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-video.mpeg.php                                          |

    18 // | Module for analyzing MPEG files                                      |

    19 // | dependencies: module.audio.mp3.php                                   |

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

    21 //

    22 // $Id: module.audio-video.mpeg.php,v 1.3 2006/11/02 10:48:00 ah Exp $

    23 

    24         

    25         

    26 class getid3_mpeg extends getid3_handler

    27 {

    28 

    29     const VIDEO_PICTURE_START   = "\x00\x00\x01\x00";

    30     const VIDEO_USER_DATA_START = "\x00\x00\x01\xB2";

    31     const VIDEO_SEQUENCE_HEADER = "\x00\x00\x01\xB3";

    32     const VIDEO_SEQUENCE_ERROR  = "\x00\x00\x01\xB4";

    33     const VIDEO_EXTENSION_START = "\x00\x00\x01\xB5";

    34     const VIDEO_SEQUENCE_END    = "\x00\x00\x01\xB7";

    35     const VIDEO_GROUP_START     = "\x00\x00\x01\xB8";

    36     const AUDIO_START           = "\x00\x00\x01\xC0";

    37     

    38 

    39     public function Analyze() {

    40         

    41         $getid3 = $this->getid3;

    42         

    43         $getid3->info['mpeg']['video']['raw'] = array ();

    44         $info_mpeg_video     = &$getid3->info['mpeg']['video'];

    45         $info_mpeg_video_raw = &$info_mpeg_video['raw'];

    46         

    47         $getid3->info['video'] = array ();

    48         $info_video = &$getid3->info['video'];

    49         

    50         $getid3->include_module('audio.mp3');

    51         

    52         if ($getid3->info['avdataend'] <= $getid3->info['avdataoffset']) {

    53             throw new getid3_exception('"avdataend" ('.$getid3->info['avdataend'].') is unexpectedly less-than-or-equal-to "avdataoffset" ('.$getid3->info['avdataoffset'].')');

    54         }

    55 

    56         $getid3->info['fileformat'] = 'mpeg';

    57         fseek($getid3->fp, $getid3->info['avdataoffset'], SEEK_SET);

    58         $mpeg_stream_data        = fread($getid3->fp, min(100000, $getid3->info['avdataend'] - $getid3->info['avdataoffset']));

    59         $mpeg_stream_data_length = strlen($mpeg_stream_data);

    60 

    61         $video_chunk_offset = 0;

    62         while (substr($mpeg_stream_data, $video_chunk_offset++, 4) !== getid3_mpeg::VIDEO_SEQUENCE_HEADER) {

    63             if ($video_chunk_offset >= $mpeg_stream_data_length) {

    64                 throw new getid3_exception('Could not find start of video block in the first 100,000 bytes (or before end of file) - this might not be an MPEG-video file?');

    65             }

    66         }

    67 

    68         // Start code                       32 bits

    69         // horizontal frame size            12 bits

    70         // vertical frame size              12 bits

    71         // pixel aspect ratio                4 bits

    72         // frame rate                        4 bits

    73         // bitrate                          18 bits

    74         // marker bit                        1 bit

    75         // VBV buffer size                  10 bits

    76         // constrained parameter flag        1 bit

    77         // intra quant. matrix flag          1 bit

    78         // intra quant. matrix values      512 bits (present if matrix flag == 1)

    79         // non-intra quant. matrix flag      1 bit

    80         // non-intra quant. matrix values  512 bits (present if matrix flag == 1)

    81 

    82         $info_video['dataformat'] = 'mpeg';

    83 

    84         $video_chunk_offset += (strlen(getid3_mpeg::VIDEO_SEQUENCE_HEADER) - 1);

    85 

    86         $frame_size_dword = getid3_lib::BigEndian2Int(substr($mpeg_stream_data, $video_chunk_offset, 3));

    87         $video_chunk_offset += 3;

    88 

    89         $aspect_ratio_frame_rate_dword = getid3_lib::BigEndian2Int(substr($mpeg_stream_data, $video_chunk_offset, 1));

    90         $video_chunk_offset += 1;

    91 

    92         $assorted_information = getid3_lib::BigEndian2Bin(substr($mpeg_stream_data, $video_chunk_offset, 4));

    93         $video_chunk_offset += 4;

    94 

    95         $info_mpeg_video_raw['framesize_horizontal']   = ($frame_size_dword & 0xFFF000) >> 12; // 12 bits for horizontal frame size

    96         $info_mpeg_video_raw['framesize_vertical']     = ($frame_size_dword & 0x000FFF);       // 12 bits for vertical frame size

    97         $info_mpeg_video_raw['pixel_aspect_ratio']     = ($aspect_ratio_frame_rate_dword & 0xF0) >> 4;

    98         $info_mpeg_video_raw['frame_rate']             = ($aspect_ratio_frame_rate_dword & 0x0F);

    99                                                                         

   100         $info_mpeg_video['framesize_horizontal']          = $info_mpeg_video_raw['framesize_horizontal'];

   101         $info_mpeg_video['framesize_vertical']            = $info_mpeg_video_raw['framesize_vertical'];

   102 

   103         $info_mpeg_video['pixel_aspect_ratio']            = $this->MPEGvideoAspectRatioLookup($info_mpeg_video_raw['pixel_aspect_ratio']);

   104         $info_mpeg_video['pixel_aspect_ratio_text']       = $this->MPEGvideoAspectRatioTextLookup($info_mpeg_video_raw['pixel_aspect_ratio']);

   105         $info_mpeg_video['frame_rate']                    = $this->MPEGvideoFramerateLookup($info_mpeg_video_raw['frame_rate']);

   106 

   107         $info_mpeg_video_raw['bitrate']                =       bindec(substr($assorted_information,  0, 18));

   108         $info_mpeg_video_raw['marker_bit']             = (bool)bindec($assorted_information{18});

   109         $info_mpeg_video_raw['vbv_buffer_size']        =       bindec(substr($assorted_information, 19, 10));

   110         $info_mpeg_video_raw['constrained_param_flag'] = (bool)bindec($assorted_information{29});

   111         $info_mpeg_video_raw['intra_quant_flag']       = (bool)bindec($assorted_information{30});

   112         

   113         if ($info_mpeg_video_raw['intra_quant_flag']) {

   114 

   115             // read 512 bits

   116             $info_mpeg_video_raw['intra_quant']          = getid3_lib::BigEndian2Bin(substr($mpeg_stream_data, $video_chunk_offset, 64));

   117             $video_chunk_offset += 64;

   118 

   119             $info_mpeg_video_raw['non_intra_quant_flag'] = (bool)bindec($info_mpeg_video_raw['intra_quant']{511});

   120             $info_mpeg_video_raw['intra_quant']          =       bindec($assorted_information{31}).substr(getid3_lib::BigEndian2Bin(substr($mpeg_stream_data, $video_chunk_offset, 64)), 0, 511);

   121 

   122             if ($info_mpeg_video_raw['non_intra_quant_flag']) {

   123                 $info_mpeg_video_raw['non_intra_quant'] = substr($mpeg_stream_data, $video_chunk_offset, 64);

   124                 $video_chunk_offset += 64;

   125             }

   126 

   127         } else {

   128 

   129             $info_mpeg_video_raw['non_intra_quant_flag'] = (bool)bindec($assorted_information{31});

   130             if ($info_mpeg_video_raw['non_intra_quant_flag']) {

   131                 $info_mpeg_video_raw['non_intra_quant'] = substr($mpeg_stream_data, $video_chunk_offset, 64);

   132                 $video_chunk_offset += 64;

   133             }

   134         }

   135 

   136         if ($info_mpeg_video_raw['bitrate'] == 0x3FFFF) { // 18 set bits

   137 

   138             $getid3->warning('This version of getID3() cannot determine average bitrate of VBR MPEG video files');

   139             $info_mpeg_video['bitrate_mode'] = 'vbr';

   140 

   141         } else {

   142 

   143             $info_mpeg_video['bitrate']      = $info_mpeg_video_raw['bitrate'] * 400;

   144             $info_mpeg_video['bitrate_mode'] = 'cbr';

   145             $info_video['bitrate']              = $info_mpeg_video['bitrate'];

   146         }

   147 

   148         $info_video['resolution_x']       = $info_mpeg_video['framesize_horizontal'];

   149         $info_video['resolution_y']       = $info_mpeg_video['framesize_vertical'];

   150         $info_video['frame_rate']         = $info_mpeg_video['frame_rate'];

   151         $info_video['bitrate_mode']       = $info_mpeg_video['bitrate_mode'];

   152         $info_video['pixel_aspect_ratio'] = $info_mpeg_video['pixel_aspect_ratio'];

   153         $info_video['lossless']           = false;

   154         $info_video['bits_per_sample']    = 24;

   155 

   156 

   157         //0x000001B3 begins the sequence_header of every MPEG video stream.

   158         //But in MPEG-2, this header must immediately be followed by an

   159         //extension_start_code (0x000001B5) with a sequence_extension ID (1).

   160         //(This extension contains all the additional MPEG-2 stuff.)

   161         //MPEG-1 doesn't have this extension, so that's a sure way to tell the

   162         //difference between MPEG-1 and MPEG-2 video streams.

   163 

   164         $info_video['codec'] = substr($mpeg_stream_data, $video_chunk_offset, 4) == getid3_mpeg::VIDEO_EXTENSION_START ? 'MPEG-2' : 'MPEG-1';

   165 

   166         $audio_chunk_offset = 0;

   167         while (true) {

   168             while (substr($mpeg_stream_data, $audio_chunk_offset++, 4) !== getid3_mpeg::AUDIO_START) {

   169                 if ($audio_chunk_offset >= $mpeg_stream_data_length) {

   170                     break 2;

   171                 }

   172             }

   173 

   174             for ($i = 0; $i <= 7; $i++) {

   175                 // some files have the MPEG-audio header 8 bytes after the end of the $00 $00 $01 $C0 signature, some have it up to 13 bytes (or more?) after

   176                 // I have no idea why or what the difference is, so this is a stupid hack.

   177                 // If anybody has any better idea of what's going on, please let me know - info@getid3.org

   178 

   179                 // make copy of info

   180                 $dummy = $getid3->info;

   181 

   182                 // clone getid3 - better safe than sorry

   183                 $clone = clone $this->getid3;

   184                 

   185                 // check

   186                 $mp3 = new getid3_mp3($clone);

   187                 if ($mp3->decodeMPEGaudioHeader($getid3->fp, ($audio_chunk_offset + 3) + 8 + $i, $dummy, false)) {

   188 

   189                     $getid3->info = $dummy;

   190                     $getid3->info['audio']['bitrate_mode'] = 'cbr';

   191                     $getid3->info['audio']['lossless']     = false;

   192                     break 2;

   193                 }

   194                 

   195                 // destroy copy

   196                 unset($dummy);

   197             }

   198         }

   199 

   200         // Temporary hack to account for interleaving overhead:

   201         if (!empty($info_video['bitrate']) && !empty($getid3->info['audio']['bitrate'])) {

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

   203 

   204             // Interleaved MPEG audio/video files have a certain amount of overhead that varies

   205             // by both video and audio bitrates, and not in any sensible, linear/logarithmic patter

   206             // Use interpolated lookup tables to approximately guess how much is overhead, because

   207             // playtime is calculated as filesize / total-bitrate

   208             $getid3->info['playtime_seconds'] *= $this->MPEGsystemNonOverheadPercentage($info_video['bitrate'], $getid3->info['audio']['bitrate']);

   209 

   210             //switch ($info_video['bitrate']) {

   211             //    case('5000000'):

   212             //        $multiplier = 0.93292642112380355828048824319889;

   213             //        break;

   214             //    case('5500000'):

   215             //        $multiplier = 0.93582895375200989965359777343219;

   216             //        break;

   217             //    case('6000000'):

   218             //        $multiplier = 0.93796247714820932532911373859139;

   219             //        break;

   220             //    case('7000000'):

   221             //        $multiplier = 0.9413264083635103463010117778776;

   222             //        break;

   223             //    default:

   224             //        $multiplier = 1;

   225             //        break;

   226             //}

   227             //$getid3->info['playtime_seconds'] *= $multiplier;

   228             //$getid3->warning('Interleaved MPEG audio/video playtime may be inaccurate. With current hack should be within a few seconds of accurate. Report to info@getid3.org if off by more than 10 seconds.');

   229         

   230             if ($info_video['bitrate'] < 50000) {

   231                 $getid3->warning('Interleaved MPEG audio/video playtime may be slightly inaccurate for video bitrates below 100kbps. Except in extreme low-bitrate situations, error should be less than 1%. Report to info@getid3.org if greater than this.');

   232             }

   233         }

   234 

   235         return true;

   236     }

   237 

   238 

   239 

   240     public static function MPEGsystemNonOverheadPercentage($video_bitrate, $audio_bitrate) {

   241         

   242         $overhead_percentage = 0;

   243 

   244         $audio_bitrate = max(min($audio_bitrate / 1000,   384), 32); // limit to range of 32kbps - 384kbps (should be only legal bitrates, but maybe VBR?)

   245         $video_bitrate = max(min($video_bitrate / 1000, 10000), 10); // limit to range of 10kbps -  10Mbps (beyond that curves flatten anyways, no big loss)

   246 

   247         //OMBB[audiobitrate]                 = array (   video-10kbps,       video-100kbps,      video-1000kbps,     video-10000kbps)

   248         static $overhead_multiplier_by_bitrate = array (

   249              32 => array (0, 0.9676287944368530, 0.9802276264360310, 0.9844916183244460, 0.9852821845179940),

   250              48 => array (0, 0.9779100089209830, 0.9787770035359320, 0.9846738664076130, 0.9852683013799960),

   251              56 => array (0, 0.9731249855367600, 0.9776624308938040, 0.9832606361852130, 0.9843922606633340),

   252              64 => array (0, 0.9755642683275760, 0.9795256705493390, 0.9836573009193170, 0.9851122539404470),

   253              96 => array (0, 0.9788025247497290, 0.9798553314148700, 0.9822956869792560, 0.9834815119124690),

   254             128 => array (0, 0.9816940050925480, 0.9821675936072120, 0.9829756927470870, 0.9839763420152050),

   255             160 => array (0, 0.9825894094561180, 0.9820913399073960, 0.9823907143253970, 0.9832821783651570),

   256             192 => array (0, 0.9832038474336260, 0.9825731694317960, 0.9821028622712400, 0.9828262076447620),

   257             224 => array (0, 0.9836516298538770, 0.9824718601823890, 0.9818302180625380, 0.9823735101626480),

   258             256 => array (0, 0.9845863022094920, 0.9837229411967540, 0.9824521662210830, 0.9828645172100790),

   259             320 => array (0, 0.9849565280263180, 0.9837683142805110, 0.9822885275960400, 0.9824424382727190),

   260             384 => array (0, 0.9856094774357600, 0.9844573394432720, 0.9825970399837330, 0.9824673808303890)

   261         );

   262 

   263         $bitrate_to_use_min = $bitrate_to_use_max = $previous_bitrate = 32;

   264 

   265         foreach ($overhead_multiplier_by_bitrate as $key => $value) {

   266         

   267             if ($audio_bitrate >= $previous_bitrate) {

   268                 $bitrate_to_use_min = $previous_bitrate;

   269             }

   270             if ($audio_bitrate < $key) {

   271                 $bitrate_to_use_max = $key;

   272                 break;

   273             }

   274             $previous_bitrate = $key;

   275         }

   276         

   277         $factor_a = ($bitrate_to_use_max - $audio_bitrate) / ($bitrate_to_use_max - $bitrate_to_use_min);

   278 

   279         $video_bitrate_log10 = log10($video_bitrate);

   280         $video_factor_min1   = $overhead_multiplier_by_bitrate[$bitrate_to_use_min][floor($video_bitrate_log10)];

   281         $video_factor_min2   = $overhead_multiplier_by_bitrate[$bitrate_to_use_max][floor($video_bitrate_log10)];

   282         $video_factor_max1   = $overhead_multiplier_by_bitrate[$bitrate_to_use_min][ceil($video_bitrate_log10)];

   283         $video_factor_max2   = $overhead_multiplier_by_bitrate[$bitrate_to_use_max][ceil($video_bitrate_log10)];

   284         $factor_v = $video_bitrate_log10 - floor($video_bitrate_log10);

   285 

   286         $overhead_percentage  = $video_factor_min1 *      $factor_a  *      $factor_v;

   287         $overhead_percentage += $video_factor_min2 * (1 - $factor_a) *      $factor_v;

   288         $overhead_percentage += $video_factor_max1 *      $factor_a  * (1 - $factor_v);

   289         $overhead_percentage += $video_factor_max2 * (1 - $factor_a) * (1 - $factor_v);

   290 

   291         return $overhead_percentage;

   292     }

   293 

   294 

   295 

   296     public static function MPEGvideoFramerateLookup($raw_frame_rate) {

   297         

   298         $lookup = array (0, 23.976, 24, 25, 29.97, 30, 50, 59.94, 60);

   299         

   300         return (float)(isset($lookup[$raw_frame_rate]) ? $lookup[$raw_frame_rate] : 0);

   301     }

   302 

   303 

   304 

   305     public static function MPEGvideoAspectRatioLookup($raw_aspect_ratio) {

   306         

   307         $lookup = array (0, 1, 0.6735, 0.7031, 0.7615, 0.8055, 0.8437, 0.8935, 0.9157, 0.9815, 1.0255, 1.0695, 1.0950, 1.1575, 1.2015, 0);

   308         

   309         return (float)(isset($lookup[$raw_aspect_ratio]) ? $lookup[$raw_aspect_ratio] : 0);

   310     }

   311 

   312 

   313 

   314     public static function MPEGvideoAspectRatioTextLookup($raw_aspect_ratio) {

   315         

   316         $lookup = array ('forbidden', 'square pixels', '0.6735', '16:9, 625 line, PAL', '0.7615', '0.8055', '16:9, 525 line, NTSC', '0.8935', '4:3, 625 line, PAL, CCIR601', '0.9815', '1.0255', '1.0695', '4:3, 525 line, NTSC, CCIR601', '1.1575', '1.2015', 'reserved');

   317         

   318         return (isset($lookup[$raw_aspect_ratio]) ? $lookup[$raw_aspect_ratio] : '');

   319     }

   320 

   321 }

   322 

   323 

   324 ?>