public function analyze()
{
/**
* Overall tag structure:
* +-----------------------------+
* | Header (10 bytes) |
* +-----------------------------+
* | Extended Header |
* | (variable length, OPTIONAL) |
* +-----------------------------+
* | Frames (variable length) |
* +-----------------------------+
* | Padding |
* | (variable length, OPTIONAL) |
* +-----------------------------+
* | Footer (10 bytes, OPTIONAL) |
* +-----------------------------+
*
* Header
* ID3v2/file identifier "ID3"
* ID3v2 version $04 00
* ID3v2 flags (%ab000000 in v2.2, %abc00000 in v2.3, %abcd0000 in v2.4.x)
* ID3v2 size 4 * %0xxxxxxx
*/
//$fp = $this->_id3->getFilePointer();
$this->_tagInfo = $this->_id3->getFileInfo();
$this->_tagInfo['id3v2']['flags'] = array();
$this->fseek($this->_startingOffset, SEEK_SET);
$header = $this->fread(10);
if (substr($header, 0, 3) == 'ID3' && strlen($header) == 10) {
$this->_tagInfo['id3v2']['majorversion'] = ord($header[3]);
$this->_tagInfo['id3v2']['minorversion'] = ord($header[4]);
$this->_tagMajorVersion = $this->_tagInfo['id3v2']['majorversion'];
} else {
return false;
}
/**
* The current max major version is 4 so that's what we support up to.
*/
if ($this->_tagMajorVersion > 4) {
include_once 'Zend/Id3/Adapter/Exception.php';
throw new Zend_Id3_Adapter_Exception('Zend_Id3_Adapter_Id3v2 can only parse upt to Id3v2.4');
}
$this->_tagInfo['id3v2']['flags'] = $this->_processTagFlags(ord($header[5]));
// length of ID3v2 tag in 10-byte header doesn't include 10-byte header length
$this->_tagInfo['id3v2']['headerlength'] = Zend_Id3_ByteConvert::bigEndianSyncSafe2Int(substr($header, 6, 4)) + 10;
$this->_tagInfo['id3v2']['tag_offset_start'] = $this->_startingOffset;
$this->_tagInfo['id3v2']['tag_offset_end'] = $this->_tagInfo['id3v2']['tag_offset_start'] + $this->_tagInfo['id3v2']['headerlength'];
$this->_parseFrameData();
$this->_id3->setFileInfo($this->_tagInfo);
return true;
}
/**
* Parse frame out from v2.3 and higher tags
*
* Frame ID $xx xx xx xx (four characters)
* Size $xx xx xx xx (32-bit integer in v2.3, 28-bit synchsafe in v2.4+)
* Flags $xx xx
*
* @param string $frameData
*/
protected function _getFrame($frameData)
{
$info = array();
// take next 10 bytes for header
$info['frameHeader'] = substr($frameData, 0, 10);
// and leave the rest in $frame_data
$info['frameData'] = substr($frameData, 10);
$info['frameName'] = substr($info['frameHeader'], 0, 4);
$info['frameSize'] = $this->_tagVersion == 3 ? Zend_Id3_ByteConvert::bigEndian2Int(substr($info['frameHeader'], 4, 4)) : Zend_Id3_ByteConvert::bigEndianSyncSafe2Int(substr($info['frameHeader'], 4, 4));
if ($info['frameSize'] < strlen($frameData) + 4) {
$arrBrokenMP3extFrames = array("" . 'MP3', "" . 'MP', ' MP3', 'MP3e');
$nextFrameID = substr($frameData, $info['frameSize'], 4);
if ($this->_isValidID3v2FrameName($nextFrameID)) {
// next frame is OK
} else {
if (in_array($info['frameName'], $arrBrokenMP3extFrames)) {
// MP3ext known broken frames - "ok" for the purposes of this test
} else {
if ($this->_tagVersion == 4 && $this->_isValidID3v2FrameName(substr($info['frameData'], Zend_Id3_ByteConvert::bigEndian2Int(substr($info['frameHeader'], 4, 4)), 4), 3)) {
$this->_tagVersion = 3;
$info['frameSize'] = Zend_Id3_ByteConvert::bigEndian2Int(substr($info['frameHeader'], 4, 4));
// 32-bit integer
}
}
}
}
$info['frameFlag'] = Zend_Id3_ByteConvert::bigEndian2Int(substr($info['frameHeader'], 8, 2));
// padding encountered
if ($info['frameName'] == "") {
return $this->_parsePadding($info['frameData'], $info['frameHeader']);
}
return $info;
}
