module.tag.id3v2.php

一个用PHP编写的

<?php
/////////////////////////////////////////////////////////////////
/// getID3() by James Heinrich <[e-mail]>               //
//  available at http://getid3.sourceforge.net                 //
//            or http://www.getid3.org                         //
/////////////////////////////////////////////////////////////////
// See readme.txt for more details                             //
/////////////////////////////////////////////////////////////////
///                                                            //
// module.tag.id3v2.php                                        //
// module for analyzing ID3v2 tags                             //
// dependencies: module.tag.id3v1.php                          //
//                                                            ///
/////////////////////////////////////////////////////////////////

getid3_lib::IncludeDependency(GETID3_INCLUDEPATH.'module.tag.id3v1.php', __FILE__, true);

class getid3_id3v2
{

	function getid3_id3v2(&$fd, &$ThisFileInfo, $StartingOffset=0) {
		//    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


		// shortcuts
		$ThisFileInfo['id3v2']['header'] = true;
		$thisfile_id3v2                  = &$ThisFileInfo['id3v2'];
		$thisfile_id3v2['flags']         =  array();
		$thisfile_id3v2_flags            = &$thisfile_id3v2['flags'];


		fseek($fd, $StartingOffset, SEEK_SET);
		$header = fread($fd, 10);
		if (substr($header, 0, 3) == 'ID3') {

			$thisfile_id3v2['majorversion'] = ord($header{3});
			$thisfile_id3v2['minorversion'] = ord($header{4});

			// shortcut
			$id3v2_majorversion = &$thisfile_id3v2['majorversion'];

		} else {

			unset($ThisFileInfo['id3v2']);
			return false;

		}

		if ($id3v2_majorversion > 4) { // this script probably won't correctly parse ID3v2.5.x and above (if it ever exists)

			$ThisFileInfo['error'][] = 'this script only parses up to ID3v2.4.x - this tag is ID3v2.'.$id3v2_majorversion.'.'.$thisfile_id3v2['minorversion'];
			return false;

		}

		$id3_flags = ord($header{5});
		switch ($id3v2_majorversion) {
			case 2:
				// %ab000000 in v2.2
				$thisfile_id3v2_flags['unsynch']     = (bool) ($id3_flags & 0x80); // a - Unsynchronisation
				$thisfile_id3v2_flags['compression'] = (bool) ($id3_flags & 0x40); // b - Compression
				break;

			case 3:
				// %abc00000 in v2.3
				$thisfile_id3v2_flags['unsynch']     = (bool) ($id3_flags & 0x80); // a - Unsynchronisation
				$thisfile_id3v2_flags['exthead']     = (bool) ($id3_flags & 0x40); // b - Extended header
				$thisfile_id3v2_flags['experim']     = (bool) ($id3_flags & 0x20); // c - Experimental indicator
				break;

			case 4:
				// %abcd0000 in v2.4
				$thisfile_id3v2_flags['unsynch']     = (bool) ($id3_flags & 0x80); // a - Unsynchronisation
				$thisfile_id3v2_flags['exthead']     = (bool) ($id3_flags & 0x40); // b - Extended header
				$thisfile_id3v2_flags['experim']     = (bool) ($id3_flags & 0x20); // c - Experimental indicator
				$thisfile_id3v2_flags['isfooter']    = (bool) ($id3_flags & 0x10); // d - Footer present
				break;
		}

		$thisfile_id3v2['headerlength'] = getid3_lib::BigEndian2Int(substr($header, 6, 4), 1) + 10; // length of ID3v2 tag in 10-byte header doesn't include 10-byte header length

		$thisfile_id3v2['tag_offset_start'] = $StartingOffset;
		$thisfile_id3v2['tag_offset_end']   = $thisfile_id3v2['tag_offset_start'] + $thisfile_id3v2['headerlength'];

		//    Extended Header
		if (isset($thisfile_id3v2_flags['exthead']) && $thisfile_id3v2_flags['exthead']) {
			// Extended header size   4 * %0xxxxxxx
			// Number of flag bytes       $01
			// Extended Flags             $xx
			// Where the 'Extended header size' is the size of the whole extended header, stored as a 32 bit synchsafe integer.
			$thisfile_id3v2['exthead_length'] = getid3_lib::BigEndian2Int(fread($fd, 4), 1);

			$thisfile_id3v2['exthead_flag_bytes'] = ord(fread($fd, 1));
			if ($thisfile_id3v2['exthead_flag_bytes'] == 1) {
				// The extended flags field, with its size described by 'number of flag  bytes', is defined as:
				//     %0bcd0000
				// b - Tag is an update
				//     Flag data length       $00
				// c - CRC data present
				//     Flag data length       $05
				//     Total frame CRC    5 * %0xxxxxxx
				// d - Tag restrictions
				//     Flag data length       $01
				$extheaderflags    = fread($fd, $thisfile_id3v2['exthead_flag_bytes']);
				$id3_exthead_flags = getid3_lib::BigEndian2Bin(substr($header, 5, 1));
				$thisfile_id3v2['exthead_flags']['update']       = substr($id3_exthead_flags, 1, 1);
				$thisfile_id3v2['exthead_flags']['CRC']          = substr($id3_exthead_flags, 2, 1);
				if ($thisfile_id3v2['exthead_flags']['CRC']) {
					$extheaderrawCRC = fread($fd, 5);
					$thisfile_id3v2['exthead_flags']['CRC'] = getid3_lib::BigEndian2Int($extheaderrawCRC, 1);
				}
				$thisfile_id3v2['exthead_flags']['restrictions'] = substr($id3_exthead_flags, 3, 1);
				if ($thisfile_id3v2['exthead_flags']['restrictions']) {
					// Restrictions           %ppqrrstt
					$extheaderrawrestrictions = fread($fd, 1);
					$thisfile_id3v2['exthead_flags']['restrictions_tagsize']  = (bindec('11000000') & ord($extheaderrawrestrictions)) >> 6; // p - Tag size restrictions
					$thisfile_id3v2['exthead_flags']['restrictions_textenc']  = (bindec('00100000') & ord($extheaderrawrestrictions)) >> 5; // q - Text encoding restrictions
					$thisfile_id3v2['exthead_flags']['restrictions_textsize'] = (bindec('00011000') & ord($extheaderrawrestrictions)) >> 3; // r - Text fields size restrictions
					$thisfile_id3v2['exthead_flags']['restrictions_imgenc']   = (bindec('00000100') & ord($extheaderrawrestrictions)) >> 2; // s - Image encoding restrictions
					$thisfile_id3v2['exthead_flags']['restrictions_imgsize']  = (bindec('00000011') & ord($extheaderrawrestrictions)) >> 0; // t - Image size restrictions
				}
			} else {
				$ThisFileInfo['warning'][] = '$thisfile_id3v2[exthead_flag_bytes] = "'.$thisfile_id3v2['exthead_flag_bytes'].'" (expecting "1")';
				fseek($fd, $thisfile_id3v2['exthead_length'] - 1, SEEK_CUR);
				//return false;
			}
		} // end extended header


		// create 'encoding' key - used by getid3::HandleAllTags()
		// in ID3v2 every field can have it's own encoding type
		// so force everything to UTF-8 so it can be handled consistantly
		$thisfile_id3v2['encoding'] = 'UTF-8';


	//    Frames

	//        All ID3v2 frames consists of one frame header followed by one or more
	//        fields containing the actual information. The header is always 10
	//        bytes and laid out as follows:
	//
	//        Frame ID      $xx xx xx xx  (four characters)
	//        Size      4 * %0xxxxxxx
	//        Flags         $xx xx

		$sizeofframes = $thisfile_id3v2['headerlength'] - 10; // not including 10-byte initial header
		if (@$thisfile_id3v2['exthead_length']) {
			$sizeofframes -= ($thisfile_id3v2['exthead_length'] + 4);
		}
		if (@$thisfile_id3v2_flags['isfooter']) {
			$sizeofframes -= 10; // footer takes last 10 bytes of ID3v2 header, after frame data, before audio
		}
		if ($sizeofframes > 0) {

			$framedata = fread($fd, $sizeofframes); // read all frames from file into $framedata variable

			//    if entire frame data is unsynched, de-unsynch it now (ID3v2.3.x)
			if (@$thisfile_id3v2_flags['unsynch'] && ($id3v2_majorversion <= 3)) {
				$framedata = $this->DeUnsynchronise($framedata);
			}
			//        [in ID3v2.4.0] Unsynchronisation [S:6.1] is done on frame level, instead
			//        of on tag level, making it easier to skip frames, increasing the streamability
			//        of the tag. The unsynchronisation flag in the header [S:3.1] indicates that
			//        there exists an unsynchronised frame, while the new unsynchronisation flag in
			//        the frame header [S:4.1.2] indicates unsynchronisation.

			$framedataoffset = 10 + (@$thisfile_id3v2['exthead_length'] ? $thisfile_id3v2['exthead_length'] + 4 : 0); // how many bytes into the stream - start from after the 10-byte header (and extended header length+4, if present)
			while (isset($framedata) && (strlen($framedata) > 0)) { // cycle through until no more frame data is left to parse
				if (strlen($framedata) <= $this->ID3v2HeaderLength($id3v2_majorversion)) {
					// insufficient room left in ID3v2 header for actual data - must be padding
					$thisfile_id3v2['padding']['start']  = $framedataoffset;
					$thisfile_id3v2['padding']['length'] = strlen($framedata);
					$thisfile_id3v2['padding']['valid']  = true;
					for ($i = 0; $i < $thisfile_id3v2['padding']['length']; $i++) {
						if ($framedata{$i} != "\x00") {
							$thisfile_id3v2['padding']['valid'] = false;
							$thisfile_id3v2['padding']['errorpos'] = $thisfile_id3v2['padding']['start'] + $i;
							$ThisFileInfo['warning'][] = 'Invalid ID3v2 padding found at offset '.$thisfile_id3v2['padding']['errorpos'].' (the remaining '.($thisfile_id3v2['padding']['length'] - $i).' bytes are considered invalid)';
							break;
						}
					}
					break; // skip rest of ID3v2 header
				}
				if ($id3v2_majorversion == 2) {
					// Frame ID  $xx xx xx (three characters)
					// Size      $xx xx xx (24-bit integer)
					// Flags     $xx xx

					$frame_header = substr($framedata, 0, 6); // take next 6 bytes for header
					$framedata    = substr($framedata, 6);    // and leave the rest in $framedata
					$frame_name   = substr($frame_header, 0, 3);
					$frame_size   = getid3_lib::BigEndian2Int(substr($frame_header, 3, 3), 0);
					$frame_flags  = 0; // not used for anything in ID3v2.2, just set to avoid E_NOTICEs

				} elseif ($id3v2_majorversion > 2) {

					// 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

					$frame_header = substr($framedata, 0, 10); // take next 10 bytes for header
					$framedata    = substr($framedata, 10);    // and leave the rest in $framedata

					$frame_name = substr($frame_header, 0, 4);
					if ($id3v2_majorversion == 3) {
						$frame_size = getid3_lib::BigEndian2Int(substr($frame_header, 4, 4), 0); // 32-bit integer
					} else { // ID3v2.4+
						$frame_size = getid3_lib::BigEndian2Int(substr($frame_header, 4, 4), 1); // 32-bit synchsafe integer (28-bit value)
					}

					if ($frame_size < (strlen($framedata) + 4)) {
						$nextFrameID = substr($framedata, $frame_size, 4);
						if ($this->IsValidID3v2FrameName($nextFrameID, $id3v2_majorversion)) {
							// next frame is OK
						} elseif (($frame_name == "\x00".'MP3') || ($frame_name == "\x00\x00".'MP') || ($frame_name == ' MP3') || ($frame_name == 'MP3e')) {
							// MP3ext known broken frames - "ok" for the purposes of this test
						} elseif (($id3v2_majorversion == 4) && ($this->IsValidID3v2FrameName(substr($framedata, getid3_lib::BigEndian2Int(substr($frame_header, 4, 4), 0), 4), 3))) {
							$ThisFileInfo['warning'][] = 'ID3v2 tag written as ID3v2.4, but with non-synchsafe integers (ID3v2.3 style). Older versions of (Helium2; iTunes) are known culprits of this. Tag has been parsed as ID3v2.3';
							$id3v2_majorversion = 3;
							$frame_size = getid3_lib::BigEndian2Int(substr($frame_header, 4, 4), 0); // 32-bit integer
						}
					}


					$frame_flags = getid3_lib::BigEndian2Int(substr($frame_header, 8, 2));
				}

				if ((($id3v2_majorversion == 2) && ($frame_name == "\x00\x00\x00")) || ($frame_name == "\x00\x00\x00\x00")) {
					// padding encountered