vendor/james-heinrich/getid3/getid3/module.audio-video.mpeg.php

   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 //          also https://github.com/JamesHeinrich/getID3       //
   7 /////////////////////////////////////////////////////////////////
   8 // See readme.txt for more details                             //
   9 /////////////////////////////////////////////////////////////////
  10 //                                                             //
  11 // module.audio-video.mpeg.php                                 //
  12 // module for analyzing MPEG files                             //
  13 // dependencies: module.audio.mp3.php                          //
  14 //                                                            ///
  15 /////////////////////////////////////////////////////////////////
  16
  17 getid3_lib::IncludeDependency(GETID3_INCLUDEPATH.'module.audio.mp3.php', __FILE__, true);
  18
  19 class getid3_mpeg extends getid3_handler {
  20
  21         const START_CODE_BASE       = "\x00\x00\x01";
  22         const VIDEO_PICTURE_START   = "\x00\x00\x01\x00";
  23         const VIDEO_USER_DATA_START = "\x00\x00\x01\xB2";
  24         const VIDEO_SEQUENCE_HEADER = "\x00\x00\x01\xB3";
  25         const VIDEO_SEQUENCE_ERROR  = "\x00\x00\x01\xB4";
  26         const VIDEO_EXTENSION_START = "\x00\x00\x01\xB5";
  27         const VIDEO_SEQUENCE_END    = "\x00\x00\x01\xB7";
  28         const VIDEO_GROUP_START     = "\x00\x00\x01\xB8";
  29         const AUDIO_START           = "\x00\x00\x01\xC0";
  30
  31
  32         public function Analyze() {
  33                 $info = &$this->getid3->info;
  34
  35                 $info['fileformat'] = 'mpeg';
  36                 $this->fseek($info['avdataoffset']);
  37
  38                 $MPEGstreamData = $this->fread($this->getid3->option_fread_buffer_size);
  39                 $MPEGstreamBaseOffset = 0; // how far are we from the beginning of the file data ($info['avdataoffset'])
  40                 $MPEGstreamDataOffset = 0; // how far are we from the beginning of the buffer data (~32kB)
  41
  42                 $StartCodeValue     = false;
  43                 $prevStartCodeValue = false;
  44
  45                 $GOPcounter = -1;
  46                 $FramesByGOP = array();
  47                 $ParsedAVchannels = array();
  48
  49                 do {
  50 //echo $MPEGstreamDataOffset.' vs '.(strlen($MPEGstreamData) - 1024).'<Br>';
  51                         if ($MPEGstreamDataOffset > (strlen($MPEGstreamData) - 16384)) {
  52                                 // buffer running low, get more data
  53 //echo 'reading more data<br>';
  54                                 $MPEGstreamData .= $this->fread($this->getid3->option_fread_buffer_size);
  55                                 if (strlen($MPEGstreamData) > $this->getid3->option_fread_buffer_size) {
  56                                         $MPEGstreamData = substr($MPEGstreamData, $MPEGstreamDataOffset);
  57                                         $MPEGstreamBaseOffset += $MPEGstreamDataOffset;
  58                                         $MPEGstreamDataOffset  = 0;
  59                                 }
  60                         }
  61                         if (($StartCodeOffset = strpos($MPEGstreamData, self::START_CODE_BASE, $MPEGstreamDataOffset)) === false) {
  62 //echo 'no more start codes found.<br>';
  63                                 break;
  64                         } else {
  65                                 $MPEGstreamDataOffset = $StartCodeOffset;
  66                                 $prevStartCodeValue = $StartCodeValue;
  67                                 $StartCodeValue = ord(substr($MPEGstreamData, $StartCodeOffset + 3, 1));
  68 //echo 'Found "'.strtoupper(dechex($StartCodeValue)).'" at offset '.($MPEGstreamBaseOffset + $StartCodeOffset).' ($MPEGstreamDataOffset = '.$MPEGstreamDataOffset.')<br>';
  69                         }
  70                         $MPEGstreamDataOffset += 4;
  71                         switch ($StartCodeValue) {
  72
  73                                 case 0x00: // picture_start_code
  74                                         if (!empty($info['mpeg']['video']['bitrate_mode']) && ($info['mpeg']['video']['bitrate_mode'] == 'vbr')) {
  75                                                 $bitstream = getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $StartCodeOffset + 4, 4));
  76                                                 $bitstreamoffset = 0;
  77
  78                                                 $PictureHeader = array();
  79
  80                                                 $PictureHeader['temporal_reference']  = self::readBitsFromStream($bitstream, $bitstreamoffset, 10); // 10-bit unsigned integer associated with each input picture. It is incremented by one, modulo 1024, for each input frame. When a frame is coded as two fields the temporal reference in the picture header of both fields is the same. Following a group start header the temporal reference of the earliest picture (in display order) shall be reset to zero.
  81                                                 $PictureHeader['picture_coding_type'] = self::readBitsFromStream($bitstream, $bitstreamoffset,  3); //  3 bits for picture_coding_type
  82                                                 $PictureHeader['vbv_delay']           = self::readBitsFromStream($bitstream, $bitstreamoffset, 16); // 16 bits for vbv_delay
  83                                                 //... etc
  84
  85                                                 $FramesByGOP[$GOPcounter][] = $PictureHeader;
  86                                         }
  87                                         break;
  88
  89                                 case 0xB3: // sequence_header_code
  90                                         /*
  91                                         Note: purposely doing the less-pretty (and probably a bit slower) method of using string of bits rather than bitwise operations.
  92                                               Mostly because PHP 32-bit doesn't handle unsigned integers well for bitwise operation.
  93                                               Also the MPEG stream is designed as a bitstream and often doesn't align nicely with byte boundaries.
  94                                         */
  95                                         $info['video']['codec'] = 'MPEG-1'; // will be updated if extension_start_code found
  96
  97                                         $bitstream = getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $StartCodeOffset + 4, 8));
  98                                         $bitstreamoffset = 0;
  99
 100                                         $info['mpeg']['video']['raw']['horizontal_size_value']       = self::readBitsFromStream($bitstream, $bitstreamoffset, 12); // 12 bits for horizontal frame size. Note: horizontal_size_extension, if present, will add 2 most-significant bits to this value
 101                                         $info['mpeg']['video']['raw']['vertical_size_value']         = self::readBitsFromStream($bitstream, $bitstreamoffset, 12); // 12 bits for vertical frame size.   Note: vertical_size_extension,   if present, will add 2 most-significant bits to this value
 102                                         $info['mpeg']['video']['raw']['aspect_ratio_information']    = self::readBitsFromStream($bitstream, $bitstreamoffset,  4); //  4 bits for aspect_ratio_information
 103                                         $info['mpeg']['video']['raw']['frame_rate_code']             = self::readBitsFromStream($bitstream, $bitstreamoffset,  4); //  4 bits for Frame Rate id code
 104                                         $info['mpeg']['video']['raw']['bitrate']                     = self::readBitsFromStream($bitstream, $bitstreamoffset, 18); // 18 bits for bit_rate_value (18 set bits = VBR, otherwise bitrate = this value * 400)
 105                                         $marker_bit                                                  = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // The term "marker_bit" indicates a one bit field in which the value zero is forbidden. These marker bits are introduced at several points in the syntax to avoid start code emulation.
 106                                         $info['mpeg']['video']['raw']['vbv_buffer_size']             = self::readBitsFromStream($bitstream, $bitstreamoffset, 10); // 10 bits vbv_buffer_size_value
 107                                         $info['mpeg']['video']['raw']['constrained_param_flag']      = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: constrained_param_flag
 108                                         $info['mpeg']['video']['raw']['load_intra_quantiser_matrix'] = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: load_intra_quantiser_matrix
 109
 110                                         if ($info['mpeg']['video']['raw']['load_intra_quantiser_matrix']) {
 111                                                 $bitstream .= getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $StartCodeOffset + 12, 64));
 112                                                 for ($i = 0; $i < 64; $i++) {
 113                                                         $info['mpeg']['video']['raw']['intra_quantiser_matrix'][$i] = self::readBitsFromStream($bitstream, $bitstreamoffset,  8);
 114                                                 }
 115                                         }
 116                                         $info['mpeg']['video']['raw']['load_non_intra_quantiser_matrix'] = self::readBitsFromStream($bitstream, $bitstreamoffset,  1);
 117
 118                                         if ($info['mpeg']['video']['raw']['load_non_intra_quantiser_matrix']) {
 119                                                 $bitstream .= getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $StartCodeOffset + 12 + ($info['mpeg']['video']['raw']['load_intra_quantiser_matrix'] ? 64 : 0), 64));
 120                                                 for ($i = 0; $i < 64; $i++) {
 121                                                         $info['mpeg']['video']['raw']['non_intra_quantiser_matrix'][$i] = self::readBitsFromStream($bitstream, $bitstreamoffset,  8);
 122                                                 }
 123                                         }
 124
 125                                         $info['mpeg']['video']['pixel_aspect_ratio']      =     self::videoAspectRatioLookup($info['mpeg']['video']['raw']['aspect_ratio_information']);
 126                                         $info['mpeg']['video']['pixel_aspect_ratio_text'] = self::videoAspectRatioTextLookup($info['mpeg']['video']['raw']['aspect_ratio_information']);
 127                                         $info['mpeg']['video']['frame_rate']              =       self::videoFramerateLookup($info['mpeg']['video']['raw']['frame_rate_code']);
 128                                         if ($info['mpeg']['video']['raw']['bitrate'] == 0x3FFFF) { // 18 set bits = VBR
 129                                                 //$this->warning('This version of getID3() ['.$this->getid3->version().'] cannot determine average bitrate of VBR MPEG video files');
 130                                                 $info['mpeg']['video']['bitrate_mode'] = 'vbr';
 131                                         } else {
 132                                                 $info['mpeg']['video']['bitrate']      = $info['mpeg']['video']['raw']['bitrate'] * 400;
 133                                                 $info['mpeg']['video']['bitrate_mode'] = 'cbr';
 134                                                 $info['video']['bitrate']              = $info['mpeg']['video']['bitrate'];
 135                                         }
 136                                         $info['video']['resolution_x']       = $info['mpeg']['video']['raw']['horizontal_size_value'];
 137                                         $info['video']['resolution_y']       = $info['mpeg']['video']['raw']['vertical_size_value'];
 138                                         $info['video']['frame_rate']         = $info['mpeg']['video']['frame_rate'];
 139                                         $info['video']['bitrate_mode']       = $info['mpeg']['video']['bitrate_mode'];
 140                                         $info['video']['pixel_aspect_ratio'] = $info['mpeg']['video']['pixel_aspect_ratio'];
 141                                         $info['video']['lossless']           = false;
 142                                         $info['video']['bits_per_sample']    = 24;
 143                                         break;
 144
 145                                 case 0xB5: // extension_start_code
 146                                         $info['video']['codec'] = 'MPEG-2';
 147
 148                                         $bitstream = getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $StartCodeOffset + 4, 8)); // 48 bits for Sequence Extension ID; 61 bits for Sequence Display Extension ID; 59 bits for Sequence Scalable Extension ID
 149                                         $bitstreamoffset = 0;
 150
 151                                         $info['mpeg']['video']['raw']['extension_start_code_identifier'] = self::readBitsFromStream($bitstream, $bitstreamoffset,  4); //  4 bits for extension_start_code_identifier
 152 //echo $info['mpeg']['video']['raw']['extension_start_code_identifier'].'<br>';
 153                                         switch ($info['mpeg']['video']['raw']['extension_start_code_identifier']) {
 154                                                 case  1: // 0001 Sequence Extension ID
 155                                                         $info['mpeg']['video']['raw']['profile_and_level_indication']    = self::readBitsFromStream($bitstream, $bitstreamoffset,  8); //  8 bits for profile_and_level_indication
 156                                                         $info['mpeg']['video']['raw']['progressive_sequence']            = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: progressive_sequence
 157                                                         $info['mpeg']['video']['raw']['chroma_format']                   = self::readBitsFromStream($bitstream, $bitstreamoffset,  2); //  2 bits for chroma_format
 158                                                         $info['mpeg']['video']['raw']['horizontal_size_extension']       = self::readBitsFromStream($bitstream, $bitstreamoffset,  2); //  2 bits for horizontal_size_extension
 159                                                         $info['mpeg']['video']['raw']['vertical_size_extension']         = self::readBitsFromStream($bitstream, $bitstreamoffset,  2); //  2 bits for vertical_size_extension
 160                                                         $info['mpeg']['video']['raw']['bit_rate_extension']              = self::readBitsFromStream($bitstream, $bitstreamoffset, 12); // 12 bits for bit_rate_extension
 161                                                         $marker_bit                                                      = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // The term "marker_bit" indicates a one bit field in which the value zero is forbidden. These marker bits are introduced at several points in the syntax to avoid start code emulation.
 162                                                         $info['mpeg']['video']['raw']['vbv_buffer_size_extension']       = self::readBitsFromStream($bitstream, $bitstreamoffset,  8); //  8 bits for vbv_buffer_size_extension
 163                                                         $info['mpeg']['video']['raw']['low_delay']                       = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: low_delay
 164                                                         $info['mpeg']['video']['raw']['frame_rate_extension_n']          = self::readBitsFromStream($bitstream, $bitstreamoffset,  2); //  2 bits for frame_rate_extension_n
 165                                                         $info['mpeg']['video']['raw']['frame_rate_extension_d']          = self::readBitsFromStream($bitstream, $bitstreamoffset,  5); //  5 bits for frame_rate_extension_d
 166
 167                                                         $info['video']['resolution_x']          = ($info['mpeg']['video']['raw']['horizontal_size_extension'] << 12) | $info['mpeg']['video']['raw']['horizontal_size_value'];
 168                                                         $info['video']['resolution_y']          = ($info['mpeg']['video']['raw']['vertical_size_extension']   << 12) | $info['mpeg']['video']['raw']['vertical_size_value'];
 169                                                         $info['video']['interlaced']            = !$info['mpeg']['video']['raw']['progressive_sequence'];
 170                                                         $info['mpeg']['video']['interlaced']    = !$info['mpeg']['video']['raw']['progressive_sequence'];
 171                                                         $info['mpeg']['video']['chroma_format'] = self::chromaFormatTextLookup($info['mpeg']['video']['raw']['chroma_format']);
 172                                                         break;
 173
 174                                                 case  2: // 0010 Sequence Display Extension ID
 175                                                         $info['mpeg']['video']['raw']['video_format']                    = self::readBitsFromStream($bitstream, $bitstreamoffset,  3); //  3 bits for video_format
 176                                                         $info['mpeg']['video']['raw']['colour_description']              = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: colour_description
 177                                                         if ($info['mpeg']['video']['raw']['colour_description']) {
 178                                                                 $info['mpeg']['video']['raw']['colour_primaries']            = self::readBitsFromStream($bitstream, $bitstreamoffset,  8); //  8 bits for colour_primaries
 179                                                                 $info['mpeg']['video']['raw']['transfer_characteristics']    = self::readBitsFromStream($bitstream, $bitstreamoffset,  8); //  8 bits for transfer_characteristics
 180                                                                 $info['mpeg']['video']['raw']['matrix_coefficients']         = self::readBitsFromStream($bitstream, $bitstreamoffset,  8); //  8 bits for matrix_coefficients
 181                                                         }
 182                                                         $info['mpeg']['video']['raw']['display_horizontal_size']         = self::readBitsFromStream($bitstream, $bitstreamoffset, 14); // 14 bits for display_horizontal_size
 183                                                         $marker_bit                                                      = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // The term "marker_bit" indicates a one bit field in which the value zero is forbidden. These marker bits are introduced at several points in the syntax to avoid start code emulation.
 184                                                         $info['mpeg']['video']['raw']['display_vertical_size']           = self::readBitsFromStream($bitstream, $bitstreamoffset, 14); // 14 bits for display_vertical_size
 185
 186                                                         $info['mpeg']['video']['video_format'] = self::videoFormatTextLookup($info['mpeg']['video']['raw']['video_format']);
 187                                                         break;
 188
 189                                                 case  3: // 0011 Quant Matrix Extension ID
 190                                                         break;
 191
 192                                                 case  5: // 0101 Sequence Scalable Extension ID
 193                                                         $info['mpeg']['video']['raw']['scalable_mode']                              = self::readBitsFromStream($bitstream, $bitstreamoffset,  2); //  2 bits for scalable_mode
 194                                                         $info['mpeg']['video']['raw']['layer_id']                                   = self::readBitsFromStream($bitstream, $bitstreamoffset,  4); //  4 bits for layer_id
 195                                                         if ($info['mpeg']['video']['raw']['scalable_mode'] == 1) { // "spatial scalability"
 196                                                                 $info['mpeg']['video']['raw']['lower_layer_prediction_horizontal_size'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 14); // 14 bits for lower_layer_prediction_horizontal_size
 197                                                                 $marker_bit                                                             = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // The term "marker_bit" indicates a one bit field in which the value zero is forbidden. These marker bits are introduced at several points in the syntax to avoid start code emulation.
 198                                                                 $info['mpeg']['video']['raw']['lower_layer_prediction_vertical_size']   = self::readBitsFromStream($bitstream, $bitstreamoffset, 14); // 14 bits for lower_layer_prediction_vertical_size
 199                                                                 $info['mpeg']['video']['raw']['horizontal_subsampling_factor_m']        = self::readBitsFromStream($bitstream, $bitstreamoffset,  5); //  5 bits for horizontal_subsampling_factor_m
 200                                                                 $info['mpeg']['video']['raw']['horizontal_subsampling_factor_n']        = self::readBitsFromStream($bitstream, $bitstreamoffset,  5); //  5 bits for horizontal_subsampling_factor_n
 201                                                                 $info['mpeg']['video']['raw']['vertical_subsampling_factor_m']          = self::readBitsFromStream($bitstream, $bitstreamoffset,  5); //  5 bits for vertical_subsampling_factor_m
 202                                                                 $info['mpeg']['video']['raw']['vertical_subsampling_factor_n']          = self::readBitsFromStream($bitstream, $bitstreamoffset,  5); //  5 bits for vertical_subsampling_factor_n
 203                                                         } elseif ($info['mpeg']['video']['raw']['scalable_mode'] == 3) { // "temporal scalability"
 204                                                                 $info['mpeg']['video']['raw']['picture_mux_enable']                     = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: picture_mux_enable
 205                                                                 if ($info['mpeg']['video']['raw']['picture_mux_enable']) {
 206                                                                         $info['mpeg']['video']['raw']['mux_to_progressive_sequence']        = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: mux_to_progressive_sequence
 207                                                                 }
 208                                                                 $info['mpeg']['video']['raw']['picture_mux_order']                      = self::readBitsFromStream($bitstream, $bitstreamoffset,  3); //  3 bits for picture_mux_order
 209                                                                 $info['mpeg']['video']['raw']['picture_mux_factor']                     = self::readBitsFromStream($bitstream, $bitstreamoffset,  3); //  3 bits for picture_mux_factor
 210                                                         }
 211
 212                                                         $info['mpeg']['video']['scalable_mode'] = self::scalableModeTextLookup($info['mpeg']['video']['raw']['scalable_mode']);
 213                                                         break;
 214
 215                                                 case  7: // 0111 Picture Display Extension ID
 216                                                         break;
 217
 218                                                 case  8: // 1000 Picture Coding Extension ID
 219                                                         $info['mpeg']['video']['raw']['f_code_00']                       = self::readBitsFromStream($bitstream, $bitstreamoffset,  4); // 4 bits for f_code[0][0] (forward horizontal)
 220                                                         $info['mpeg']['video']['raw']['f_code_01']                       = self::readBitsFromStream($bitstream, $bitstreamoffset,  4); // 4 bits for f_code[0][1] (forward vertical)
 221                                                         $info['mpeg']['video']['raw']['f_code_10']                       = self::readBitsFromStream($bitstream, $bitstreamoffset,  4); // 4 bits for f_code[1][0] (backward horizontal)
 222                                                         $info['mpeg']['video']['raw']['f_code_11']                       = self::readBitsFromStream($bitstream, $bitstreamoffset,  4); // 4 bits for f_code[1][1] (backward vertical)
 223                                                         $info['mpeg']['video']['raw']['intra_dc_precision']              = self::readBitsFromStream($bitstream, $bitstreamoffset,  2); // 2 bits for intra_dc_precision
 224                                                         $info['mpeg']['video']['raw']['picture_structure']               = self::readBitsFromStream($bitstream, $bitstreamoffset,  2); // 2 bits for picture_structure
 225                                                         $info['mpeg']['video']['raw']['top_field_first']                 = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // 1 bit flag: top_field_first
 226                                                         $info['mpeg']['video']['raw']['frame_pred_frame_dct']            = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // 1 bit flag: frame_pred_frame_dct
 227                                                         $info['mpeg']['video']['raw']['concealment_motion_vectors']      = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // 1 bit flag: concealment_motion_vectors
 228                                                         $info['mpeg']['video']['raw']['q_scale_type']                    = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // 1 bit flag: q_scale_type
 229                                                         $info['mpeg']['video']['raw']['intra_vlc_format']                = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // 1 bit flag: intra_vlc_format
 230                                                         $info['mpeg']['video']['raw']['alternate_scan']                  = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // 1 bit flag: alternate_scan
 231                                                         $info['mpeg']['video']['raw']['repeat_first_field']              = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // 1 bit flag: repeat_first_field
 232                                                         $info['mpeg']['video']['raw']['chroma_420_type']                 = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // 1 bit flag: chroma_420_type
 233                                                         $info['mpeg']['video']['raw']['progressive_frame']               = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // 1 bit flag: progressive_frame
 234                                                         $info['mpeg']['video']['raw']['composite_display_flag']          = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // 1 bit flag: composite_display_flag
 235                                                         if ($info['mpeg']['video']['raw']['composite_display_flag']) {
 236                                                                 $info['mpeg']['video']['raw']['v_axis']                      = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // 1 bit flag: v_axis
 237                                                                 $info['mpeg']['video']['raw']['field_sequence']              = self::readBitsFromStream($bitstream, $bitstreamoffset,  3); // 3 bits for field_sequence
 238                                                                 $info['mpeg']['video']['raw']['sub_carrier']                 = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // 1 bit flag: sub_carrier
 239                                                                 $info['mpeg']['video']['raw']['burst_amplitude']             = self::readBitsFromStream($bitstream, $bitstreamoffset,  7); // 7 bits for burst_amplitude
 240                                                                 $info['mpeg']['video']['raw']['sub_carrier_phase']           = self::readBitsFromStream($bitstream, $bitstreamoffset,  8); // 8 bits for sub_carrier_phase
 241                                                         }
 242
 243                                                         $info['mpeg']['video']['intra_dc_precision_bits'] = $info['mpeg']['video']['raw']['intra_dc_precision'] + 8;
 244                                                         $info['mpeg']['video']['picture_structure'] = self::pictureStructureTextLookup($info['mpeg']['video']['raw']['picture_structure']);
 245                                                         break;
 246
 247                                                 case  9: // 1001 Picture Spatial Scalable Extension ID
 248                                                         break;
 249                                                 case 10: // 1010 Picture Temporal Scalable Extension ID
 250                                                         break;
 251
 252                                                 default:
 253                                                         $this->warning('Unexpected $info[mpeg][video][raw][extension_start_code_identifier] value of '.$info['mpeg']['video']['raw']['extension_start_code_identifier']);
 254                                                         break;
 255                                         }
 256                                         break;
 257
 258
 259                                 case 0xB8: // group_of_pictures_header
 260                                         $GOPcounter++;
 261                                         if ($info['mpeg']['video']['bitrate_mode'] == 'vbr') {
 262                                                 $bitstream = getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $StartCodeOffset + 4, 4)); // 27 bits needed for group_of_pictures_header
 263                                                 $bitstreamoffset = 0;
 264
 265                                                 $GOPheader = array();
 266
 267                                                 $GOPheader['byte_offset'] = $MPEGstreamBaseOffset + $StartCodeOffset;
 268                                                 $GOPheader['drop_frame_flag']    = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: drop_frame_flag
 269                                                 $GOPheader['time_code_hours']    = self::readBitsFromStream($bitstream, $bitstreamoffset,  5); //  5 bits for time_code_hours
 270                                                 $GOPheader['time_code_minutes']  = self::readBitsFromStream($bitstream, $bitstreamoffset,  6); //  6 bits for time_code_minutes
 271                                                 $marker_bit                      = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); // The term "marker_bit" indicates a one bit field in which the value zero is forbidden. These marker bits are introduced at several points in the syntax to avoid start code emulation.
 272                                                 $GOPheader['time_code_seconds']  = self::readBitsFromStream($bitstream, $bitstreamoffset,  6); //  6 bits for time_code_seconds
 273                                                 $GOPheader['time_code_pictures'] = self::readBitsFromStream($bitstream, $bitstreamoffset,  6); //  6 bits for time_code_pictures
 274                                                 $GOPheader['closed_gop']         = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: closed_gop
 275                                                 $GOPheader['broken_link']        = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: broken_link
 276
 277                                                 $time_code_separator = ($GOPheader['drop_frame_flag'] ? ';' : ':'); // While non-drop time code is displayed with colons separating the digit pairs\97"HH:MM:SS:FF"\97drop frame is usually represented with a semi-colon (;) or period (.) as the divider between all the digit pairs\97"HH;MM;SS;FF", "HH.MM.SS.FF"
 278                                                 $GOPheader['time_code'] = sprintf('%02d'.$time_code_separator.'%02d'.$time_code_separator.'%02d'.$time_code_separator.'%02d', $GOPheader['time_code_hours'], $GOPheader['time_code_minutes'], $GOPheader['time_code_seconds'], $GOPheader['time_code_pictures']);
 279
 280                                                 $info['mpeg']['group_of_pictures'][] = $GOPheader;
 281                                         }
 282                                         break;
 283
 284                                 case 0xC0: // audio stream
 285                                 case 0xC1: // audio stream
 286                                 case 0xC2: // audio stream
 287                                 case 0xC3: // audio stream
 288                                 case 0xC4: // audio stream
 289                                 case 0xC5: // audio stream
 290                                 case 0xC6: // audio stream
 291                                 case 0xC7: // audio stream
 292                                 case 0xC8: // audio stream
 293                                 case 0xC9: // audio stream
 294                                 case 0xCA: // audio stream
 295                                 case 0xCB: // audio stream
 296                                 case 0xCC: // audio stream
 297                                 case 0xCD: // audio stream
 298                                 case 0xCE: // audio stream
 299                                 case 0xCF: // audio stream
 300                                 case 0xD0: // audio stream
 301                                 case 0xD1: // audio stream
 302                                 case 0xD2: // audio stream
 303                                 case 0xD3: // audio stream
 304                                 case 0xD4: // audio stream
 305                                 case 0xD5: // audio stream
 306                                 case 0xD6: // audio stream
 307                                 case 0xD7: // audio stream
 308                                 case 0xD8: // audio stream
 309                                 case 0xD9: // audio stream
 310                                 case 0xDA: // audio stream
 311                                 case 0xDB: // audio stream
 312                                 case 0xDC: // audio stream
 313                                 case 0xDD: // audio stream
 314                                 case 0xDE: // audio stream
 315                                 case 0xDF: // audio stream
 316                                 //case 0xE0: // video stream
 317                                 //case 0xE1: // video stream
 318                                 //case 0xE2: // video stream
 319                                 //case 0xE3: // video stream
 320                                 //case 0xE4: // video stream
 321                                 //case 0xE5: // video stream
 322                                 //case 0xE6: // video stream
 323                                 //case 0xE7: // video stream
 324                                 //case 0xE8: // video stream
 325                                 //case 0xE9: // video stream
 326                                 //case 0xEA: // video stream
 327                                 //case 0xEB: // video stream
 328                                 //case 0xEC: // video stream
 329                                 //case 0xED: // video stream
 330                                 //case 0xEE: // video stream
 331                                 //case 0xEF: // video stream
 332                                         if (isset($ParsedAVchannels[$StartCodeValue])) {
 333                                                 break;
 334                                         }
 335                                         $ParsedAVchannels[$StartCodeValue] = $StartCodeValue;
 336                                         // http://en.wikipedia.org/wiki/Packetized_elementary_stream
 337                                         // http://dvd.sourceforge.net/dvdinfo/pes-hdr.html
 338 /*
 339                                         $PackedElementaryStream = array();
 340                                         if ($StartCodeValue >= 0xE0) {
 341                                                 $PackedElementaryStream['stream_type'] = 'video';
 342                                                 $PackedElementaryStream['stream_id']   = $StartCodeValue - 0xE0;
 343                                         } else {
 344                                                 $PackedElementaryStream['stream_type'] = 'audio';
 345                                                 $PackedElementaryStream['stream_id']   = $StartCodeValue - 0xC0;
 346                                         }
 347                                         $PackedElementaryStream['packet_length'] = getid3_lib::BigEndian2Int(substr($MPEGstreamData, $StartCodeOffset + 4, 2));
 348
 349                                         $bitstream = getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $StartCodeOffset + 6, 3)); // more may be needed below
 350                                         $bitstreamoffset = 0;
 351
 352                                         $PackedElementaryStream['marker_bits']               = self::readBitsFromStream($bitstream, $bitstreamoffset,  2); //  2 bits for marker_bits -- should be "10" = 2
 353 echo 'marker_bits = '.$PackedElementaryStream['marker_bits'].'<br>';
 354                                         $PackedElementaryStream['scrambling_control']        = self::readBitsFromStream($bitstream, $bitstreamoffset,  2); //  2 bits for scrambling_control -- 00 implies not scrambled
 355                                         $PackedElementaryStream['priority']                  = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: priority
 356                                         $PackedElementaryStream['data_alignment_indicator']  = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: data_alignment_indicator -- 1 indicates that the PES packet header is immediately followed by the video start code or audio syncword
 357                                         $PackedElementaryStream['copyright']                 = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: copyright -- 1 implies copyrighted
 358                                         $PackedElementaryStream['original_or_copy']          = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: original_or_copy -- 1 implies original
 359                                         $PackedElementaryStream['pts_flag']                  = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: pts_flag -- Presentation Time Stamp
 360                                         $PackedElementaryStream['dts_flag']                  = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: dts_flag -- Decode Time Stamp
 361                                         $PackedElementaryStream['escr_flag']                 = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: escr_flag -- Elementary Stream Clock Reference
 362                                         $PackedElementaryStream['es_rate_flag']              = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: es_rate_flag -- Elementary Stream [data] Rate
 363                                         $PackedElementaryStream['dsm_trick_mode_flag']       = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: dsm_trick_mode_flag -- DSM trick mode - not used by DVD
 364                                         $PackedElementaryStream['additional_copy_info_flag'] = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: additional_copy_info_flag
 365                                         $PackedElementaryStream['crc_flag']                  = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: crc_flag
 366                                         $PackedElementaryStream['extension_flag']            = self::readBitsFromStream($bitstream, $bitstreamoffset,  1); //  1 bit flag: extension_flag
 367                                         $PackedElementaryStream['pes_remain_header_length']  = self::readBitsFromStream($bitstream, $bitstreamoffset,  8); //  1 bit flag: priority
 368
 369                                         $additional_header_bytes = 0;
 370                                         $additional_header_bytes += ($PackedElementaryStream['pts_flag']                  ? 5 : 0);
 371                                         $additional_header_bytes += ($PackedElementaryStream['dts_flag']                  ? 5 : 0);
 372                                         $additional_header_bytes += ($PackedElementaryStream['escr_flag']                 ? 6 : 0);
 373                                         $additional_header_bytes += ($PackedElementaryStream['es_rate_flag']              ? 3 : 0);
 374                                         $additional_header_bytes += ($PackedElementaryStream['additional_copy_info_flag'] ? 1 : 0);
 375                                         $additional_header_bytes += ($PackedElementaryStream['crc_flag']                  ? 2 : 0);
 376                                         $additional_header_bytes += ($PackedElementaryStream['extension_flag']            ? 1 : 0);
 377 $PackedElementaryStream['additional_header_bytes'] = $additional_header_bytes;
 378                                         $bitstream .= getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $StartCodeOffset + 9, $additional_header_bytes));
 379
 380                                         $info['mpeg']['packed_elementary_streams'][$PackedElementaryStream['stream_type']][$PackedElementaryStream['stream_id']][] = $PackedElementaryStream;
 381 */
 382                                         $getid3_temp = new getID3();
 383                                         $getid3_temp->openfile($this->getid3->filename);
 384                                         $getid3_temp->info = $info;
 385                                         $getid3_mp3 = new getid3_mp3($getid3_temp);
 386                                         for ($i = 0; $i <= 7; $i++) {
 387                                                 // 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
 388                                                 // I have no idea why or what the difference is, so this is a stupid hack.
 389                                                 // If anybody has any better idea of what's going on, please let me know - info@getid3.org
 390                                                 $getid3_temp->info = $info; // only overwrite real data if valid header found
 391 //echo 'audio at? '.($MPEGstreamBaseOffset + $StartCodeOffset + 4 + 8 + $i).'<br>';
 392                                                 if ($getid3_mp3->decodeMPEGaudioHeader($MPEGstreamBaseOffset + $StartCodeOffset + 4 + 8 + $i, $getid3_temp->info, false)) {
 393 //echo 'yes!<br>';
 394                                                         $info = $getid3_temp->info;
 395                                                         $info['audio']['bitrate_mode'] = 'cbr';
 396                                                         $info['audio']['lossless']     = false;
 397                                                         break;
 398                                                 }
 399                                         }
 400                                         unset($getid3_temp, $getid3_mp3);
 401                                         break;
 402
 403                                 case 0xBC: // Program Stream Map
 404                                 case 0xBD: // Private stream 1 (non MPEG audio, subpictures)
 405                                 case 0xBE: // Padding stream
 406                                 case 0xBF: // Private stream 2 (navigation data)
 407                                 case 0xF0: // ECM stream
 408                                 case 0xF1: // EMM stream
 409                                 case 0xF2: // DSM-CC stream
 410                                 case 0xF3: // ISO/IEC_13522_stream
 411                                 case 0xF4: // ITU-I Rec. H.222.1 type A
 412                                 case 0xF5: // ITU-I Rec. H.222.1 type B
 413                                 case 0xF6: // ITU-I Rec. H.222.1 type C
 414                                 case 0xF7: // ITU-I Rec. H.222.1 type D
 415                                 case 0xF8: // ITU-I Rec. H.222.1 type E
 416                                 case 0xF9: // ancilliary stream
 417                                 case 0xFA: // ISO/IEC 14496-1 SL-packtized stream
 418                                 case 0xFB: // ISO/IEC 14496-1 FlexMux stream
 419                                 case 0xFC: // metadata stream
 420                                 case 0xFD: // extended stream ID
 421                                 case 0xFE: // reserved data stream
 422                                 case 0xFF: // program stream directory
 423                                         // ignore
 424                                         break;
 425
 426                                 default:
 427                                         // ignore
 428                                         break;
 429                         }
 430                 } while (true);
 431
 432
 433
 434 //              // Temporary hack to account for interleaving overhead:
 435 //              if (!empty($info['video']['bitrate']) && !empty($info['audio']['bitrate'])) {
 436 //                      $info['playtime_seconds'] = (($info['avdataend'] - $info['avdataoffset']) * 8) / ($info['video']['bitrate'] + $info['audio']['bitrate']);
 437 //
 438 //                      // Interleaved MPEG audio/video files have a certain amount of overhead that varies
 439 //                      // by both video and audio bitrates, and not in any sensible, linear/logarithmic pattern
 440 //                      // Use interpolated lookup tables to approximately guess how much is overhead, because
 441 //                      // playtime is calculated as filesize / total-bitrate
 442 //                      $info['playtime_seconds'] *= self::systemNonOverheadPercentage($info['video']['bitrate'], $info['audio']['bitrate']);
 443 //
 444 //                      //switch ($info['video']['bitrate']) {
 445 //                      //      case('5000000'):
 446 //                      //              $multiplier = 0.93292642112380355828048824319889;
 447 //                      //              break;
 448 //                      //      case('5500000'):
 449 //                      //              $multiplier = 0.93582895375200989965359777343219;
 450 //                      //              break;
 451 //                      //      case('6000000'):
 452 //                      //              $multiplier = 0.93796247714820932532911373859139;
 453 //                      //              break;
 454 //                      //      case('7000000'):
 455 //                      //              $multiplier = 0.9413264083635103463010117778776;
 456 //                      //              break;
 457 //                      //      default:
 458 //                      //              $multiplier = 1;
 459 //                      //              break;
 460 //                      //}
 461 //                      //$info['playtime_seconds'] *= $multiplier;
 462 //                      //$this->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.');
 463 //                      if ($info['video']['bitrate'] < 50000) {
 464 //                              $this->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.');
 465 //                      }
 466 //              }
 467 //
 468 /*
 469 $time_prev = 0;
 470 $byte_prev = 0;
 471 $vbr_bitrates = array();
 472 foreach ($info['mpeg']['group_of_pictures'] as $gopkey => $gopdata) {
 473         $time_this = ($gopdata['time_code_hours'] * 3600) + ($gopdata['time_code_minutes'] * 60) + $gopdata['time_code_seconds'] + ($gopdata['time_code_seconds'] / 30);
 474         $byte_this = $gopdata['byte_offset'];
 475         if ($gopkey > 0) {
 476                 if ($time_this > $time_prev) {
 477                         $bytedelta = $byte_this - $byte_prev;
 478                         $timedelta = $time_this - $time_prev;
 479                         $this_bitrate = ($bytedelta * 8) / $timedelta;
 480 echo $gopkey.': ('.number_format($time_prev, 2).'-'.number_format($time_this, 2).') '.number_format($bytedelta).' bytes over '.number_format($timedelta, 3).' seconds = '.number_format($this_bitrate / 1000, 2).'kbps<br>';
 481                         $time_prev = $time_this;
 482                         $byte_prev = $byte_this;
 483                         $vbr_bitrates[] = $this_bitrate;
 484                 }
 485         }
 486 }
 487 echo 'average_File_bitrate = '.number_format(array_sum($vbr_bitrates) / count($vbr_bitrates), 1).'<br>';
 488 */
 489 //echo '<pre>'.print_r($FramesByGOP, true).'</pre>';
 490                 if (!empty($info['mpeg']['video']['bitrate_mode']) && ($info['mpeg']['video']['bitrate_mode'] == 'vbr')) {
 491                         $last_GOP_id = max(array_keys($FramesByGOP));
 492                         $frames_in_last_GOP = count($FramesByGOP[$last_GOP_id]);
 493                         $gopdata = &$info['mpeg']['group_of_pictures'][$last_GOP_id];
 494                         $info['playtime_seconds'] = ($gopdata['time_code_hours'] * 3600) + ($gopdata['time_code_minutes'] * 60) + $gopdata['time_code_seconds'] + (($gopdata['time_code_pictures'] + $frames_in_last_GOP + 1) / $info['mpeg']['video']['frame_rate']);
 495                         if (!isset($info['video']['bitrate'])) {
 496                                 $overall_bitrate = ($info['avdataend'] - $info['avdataoffset']) * 8 / $info['playtime_seconds'];
 497                                 $info['video']['bitrate'] = $overall_bitrate - (isset($info['audio']['bitrate']) ? $info['audio']['bitrate'] : 0);
 498                         }
 499                         unset($info['mpeg']['group_of_pictures']);
 500                 }
 501
 502                 return true;
 503         }
 504
 505         private function readBitsFromStream(&$bitstream, &$bitstreamoffset, $bits_to_read, $return_singlebit_as_boolean=true) {
 506                 $return = bindec(substr($bitstream, $bitstreamoffset, $bits_to_read));
 507                 $bitstreamoffset += $bits_to_read;
 508                 if (($bits_to_read == 1) && $return_singlebit_as_boolean) {
 509                         $return = (bool) $return;
 510                 }
 511                 return $return;
 512         }
 513
 514
 515         public static function systemNonOverheadPercentage($VideoBitrate, $AudioBitrate) {
 516                 $OverheadPercentage = 0;
 517
 518                 $AudioBitrate = max(min($AudioBitrate / 1000,   384), 32); // limit to range of 32kbps - 384kbps (should be only legal bitrates, but maybe VBR?)
 519                 $VideoBitrate = max(min($VideoBitrate / 1000, 10000), 10); // limit to range of 10kbps -  10Mbps (beyond that curves flatten anyways, no big loss)
 520
 521
 522                 //OMBB[audiobitrate]              = array(video-10kbps,       video-100kbps,      video-1000kbps,     video-10000kbps)
 523                 $OverheadMultiplierByBitrate[32]  = array(0, 0.9676287944368530, 0.9802276264360310, 0.9844916183244460, 0.9852821845179940);
 524                 $OverheadMultiplierByBitrate[48]  = array(0, 0.9779100089209830, 0.9787770035359320, 0.9846738664076130, 0.9852683013799960);
 525                 $OverheadMultiplierByBitrate[56]  = array(0, 0.9731249855367600, 0.9776624308938040, 0.9832606361852130, 0.9843922606633340);
 526                 $OverheadMultiplierByBitrate[64]  = array(0, 0.9755642683275760, 0.9795256705493390, 0.9836573009193170, 0.9851122539404470);
 527                 $OverheadMultiplierByBitrate[96]  = array(0, 0.9788025247497290, 0.9798553314148700, 0.9822956869792560, 0.9834815119124690);
 528                 $OverheadMultiplierByBitrate[128] = array(0, 0.9816940050925480, 0.9821675936072120, 0.9829756927470870, 0.9839763420152050);
 529                 $OverheadMultiplierByBitrate[160] = array(0, 0.9825894094561180, 0.9820913399073960, 0.9823907143253970, 0.9832821783651570);
 530                 $OverheadMultiplierByBitrate[192] = array(0, 0.9832038474336260, 0.9825731694317960, 0.9821028622712400, 0.9828262076447620);
 531                 $OverheadMultiplierByBitrate[224] = array(0, 0.9836516298538770, 0.9824718601823890, 0.9818302180625380, 0.9823735101626480);
 532                 $OverheadMultiplierByBitrate[256] = array(0, 0.9845863022094920, 0.9837229411967540, 0.9824521662210830, 0.9828645172100790);
 533                 $OverheadMultiplierByBitrate[320] = array(0, 0.9849565280263180, 0.9837683142805110, 0.9822885275960400, 0.9824424382727190);
 534                 $OverheadMultiplierByBitrate[384] = array(0, 0.9856094774357600, 0.9844573394432720, 0.9825970399837330, 0.9824673808303890);
 535
 536                 $BitrateToUseMin = 32;
 537                 $BitrateToUseMax = 32;
 538                 $previousBitrate = 32;
 539                 foreach ($OverheadMultiplierByBitrate as $key => $value) {
 540                         if ($AudioBitrate >= $previousBitrate) {
 541                                 $BitrateToUseMin = $previousBitrate;
 542                         }
 543                         if ($AudioBitrate < $key) {
 544                                 $BitrateToUseMax = $key;
 545                                 break;
 546                         }
 547                         $previousBitrate = $key;
 548                 }
 549                 $FactorA = ($BitrateToUseMax - $AudioBitrate) / ($BitrateToUseMax - $BitrateToUseMin);
 550
 551                 $VideoBitrateLog10 = log10($VideoBitrate);
 552                 $VideoFactorMin1 = $OverheadMultiplierByBitrate[$BitrateToUseMin][floor($VideoBitrateLog10)];
 553                 $VideoFactorMin2 = $OverheadMultiplierByBitrate[$BitrateToUseMax][floor($VideoBitrateLog10)];
 554                 $VideoFactorMax1 = $OverheadMultiplierByBitrate[$BitrateToUseMin][ceil($VideoBitrateLog10)];
 555                 $VideoFactorMax2 = $OverheadMultiplierByBitrate[$BitrateToUseMax][ceil($VideoBitrateLog10)];
 556                 $FactorV = $VideoBitrateLog10 - floor($VideoBitrateLog10);
 557
 558                 $OverheadPercentage  = $VideoFactorMin1 *      $FactorA  *      $FactorV;
 559                 $OverheadPercentage += $VideoFactorMin2 * (1 - $FactorA) *      $FactorV;
 560                 $OverheadPercentage += $VideoFactorMax1 *      $FactorA  * (1 - $FactorV);
 561                 $OverheadPercentage += $VideoFactorMax2 * (1 - $FactorA) * (1 - $FactorV);
 562
 563                 return $OverheadPercentage;
 564         }
 565
 566
 567         public static function videoFramerateLookup($rawframerate) {
 568                 $lookup = array(0, 23.976, 24, 25, 29.97, 30, 50, 59.94, 60);
 569                 return (isset($lookup[$rawframerate]) ? (float) $lookup[$rawframerate] : (float) 0);
 570         }
 571
 572         public static function videoAspectRatioLookup($rawaspectratio) {
 573                 $lookup = array(0, 1, 0.6735, 0.7031, 0.7615, 0.8055, 0.8437, 0.8935, 0.9157, 0.9815, 1.0255, 1.0695, 1.0950, 1.1575, 1.2015, 0);
 574                 return (isset($lookup[$rawaspectratio]) ? (float) $lookup[$rawaspectratio] : (float) 0);
 575         }
 576
 577         public static function videoAspectRatioTextLookup($rawaspectratio) {
 578                 $lookup = array('forbidden', 'square pixels', '0.6735', '16:9, 625 line, PAL', '0.7615', '0.8055', '16:9, 525 line, NTSC', '0.8935', '4:3, 625 line, PAL, CCIR601', '0.9815', '1.0255', '1.0695', '4:3, 525 line, NTSC, CCIR601', '1.1575', '1.2015', 'reserved');
 579                 return (isset($lookup[$rawaspectratio]) ? $lookup[$rawaspectratio] : '');
 580         }
 581
 582         public static function videoFormatTextLookup($video_format) {
 583                 // ISO/IEC 13818-2, section 6.3.6, Table 6-6. Meaning of video_format
 584                 $lookup = array('component', 'PAL', 'NTSC', 'SECAM', 'MAC', 'Unspecified video format', 'reserved(6)', 'reserved(7)');
 585                 return (isset($lookup[$video_format]) ? $lookup[$video_format] : '');
 586         }
 587
 588         public static function scalableModeTextLookup($scalable_mode) {
 589                 // ISO/IEC 13818-2, section 6.3.8, Table 6-10. Definition of scalable_mode
 590                 $lookup = array('data partitioning', 'spatial scalability', 'SNR scalability', 'temporal scalability');
 591                 return (isset($lookup[$scalable_mode]) ? $lookup[$scalable_mode] : '');
 592         }
 593
 594         public static function pictureStructureTextLookup($picture_structure) {
 595                 // ISO/IEC 13818-2, section 6.3.11, Table 6-14 Meaning of picture_structure
 596                 $lookup = array('reserved', 'Top Field', 'Bottom Field', 'Frame picture');
 597                 return (isset($lookup[$picture_structure]) ? $lookup[$picture_structure] : '');
 598         }
 599
 600         public static function chromaFormatTextLookup($chroma_format) {
 601                 // ISO/IEC 13818-2, section 6.3.11, Table 6-14 Meaning of picture_structure
 602                 $lookup = array('reserved', '4:2:0', '4:2:2', '4:4:4');
 603                 return (isset($lookup[$chroma_format]) ? $lookup[$chroma_format] : '');
 604         }
 605
 606 }