getid3_id3v1::Analyze

	/**
	 * @return bool
	 */
	public function Analyze() {
		$info = &$this->getid3->info;

		if (!getid3_lib::intValueSupported($info['filesize'])) {
			$this->warning('Unable to check for ID3v1 because file is larger than '.round(PHP_INT_MAX / 1073741824).'GB');
			return false;
		}

		$this->fseek(-256, SEEK_END);
		$preid3v1 = $this->fread(128);
		$id3v1tag = $this->fread(128);

		if (substr($id3v1tag, 0, 3) == 'TAG') {

			$info['avdataend'] = $info['filesize'] - 128;

			$ParsedID3v1['title']   = $this->cutfield(substr($id3v1tag,   3, 30));
			$ParsedID3v1['artist']  = $this->cutfield(substr($id3v1tag,  33, 30));
			$ParsedID3v1['album']   = $this->cutfield(substr($id3v1tag,  63, 30));
			$ParsedID3v1['year']    = $this->cutfield(substr($id3v1tag,  93,  4));
			$ParsedID3v1['comment'] =                 substr($id3v1tag,  97, 30);  // can't remove nulls yet, track detection depends on them
			$ParsedID3v1['genreid'] =             ord(substr($id3v1tag, 127,  1));

			// If second-last byte of comment field is null and last byte of comment field is non-null
			// then this is ID3v1.1 and the comment field is 28 bytes long and the 30th byte is the track number
			if (($id3v1tag[125] === "\x00") && ($id3v1tag[126] !== "\x00")) {
				$ParsedID3v1['track_number'] = ord(substr($ParsedID3v1['comment'], 29,  1));
				$ParsedID3v1['comment']      =     substr($ParsedID3v1['comment'],  0, 28);
			}
			$ParsedID3v1['comment'] = $this->cutfield($ParsedID3v1['comment']);

			$ParsedID3v1['genre'] = $this->LookupGenreName($ParsedID3v1['genreid']);
			if (!empty($ParsedID3v1['genre'])) {
				unset($ParsedID3v1['genreid']);
			}
			if (isset($ParsedID3v1['genre']) && (empty($ParsedID3v1['genre']) || ($ParsedID3v1['genre'] == 'Unknown'))) {
				unset($ParsedID3v1['genre']);
			}

			foreach ($ParsedID3v1 as $key => $value) {
				$ParsedID3v1['comments'][$key][0] = $value;
			}
			$ID3v1encoding = $this->getid3->encoding_id3v1;
			if ($this->getid3->encoding_id3v1_autodetect) {
				// ID3v1 encoding detection hack START
				// ID3v1 is defined as always using ISO-8859-1 encoding, but it is not uncommon to find files tagged with ID3v1 using Windows-1251 or other character sets
				// Since ID3v1 has no concept of character sets there is no certain way to know we have the correct non-ISO-8859-1 character set, but we can guess
				foreach ($ParsedID3v1['comments'] as $tag_key => $valuearray) {
					foreach ($valuearray as $key => $value) {
						if (preg_match('#^[\\x00-\\x40\\x80-\\xFF]+$#', $value) && !ctype_digit((string) $value)) { // check for strings with only characters above chr(128) and punctuation/numbers, but not just numeric strings (e.g. track numbers or years)
							foreach (array('Windows-1251', 'KOI8-R') as $id3v1_bad_encoding) {
								if (function_exists('mb_convert_encoding') && @mb_convert_encoding($value, $id3v1_bad_encoding, $id3v1_bad_encoding) === $value) {
									$ID3v1encoding = $id3v1_bad_encoding;
									$this->warning('ID3v1 detected as '.$id3v1_bad_encoding.' text encoding in '.$tag_key);
									break 3;
								} elseif (function_exists('iconv') && @iconv($id3v1_bad_encoding, $id3v1_bad_encoding, $value) === $value) {
									$ID3v1encoding = $id3v1_bad_encoding;
									$this->warning('ID3v1 detected as '.$id3v1_bad_encoding.' text encoding in '.$tag_key);
									break 3;
								}
							}
						}
					}
				}
				// ID3v1 encoding detection hack END
			}

			// ID3v1 data is supposed to be padded with NULL characters, but some taggers pad with spaces
			$GoodFormatID3v1tag = $this->GenerateID3v1Tag(
											$ParsedID3v1['title'],
											$ParsedID3v1['artist'],
											$ParsedID3v1['album'],
											$ParsedID3v1['year'],
											(isset($ParsedID3v1['genre']) ? $this->LookupGenreID($ParsedID3v1['genre']) : false),
											$ParsedID3v1['comment'],
											(!empty($ParsedID3v1['track_number']) ? $ParsedID3v1['track_number'] : ''));
			$ParsedID3v1['padding_valid'] = true;
			if ($id3v1tag !== $GoodFormatID3v1tag) {
				$ParsedID3v1['padding_valid'] = false;
				$this->warning('Some ID3v1 fields do not use NULL characters for padding');
			}

			$ParsedID3v1['tag_offset_end']   = $info['filesize'];
			$ParsedID3v1['tag_offset_start'] = $ParsedID3v1['tag_offset_end'] - 128;

			$info['id3v1'] = $ParsedID3v1;
			$info['id3v1']['encoding'] = $ID3v1encoding;
		}

		if (substr($preid3v1, 0, 3) == 'TAG') {
			// The way iTunes handles tags is, well, brain-damaged.
			// It completely ignores v1 if ID3v2 is present.
			// This goes as far as adding a new v1 tag *even if there already is one*

			// A suspected double-ID3v1 tag has been detected, but it could be that
			// the "TAG" identifier is a legitimate part of an APE or Lyrics3 tag
			if (substr($preid3v1, 96, 8) == 'APETAGEX') {
				// an APE tag footer was found before the last ID3v1, assume false "TAG" synch
			} elseif (substr($preid3v1, 119, 6) == 'LYRICS') {
				// a Lyrics3 tag footer was found before the last ID3v1, assume false "TAG" synch
			} else {
				// APE and Lyrics3 footers not found - assume double ID3v1