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/wp-includes/ID3/ -> module.audio.ac3.php (source)

   1  <?php
   2  
   3  /////////////////////////////////////////////////////////////////
   4  /// getID3() by James Heinrich <info@getid3.org>               //
   5  //  available at https://github.com/JamesHeinrich/getID3       //
   6  //            or https://www.getid3.org                        //
   7  //            or http://getid3.sourceforge.net                 //
   8  //  see readme.txt for more details                            //
   9  /////////////////////////////////////////////////////////////////
  10  //                                                             //
  11  // module.audio.ac3.php                                        //
  12  // module for analyzing AC-3 (aka Dolby Digital) audio files   //
  13  // dependencies: NONE                                          //
  14  //                                                            ///
  15  /////////////////////////////////////////////////////////////////
  16  
  17  
  18  class getid3_ac3 extends getid3_handler
  19  {
  20      /**
  21       * @var array
  22       */
  23      private $AC3header = array();
  24  
  25      /**
  26       * @var int
  27       */
  28      private $BSIoffset = 0;
  29  
  30      const syncword = 0x0B77;
  31  
  32      /**
  33       * @return bool
  34       */
  35  	public function Analyze() {
  36          $info = &$this->getid3->info;
  37  
  38          ///AH
  39          $info['ac3']['raw']['bsi'] = array();
  40          $thisfile_ac3              = &$info['ac3'];
  41          $thisfile_ac3_raw          = &$thisfile_ac3['raw'];
  42          $thisfile_ac3_raw_bsi      = &$thisfile_ac3_raw['bsi'];
  43  
  44  
  45          // http://www.atsc.org/standards/a_52a.pdf
  46  
  47          $info['fileformat'] = 'ac3';
  48  
  49          // An AC-3 serial coded audio bit stream is made up of a sequence of synchronization frames
  50          // Each synchronization frame contains 6 coded audio blocks (AB), each of which represent 256
  51          // new audio samples per channel. A synchronization information (SI) header at the beginning
  52          // of each frame contains information needed to acquire and maintain synchronization. A
  53          // bit stream information (BSI) header follows SI, and contains parameters describing the coded
  54          // audio service. The coded audio blocks may be followed by an auxiliary data (Aux) field. At the
  55          // end of each frame is an error check field that includes a CRC word for error detection. An
  56          // additional CRC word is located in the SI header, the use of which, by a decoder, is optional.
  57          //
  58          // syncinfo() | bsi() | AB0 | AB1 | AB2 | AB3 | AB4 | AB5 | Aux | CRC
  59  
  60          // syncinfo() {
  61          //      syncword    16
  62          //      crc1        16
  63          //      fscod        2
  64          //      frmsizecod   6
  65          // } /* end of syncinfo */
  66  
  67          $this->fseek($info['avdataoffset']);
  68          $tempAC3header = $this->fread(100); // should be enough to cover all data, there are some variable-length fields...?
  69          $this->AC3header['syncinfo']  =     getid3_lib::BigEndian2Int(substr($tempAC3header, 0, 2));
  70          $this->AC3header['bsi']       =     getid3_lib::BigEndian2Bin(substr($tempAC3header, 2));
  71          $thisfile_ac3_raw_bsi['bsid'] = (getid3_lib::LittleEndian2Int(substr($tempAC3header, 5, 1)) & 0xF8) >> 3; // AC3 and E-AC3 put the "bsid" version identifier in the same place, but unfortnately the 4 bytes between the syncword and the version identifier are interpreted differently, so grab it here so the following code structure can make sense
  72          unset($tempAC3header);
  73  
  74          if ($this->AC3header['syncinfo'] !== self::syncword) {
  75              if (!$this->isDependencyFor('matroska')) {
  76                  unset($info['fileformat'], $info['ac3']);
  77                  return $this->error('Expecting "'.dechex(self::syncword).'" at offset '.$info['avdataoffset'].', found "'.dechex($this->AC3header['syncinfo']).'"');
  78              }
  79          }
  80  
  81          $info['audio']['dataformat']   = 'ac3';
  82          $info['audio']['bitrate_mode'] = 'cbr';
  83          $info['audio']['lossless']     = false;
  84  
  85          if ($thisfile_ac3_raw_bsi['bsid'] <= 8) {
  86  
  87              $thisfile_ac3_raw_bsi['crc1']       = getid3_lib::Bin2Dec($this->readHeaderBSI(16));
  88              $thisfile_ac3_raw_bsi['fscod']      =                     $this->readHeaderBSI(2);   // 5.4.1.3
  89              $thisfile_ac3_raw_bsi['frmsizecod'] =                     $this->readHeaderBSI(6);   // 5.4.1.4
  90              if ($thisfile_ac3_raw_bsi['frmsizecod'] > 37) { // binary: 100101 - see Table 5.18 Frame Size Code Table (1 word = 16 bits)
  91                  $this->warning('Unexpected ac3.bsi.frmsizecod value: '.$thisfile_ac3_raw_bsi['frmsizecod'].', bitrate not set correctly');
  92              }
  93  
  94              $thisfile_ac3_raw_bsi['bsid']  = $this->readHeaderBSI(5); // we already know this from pre-parsing the version identifier, but re-read it to let the bitstream flow as intended
  95              $thisfile_ac3_raw_bsi['bsmod'] = $this->readHeaderBSI(3);
  96              $thisfile_ac3_raw_bsi['acmod'] = $this->readHeaderBSI(3);
  97  
  98              if ($thisfile_ac3_raw_bsi['acmod'] & 0x01) {
  99                  // If the lsb of acmod is a 1, center channel is in use and cmixlev follows in the bit stream.
 100                  $thisfile_ac3_raw_bsi['cmixlev'] = $this->readHeaderBSI(2);
 101                  $thisfile_ac3['center_mix_level'] = self::centerMixLevelLookup($thisfile_ac3_raw_bsi['cmixlev']);
 102              }
 103  
 104              if ($thisfile_ac3_raw_bsi['acmod'] & 0x04) {
 105                  // If the msb of acmod is a 1, surround channels are in use and surmixlev follows in the bit stream.
 106                  $thisfile_ac3_raw_bsi['surmixlev'] = $this->readHeaderBSI(2);
 107                  $thisfile_ac3['surround_mix_level'] = self::surroundMixLevelLookup($thisfile_ac3_raw_bsi['surmixlev']);
 108              }
 109  
 110              if ($thisfile_ac3_raw_bsi['acmod'] == 0x02) {
 111                  // When operating in the two channel mode, this 2-bit code indicates whether or not the program has been encoded in Dolby Surround.
 112                  $thisfile_ac3_raw_bsi['dsurmod'] = $this->readHeaderBSI(2);
 113                  $thisfile_ac3['dolby_surround_mode'] = self::dolbySurroundModeLookup($thisfile_ac3_raw_bsi['dsurmod']);
 114              }
 115  
 116              $thisfile_ac3_raw_bsi['flags']['lfeon'] = (bool) $this->readHeaderBSI(1);
 117  
 118              // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1-31.
 119              // The value of 0 is reserved. The values of 1 to 31 are interpreted as -1 dB to -31 dB with respect to digital 100 percent.
 120              $thisfile_ac3_raw_bsi['dialnorm'] = $this->readHeaderBSI(5);                 // 5.4.2.8 dialnorm: Dialogue Normalization, 5 Bits
 121  
 122              $thisfile_ac3_raw_bsi['flags']['compr'] = (bool) $this->readHeaderBSI(1);       // 5.4.2.9 compre: Compression Gain Word Exists, 1 Bit
 123              if ($thisfile_ac3_raw_bsi['flags']['compr']) {
 124                  $thisfile_ac3_raw_bsi['compr'] = $this->readHeaderBSI(8);                // 5.4.2.10 compr: Compression Gain Word, 8 Bits
 125                  $thisfile_ac3['heavy_compression'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr']);
 126              }
 127  
 128              $thisfile_ac3_raw_bsi['flags']['langcod'] = (bool) $this->readHeaderBSI(1);     // 5.4.2.11 langcode: Language Code Exists, 1 Bit
 129              if ($thisfile_ac3_raw_bsi['flags']['langcod']) {
 130                  $thisfile_ac3_raw_bsi['langcod'] = $this->readHeaderBSI(8);              // 5.4.2.12 langcod: Language Code, 8 Bits
 131              }
 132  
 133              $thisfile_ac3_raw_bsi['flags']['audprodinfo'] = (bool) $this->readHeaderBSI(1);  // 5.4.2.13 audprodie: Audio Production Information Exists, 1 Bit
 134              if ($thisfile_ac3_raw_bsi['flags']['audprodinfo']) {
 135                  $thisfile_ac3_raw_bsi['mixlevel'] = $this->readHeaderBSI(5);             // 5.4.2.14 mixlevel: Mixing Level, 5 Bits
 136                  $thisfile_ac3_raw_bsi['roomtyp']  = $this->readHeaderBSI(2);             // 5.4.2.15 roomtyp: Room Type, 2 Bits
 137  
 138                  $thisfile_ac3['mixing_level'] = (80 + $thisfile_ac3_raw_bsi['mixlevel']).'dB';
 139                  $thisfile_ac3['room_type']    = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp']);
 140              }
 141  
 142  
 143              $thisfile_ac3_raw_bsi['dialnorm2'] = $this->readHeaderBSI(5);                // 5.4.2.16 dialnorm2: Dialogue Normalization, ch2, 5 Bits
 144              $thisfile_ac3['dialogue_normalization2'] = '-'.$thisfile_ac3_raw_bsi['dialnorm2'].'dB';  // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1-31. The value of 0 is reserved. The values of 1 to 31 are interpreted as -1 dB to -31 dB with respect to digital 100 percent.
 145  
 146              $thisfile_ac3_raw_bsi['flags']['compr2'] = (bool) $this->readHeaderBSI(1);       // 5.4.2.17 compr2e: Compression Gain Word Exists, ch2, 1 Bit
 147              if ($thisfile_ac3_raw_bsi['flags']['compr2']) {
 148                  $thisfile_ac3_raw_bsi['compr2'] = $this->readHeaderBSI(8);               // 5.4.2.18 compr2: Compression Gain Word, ch2, 8 Bits
 149                  $thisfile_ac3['heavy_compression2'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr2']);
 150              }
 151  
 152              $thisfile_ac3_raw_bsi['flags']['langcod2'] = (bool) $this->readHeaderBSI(1);    // 5.4.2.19 langcod2e: Language Code Exists, ch2, 1 Bit
 153              if ($thisfile_ac3_raw_bsi['flags']['langcod2']) {
 154                  $thisfile_ac3_raw_bsi['langcod2'] = $this->readHeaderBSI(8);             // 5.4.2.20 langcod2: Language Code, ch2, 8 Bits
 155              }
 156  
 157              $thisfile_ac3_raw_bsi['flags']['audprodinfo2'] = (bool) $this->readHeaderBSI(1); // 5.4.2.21 audprodi2e: Audio Production Information Exists, ch2, 1 Bit
 158              if ($thisfile_ac3_raw_bsi['flags']['audprodinfo2']) {
 159                  $thisfile_ac3_raw_bsi['mixlevel2'] = $this->readHeaderBSI(5);            // 5.4.2.22 mixlevel2: Mixing Level, ch2, 5 Bits
 160                  $thisfile_ac3_raw_bsi['roomtyp2']  = $this->readHeaderBSI(2);            // 5.4.2.23 roomtyp2: Room Type, ch2, 2 Bits
 161  
 162                  $thisfile_ac3['mixing_level2'] = (80 + $thisfile_ac3_raw_bsi['mixlevel2']).'dB';
 163                  $thisfile_ac3['room_type2']    = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp2']);
 164              }
 165  
 166              $thisfile_ac3_raw_bsi['copyright'] = (bool) $this->readHeaderBSI(1);         // 5.4.2.24 copyrightb: Copyright Bit, 1 Bit
 167  
 168              $thisfile_ac3_raw_bsi['original']  = (bool) $this->readHeaderBSI(1);         // 5.4.2.25 origbs: Original Bit Stream, 1 Bit
 169  
 170              $thisfile_ac3_raw_bsi['flags']['timecod1'] = $this->readHeaderBSI(2);            // 5.4.2.26 timecod1e, timcode2e: Time Code (first and second) Halves Exist, 2 Bits
 171              if ($thisfile_ac3_raw_bsi['flags']['timecod1'] & 0x01) {
 172                  $thisfile_ac3_raw_bsi['timecod1'] = $this->readHeaderBSI(14);            // 5.4.2.27 timecod1: Time code first half, 14 bits
 173                  $thisfile_ac3['timecode1'] = 0;
 174                  $thisfile_ac3['timecode1'] += (($thisfile_ac3_raw_bsi['timecod1'] & 0x3E00) >>  9) * 3600;  // The first 5 bits of this 14-bit field represent the time in hours, with valid values of 0�23
 175                  $thisfile_ac3['timecode1'] += (($thisfile_ac3_raw_bsi['timecod1'] & 0x01F8) >>  3) *   60;  // The next 6 bits represent the time in minutes, with valid values of 0�59
 176                  $thisfile_ac3['timecode1'] += (($thisfile_ac3_raw_bsi['timecod1'] & 0x0003) >>  0) *    8;  // The final 3 bits represents the time in 8 second increments, with valid values of 0�7 (representing 0, 8, 16, ... 56 seconds)
 177              }
 178              if ($thisfile_ac3_raw_bsi['flags']['timecod1'] & 0x02) {
 179                  $thisfile_ac3_raw_bsi['timecod2'] = $this->readHeaderBSI(14);            // 5.4.2.28 timecod2: Time code second half, 14 bits
 180                  $thisfile_ac3['timecode2'] = 0;
 181                  $thisfile_ac3['timecode2'] += (($thisfile_ac3_raw_bsi['timecod2'] & 0x3800) >> 11) *   1;              // The first 3 bits of this 14-bit field represent the time in seconds, with valid values from 0�7 (representing 0-7 seconds)
 182                  $thisfile_ac3['timecode2'] += (($thisfile_ac3_raw_bsi['timecod2'] & 0x07C0) >>  6) *  (1 / 30);        // The next 5 bits represents the time in frames, with valid values from 0�29 (one frame = 1/30th of a second)
 183                  $thisfile_ac3['timecode2'] += (($thisfile_ac3_raw_bsi['timecod2'] & 0x003F) >>  0) * ((1 / 30) / 60);  // The final 6 bits represents fractions of 1/64 of a frame, with valid values from 0�63
 184              }
 185  
 186              $thisfile_ac3_raw_bsi['flags']['addbsi'] = (bool) $this->readHeaderBSI(1);
 187              if ($thisfile_ac3_raw_bsi['flags']['addbsi']) {
 188                  $thisfile_ac3_raw_bsi['addbsi_length'] = $this->readHeaderBSI(6) + 1; // This 6-bit code, which exists only if addbside is a 1, indicates the length in bytes of additional bit stream information. The valid range of addbsil is 0�63, indicating 1�64 additional bytes, respectively.
 189  
 190                  $this->AC3header['bsi'] .= getid3_lib::BigEndian2Bin($this->fread($thisfile_ac3_raw_bsi['addbsi_length']));
 191  
 192                  $thisfile_ac3_raw_bsi['addbsi_data'] = substr($this->AC3header['bsi'], $this->BSIoffset, $thisfile_ac3_raw_bsi['addbsi_length'] * 8);
 193                  $this->BSIoffset += $thisfile_ac3_raw_bsi['addbsi_length'] * 8;
 194              }
 195  
 196  
 197          } elseif ($thisfile_ac3_raw_bsi['bsid'] <= 16) { // E-AC3
 198  
 199  
 200              $this->error('E-AC3 parsing is incomplete and experimental in this version of getID3 ('.$this->getid3->version().'). Notably the bitrate calculations are wrong -- value might (or not) be correct, but it is not calculated correctly. Email info@getid3.org if you know how to calculate EAC3 bitrate correctly.');
 201              $info['audio']['dataformat'] = 'eac3';
 202  
 203              $thisfile_ac3_raw_bsi['strmtyp']          =        $this->readHeaderBSI(2);
 204              $thisfile_ac3_raw_bsi['substreamid']      =        $this->readHeaderBSI(3);
 205              $thisfile_ac3_raw_bsi['frmsiz']           =        $this->readHeaderBSI(11);
 206              $thisfile_ac3_raw_bsi['fscod']            =        $this->readHeaderBSI(2);
 207              if ($thisfile_ac3_raw_bsi['fscod'] == 3) {
 208                  $thisfile_ac3_raw_bsi['fscod2']       =        $this->readHeaderBSI(2);
 209                  $thisfile_ac3_raw_bsi['numblkscod'] = 3; // six blocks per syncframe
 210              } else {
 211                  $thisfile_ac3_raw_bsi['numblkscod']   =        $this->readHeaderBSI(2);
 212              }
 213              $thisfile_ac3['bsi']['blocks_per_sync_frame'] = self::blocksPerSyncFrame($thisfile_ac3_raw_bsi['numblkscod']);
 214              $thisfile_ac3_raw_bsi['acmod']            =        $this->readHeaderBSI(3);
 215              $thisfile_ac3_raw_bsi['flags']['lfeon']   = (bool) $this->readHeaderBSI(1);
 216              $thisfile_ac3_raw_bsi['bsid']             =        $this->readHeaderBSI(5); // we already know this from pre-parsing the version identifier, but re-read it to let the bitstream flow as intended
 217              $thisfile_ac3_raw_bsi['dialnorm']         =        $this->readHeaderBSI(5);
 218              $thisfile_ac3_raw_bsi['flags']['compr']       = (bool) $this->readHeaderBSI(1);
 219              if ($thisfile_ac3_raw_bsi['flags']['compr']) {
 220                  $thisfile_ac3_raw_bsi['compr']        =        $this->readHeaderBSI(8);
 221              }
 222              if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value)
 223                  $thisfile_ac3_raw_bsi['dialnorm2']    =        $this->readHeaderBSI(5);
 224                  $thisfile_ac3_raw_bsi['flags']['compr2']  = (bool) $this->readHeaderBSI(1);
 225                  if ($thisfile_ac3_raw_bsi['flags']['compr2']) {
 226                      $thisfile_ac3_raw_bsi['compr2']   =        $this->readHeaderBSI(8);
 227                  }
 228              }
 229              if ($thisfile_ac3_raw_bsi['strmtyp'] == 1) { // if dependent stream
 230                  $thisfile_ac3_raw_bsi['flags']['chanmap'] = (bool) $this->readHeaderBSI(1);
 231                  if ($thisfile_ac3_raw_bsi['flags']['chanmap']) {
 232                      $thisfile_ac3_raw_bsi['chanmap']  =        $this->readHeaderBSI(8);
 233                  }
 234              }
 235              $thisfile_ac3_raw_bsi['flags']['mixmdat']     = (bool) $this->readHeaderBSI(1);
 236              if ($thisfile_ac3_raw_bsi['flags']['mixmdat']) { // Mixing metadata
 237                  if ($thisfile_ac3_raw_bsi['acmod'] > 2) { // if more than 2 channels
 238                      $thisfile_ac3_raw_bsi['dmixmod']  =        $this->readHeaderBSI(2);
 239                  }
 240                  if (($thisfile_ac3_raw_bsi['acmod'] & 0x01) && ($thisfile_ac3_raw_bsi['acmod'] > 2)) { // if three front channels exist
 241                      $thisfile_ac3_raw_bsi['ltrtcmixlev'] =        $this->readHeaderBSI(3);
 242                      $thisfile_ac3_raw_bsi['lorocmixlev'] =        $this->readHeaderBSI(3);
 243                  }
 244                  if ($thisfile_ac3_raw_bsi['acmod'] & 0x04) { // if a surround channel exists
 245                      $thisfile_ac3_raw_bsi['ltrtsurmixlev'] =        $this->readHeaderBSI(3);
 246                      $thisfile_ac3_raw_bsi['lorosurmixlev'] =        $this->readHeaderBSI(3);
 247                  }
 248                  if ($thisfile_ac3_raw_bsi['flags']['lfeon']) { // if the LFE channel exists
 249                      $thisfile_ac3_raw_bsi['flags']['lfemixlevcod'] = (bool) $this->readHeaderBSI(1);
 250                      if ($thisfile_ac3_raw_bsi['flags']['lfemixlevcod']) {
 251                          $thisfile_ac3_raw_bsi['lfemixlevcod']  =        $this->readHeaderBSI(5);
 252                      }
 253                  }
 254                  if ($thisfile_ac3_raw_bsi['strmtyp'] == 0) { // if independent stream
 255                      $thisfile_ac3_raw_bsi['flags']['pgmscl'] = (bool) $this->readHeaderBSI(1);
 256                      if ($thisfile_ac3_raw_bsi['flags']['pgmscl']) {
 257                          $thisfile_ac3_raw_bsi['pgmscl']  =        $this->readHeaderBSI(6);
 258                      }
 259                      if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value)
 260                          $thisfile_ac3_raw_bsi['flags']['pgmscl2'] = (bool) $this->readHeaderBSI(1);
 261                          if ($thisfile_ac3_raw_bsi['flags']['pgmscl2']) {
 262                              $thisfile_ac3_raw_bsi['pgmscl2']  =        $this->readHeaderBSI(6);
 263                          }
 264                      }
 265                      $thisfile_ac3_raw_bsi['flags']['extpgmscl'] = (bool) $this->readHeaderBSI(1);
 266                      if ($thisfile_ac3_raw_bsi['flags']['extpgmscl']) {
 267                          $thisfile_ac3_raw_bsi['extpgmscl']  =        $this->readHeaderBSI(6);
 268                      }
 269                      $thisfile_ac3_raw_bsi['mixdef']  =        $this->readHeaderBSI(2);
 270                      if ($thisfile_ac3_raw_bsi['mixdef'] == 1) { // mixing option 2
 271                          $thisfile_ac3_raw_bsi['premixcmpsel']  = (bool) $this->readHeaderBSI(1);
 272                          $thisfile_ac3_raw_bsi['drcsrc']        = (bool) $this->readHeaderBSI(1);
 273                          $thisfile_ac3_raw_bsi['premixcmpscl']  =        $this->readHeaderBSI(3);
 274                      } elseif ($thisfile_ac3_raw_bsi['mixdef'] == 2) { // mixing option 3
 275                          $thisfile_ac3_raw_bsi['mixdata']       =        $this->readHeaderBSI(12);
 276                      } elseif ($thisfile_ac3_raw_bsi['mixdef'] == 3) { // mixing option 4
 277                          $mixdefbitsread = 0;
 278                          $thisfile_ac3_raw_bsi['mixdeflen']     =        $this->readHeaderBSI(5); $mixdefbitsread += 5;
 279                          $thisfile_ac3_raw_bsi['flags']['mixdata2'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
 280                          if ($thisfile_ac3_raw_bsi['flags']['mixdata2']) {
 281                              $thisfile_ac3_raw_bsi['premixcmpsel']  = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
 282                              $thisfile_ac3_raw_bsi['drcsrc']        = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
 283                              $thisfile_ac3_raw_bsi['premixcmpscl']  =        $this->readHeaderBSI(3); $mixdefbitsread += 3;
 284                              $thisfile_ac3_raw_bsi['flags']['extpgmlscl']   = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
 285                              if ($thisfile_ac3_raw_bsi['flags']['extpgmlscl']) {
 286                                  $thisfile_ac3_raw_bsi['extpgmlscl']    =        $this->readHeaderBSI(4); $mixdefbitsread += 4;
 287                              }
 288                              $thisfile_ac3_raw_bsi['flags']['extpgmcscl']   = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
 289                              if ($thisfile_ac3_raw_bsi['flags']['extpgmcscl']) {
 290                                  $thisfile_ac3_raw_bsi['extpgmcscl']    =        $this->readHeaderBSI(4); $mixdefbitsread += 4;
 291                              }
 292                              $thisfile_ac3_raw_bsi['flags']['extpgmrscl']   = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
 293                              if ($thisfile_ac3_raw_bsi['flags']['extpgmrscl']) {
 294                                  $thisfile_ac3_raw_bsi['extpgmrscl']    =        $this->readHeaderBSI(4);
 295                              }
 296                              $thisfile_ac3_raw_bsi['flags']['extpgmlsscl']  = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
 297                              if ($thisfile_ac3_raw_bsi['flags']['extpgmlsscl']) {
 298                                  $thisfile_ac3_raw_bsi['extpgmlsscl']   =        $this->readHeaderBSI(4); $mixdefbitsread += 4;
 299                              }
 300                              $thisfile_ac3_raw_bsi['flags']['extpgmrsscl']  = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
 301                              if ($thisfile_ac3_raw_bsi['flags']['extpgmrsscl']) {
 302                                  $thisfile_ac3_raw_bsi['extpgmrsscl']   =        $this->readHeaderBSI(4); $mixdefbitsread += 4;
 303                              }
 304                              $thisfile_ac3_raw_bsi['flags']['extpgmlfescl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
 305                              if ($thisfile_ac3_raw_bsi['flags']['extpgmlfescl']) {
 306                                  $thisfile_ac3_raw_bsi['extpgmlfescl']  =        $this->readHeaderBSI(4); $mixdefbitsread += 4;
 307                              }
 308                              $thisfile_ac3_raw_bsi['flags']['dmixscl']      = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
 309                              if ($thisfile_ac3_raw_bsi['flags']['dmixscl']) {
 310                                  $thisfile_ac3_raw_bsi['dmixscl']       =        $this->readHeaderBSI(4); $mixdefbitsread += 4;
 311                              }
 312                              $thisfile_ac3_raw_bsi['flags']['addch']        = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
 313                              if ($thisfile_ac3_raw_bsi['flags']['addch']) {
 314                                  $thisfile_ac3_raw_bsi['flags']['extpgmaux1scl']   = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
 315                                  if ($thisfile_ac3_raw_bsi['flags']['extpgmaux1scl']) {
 316                                      $thisfile_ac3_raw_bsi['extpgmaux1scl']    =        $this->readHeaderBSI(4); $mixdefbitsread += 4;
 317                                  }
 318                                  $thisfile_ac3_raw_bsi['flags']['extpgmaux2scl']   = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
 319                                  if ($thisfile_ac3_raw_bsi['flags']['extpgmaux2scl']) {
 320                                      $thisfile_ac3_raw_bsi['extpgmaux2scl']    =        $this->readHeaderBSI(4); $mixdefbitsread += 4;
 321                                  }
 322                              }
 323                          }
 324                          $thisfile_ac3_raw_bsi['flags']['mixdata3'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
 325                          if ($thisfile_ac3_raw_bsi['flags']['mixdata3']) {
 326                              $thisfile_ac3_raw_bsi['spchdat']   =        $this->readHeaderBSI(5); $mixdefbitsread += 5;
 327                              $thisfile_ac3_raw_bsi['flags']['addspchdat'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
 328                              if ($thisfile_ac3_raw_bsi['flags']['addspchdat']) {
 329                                  $thisfile_ac3_raw_bsi['spchdat1']   =         $this->readHeaderBSI(5); $mixdefbitsread += 5;
 330                                  $thisfile_ac3_raw_bsi['spchan1att'] =         $this->readHeaderBSI(2); $mixdefbitsread += 2;
 331                                  $thisfile_ac3_raw_bsi['flags']['addspchdat1'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
 332                                  if ($thisfile_ac3_raw_bsi['flags']['addspchdat1']) {
 333                                      $thisfile_ac3_raw_bsi['spchdat2']   =         $this->readHeaderBSI(5); $mixdefbitsread += 5;
 334                                      $thisfile_ac3_raw_bsi['spchan2att'] =         $this->readHeaderBSI(3); $mixdefbitsread += 3;
 335                                  }
 336                              }
 337                          }
 338                          $mixdata_bits = (8 * ($thisfile_ac3_raw_bsi['mixdeflen'] + 2)) - $mixdefbitsread;
 339                          $mixdata_fill = (($mixdata_bits % 8) ? 8 - ($mixdata_bits % 8) : 0);
 340                          $thisfile_ac3_raw_bsi['mixdata']     =        $this->readHeaderBSI($mixdata_bits);
 341                          $thisfile_ac3_raw_bsi['mixdatafill'] =        $this->readHeaderBSI($mixdata_fill);
 342                          unset($mixdefbitsread, $mixdata_bits, $mixdata_fill);
 343                      }
 344                      if ($thisfile_ac3_raw_bsi['acmod'] < 2) { // if mono or dual mono source
 345                          $thisfile_ac3_raw_bsi['flags']['paninfo'] = (bool) $this->readHeaderBSI(1);
 346                          if ($thisfile_ac3_raw_bsi['flags']['paninfo']) {
 347                              $thisfile_ac3_raw_bsi['panmean']   =        $this->readHeaderBSI(8);
 348                              $thisfile_ac3_raw_bsi['paninfo']   =        $this->readHeaderBSI(6);
 349                          }
 350                          if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value)
 351                              $thisfile_ac3_raw_bsi['flags']['paninfo2'] = (bool) $this->readHeaderBSI(1);
 352                              if ($thisfile_ac3_raw_bsi['flags']['paninfo2']) {
 353                                  $thisfile_ac3_raw_bsi['panmean2']   =        $this->readHeaderBSI(8);
 354                                  $thisfile_ac3_raw_bsi['paninfo2']   =        $this->readHeaderBSI(6);
 355                              }
 356                          }
 357                      }
 358                      $thisfile_ac3_raw_bsi['flags']['frmmixcfginfo'] = (bool) $this->readHeaderBSI(1);
 359                      if ($thisfile_ac3_raw_bsi['flags']['frmmixcfginfo']) { // mixing configuration information
 360                          if ($thisfile_ac3_raw_bsi['numblkscod'] == 0) {
 361                              $thisfile_ac3_raw_bsi['blkmixcfginfo'][0]  =        $this->readHeaderBSI(5);
 362                          } else {
 363                              for ($blk = 0; $blk < $thisfile_ac3_raw_bsi['numblkscod']; $blk++) {
 364                                  $thisfile_ac3_raw_bsi['flags']['blkmixcfginfo'.$blk] = (bool) $this->readHeaderBSI(1);
 365                                  if ($thisfile_ac3_raw_bsi['flags']['blkmixcfginfo'.$blk]) { // mixing configuration information
 366                                      $thisfile_ac3_raw_bsi['blkmixcfginfo'][$blk]  =        $this->readHeaderBSI(5);
 367                                  }
 368                              }
 369                          }
 370                      }
 371                  }
 372              }
 373              $thisfile_ac3_raw_bsi['flags']['infomdat']          = (bool) $this->readHeaderBSI(1);
 374              if ($thisfile_ac3_raw_bsi['flags']['infomdat']) { // Informational metadata
 375                  $thisfile_ac3_raw_bsi['bsmod']                  =        $this->readHeaderBSI(3);
 376                  $thisfile_ac3_raw_bsi['flags']['copyrightb']    = (bool) $this->readHeaderBSI(1);
 377                  $thisfile_ac3_raw_bsi['flags']['origbs']        = (bool) $this->readHeaderBSI(1);
 378                  if ($thisfile_ac3_raw_bsi['acmod'] == 2) { //  if in 2/0 mode
 379                      $thisfile_ac3_raw_bsi['dsurmod']            =        $this->readHeaderBSI(2);
 380                      $thisfile_ac3_raw_bsi['dheadphonmod']       =        $this->readHeaderBSI(2);
 381                  }
 382                  if ($thisfile_ac3_raw_bsi['acmod'] >= 6) { //  if both surround channels exist
 383                      $thisfile_ac3_raw_bsi['dsurexmod']          =        $this->readHeaderBSI(2);
 384                  }
 385                  $thisfile_ac3_raw_bsi['flags']['audprodi']      = (bool) $this->readHeaderBSI(1);
 386                  if ($thisfile_ac3_raw_bsi['flags']['audprodi']) {
 387                      $thisfile_ac3_raw_bsi['mixlevel']           =        $this->readHeaderBSI(5);
 388                      $thisfile_ac3_raw_bsi['roomtyp']            =        $this->readHeaderBSI(2);
 389                      $thisfile_ac3_raw_bsi['flags']['adconvtyp'] = (bool) $this->readHeaderBSI(1);
 390                  }
 391                  if ($thisfile_ac3_raw_bsi['acmod'] == 0) { //  if 1+1 mode (dual mono, so some items need a second value)
 392                      $thisfile_ac3_raw_bsi['flags']['audprodi2']      = (bool) $this->readHeaderBSI(1);
 393                      if ($thisfile_ac3_raw_bsi['flags']['audprodi2']) {
 394                          $thisfile_ac3_raw_bsi['mixlevel2']           =        $this->readHeaderBSI(5);
 395                          $thisfile_ac3_raw_bsi['roomtyp2']            =        $this->readHeaderBSI(2);
 396                          $thisfile_ac3_raw_bsi['flags']['adconvtyp2'] = (bool) $this->readHeaderBSI(1);
 397                      }
 398                  }
 399                  if ($thisfile_ac3_raw_bsi['fscod'] < 3) { // if not half sample rate
 400                      $thisfile_ac3_raw_bsi['flags']['sourcefscod'] = (bool) $this->readHeaderBSI(1);
 401                  }
 402              }
 403              if (($thisfile_ac3_raw_bsi['strmtyp'] == 0) && ($thisfile_ac3_raw_bsi['numblkscod'] != 3)) { //  if both surround channels exist
 404                  $thisfile_ac3_raw_bsi['flags']['convsync'] = (bool) $this->readHeaderBSI(1);
 405              }
 406              if ($thisfile_ac3_raw_bsi['strmtyp'] == 2) { //  if bit stream converted from AC-3
 407                  if ($thisfile_ac3_raw_bsi['numblkscod'] != 3) { // 6 blocks per syncframe
 408                      $thisfile_ac3_raw_bsi['flags']['blkid']  = 1;
 409                  } else {
 410                      $thisfile_ac3_raw_bsi['flags']['blkid']  = (bool) $this->readHeaderBSI(1);
 411                  }
 412                  if ($thisfile_ac3_raw_bsi['flags']['blkid']) {
 413                      $thisfile_ac3_raw_bsi['frmsizecod']  =        $this->readHeaderBSI(6);
 414                  }
 415              }
 416              $thisfile_ac3_raw_bsi['flags']['addbsi']  = (bool) $this->readHeaderBSI(1);
 417              if ($thisfile_ac3_raw_bsi['flags']['addbsi']) {
 418                  $thisfile_ac3_raw_bsi['addbsil']  =        $this->readHeaderBSI(6);
 419                  $thisfile_ac3_raw_bsi['addbsi']   =        $this->readHeaderBSI(($thisfile_ac3_raw_bsi['addbsil'] + 1) * 8);
 420              }
 421  
 422          } else {
 423  
 424              $this->error('Bit stream identification is version '.$thisfile_ac3_raw_bsi['bsid'].', but getID3() only understands up to version 16. Please submit a support ticket with a sample file.');
 425              unset($info['ac3']);
 426              return false;
 427  
 428          }
 429  
 430          if (isset($thisfile_ac3_raw_bsi['fscod2'])) {
 431              $thisfile_ac3['sample_rate'] = self::sampleRateCodeLookup2($thisfile_ac3_raw_bsi['fscod2']);
 432          } else {
 433              $thisfile_ac3['sample_rate'] = self::sampleRateCodeLookup($thisfile_ac3_raw_bsi['fscod']);
 434          }
 435          if ($thisfile_ac3_raw_bsi['fscod'] <= 3) {
 436              $info['audio']['sample_rate'] = $thisfile_ac3['sample_rate'];
 437          } else {
 438              $this->warning('Unexpected ac3.bsi.fscod value: '.$thisfile_ac3_raw_bsi['fscod']);
 439          }
 440          if (isset($thisfile_ac3_raw_bsi['frmsizecod'])) {
 441              $thisfile_ac3['frame_length'] = self::frameSizeLookup($thisfile_ac3_raw_bsi['frmsizecod'], $thisfile_ac3_raw_bsi['fscod']);
 442              $thisfile_ac3['bitrate']      = self::bitrateLookup($thisfile_ac3_raw_bsi['frmsizecod']);
 443          } elseif (!empty($thisfile_ac3_raw_bsi['frmsiz'])) {
 444              // this isn't right, but it's (usually) close, roughly 5% less than it should be.
 445              // but WHERE is the actual bitrate value stored in EAC3?? email info@getid3.org if you know!
 446              $thisfile_ac3['bitrate']      = ($thisfile_ac3_raw_bsi['frmsiz'] + 1) * 16 * 30; // The frmsiz field shall contain a value one less than the overall size of the coded syncframe in 16-bit words. That is, this field may assume a value ranging from 0 to 2047, and these values correspond to syncframe sizes ranging from 1 to 2048.
 447              // kludge-fix to make it approximately the expected value, still not "right":
 448              $thisfile_ac3['bitrate'] = round(($thisfile_ac3['bitrate'] * 1.05) / 16000) * 16000;
 449          }
 450          $info['audio']['bitrate'] = $thisfile_ac3['bitrate'];
 451  
 452          if (isset($thisfile_ac3_raw_bsi['bsmod']) && isset($thisfile_ac3_raw_bsi['acmod'])) {
 453              $thisfile_ac3['service_type'] = self::serviceTypeLookup($thisfile_ac3_raw_bsi['bsmod'], $thisfile_ac3_raw_bsi['acmod']);
 454          }
 455          $ac3_coding_mode = self::audioCodingModeLookup($thisfile_ac3_raw_bsi['acmod']);
 456          foreach($ac3_coding_mode as $key => $value) {
 457              $thisfile_ac3[$key] = $value;
 458          }
 459          switch ($thisfile_ac3_raw_bsi['acmod']) {
 460              case 0:
 461              case 1:
 462                  $info['audio']['channelmode'] = 'mono';
 463                  break;
 464              case 3:
 465              case 4:
 466                  $info['audio']['channelmode'] = 'stereo';
 467                  break;
 468              default:
 469                  $info['audio']['channelmode'] = 'surround';
 470                  break;
 471          }
 472          $info['audio']['channels'] = $thisfile_ac3['num_channels'];
 473  
 474          $thisfile_ac3['lfe_enabled'] = $thisfile_ac3_raw_bsi['flags']['lfeon'];
 475          if ($thisfile_ac3_raw_bsi['flags']['lfeon']) {
 476              $info['audio']['channels'] .= '.1';
 477          }
 478  
 479          $thisfile_ac3['channels_enabled'] = self::channelsEnabledLookup($thisfile_ac3_raw_bsi['acmod'], $thisfile_ac3_raw_bsi['flags']['lfeon']);
 480          $thisfile_ac3['dialogue_normalization'] = '-'.$thisfile_ac3_raw_bsi['dialnorm'].'dB';
 481  
 482          return true;
 483      }
 484  
 485      /**
 486       * @param int $length
 487       *
 488       * @return float|int
 489       */
 490  	private function readHeaderBSI($length) {
 491          $data = substr($this->AC3header['bsi'], $this->BSIoffset, $length);
 492          $this->BSIoffset += $length;
 493  
 494          return bindec($data);
 495      }
 496  
 497      /**
 498       * @param int $fscod
 499       *
 500       * @return int|string|false
 501       */
 502  	public static function sampleRateCodeLookup($fscod) {
 503          static $sampleRateCodeLookup = array(
 504              0 => 48000,
 505              1 => 44100,
 506              2 => 32000,
 507              3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute.
 508          );
 509          return (isset($sampleRateCodeLookup[$fscod]) ? $sampleRateCodeLookup[$fscod] : false);
 510      }
 511  
 512      /**
 513       * @param int $fscod2
 514       *
 515       * @return int|string|false
 516       */
 517  	public static function sampleRateCodeLookup2($fscod2) {
 518          static $sampleRateCodeLookup2 = array(
 519              0 => 24000,
 520              1 => 22050,
 521              2 => 16000,
 522              3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute.
 523          );
 524          return (isset($sampleRateCodeLookup2[$fscod2]) ? $sampleRateCodeLookup2[$fscod2] : false);
 525      }
 526  
 527      /**
 528       * @param int $bsmod
 529       * @param int $acmod
 530       *
 531       * @return string|false
 532       */
 533  	public static function serviceTypeLookup($bsmod, $acmod) {
 534          static $serviceTypeLookup = array();
 535          if (empty($serviceTypeLookup)) {
 536              for ($i = 0; $i <= 7; $i++) {
 537                  $serviceTypeLookup[0][$i] = 'main audio service: complete main (CM)';
 538                  $serviceTypeLookup[1][$i] = 'main audio service: music and effects (ME)';
 539                  $serviceTypeLookup[2][$i] = 'associated service: visually impaired (VI)';
 540                  $serviceTypeLookup[3][$i] = 'associated service: hearing impaired (HI)';
 541                  $serviceTypeLookup[4][$i] = 'associated service: dialogue (D)';
 542                  $serviceTypeLookup[5][$i] = 'associated service: commentary (C)';
 543                  $serviceTypeLookup[6][$i] = 'associated service: emergency (E)';
 544              }
 545  
 546              $serviceTypeLookup[7][1]      = 'associated service: voice over (VO)';
 547              for ($i = 2; $i <= 7; $i++) {
 548                  $serviceTypeLookup[7][$i] = 'main audio service: karaoke';
 549              }
 550          }
 551          return (isset($serviceTypeLookup[$bsmod][$acmod]) ? $serviceTypeLookup[$bsmod][$acmod] : false);
 552      }
 553  
 554      /**
 555       * @param int $acmod
 556       *
 557       * @return array|false
 558       */
 559  	public static function audioCodingModeLookup($acmod) {
 560          // array(channel configuration, # channels (not incl LFE), channel order)
 561          static $audioCodingModeLookup = array (
 562              0 => array('channel_config'=>'1+1', 'num_channels'=>2, 'channel_order'=>'Ch1,Ch2'),
 563              1 => array('channel_config'=>'1/0', 'num_channels'=>1, 'channel_order'=>'C'),
 564              2 => array('channel_config'=>'2/0', 'num_channels'=>2, 'channel_order'=>'L,R'),
 565              3 => array('channel_config'=>'3/0', 'num_channels'=>3, 'channel_order'=>'L,C,R'),
 566              4 => array('channel_config'=>'2/1', 'num_channels'=>3, 'channel_order'=>'L,R,S'),
 567              5 => array('channel_config'=>'3/1', 'num_channels'=>4, 'channel_order'=>'L,C,R,S'),
 568              6 => array('channel_config'=>'2/2', 'num_channels'=>4, 'channel_order'=>'L,R,SL,SR'),
 569              7 => array('channel_config'=>'3/2', 'num_channels'=>5, 'channel_order'=>'L,C,R,SL,SR'),
 570          );
 571          return (isset($audioCodingModeLookup[$acmod]) ? $audioCodingModeLookup[$acmod] : false);
 572      }
 573  
 574      /**
 575       * @param int $cmixlev
 576       *
 577       * @return int|float|string|false
 578       */
 579  	public static function centerMixLevelLookup($cmixlev) {
 580          static $centerMixLevelLookup;
 581          if (empty($centerMixLevelLookup)) {
 582              $centerMixLevelLookup = array(
 583                  0 => pow(2, -3.0 / 6), // 0.707 (-3.0 dB)
 584                  1 => pow(2, -4.5 / 6), // 0.595 (-4.5 dB)
 585                  2 => pow(2, -6.0 / 6), // 0.500 (-6.0 dB)
 586                  3 => 'reserved'
 587              );
 588          }
 589          return (isset($centerMixLevelLookup[$cmixlev]) ? $centerMixLevelLookup[$cmixlev] : false);
 590      }
 591  
 592      /**
 593       * @param int $surmixlev
 594       *
 595       * @return int|float|string|false
 596       */
 597  	public static function surroundMixLevelLookup($surmixlev) {
 598          static $surroundMixLevelLookup;
 599          if (empty($surroundMixLevelLookup)) {
 600              $surroundMixLevelLookup = array(
 601                  0 => pow(2, -3.0 / 6),
 602                  1 => pow(2, -6.0 / 6),
 603                  2 => 0,
 604                  3 => 'reserved'
 605              );
 606          }
 607          return (isset($surroundMixLevelLookup[$surmixlev]) ? $surroundMixLevelLookup[$surmixlev] : false);
 608      }
 609  
 610      /**
 611       * @param int $dsurmod
 612       *
 613       * @return string|false
 614       */
 615  	public static function dolbySurroundModeLookup($dsurmod) {
 616          static $dolbySurroundModeLookup = array(
 617              0 => 'not indicated',
 618              1 => 'Not Dolby Surround encoded',
 619              2 => 'Dolby Surround encoded',
 620              3 => 'reserved'
 621          );
 622          return (isset($dolbySurroundModeLookup[$dsurmod]) ? $dolbySurroundModeLookup[$dsurmod] : false);
 623      }
 624  
 625      /**
 626       * @param int  $acmod
 627       * @param bool $lfeon
 628       *
 629       * @return array
 630       */
 631  	public static function channelsEnabledLookup($acmod, $lfeon) {
 632          $lookup = array(
 633              'ch1'=>($acmod == 0),
 634              'ch2'=>($acmod == 0),
 635              'left'=>($acmod > 1),
 636              'right'=>($acmod > 1),
 637              'center'=>(bool) ($acmod & 0x01),
 638              'surround_mono'=>false,
 639              'surround_left'=>false,
 640              'surround_right'=>false,
 641              'lfe'=>$lfeon);
 642          switch ($acmod) {
 643              case 4:
 644              case 5:
 645                  $lookup['surround_mono']  = true;
 646                  break;
 647              case 6:
 648              case 7:
 649                  $lookup['surround_left']  = true;
 650                  $lookup['surround_right'] = true;
 651                  break;
 652          }
 653          return $lookup;
 654      }
 655  
 656      /**
 657       * @param int $compre
 658       *
 659       * @return float|int
 660       */
 661  	public static function heavyCompression($compre) {
 662          // The first four bits indicate gain changes in 6.02dB increments which can be
 663          // implemented with an arithmetic shift operation. The following four bits
 664          // indicate linear gain changes, and require a 5-bit multiply.
 665          // We will represent the two 4-bit fields of compr as follows:
 666          //   X0 X1 X2 X3 . Y4 Y5 Y6 Y7
 667          // The meaning of the X values is most simply described by considering X to represent a 4-bit
 668          // signed integer with values from -8 to +7. The gain indicated by X is then (X + 1) * 6.02 dB. The
 669          // following table shows this in detail.
 670  
 671          // Meaning of 4 msb of compr
 672          //  7    +48.16 dB
 673          //  6    +42.14 dB
 674          //  5    +36.12 dB
 675          //  4    +30.10 dB
 676          //  3    +24.08 dB
 677          //  2    +18.06 dB
 678          //  1    +12.04 dB
 679          //  0     +6.02 dB
 680          // -1         0 dB
 681          // -2     -6.02 dB
 682          // -3    -12.04 dB
 683          // -4    -18.06 dB
 684          // -5    -24.08 dB
 685          // -6    -30.10 dB
 686          // -7    -36.12 dB
 687          // -8    -42.14 dB
 688  
 689          $fourbit = str_pad(decbin(($compre & 0xF0) >> 4), 4, '0', STR_PAD_LEFT);
 690          if ($fourbit[0] == '1') {
 691              $log_gain = -8 + bindec(substr($fourbit, 1));
 692          } else {
 693              $log_gain = bindec(substr($fourbit, 1));
 694          }
 695          $log_gain = ($log_gain + 1) * getid3_lib::RGADamplitude2dB(2);
 696  
 697          // The value of Y is a linear representation of a gain change of up to -6 dB. Y is considered to
 698          // be an unsigned fractional integer, with a leading value of 1, or: 0.1 Y4 Y5 Y6 Y7 (base 2). Y can
 699          // represent values between 0.111112 (or 31/32) and 0.100002 (or 1/2). Thus, Y can represent gain
 700          // changes from -0.28 dB to -6.02 dB.
 701  
 702          $lin_gain = (16 + ($compre & 0x0F)) / 32;
 703  
 704          // The combination of X and Y values allows compr to indicate gain changes from
 705          //  48.16 - 0.28 = +47.89 dB, to
 706          // -42.14 - 6.02 = -48.16 dB.
 707  
 708          return $log_gain - $lin_gain;
 709      }
 710  
 711      /**
 712       * @param int $roomtyp
 713       *
 714       * @return string|false
 715       */
 716  	public static function roomTypeLookup($roomtyp) {
 717          static $roomTypeLookup = array(
 718              0 => 'not indicated',
 719              1 => 'large room, X curve monitor',
 720              2 => 'small room, flat monitor',
 721              3 => 'reserved'
 722          );
 723          return (isset($roomTypeLookup[$roomtyp]) ? $roomTypeLookup[$roomtyp] : false);
 724      }
 725  
 726      /**
 727       * @param int $frmsizecod
 728       * @param int $fscod
 729       *
 730       * @return int|false
 731       */
 732  	public static function frameSizeLookup($frmsizecod, $fscod) {
 733          // LSB is whether padding is used or not
 734          $padding     = (bool) ($frmsizecod & 0x01);
 735          $framesizeid =        ($frmsizecod & 0x3E) >> 1;
 736  
 737          static $frameSizeLookup = array();
 738          if (empty($frameSizeLookup)) {
 739              $frameSizeLookup = array (
 740                  0  => array( 128,  138,  192),  //  32 kbps
 741                  1  => array( 160,  174,  240),  //  40 kbps
 742                  2  => array( 192,  208,  288),  //  48 kbps
 743                  3  => array( 224,  242,  336),  //  56 kbps
 744                  4  => array( 256,  278,  384),  //  64 kbps
 745                  5  => array( 320,  348,  480),  //  80 kbps
 746                  6  => array( 384,  416,  576),  //  96 kbps
 747                  7  => array( 448,  486,  672),  // 112 kbps
 748                  8  => array( 512,  556,  768),  // 128 kbps
 749                  9  => array( 640,  696,  960),  // 160 kbps
 750                  10 => array( 768,  834, 1152),  // 192 kbps
 751                  11 => array( 896,  974, 1344),  // 224 kbps
 752                  12 => array(1024, 1114, 1536),  // 256 kbps
 753                  13 => array(1280, 1392, 1920),  // 320 kbps
 754                  14 => array(1536, 1670, 2304),  // 384 kbps
 755                  15 => array(1792, 1950, 2688),  // 448 kbps
 756                  16 => array(2048, 2228, 3072),  // 512 kbps
 757                  17 => array(2304, 2506, 3456),  // 576 kbps
 758                  18 => array(2560, 2786, 3840)   // 640 kbps
 759              );
 760          }
 761          $paddingBytes = 0;
 762          if (($fscod == 1) && $padding) {
 763              // frame lengths are padded by 1 word (16 bits) at 44100
 764              // (fscode==1) means 44100Hz (see sampleRateCodeLookup)
 765              $paddingBytes = 2;
 766          }
 767          return (isset($frameSizeLookup[$framesizeid][$fscod]) ? $frameSizeLookup[$framesizeid][$fscod] + $paddingBytes : false);
 768      }
 769  
 770      /**
 771       * @param int $frmsizecod
 772       *
 773       * @return int|false
 774       */
 775  	public static function bitrateLookup($frmsizecod) {
 776          // LSB is whether padding is used or not
 777          $padding     = (bool) ($frmsizecod & 0x01);
 778          $framesizeid =        ($frmsizecod & 0x3E) >> 1;
 779  
 780          static $bitrateLookup = array(
 781               0 =>  32000,
 782               1 =>  40000,
 783               2 =>  48000,
 784               3 =>  56000,
 785               4 =>  64000,
 786               5 =>  80000,
 787               6 =>  96000,
 788               7 => 112000,
 789               8 => 128000,
 790               9 => 160000,
 791              10 => 192000,
 792              11 => 224000,
 793              12 => 256000,
 794              13 => 320000,
 795              14 => 384000,
 796              15 => 448000,
 797              16 => 512000,
 798              17 => 576000,
 799              18 => 640000,
 800          );
 801          return (isset($bitrateLookup[$framesizeid]) ? $bitrateLookup[$framesizeid] : false);
 802      }
 803  
 804      /**
 805       * @param int $numblkscod
 806       *
 807       * @return int|false
 808       */
 809  	public static function blocksPerSyncFrame($numblkscod) {
 810          static $blocksPerSyncFrameLookup = array(
 811              0 => 1,
 812              1 => 2,
 813              2 => 3,
 814              3 => 6,
 815          );
 816          return (isset($blocksPerSyncFrameLookup[$numblkscod]) ? $blocksPerSyncFrameLookup[$numblkscod] : false);
 817      }
 818  
 819  
 820  }


Generated: Wed Sep 18 01:00:03 2019 Cross-referenced by PHPXref 0.7.1