   282 ?>
author	Robert McIntyre <rlm@mit.edu>
date	Sun, 08 Sep 2013 00:47:09 -0400
parents	3f6b44aa6b35
children