getid3_mp3::Analyze

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

		$initialOffset = $info['avdataoffset'];

		if (!$this->getOnlyMPEGaudioInfo($info['avdataoffset'])) {
			if ($this->allow_bruteforce) {
				$this->error('Rescanning file in BruteForce mode');
				$this->getOnlyMPEGaudioInfoBruteForce();
			}
		}


		if (isset($info['mpeg']['audio']['bitrate_mode'])) {
			$info['audio']['bitrate_mode'] = strtolower($info['mpeg']['audio']['bitrate_mode']);
		}

		if (((isset($info['id3v2']['headerlength']) && ($info['avdataoffset'] > $info['id3v2']['headerlength'])) || (!isset($info['id3v2']) && ($info['avdataoffset'] > 0) && ($info['avdataoffset'] != $initialOffset)))) {

			$synchoffsetwarning = 'Unknown data before synch ';
			if (isset($info['id3v2']['headerlength'])) {
				$synchoffsetwarning .= '(ID3v2 header ends at '.$info['id3v2']['headerlength'].', then '.($info['avdataoffset'] - $info['id3v2']['headerlength']).' bytes garbage, ';
			} elseif ($initialOffset > 0) {
				$synchoffsetwarning .= '(should be at '.$initialOffset.', ';
			} else {
				$synchoffsetwarning .= '(should be at beginning of file, ';
			}
			$synchoffsetwarning .= 'synch detected at '.$info['avdataoffset'].')';
			if (isset($info['audio']['bitrate_mode']) && ($info['audio']['bitrate_mode'] == 'cbr')) {

				if (!empty($info['id3v2']['headerlength']) && (($info['avdataoffset'] - $info['id3v2']['headerlength']) == $info['mpeg']['audio']['framelength'])) {

					$synchoffsetwarning .= '. This is a known problem with some versions of LAME (3.90-3.92) DLL in CBR mode.';
					$info['audio']['codec'] = 'LAME';
					$CurrentDataLAMEversionString = 'LAME3.';

				} elseif (empty($info['id3v2']['headerlength']) && ($info['avdataoffset'] == $info['mpeg']['audio']['framelength'])) {

					$synchoffsetwarning .= '. This is a known problem with some versions of LAME (3.90 - 3.92) DLL in CBR mode.';
					$info['audio']['codec'] = 'LAME';
					$CurrentDataLAMEversionString = 'LAME3.';

				}

			}
			$this->warning($synchoffsetwarning);

		}

		if (isset($info['mpeg']['audio']['LAME'])) {
			$info['audio']['codec'] = 'LAME';
			if (!empty($info['mpeg']['audio']['LAME']['long_version'])) {
				$info['audio']['encoder'] = rtrim($info['mpeg']['audio']['LAME']['long_version'], "\x00");
			} elseif (!empty($info['mpeg']['audio']['LAME']['short_version'])) {
				$info['audio']['encoder'] = rtrim($info['mpeg']['audio']['LAME']['short_version'], "\x00");
			}
		}

		$CurrentDataLAMEversionString = (!empty($CurrentDataLAMEversionString) ? $CurrentDataLAMEversionString : (isset($info['audio']['encoder']) ? $info['audio']['encoder'] : ''));
		if (!empty($CurrentDataLAMEversionString) && (substr($CurrentDataLAMEversionString, 0, 6) == 'LAME3.') && !preg_match('[0-9\)]', substr($CurrentDataLAMEversionString, -1))) {
			// a version number of LAME that does not end with a number like "LAME3.92"
			// or with a closing parenthesis like "LAME3.88 (alpha)"
			// or a version of LAME with the LAMEtag-not-filled-in-DLL-mode bug (3.90-3.92)

			// not sure what the actual last frame length will be, but will be less than or equal to 1441
			$PossiblyLongerLAMEversion_FrameLength = 1441;

			// Not sure what version of LAME this is - look in padding of last frame for longer version string
			$PossibleLAMEversionStringOffset = $info['avdataend'] - $PossiblyLongerLAMEversion_FrameLength;
			$this->fseek($PossibleLAMEversionStringOffset);
			$PossiblyLongerLAMEversion_Data = $this->fread($PossiblyLongerLAMEversion_FrameLength);
			switch (substr($CurrentDataLAMEversionString, -1)) {
				case 'a':
				case 'b':
					// "LAME3.94a" will have a longer version string of "LAME3.94 (alpha)" for example
					// need to trim off "a" to match longer string
					$CurrentDataLAMEversionString = substr($CurrentDataLAMEversionString, 0, -1);
					break;
			}
			if (($PossiblyLongerLAMEversion_String = strstr($PossiblyLongerLAMEversion_Data, $CurrentDataLAMEversionString)) !== false) {
				if (substr($PossiblyLongerLAMEversion_String, 0, strlen($CurrentDataLAMEversionString)) == $CurrentDataLAMEversionString) {
					$PossiblyLongerLAMEversion_NewString = substr($PossiblyLongerLAMEversion_String, 0, strspn($PossiblyLongerLAMEversion_String, 'LAME0123456789., (abcdefghijklmnopqrstuvwxyzJFSOND)')); //"LAME3.90.3"  "LAME3.87 (beta 1, Sep 27 2000)" "LAME3.88 (beta)"
					if (empty($info['audio']['encoder']) || (strlen($PossiblyLongerLAMEversion_NewString) > strlen($info['audio']['encoder']))) {
						$info['audio']['encoder'] = $PossiblyLongerLAMEversion_NewString;
					}
				}
			}
		}
		if (!empty($info['audio']['encoder'])) {
			$info['audio']['encoder'] = rtrim($info['audio']['encoder'], "\x00 ");
		}

		switch (isset($info['mpeg']['audio']['layer']) ? $info['mpeg']['audio']['layer'] : '') {
			case 1:
			case 2:
				$info['audio']['dataformat'] = 'mp'.$info['mpeg']['audio']['layer'];
				break;
		}
		if (isset($info['fileformat']) && ($info['fileformat'] == 'mp3')) {
			switch ($info['audio']['dataformat']) {
				case 'mp1':
				case 'mp2':
				case 'mp3':
					$info['fileformat'] = $info['audio']['dataformat'];
					break;

				default:
					$this->warning('Expecting [audio][dataformat] to be mp1/mp2/mp3 when fileformat == mp3, [audio][dataformat] actually "'.$info['audio']['dataformat'].'"');
					break;
			}
		}

		if (empty($info['fileformat'])) {
			unset($info['fileformat']);
			unset($info['audio']['bitrate_mode']);
			unset($info['avdataoffset']);
			unset($info['avdataend']);
			return false;
		}

		$info['mime_type']         = 'audio/mpeg';
		$info['audio']['lossless'] = false;

		// Calculate playtime
		if (!isset($info['playtime_seconds']) && isset($info['audio']['bitrate']) && ($info['audio']['bitrate'] > 0)) {
			// https://github.com/JamesHeinrich/getID3/issues/161
			// VBR header frame contains ~0.026s of silent audio data, but is not actually part of the original encoding and should be ignored
			$xingVBRheaderFrameLength = ((isset($info['mpeg']['audio']['VBR_frames']) && isset($info['mpeg']['audio']['framelength'])) ? $info['mpeg']['audio']['framelength'] : 0);

			$info['playtime_seconds'] = ($info['avdataend'] - $info['avdataoffset'] - $xingVBRheaderFrameLength) * 8 / $info['audio']['bitrate'];
		}

		$info['audio']['encoder_options'] = $this->GuessEncoderOptions();