www/plugins-dist/medias/lib/getid3/module.audio.wavpack.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.wavpack.php                                    //
  12 // module for analyzing WavPack v4.0+ Audio files              //
  13 // dependencies: NONE                                          //
  14 //                                                            ///
  15 /////////////////////////////////////////////////////////////////
  16
  17
  18 class getid3_wavpack extends getid3_handler
  19 {
  20
  21         public function Analyze() {
  22                 $info = &$this->getid3->info;
  23
  24                 $this->fseek($info['avdataoffset']);
  25
  26                 while (true) {
  27
  28                         $wavpackheader = $this->fread(32);
  29
  30                         if ($this->ftell() >= $info['avdataend']) {
  31                                 break;
  32                         } elseif (feof($this->getid3->fp)) {
  33                                 break;
  34                         } elseif (
  35                                 isset($info['wavpack']['blockheader']['total_samples']) &&
  36                                 isset($info['wavpack']['blockheader']['block_samples']) &&
  37                                 ($info['wavpack']['blockheader']['total_samples'] > 0) &&
  38                                 ($info['wavpack']['blockheader']['block_samples'] > 0) &&
  39                                 (!isset($info['wavpack']['riff_trailer_size']) || ($info['wavpack']['riff_trailer_size'] <= 0)) &&
  40                                 ((isset($info['wavpack']['config_flags']['md5_checksum']) && ($info['wavpack']['config_flags']['md5_checksum'] === false)) || !empty($info['md5_data_source']))) {
  41                                         break;
  42                         }
  43
  44                         $blockheader_offset = $this->ftell() - 32;
  45                         $blockheader_magic  =                              substr($wavpackheader,  0,  4);
  46                         $blockheader_size   = getid3_lib::LittleEndian2Int(substr($wavpackheader,  4,  4));
  47
  48                         $magic = 'wvpk';
  49                         if ($blockheader_magic != $magic) {
  50                                 $this->error('Expecting "'.getid3_lib::PrintHexBytes($magic).'" at offset '.$blockheader_offset.', found "'.getid3_lib::PrintHexBytes($blockheader_magic).'"');
  51                                 switch (isset($info['audio']['dataformat']) ? $info['audio']['dataformat'] : '') {
  52                                         case 'wavpack':
  53                                         case 'wvc':
  54                                                 break;
  55                                         default:
  56                                                 unset($info['fileformat']);
  57                                                 unset($info['audio']);
  58                                                 unset($info['wavpack']);
  59                                                 break;
  60                                 }
  61                                 return false;
  62                         }
  63
  64                         if (empty($info['wavpack']['blockheader']['block_samples']) ||
  65                                 empty($info['wavpack']['blockheader']['total_samples']) ||
  66                                 ($info['wavpack']['blockheader']['block_samples'] <= 0) ||
  67                                 ($info['wavpack']['blockheader']['total_samples'] <= 0)) {
  68                                 // Also, it is possible that the first block might not have
  69                                 // any samples (block_samples == 0) and in this case you should skip blocks
  70                                 // until you find one with samples because the other information (like
  71                                 // total_samples) are not guaranteed to be correct until (block_samples > 0)
  72
  73                                 // Finally, I have defined a format for files in which the length is not known
  74                                 // (for example when raw files are created using pipes). In these cases
  75                                 // total_samples will be -1 and you must seek to the final block to determine
  76                                 // the total number of samples.
  77
  78
  79                                 $info['audio']['dataformat']   = 'wavpack';
  80                                 $info['fileformat']            = 'wavpack';
  81                                 $info['audio']['lossless']     = true;
  82                                 $info['audio']['bitrate_mode'] = 'vbr';
  83
  84                                 $info['wavpack']['blockheader']['offset'] = $blockheader_offset;
  85                                 $info['wavpack']['blockheader']['magic']  = $blockheader_magic;
  86                                 $info['wavpack']['blockheader']['size']   = $blockheader_size;
  87
  88                                 if ($info['wavpack']['blockheader']['size'] >= 0x100000) {
  89                                         $this->error('Expecting WavPack block size less than "0x100000", found "'.$info['wavpack']['blockheader']['size'].'" at offset '.$info['wavpack']['blockheader']['offset']);
  90                                         switch (isset($info['audio']['dataformat']) ? $info['audio']['dataformat'] : '') {
  91                                                 case 'wavpack':
  92                                                 case 'wvc':
  93                                                         break;
  94                                                 default:
  95                                                         unset($info['fileformat']);
  96                                                         unset($info['audio']);
  97                                                         unset($info['wavpack']);
  98                                                         break;
  99                                         }
 100                                         return false;
 101                                 }
 102
 103                                 $info['wavpack']['blockheader']['minor_version'] = ord($wavpackheader{8});
 104                                 $info['wavpack']['blockheader']['major_version'] = ord($wavpackheader{9});
 105
 106                                 if (($info['wavpack']['blockheader']['major_version'] != 4) ||
 107                                         (($info['wavpack']['blockheader']['minor_version'] < 4) &&
 108                                         ($info['wavpack']['blockheader']['minor_version'] > 16))) {
 109                                                 $this->error('Expecting WavPack version between "4.2" and "4.16", found version "'.$info['wavpack']['blockheader']['major_version'].'.'.$info['wavpack']['blockheader']['minor_version'].'" at offset '.$info['wavpack']['blockheader']['offset']);
 110                                                 switch (isset($info['audio']['dataformat']) ? $info['audio']['dataformat'] : '') {
 111                                                         case 'wavpack':
 112                                                         case 'wvc':
 113                                                                 break;
 114                                                         default:
 115                                                                 unset($info['fileformat']);
 116                                                                 unset($info['audio']);
 117                                                                 unset($info['wavpack']);
 118                                                                 break;
 119                                                 }
 120                                                 return false;
 121                                 }
 122
 123                                 $info['wavpack']['blockheader']['track_number']  = ord($wavpackheader{10}); // unused
 124                                 $info['wavpack']['blockheader']['index_number']  = ord($wavpackheader{11}); // unused
 125                                 $info['wavpack']['blockheader']['total_samples'] = getid3_lib::LittleEndian2Int(substr($wavpackheader, 12,  4));
 126                                 $info['wavpack']['blockheader']['block_index']   = getid3_lib::LittleEndian2Int(substr($wavpackheader, 16,  4));
 127                                 $info['wavpack']['blockheader']['block_samples'] = getid3_lib::LittleEndian2Int(substr($wavpackheader, 20,  4));
 128                                 $info['wavpack']['blockheader']['flags_raw']     = getid3_lib::LittleEndian2Int(substr($wavpackheader, 24,  4));
 129                                 $info['wavpack']['blockheader']['crc']           = getid3_lib::LittleEndian2Int(substr($wavpackheader, 28,  4));
 130
 131                                 $info['wavpack']['blockheader']['flags']['bytes_per_sample']     =    1 + ($info['wavpack']['blockheader']['flags_raw'] & 0x00000003);
 132                                 $info['wavpack']['blockheader']['flags']['mono']                 = (bool) ($info['wavpack']['blockheader']['flags_raw'] & 0x00000004);
 133                                 $info['wavpack']['blockheader']['flags']['hybrid']               = (bool) ($info['wavpack']['blockheader']['flags_raw'] & 0x00000008);
 134                                 $info['wavpack']['blockheader']['flags']['joint_stereo']         = (bool) ($info['wavpack']['blockheader']['flags_raw'] & 0x00000010);
 135                                 $info['wavpack']['blockheader']['flags']['cross_decorrelation']  = (bool) ($info['wavpack']['blockheader']['flags_raw'] & 0x00000020);
 136                                 $info['wavpack']['blockheader']['flags']['hybrid_noiseshape']    = (bool) ($info['wavpack']['blockheader']['flags_raw'] & 0x00000040);
 137                                 $info['wavpack']['blockheader']['flags']['ieee_32bit_float']     = (bool) ($info['wavpack']['blockheader']['flags_raw'] & 0x00000080);
 138                                 $info['wavpack']['blockheader']['flags']['int_32bit']            = (bool) ($info['wavpack']['blockheader']['flags_raw'] & 0x00000100);
 139                                 $info['wavpack']['blockheader']['flags']['hybrid_bitrate_noise'] = (bool) ($info['wavpack']['blockheader']['flags_raw'] & 0x00000200);
 140                                 $info['wavpack']['blockheader']['flags']['hybrid_balance_noise'] = (bool) ($info['wavpack']['blockheader']['flags_raw'] & 0x00000400);
 141                                 $info['wavpack']['blockheader']['flags']['multichannel_initial'] = (bool) ($info['wavpack']['blockheader']['flags_raw'] & 0x00000800);
 142                                 $info['wavpack']['blockheader']['flags']['multichannel_final']   = (bool) ($info['wavpack']['blockheader']['flags_raw'] & 0x00001000);
 143
 144                                 $info['audio']['lossless'] = !$info['wavpack']['blockheader']['flags']['hybrid'];
 145                         }
 146
 147                         while (!feof($this->getid3->fp) && ($this->ftell() < ($blockheader_offset + $blockheader_size + 8))) {
 148
 149                                 $metablock = array('offset'=>$this->ftell());
 150                                 $metablockheader = $this->fread(2);
 151                                 if (feof($this->getid3->fp)) {
 152                                         break;
 153                                 }
 154                                 $metablock['id'] = ord($metablockheader{0});
 155                                 $metablock['function_id'] = ($metablock['id'] & 0x3F);
 156                                 $metablock['function_name'] = $this->WavPackMetablockNameLookup($metablock['function_id']);
 157
 158                                 // The 0x20 bit in the id of the meta subblocks (which is defined as
 159                                 // ID_OPTIONAL_DATA) is a permanent part of the id. The idea is that
 160                                 // if a decoder encounters an id that it does not know about, it uses
 161                                 // that "ID_OPTIONAL_DATA" flag to determine what to do. If it is set
 162                                 // then the decoder simply ignores the metadata, but if it is zero
 163                                 // then the decoder should quit because it means that an understanding
 164                                 // of the metadata is required to correctly decode the audio.
 165                                 $metablock['non_decoder'] = (bool) ($metablock['id'] & 0x20);
 166
 167                                 $metablock['padded_data'] = (bool) ($metablock['id'] & 0x40);
 168                                 $metablock['large_block'] = (bool) ($metablock['id'] & 0x80);
 169                                 if ($metablock['large_block']) {
 170                                         $metablockheader .= $this->fread(2);
 171                                 }
 172                                 $metablock['size'] = getid3_lib::LittleEndian2Int(substr($metablockheader, 1)) * 2; // size is stored in words
 173                                 $metablock['data'] = null;
 174
 175                                 if ($metablock['size'] > 0) {
 176
 177                                         switch ($metablock['function_id']) {
 178                                                 case 0x21: // ID_RIFF_HEADER
 179                                                 case 0x22: // ID_RIFF_TRAILER
 180                                                 case 0x23: // ID_REPLAY_GAIN
 181                                                 case 0x24: // ID_CUESHEET
 182                                                 case 0x25: // ID_CONFIG_BLOCK
 183                                                 case 0x26: // ID_MD5_CHECKSUM
 184                                                         $metablock['data'] = $this->fread($metablock['size']);
 185
 186                                                         if ($metablock['padded_data']) {
 187                                                                 // padded to the nearest even byte
 188                                                                 $metablock['size']--;
 189                                                                 $metablock['data'] = substr($metablock['data'], 0, -1);
 190                                                         }
 191                                                         break;
 192
 193                                                 case 0x00: // ID_DUMMY
 194                                                 case 0x01: // ID_ENCODER_INFO
 195                                                 case 0x02: // ID_DECORR_TERMS
 196                                                 case 0x03: // ID_DECORR_WEIGHTS
 197                                                 case 0x04: // ID_DECORR_SAMPLES
 198                                                 case 0x05: // ID_ENTROPY_VARS
 199                                                 case 0x06: // ID_HYBRID_PROFILE
 200                                                 case 0x07: // ID_SHAPING_WEIGHTS
 201                                                 case 0x08: // ID_FLOAT_INFO
 202                                                 case 0x09: // ID_INT32_INFO
 203                                                 case 0x0A: // ID_WV_BITSTREAM
 204                                                 case 0x0B: // ID_WVC_BITSTREAM
 205                                                 case 0x0C: // ID_WVX_BITSTREAM
 206                                                 case 0x0D: // ID_CHANNEL_INFO
 207                                                         $this->fseek($metablock['offset'] + ($metablock['large_block'] ? 4 : 2) + $metablock['size']);
 208                                                         break;
 209
 210                                                 default:
 211                                                         $this->warning('Unexpected metablock type "0x'.str_pad(dechex($metablock['function_id']), 2, '0', STR_PAD_LEFT).'" at offset '.$metablock['offset']);
 212                                                         $this->fseek($metablock['offset'] + ($metablock['large_block'] ? 4 : 2) + $metablock['size']);
 213                                                         break;
 214                                         }
 215
 216                                         switch ($metablock['function_id']) {
 217                                                 case 0x21: // ID_RIFF_HEADER
 218                                                         getid3_lib::IncludeDependency(GETID3_INCLUDEPATH.'module.audio-video.riff.php', __FILE__, true);
 219                                                         $original_wav_filesize = getid3_lib::LittleEndian2Int(substr($metablock['data'], 4, 4));
 220
 221                                                         $getid3_temp = new getID3();
 222                                                         $getid3_temp->openfile($this->getid3->filename);
 223                                                         $getid3_riff = new getid3_riff($getid3_temp);
 224                                                         $getid3_riff->ParseRIFFdata($metablock['data']);
 225                                                         $metablock['riff']            = $getid3_temp->info['riff'];
 226                                                         $info['audio']['sample_rate'] = $getid3_temp->info['riff']['raw']['fmt ']['nSamplesPerSec'];
 227                                                         unset($getid3_riff, $getid3_temp);
 228
 229                                                         $metablock['riff']['original_filesize'] = $original_wav_filesize;
 230                                                         $info['wavpack']['riff_trailer_size'] = $original_wav_filesize - $metablock['riff']['WAVE']['data'][0]['size'] - $metablock['riff']['header_size'];
 231                                                         $info['playtime_seconds'] = $info['wavpack']['blockheader']['total_samples'] / $info['audio']['sample_rate'];
 232
 233                                                         // Safe RIFF header in case there's a RIFF footer later
 234                                                         $metablockRIFFheader = $metablock['data'];
 235                                                         break;
 236
 237
 238                                                 case 0x22: // ID_RIFF_TRAILER
 239                                                         $metablockRIFFfooter = $metablockRIFFheader.$metablock['data'];
 240                                                         getid3_lib::IncludeDependency(GETID3_INCLUDEPATH.'module.audio-video.riff.php', __FILE__, true);
 241
 242                                                         $startoffset = $metablock['offset'] + ($metablock['large_block'] ? 4 : 2);
 243                                                         $getid3_temp = new getID3();
 244                                                         $getid3_temp->openfile($this->getid3->filename);
 245                                                         $getid3_temp->info['avdataend']  = $info['avdataend'];
 246                                                         //$getid3_temp->info['fileformat'] = 'riff';
 247                                                         $getid3_riff = new getid3_riff($getid3_temp);
 248                                                         $metablock['riff'] = $getid3_riff->ParseRIFF($startoffset, $startoffset + $metablock['size']);
 249
 250                                                         if (!empty($metablock['riff']['INFO'])) {
 251                                                                 getid3_riff::parseComments($metablock['riff']['INFO'], $metablock['comments']);
 252                                                                 $info['tags']['riff'] = $metablock['comments'];
 253                                                         }
 254                                                         unset($getid3_temp, $getid3_riff);
 255                                                         break;
 256
 257
 258                                                 case 0x23: // ID_REPLAY_GAIN
 259                                                         $this->warning('WavPack "Replay Gain" contents not yet handled by getID3() in metablock at offset '.$metablock['offset']);
 260                                                         break;
 261
 262
 263                                                 case 0x24: // ID_CUESHEET
 264                                                         $this->warning('WavPack "Cuesheet" contents not yet handled by getID3() in metablock at offset '.$metablock['offset']);
 265                                                         break;
 266
 267
 268                                                 case 0x25: // ID_CONFIG_BLOCK
 269                                                         $metablock['flags_raw'] = getid3_lib::LittleEndian2Int(substr($metablock['data'], 0, 3));
 270
 271                                                         $metablock['flags']['adobe_mode']     = (bool) ($metablock['flags_raw'] & 0x000001); // "adobe" mode for 32-bit floats
 272                                                         $metablock['flags']['fast_flag']      = (bool) ($metablock['flags_raw'] & 0x000002); // fast mode
 273                                                         $metablock['flags']['very_fast_flag'] = (bool) ($metablock['flags_raw'] & 0x000004); // double fast
 274                                                         $metablock['flags']['high_flag']      = (bool) ($metablock['flags_raw'] & 0x000008); // high quality mode
 275                                                         $metablock['flags']['very_high_flag'] = (bool) ($metablock['flags_raw'] & 0x000010); // double high (not used yet)
 276                                                         $metablock['flags']['bitrate_kbps']   = (bool) ($metablock['flags_raw'] & 0x000020); // bitrate is kbps, not bits / sample
 277                                                         $metablock['flags']['auto_shaping']   = (bool) ($metablock['flags_raw'] & 0x000040); // automatic noise shaping
 278                                                         $metablock['flags']['shape_override'] = (bool) ($metablock['flags_raw'] & 0x000080); // shaping mode specified
 279                                                         $metablock['flags']['joint_override'] = (bool) ($metablock['flags_raw'] & 0x000100); // joint-stereo mode specified
 280                                                         $metablock['flags']['copy_time']      = (bool) ($metablock['flags_raw'] & 0x000200); // copy file-time from source
 281                                                         $metablock['flags']['create_exe']     = (bool) ($metablock['flags_raw'] & 0x000400); // create executable
 282                                                         $metablock['flags']['create_wvc']     = (bool) ($metablock['flags_raw'] & 0x000800); // create correction file
 283                                                         $metablock['flags']['optimize_wvc']   = (bool) ($metablock['flags_raw'] & 0x001000); // maximize bybrid compression
 284                                                         $metablock['flags']['quality_mode']   = (bool) ($metablock['flags_raw'] & 0x002000); // psychoacoustic quality mode
 285                                                         $metablock['flags']['raw_flag']       = (bool) ($metablock['flags_raw'] & 0x004000); // raw mode (not implemented yet)
 286                                                         $metablock['flags']['calc_noise']     = (bool) ($metablock['flags_raw'] & 0x008000); // calc noise in hybrid mode
 287                                                         $metablock['flags']['lossy_mode']     = (bool) ($metablock['flags_raw'] & 0x010000); // obsolete (for information)
 288                                                         $metablock['flags']['extra_mode']     = (bool) ($metablock['flags_raw'] & 0x020000); // extra processing mode
 289                                                         $metablock['flags']['skip_wvx']       = (bool) ($metablock['flags_raw'] & 0x040000); // no wvx stream w/ floats & big ints
 290                                                         $metablock['flags']['md5_checksum']   = (bool) ($metablock['flags_raw'] & 0x080000); // compute & store MD5 signature
 291                                                         $metablock['flags']['quiet_mode']     = (bool) ($metablock['flags_raw'] & 0x100000); // don't report progress %
 292
 293                                                         $info['wavpack']['config_flags'] = $metablock['flags'];
 294
 295
 296                                                         $info['audio']['encoder_options'] = '';
 297                                                         if ($info['wavpack']['blockheader']['flags']['hybrid']) {
 298                                                                 $info['audio']['encoder_options'] .= ' -b???';
 299                                                         }
 300                                                         $info['audio']['encoder_options'] .= ($metablock['flags']['adobe_mode']     ? ' -a' : '');
 301                                                         $info['audio']['encoder_options'] .= ($metablock['flags']['optimize_wvc']   ? ' -cc' : '');
 302                                                         $info['audio']['encoder_options'] .= ($metablock['flags']['create_exe']     ? ' -e' : '');
 303                                                         $info['audio']['encoder_options'] .= ($metablock['flags']['fast_flag']      ? ' -f' : '');
 304                                                         $info['audio']['encoder_options'] .= ($metablock['flags']['joint_override'] ? ' -j?' : '');
 305                                                         $info['audio']['encoder_options'] .= ($metablock['flags']['high_flag']      ? ' -h' : '');
 306                                                         $info['audio']['encoder_options'] .= ($metablock['flags']['md5_checksum']   ? ' -m' : '');
 307                                                         $info['audio']['encoder_options'] .= ($metablock['flags']['calc_noise']     ? ' -n' : '');
 308                                                         $info['audio']['encoder_options'] .= ($metablock['flags']['shape_override'] ? ' -s?' : '');
 309                                                         $info['audio']['encoder_options'] .= ($metablock['flags']['extra_mode']     ? ' -x?' : '');
 310                                                         if (!empty($info['audio']['encoder_options'])) {
 311                                                                 $info['audio']['encoder_options'] = trim($info['audio']['encoder_options']);
 312                                                         } elseif (isset($info['audio']['encoder_options'])) {
 313                                                                 unset($info['audio']['encoder_options']);
 314                                                         }
 315                                                         break;
 316
 317
 318                                                 case 0x26: // ID_MD5_CHECKSUM
 319                                                         if (strlen($metablock['data']) == 16) {
 320                                                                 $info['md5_data_source'] = strtolower(getid3_lib::PrintHexBytes($metablock['data'], true, false, false));
 321                                                         } else {
 322                                                                 $this->warning('Expecting 16 bytes of WavPack "MD5 Checksum" in metablock at offset '.$metablock['offset'].', but found '.strlen($metablock['data']).' bytes');
 323                                                         }
 324                                                         break;
 325
 326
 327                                                 case 0x00: // ID_DUMMY
 328                                                 case 0x01: // ID_ENCODER_INFO
 329                                                 case 0x02: // ID_DECORR_TERMS
 330                                                 case 0x03: // ID_DECORR_WEIGHTS
 331                                                 case 0x04: // ID_DECORR_SAMPLES
 332                                                 case 0x05: // ID_ENTROPY_VARS
 333                                                 case 0x06: // ID_HYBRID_PROFILE
 334                                                 case 0x07: // ID_SHAPING_WEIGHTS
 335                                                 case 0x08: // ID_FLOAT_INFO
 336                                                 case 0x09: // ID_INT32_INFO
 337                                                 case 0x0A: // ID_WV_BITSTREAM
 338                                                 case 0x0B: // ID_WVC_BITSTREAM
 339                                                 case 0x0C: // ID_WVX_BITSTREAM
 340                                                 case 0x0D: // ID_CHANNEL_INFO
 341                                                         unset($metablock);
 342                                                         break;
 343                                         }
 344
 345                                 }
 346                                 if (!empty($metablock)) {
 347                                         $info['wavpack']['metablocks'][] = $metablock;
 348                                 }
 349
 350                         }
 351
 352                 }
 353
 354                 $info['audio']['encoder']         = 'WavPack v'.$info['wavpack']['blockheader']['major_version'].'.'.str_pad($info['wavpack']['blockheader']['minor_version'], 2, '0', STR_PAD_LEFT);
 355                 $info['audio']['bits_per_sample'] = $info['wavpack']['blockheader']['flags']['bytes_per_sample'] * 8;
 356                 $info['audio']['channels']        = ($info['wavpack']['blockheader']['flags']['mono'] ? 1 : 2);
 357
 358                 if (!empty($info['playtime_seconds'])) {
 359
 360                         $info['audio']['bitrate']     = (($info['avdataend'] - $info['avdataoffset']) * 8) / $info['playtime_seconds'];
 361
 362                 } else {
 363
 364                         $info['audio']['dataformat']  = 'wvc';
 365
 366                 }
 367
 368                 return true;
 369         }
 370
 371
 372         public function WavPackMetablockNameLookup(&$id) {
 373                 static $WavPackMetablockNameLookup = array(
 374                         0x00 => 'Dummy',
 375                         0x01 => 'Encoder Info',
 376                         0x02 => 'Decorrelation Terms',
 377                         0x03 => 'Decorrelation Weights',
 378                         0x04 => 'Decorrelation Samples',
 379                         0x05 => 'Entropy Variables',
 380                         0x06 => 'Hybrid Profile',
 381                         0x07 => 'Shaping Weights',
 382                         0x08 => 'Float Info',
 383                         0x09 => 'Int32 Info',
 384                         0x0A => 'WV Bitstream',
 385                         0x0B => 'WVC Bitstream',
 386                         0x0C => 'WVX Bitstream',
 387                         0x0D => 'Channel Info',
 388                         0x21 => 'RIFF header',
 389                         0x22 => 'RIFF trailer',
 390                         0x23 => 'Replay Gain',
 391                         0x24 => 'Cuesheet',
 392                         0x25 => 'Config Block',
 393                         0x26 => 'MD5 Checksum',
 394                 );
 395                 return (isset($WavPackMetablockNameLookup[$id]) ? $WavPackMetablockNameLookup[$id] : '');
 396         }
 397
 398 }