getid3_flac::parseMETAdata

	 * @return bool
	 */
	public function parseMETAdata() {
		$info = &$this->getid3->info;
		do {
			$BlockOffset   = $this->ftell();
			$BlockHeader   = $this->fread(4);
			$LBFBT         = getid3_lib::BigEndian2Int(substr($BlockHeader, 0, 1));  // LBFBT = LastBlockFlag + BlockType
			$LastBlockFlag = (bool) ($LBFBT & 0x80);
			$BlockType     =        ($LBFBT & 0x7F);
			$BlockLength   = getid3_lib::BigEndian2Int(substr($BlockHeader, 1, 3));
			$BlockTypeText = self::metaBlockTypeLookup($BlockType);

			if (($BlockOffset + 4 + $BlockLength) > $info['avdataend']) {
				$this->warning('METADATA_BLOCK_HEADER.BLOCK_TYPE ('.$BlockTypeText.') at offset '.$BlockOffset.' extends beyond end of file');
				break;
			}
			if ($BlockLength < 1) {
				if ($BlockTypeText != 'reserved') {
					// probably supposed to be zero-length
					$this->warning('METADATA_BLOCK_HEADER.BLOCK_LENGTH ('.$BlockTypeText.') at offset '.$BlockOffset.' is zero bytes');
					continue;
				}
				$this->error('METADATA_BLOCK_HEADER.BLOCK_LENGTH ('.$BlockLength.') at offset '.$BlockOffset.' is invalid');
				break;
			}

			$info['flac'][$BlockTypeText]['raw'] = array();
			$BlockTypeText_raw = &$info['flac'][$BlockTypeText]['raw'];

			$BlockTypeText_raw['offset']          = $BlockOffset;
			$BlockTypeText_raw['last_meta_block'] = $LastBlockFlag;
			$BlockTypeText_raw['block_type']      = $BlockType;
			$BlockTypeText_raw['block_type_text'] = $BlockTypeText;
			$BlockTypeText_raw['block_length']    = $BlockLength;
			if ($BlockTypeText_raw['block_type'] != 0x06) { // do not read attachment data automatically
				$BlockTypeText_raw['block_data']  = $this->fread($BlockLength);
			}

			switch ($BlockTypeText) {
				case 'STREAMINFO':     // 0x00
					if (!$this->parseSTREAMINFO($BlockTypeText_raw['block_data'])) {
						return false;
					}
					break;

				case 'PADDING':        // 0x01
					unset($info['flac']['PADDING']); // ignore
					break;

				case 'APPLICATION':    // 0x02
					if (!$this->parseAPPLICATION($BlockTypeText_raw['block_data'])) {
						return false;
					}
					break;

				case 'SEEKTABLE':      // 0x03
					if (!$this->parseSEEKTABLE($BlockTypeText_raw['block_data'])) {
						return false;
					}
					break;

				case 'VORBIS_COMMENT': // 0x04
					if (!$this->parseVORBIS_COMMENT($BlockTypeText_raw['block_data'])) {
						return false;
					}
					break;

				case 'CUESHEET':       // 0x05
					if (!$this->parseCUESHEET($BlockTypeText_raw['block_data'])) {
						return false;
					}
					break;

				case 'PICTURE':        // 0x06
					if (!$this->parsePICTURE()) {
						return false;
					}
					break;

				default:
					$this->warning('Unhandled METADATA_BLOCK_HEADER.BLOCK_TYPE ('.$BlockType.') at offset '.$BlockOffset);
			}

			unset($info['flac'][$BlockTypeText]['raw']);
			$info['avdataoffset'] = $this->ftell();
		}
		while ($LastBlockFlag === false);

		// handle tags
		if (!empty($info['flac']['VORBIS_COMMENT']['comments'])) {
			$info['flac']['comments'] = $info['flac']['VORBIS_COMMENT']['comments'];
		}
		if (!empty($info['flac']['VORBIS_COMMENT']['vendor'])) {
			$info['audio']['encoder'] = str_replace('reference ', '', $info['flac']['VORBIS_COMMENT']['vendor']);
		}

		// copy attachments to 'comments' array if nesesary
		if (isset($info['flac']['PICTURE']) && ($this->getid3->option_save_attachments !== getID3::ATTACHMENTS_NONE)) {
			foreach ($info['flac']['PICTURE'] as $entry) {
				if (!empty($entry['data'])) {
					if (!isset($info['flac']['comments']['picture'])) {
						$info['flac']['comments']['picture'] = array();
					}
					$comments_picture_data = array();
					foreach (array('data', 'image_mime', 'image_width', 'image_height', 'imagetype', 'picturetype', 'description', 'datalength') as $picture_key) {
						if (isset($entry[$picture_key])) {
							$comments_picture_data[$picture_key] = $entry[$picture_key];
						}
					}
					$info['flac']['comments']['picture'][] = $comments_picture_data;
					unset($comments_picture_data);
				}
			}
		}

		if (isset($info['flac']['STREAMINFO'])) {
			if (!$this->isDependencyFor('matroska')) {
				$info['flac']['compressed_audio_bytes'] = $info['avdataend'] - $info['avdataoffset'];
			}
			$info['flac']['uncompressed_audio_bytes'] = $info['flac']['STREAMINFO']['samples_stream'] * $info['flac']['STREAMINFO']['channels'] * ($info['flac']['STREAMINFO']['bits_per_sample'] / 8);
			if ($info['flac']['uncompressed_audio_bytes'] == 0) {
				return $this->error('Corrupt FLAC file: uncompressed_audio_bytes == zero');
			}
			if (!empty($info['flac']['compressed_audio_bytes'])) {
				$info['flac']['compression_ratio'] = $info['flac']['compressed_audio_bytes'] / $info['flac']['uncompressed_audio_bytes'];
			}
		}

		// set md5_data_source - built into flac 0.5+
		if (isset($info['flac']['STREAMINFO']['audio_signature'])) {

			if ($info['flac']['STREAMINFO']['audio_signature'] === str_repeat("\x00", 16)) {
				$this->warning('FLAC STREAMINFO.audio_signature is null (known issue with libOggFLAC)');
			}
			else {
				$info['md5_data_source'] = '';
				$md5 = $info['flac']['STREAMINFO']['audio_signature'];
				for ($i = 0; $i < strlen($md5); $i++) {
					$info['md5_data_source'] .= str_pad(dechex(ord($md5[$i])), 2, '00', STR_PAD_LEFT);
				}
				if (!preg_match('/^[0-9a-f]{32}$/', $info['md5_data_source'])) {
					unset($info['md5_data_source']);
				}
			}
		}

		if (isset($info['flac']['STREAMINFO']['bits_per_sample'])) {
			$info['audio']['bits_per_sample'] = $info['flac']['STREAMINFO']['bits_per_sample'];
			if ($info['audio']['bits_per_sample'] == 8) {
				// special case
				// must invert sign bit on all data bytes before MD5'ing to match FLAC's calculated value
				// MD5sum calculates on unsigned bytes, but FLAC calculated MD5 on 8-bit audio data as signed
				$this->warning('FLAC calculates MD5 data strangely on 8-bit audio, so the stored md5_data_source value will not match the decoded WAV file');
			}
		}