/getid3/getid3.lib.php

<?php
/////////////////////////////////////////////////////////////////
/// getID3() by James Heinrich <info@getid3.org>               //
//  available at http://getid3.sourceforge.net                 //
//            or http://www.getid3.org                         //
/////////////////////////////////////////////////////////////////
//                                                             //
// getid3.lib.php - part of getID3()                           //
// See readme.txt for more details                             //
//                                                            ///
/////////////////////////////////////////////////////////////////


class getid3_lib {
	
	static function PrintHexBytes($string, $hex = true, $spaces = true, $htmlencoding = 'UTF-8') {
		$returnstring = '';
		for($i = 0; $i < strlen ( $string ); $i ++) {
			if ($hex) {
				$returnstring .= str_pad ( dechex ( ord ( $string {$i} ) ), 2, '0', STR_PAD_LEFT );
			} else {
				$returnstring .= ' ' . (preg_match ( "#[\x20-\x7E]#", $string {$i} ) ? $string {$i} : '¤');
			}
			if ($spaces) {
				$returnstring .= ' ';
			}
		}
		if (! empty ( $htmlencoding )) {
			if ($htmlencoding === true) {
				$htmlencoding = 'UTF-8'; // prior to getID3 v1.9.0 the function's 4th parameter was boolean
			}
			$returnstring = htmlentities ( $returnstring, ENT_QUOTES, $htmlencoding );
		}
		return $returnstring;
	}
	
	static function trunc($floatnumber) {
		// truncates a floating-point number at the decimal point
		// returns int (if possible, otherwise float)
		if ($floatnumber >= 1) {
			$truncatednumber = floor ( $floatnumber );
		} elseif ($floatnumber <= - 1) {
			$truncatednumber = ceil ( $floatnumber );
		} else {
			$truncatednumber = 0;
		}
		if (getid3_lib::intValueSupported ( $truncatednumber )) {
			$truncatednumber = ( int ) $truncatednumber;
		}
		return $truncatednumber;
	}
	
	static function safe_inc(&$variable, $increment = 1) {
		if (isset ( $variable )) {
			$variable += $increment;
		} else {
			$variable = $increment;
		}
		return true;
	}
	
	static function CastAsInt($floatnum) {
		// convert to float if not already
		$floatnum = ( float ) $floatnum;
		
		// convert a float to type int, only if possible
		if (getid3_lib::trunc ( $floatnum ) == $floatnum) {
			// it's not floating point
			if (getid3_lib::intValueSupported ( $floatnum )) {
				// it's within int range
				$floatnum = ( int ) $floatnum;
			}
		}
		return $floatnum;
	}
	
	public static function intValueSupported($num) {
		// check if integers are 64-bit
		static $hasINT64 = null;
		if ($hasINT64 === null) { // 10x faster than is_null()
			$hasINT64 = is_int ( pow ( 2, 31 ) ); // 32-bit int are limited to (2^31)-1
			if (! $hasINT64 && ! defined ( 'PHP_INT_MIN' )) {
				define ( 'PHP_INT_MIN', ~ PHP_INT_MAX );
			}
		}
		// if integers are 64-bit - no other check required
		if ($hasINT64 || (($num <= PHP_INT_MAX) && ($num >= PHP_INT_MIN))) {
			return true;
		}
		return false;
	}
	
	static function DecimalizeFraction($fraction) {
		list ( $numerator, $denominator ) = explode ( '/', $fraction );
		return $numerator / ($denominator ? $denominator : 1);
	}
	
	static function DecimalBinary2Float($binarynumerator) {
		$numerator = getid3_lib::Bin2Dec ( $binarynumerator );
		$denominator = getid3_lib::Bin2Dec ( '1' . str_repeat ( '0', strlen ( $binarynumerator ) ) );
		return ($numerator / $denominator);
	}
	
	static function NormalizeBinaryPoint($binarypointnumber, $maxbits = 52) {
		// http://www.scri.fsu.edu/~jac/MAD3401/Backgrnd/binary.html
		if (strpos ( $binarypointnumber, '.' ) === false) {
			$binarypointnumber = '0.' . $binarypointnumber;
		} elseif ($binarypointnumber {0} == '.') {
			$binarypointnumber = '0' . $binarypointnumber;
		}
		$exponent = 0;
		while ( ($binarypointnumber {0} != '1') || (substr ( $binarypointnumber, 1, 1 ) != '.') ) {
			if (substr ( $binarypointnumber, 1, 1 ) == '.') {
				$exponent --;
				$binarypointnumber = substr ( $binarypointnumber, 2, 1 ) . '.' . substr ( $binarypointnumber, 3 );
			} else {
				$pointpos = strpos ( $binarypointnumber, '.' );
				$exponent += ($pointpos - 1);
				$binarypointnumber = str_replace ( '.', '', $binarypointnumber );
				$binarypointnumber = $binarypointnumber {0} . '.' . substr ( $binarypointnumber, 1 );
			}
		}
		$binarypointnumber = str_pad ( substr ( $binarypointnumber, 0, $maxbits + 2 ), $maxbits + 2, '0', STR_PAD_RIGHT );
		return array ('normalized' => $binarypointnumber, 'exponent' => ( int ) $exponent );
	}
	
	static function Float2BinaryDecimal($floatvalue) {
		// http://www.scri.fsu.edu/~jac/MAD3401/Backgrnd/binary.html
		$maxbits = 128; // to how many bits of precision should the calculations be taken?
		$intpart = getid3_lib::trunc ( $floatvalue );
		$floatpart = abs ( $floatvalue - $intpart );
		$pointbitstring = '';
		while ( ($floatpart != 0) && (strlen ( $pointbitstring ) < $maxbits) ) {
			$floatpart *= 2;
			$pointbitstring .= ( string ) getid3_lib::trunc ( $floatpart );
			$floatpart -= getid3_lib::trunc ( $floatpart );
		}
		$binarypointnumber = decbin ( $intpart ) . '.' . $pointbitstring;
		return $binarypointnumber;
	}
	
	static function Float2String($floatvalue, $bits) {
		// http://www.scri.fsu.edu/~jac/MAD3401/Backgrnd/ieee-expl.html
		switch ($bits) {
			case 32 :
				$exponentbits = 8;
				$fractionbits = 23;
				break;
			
			case 64 :
				$exponentbits = 11;
				$fractionbits = 52;
				break;
			
			default :
				return false;
				break;
		}
		if ($floatvalue >= 0) {
			$signbit = '0';
		} else {
			$signbit = '1';
		}
		$normalizedbinary = getid3_lib::NormalizeBinaryPoint ( getid3_lib::Float2BinaryDecimal ( $floatvalue ), $fractionbits );
		$biasedexponent = pow ( 2, $exponentbits - 1 ) - 1 + $normalizedbinary ['exponent']; // (127 or 1023) +/- exponent
		$exponentbitstring = str_pad ( decbin ( $biasedexponent ), $exponentbits, '0', STR_PAD_LEFT );
		$fractionbitstring = str_pad ( substr ( $normalizedbinary ['normalized'], 2 ), $fractionbits, '0', STR_PAD_RIGHT );
		
		return getid3_lib::BigEndian2String ( getid3_lib::Bin2Dec ( $signbit . $exponentbitstring . $fractionbitstring ), $bits % 8, false );
	}
	
	static function LittleEndian2Float($byteword) {
		return getid3_lib::BigEndian2Float ( strrev ( $byteword ) );
	}
	
	static function BigEndian2Float($byteword) {
		// ANSI/IEEE Standard 754-1985, Standard for Binary Floating Point Arithmetic
		// http://www.psc.edu/general/software/packages/ieee/ieee.html
		// http://www.scri.fsu.edu/~jac/MAD3401/Backgrnd/ieee.html
		

		$bitword = getid3_lib::BigEndian2Bin ( $byteword );
		if (! $bitword) {
			return 0;
		}
		$signbit = $bitword {0};
		
		switch (strlen ( $byteword ) * 8) {
			case 32 :
				$exponentbits = 8;
				$fractionbits = 23;
				break;
			
			case 64 :
				$exponentbits = 11;
				$fractionbits = 52;
				break;
			
			case 80 :
				// 80-bit Apple SANE format
				// http://www.mactech.com/articles/mactech/Vol.06/06.01/SANENormalized/
				$exponentstring = substr ( $bitword, 1, 15 );
				$isnormalized = intval ( $bitword {16} );
				$fractionstring = substr ( $bitword, 17, 63 );
				$exponent = pow ( 2, getid3_lib::Bin2Dec ( $exponentstring ) - 16383 );
				$fraction = $isnormalized + getid3_lib::DecimalBinary2Float ( $fractionstring );
				$floatvalue = $exponent * $fraction;
				if ($signbit == '1') {
					$floatvalue *= - 1;
				}
				return $floatvalue;
				break;
			
			default :
				return false;
				break;
		}
		$exponentstring = substr ( $bitword, 1, $exponentbits );
		$fractionstring = substr ( $bitword, $exponentbits + 1, $fractionbits );
		$exponent = getid3_lib::Bin2Dec ( $exponentstring );
		$fraction = getid3_lib::Bin2Dec ( $fractionstring );
		
		if (($exponent == (pow ( 2, $exponentbits ) - 1)) && ($fraction != 0)) {
			// Not a Number
			$floatvalue = false;
		} elseif (($exponent == (pow ( 2, $exponentbits ) - 1)) && ($fraction == 0)) {
			if ($signbit == '1') {
				$floatvalue = '-infinity';
			} else {
				$floatvalue = '+infinity';
			}
		} elseif (($exponent == 0) && ($fraction == 0)) {
			if ($signbit == '1') {
				$floatvalue = - 0;
			} else {
				$floatvalue = 0;
			}
			$floatvalue = ($signbit ? 0 : - 0);
		} elseif (($exponent == 0) && ($fraction != 0)) {
			// These are 'unnormalized' values
			$floatvalue = pow ( 2, (- 1 * (pow ( 2, $exponentbits - 1 ) - 2)) ) * getid3_lib::DecimalBinary2Float ( $fractionstring );
			if ($signbit == '1') {
				$floatvalue *= - 1;
			}
		} elseif ($exponent != 0) {
			$floatvalue = pow ( 2, ($exponent - (pow ( 2, $exponentbits - 1 ) - 1)) ) * (1 + getid3_lib::DecimalBinary2Float ( $fractionstring ));
			if ($signbit == '1') {
				$floatvalue *= - 1;
			}
		}
		return ( float ) $floatvalue;
	}
	
	static function BigEndian2Int($byteword, $synchsafe = false, $signed = false) {
		$intvalue = 0;
		$bytewordlen = strlen ( $byteword );
		if ($bytewordlen == 0) {
			return false;
		}
		for($i = 0; $i < $bytewordlen; $i ++) {
			if ($synchsafe) { // disregard MSB, effectively 7-bit bytes
				//$intvalue = $intvalue | (ord($byteword{$i}) & 0x7F) << (($bytewordlen - 1 - $i) * 7); // faster, but runs into problems past 2^31 on 32-bit systems
				$intvalue += (ord ( $byteword {$i} ) & 0x7F) * pow ( 2, ($bytewordlen - 1 - $i) * 7 );
			} else {
				$intvalue += ord ( $byteword {$i} ) * pow ( 256, ($bytewordlen - 1 - $i) );
			}
		}
		if ($signed && ! $synchsafe) {
			// synchsafe ints are not allowed to be signed
			if ($bytewordlen <= PHP_INT_SIZE) {
				$signMaskBit = 0x80 << (8 * ($bytewordlen - 1));
				if ($intvalue & $signMaskBit) {
					$intvalue = 0 - ($intvalue & ($signMaskBit - 1));
				}
			} else {
				throw new Exception ( 'ERROR: Cannot have signed integers larger than ' . (8 * PHP_INT_SIZE) . '-bits (' . strlen ( $byteword ) . ') in getid3_lib::BigEndian2Int()' );
				break;
			}
		}
		return getid3_lib::CastAsInt ( $intvalue );
	}
	
	static function LittleEndian2Int($byteword, $signed = false) {
		return getid3_lib::BigEndian2Int ( strrev ( $byteword ), false, $signed );
	}
	
	static function BigEndian2Bin($byteword) {
		$binvalue = '';
		$bytewordlen = strlen ( $byteword );
		for($i = 0; $i < $bytewordlen; $i ++) {
			$binvalue .= str_pad ( decbin ( ord ( $byteword {$i} ) ), 8, '0', STR_PAD_LEFT );
		}
		return $binvalue;
	}
	
	static function BigEndian2String($number, $minbytes = 1, $synchsafe = false, $signed = false) {
		if ($number < 0) {
			throw new Exception ( 'ERROR: getid3_lib::BigEndian2String() does not support negative numbers' );
		}
		$maskbyte = (($synchsafe || $signed) ? 0x7F : 0xFF);
		$intstring = '';
		if ($signed) {
			if ($minbytes > PHP_INT_SIZE) {
				throw new Exception ( 'ERROR: Cannot have signed integers larger than ' . (8 * PHP_INT_SIZE) . '-bits in getid3_lib::BigEndian2String()' );
			}
			$number = $number & (0x80 << (8 * ($minbytes - 1)));
		}
		while ( $number != 0 ) {
			$quotient = ($number / ($maskbyte + 1));
			$intstring = chr ( ceil ( ($quotient - floor ( $quotient )) * $maskbyte ) ) . $intstring;
			$number = floor ( $quotient );
		}
		return str_pad ( $intstring, $minbytes, "\x00", STR_PAD_LEFT );
	}
	
	static function Dec2Bin($number) {
		while ( $number >= 256 ) {
			$bytes [] = (($number / 256) - (floor ( $number / 256 ))) * 256;
			$number = floor ( $number / 256 );
		}
		$bytes [] = $number;
		$binstring = '';
		for($i = 0; $i < count ( $bytes ); $i ++) {
			$binstring = (($i == count ( $bytes ) - 1) ? decbin ( $bytes [$i] ) : str_pad ( decbin ( $bytes [$i] ), 8, '0', STR_PAD_LEFT )) . $binstring;
		}
		return $binstring;
	}
	
	static function Bin2Dec($binstring, $signed = false) {
		$signmult = 1;
		if ($signed) {
			if ($binstring {0} == '1') {
				$signmult = - 1;
			}
			$binstring = substr ( $binstring, 1 );
		}
		$decvalue = 0;
		for($i = 0; $i < strlen ( $binstring ); $i ++) {
			$decvalue += (( int ) substr ( $binstring, strlen ( $binstring ) - $i - 1, 1 )) * pow ( 2, $i );
		}
		return getid3_lib::CastAsInt ( $decvalue * $signmult );
	}
	
	static function Bin2String($binstring) {
		// return 'hi' for input of '0110100001101001'
		$string = '';
		$binstringreversed = strrev ( $binstring );
		for($i = 0; $i < strlen ( $binstringreversed ); $i += 8) {
			$string = chr ( getid3_lib::Bin2Dec ( strrev ( substr ( $binstringreversed, $i, 8 ) ) ) ) . $string;
		}
		return $string;
	}
	
	static function LittleEndian2String($number, $minbytes = 1, $synchsafe = false) {
		$intstring = '';
		while ( $number > 0 ) {
			if ($synchsafe) {
				$intstring = $intstring . chr ( $number & 127 );
				$number >>= 7;
			} else {
				$intstring = $intstring . chr ( $number & 255 );
				$number >>= 8;
			}
		}
		return str_pad ( $intstring, $minbytes, "\x00", STR_PAD_RIGHT );
	}
	
	static function array_merge_clobber($array1, $array2) {
		// written by kcØhireability*com
		// taken from http://www.php.net/manual/en/function.array-merge-recursive.php
		if (! is_array ( $array1 ) || ! is_array ( $array2 )) {
			return false;
		}
		$newarray = $array1;
		foreach ( $array2 as $key => $val ) {
			if (is_array ( $val ) && isset ( $newarray [$key] ) && is_array ( $newarray [$key] )) {
				$newarray [$key] = getid3_lib::array_merge_clobber ( $newarray [$key], $val );
			} else {
				$newarray [$key] = $val;
			}
		}
		return $newarray;
	}
	
	static function array_merge_noclobber($array1, $array2) {
		if (! is_array ( $array1 ) || ! is_array ( $array2 )) {
			return false;
		}
		$newarray = $array1;
		foreach ( $array2 as $key => $val ) {
			if (is_array ( $val ) && isset ( $newarray [$key] ) && is_array ( $newarray [$key] )) {
				$newarray [$key] = getid3_lib::array_merge_noclobber ( $newarray [$key], $val );
			} elseif (! isset ( $newarray [$key] )) {
				$newarray [$key] = $val;
			}
		}
		return $newarray;
	}
	
	static function ksort_recursive(&$theArray) {
		ksort ( $theArray );
		foreach ( $theArray as $key => $value ) {
			if (is_array ( $value )) {
				self::ksort_recursive ( $theArray [$key] );
			}
		}
		return true;
	}
	
	static function fileextension($filename, $numextensions = 1) {
		if (strstr ( $filename, '.' )) {
			$reversedfilename = strrev ( $filename );
			$offset = 0;
			for($i = 0; $i < $numextensions; $i ++) {
				$offset = strpos ( $reversedfilename, '.', $offset + 1 );
				if ($offset === false) {
					return '';
				}
			}
			return strrev ( substr ( $reversedfilename, 0, $offset ) );
		}
		return '';
	}
	
	static function PlaytimeString($seconds) {
		$sign = (($seconds < 0) ? '-' : '');
		$seconds = abs ( $seconds );
		$H = floor ( $seconds / 3600 );
		$M = floor ( ($seconds - (3600 * $H)) / 60 );
		$S = round ( $seconds - (3600 * $H) - (60 * $M) );
		return $sign . ($H ? $H . ':' : '') . ($H ? str_pad ( $M, 2, '0', STR_PAD_LEFT ) : intval ( $M )) . ':' . str_pad ( $S, 2, 0, STR_PAD_LEFT );
	}
	
	static function DateMac2Unix($macdate) {
		// Macintosh timestamp: seconds since 00:00h January 1, 1904
		// UNIX timestamp:      seconds since 00:00h January 1, 1970
		return getid3_lib::CastAsInt ( $macdate - 2082844800 );
	}
	
	static function FixedPoint8_8($rawdata) {
		return getid3_lib::BigEndian2Int ( substr ( $rawdata, 0, 1 ) ) + ( float ) (getid3_lib::BigEndian2Int ( substr ( $rawdata, 1, 1 ) ) / pow ( 2, 8 ));
	}
	
	static function FixedPoint16_16($rawdata) {
		return getid3_lib::BigEndian2Int ( substr ( $rawdata, 0, 2 ) ) + ( float ) (getid3_lib::BigEndian2Int ( substr ( $rawdata, 2, 2 ) ) / pow ( 2, 16 ));
	}
	
	static function FixedPoint2_30($rawdata) {
		$binarystring = getid3_lib::BigEndian2Bin ( $rawdata );
		return getid3_lib::Bin2Dec ( substr ( $binarystring, 0, 2 ) ) + ( float ) (getid3_lib::Bin2Dec ( substr ( $binarystring, 2, 30 ) ) / pow ( 2, 30 ));
	}
	
	static function CreateDeepArray($ArrayPath, $Separator, $Value) {
		// assigns $Value to a nested array path:
		//   $foo = getid3_lib::CreateDeepArray('/path/to/my', '/', 'file.txt')
		// is the same as:
		//   $foo = array('path'=>array('to'=>'array('my'=>array('file.txt'))));
		// or
		//   $foo['path']['to']['my'] = 'file.txt';
		while ( $ArrayPath && ($ArrayPath {0} == $Separator) ) {
			$ArrayPath = substr ( $ArrayPath, 1 );
		}
		if (($pos = strpos ( $ArrayPath, $Separator )) !== false) {
			$ReturnedArray [substr ( $ArrayPath, 0, $pos )] = getid3_lib::CreateDeepArray ( substr ( $ArrayPath, $pos + 1 ), $Separator, $Value );
		} else {
			$ReturnedArray [$ArrayPath] = $Value;
		}
		return $ReturnedArray;
	}
	
	static function array_max($arraydata, $returnkey = false) {
		$maxvalue = false;
		$maxkey = false;
		foreach ( $arraydata as $key => $value ) {
			if (! is_array ( $value )) {
				if ($value > $maxvalue) {
					$maxvalue = $value;
					$maxkey = $key;
				}
			}
		}
		return ($returnkey ? $maxkey : $maxvalue);
	}
	
	static function array_min($arraydata, $returnkey = false) {
		$minvalue = false;
		$minkey = false;
		foreach ( $arraydata as $key => $value ) {
			if (! is_array ( $value )) {
				if ($value > $minvalue) {
					$minvalue = $value;
					$minkey = $key;
				}
			}
		}
		return ($returnkey ? $minkey : $minvalue);
	}
	
	static function XML2array($XMLstring) {
		if (function_exists ( 'simplexml_load_string' )) {
			if (function_exists ( 'get_object_vars' )) {
				$XMLobject = simplexml_load_string ( $XMLstring );
				return self::SimpleXMLelement2array ( $XMLobject );
			}
		}
		return false;
	}
	
	static function SimpleXMLelement2array($XMLobject) {
		if (! is_object ( $XMLobject ) && ! is_array ( $XMLobject )) {
			return $XMLobject;
		}
		$XMLarray = (is_object ( $XMLobject ) ? get_object_vars ( $XMLobject ) : $XMLobject);
		foreach ( $XMLarray as $key => $value ) {
			$XMLarray [$key] = self::SimpleXMLelement2array ( $value );
		}
		return $XMLarray;
	}
	
	// Allan Hansen <ahØartemis*dk>
	// getid3_lib::md5_data() - returns md5sum for a file from startuing position to absolute end position
	static function hash_data($file, $offset, $end, $algorithm) {
		static $tempdir = '';
		if (! getid3_lib::intValueSupported ( $end )) {
			return false;
		}
		switch ($algorithm) {
			case 'md5' :
				$hash_function = 'md5_file';
				$unix_call = 'md5sum';
				$windows_call = 'md5sum.exe';
				$hash_length = 32;
				break;
			
			case 'sha1' :
				$hash_function = 'sha1_file';
				$unix_call = 'sha1sum';
				$windows_call = 'sha1sum.exe';
				$hash_length = 40;
				break;
			
			default :
				throw new Exception ( 'Invalid algorithm (' . $algorithm . ') in getid3_lib::hash_data()' );
				break;
		}
		$size = $end - $offset;
		while ( true ) {
			if (GETID3_OS_ISWINDOWS) {
				
				// It seems that sha1sum.exe for Windows only works on physical files, does not accept piped data
				// Fall back to create-temp-file method:
				if ($algorithm == 'sha1') {
					break;
				}
				
				$RequiredFiles = array ('cygwin1.dll', 'head.exe', 'tail.exe', $windows_call );
				foreach ( $RequiredFiles as $required_file ) {
					if (! is_readable ( GETID3_HELPERAPPSDIR . $required_file )) {
						// helper apps not available - fall back to old method
						break;
					}
				}
				$commandline = GETID3_HELPERAPPSDIR . 'head.exe -c ' . $end . ' "' . escapeshellarg ( str_replace ( '/', DIRECTORY_SEPARATOR, $file ) ) . '" | ';
				$commandline .= GETID3_HELPERAPPSDIR . 'tail.exe -c ' . $size . ' | ';
				$commandline .= GETID3_HELPERAPPSDIR . $windows_call;
			
			} else {
				
				$commandline = 'head -c' . $end . ' ' . escapeshellarg ( $file ) . ' | ';
				$commandline .= 'tail -c' . $size . ' | ';
				$commandline .= $unix_call;
			
			}
			if (preg_match ( '#(1|ON)#i', ini_get ( 'safe_mode' ) )) {
				//throw new Exception('PHP running in Safe Mode - backtick operator not available, using slower non-system-call '.$algorithm.' algorithm');
				break;
			}
			return substr ( `$commandline`, 0, $hash_length );
		}
		
		if (empty ( $tempdir )) {
			// yes this is ugly, feel free to suggest a better way
			require_once (dirname ( __FILE__ ) . '/getid3.php');
			$getid3_temp = new getID3 ();
			$tempdir = $getid3_temp->tempdir;
			unset ( $getid3_temp );
		}
		// try to create a temporary file in the system temp directory - invalid dirname should force to system temp dir
		if (($data_filename = tempnam ( $tempdir, 'gI3' )) === false) {
			// can't find anywhere to create a temp file, just fail
			return false;
		}
		
		// Init
		$result = false;
		
		// copy parts of file
		try {
			getid3_lib::CopyFileParts ( $file, $data_filename, $offset, $end - $offset );
			$result = $hash_function ( $data_filename );
		} catch ( Exception $e ) {
			throw new Exception ( 'getid3_lib::CopyFileParts() failed in getid_lib::hash_data(): ' . $e->getMessage () );
		}
		unlink ( $data_filename );
		return $result;
	}
	
	static function CopyFileParts($filename_source, $filename_dest, $offset, $length) {
		if (! getid3_lib::intValueSupported ( $offset + $length )) {
			throw new Exception ( 'cannot copy file portion, it extends beyond the ' . round ( PHP_INT_MAX / 1073741824 ) . 'GB limit' );
		}
		if (is_readable ( $filename_source ) && is_file ( $filename_source ) && ($fp_src = fopen ( $filename_source, 'rb' ))) {
			if (($fp_dest = fopen ( $filename_dest, 'wb' )) != false) {
				if (fseek ( $fp_src, $offset, SEEK_SET ) == 0) {
					$byteslefttowrite = $length;
					while ( ($byteslefttowrite > 0) && ($buffer = fread ( $fp_src, min ( $byteslefttowrite, getID3::FREAD_BUFFER_SIZE ) )) ) {
						$byteswritten = fwrite ( $fp_dest, $buffer, $byteslefttowrite );
						$byteslefttowrite -= $byteswritten;
					}
					return true;
				} else {
					throw new Exception ( 'failed to seek to offset ' . $offset . ' in ' . $filename_source );
				}
				fclose ( $fp_dest );
			} else {
				throw new Exception ( 'failed to create file for writing ' . $filename_dest );
			}
			fclose ( $fp_src );
		} else {
			throw new Exception ( 'failed to open file for reading ' . $filename_source );
		}
		return false;
	}
	
	static function iconv_fallback_int_utf8($charval) {
		if ($charval < 128) {
			// 0bbbbbbb
			$newcharstring = chr ( $charval );
		} elseif ($charval < 2048) {
			// 110bbbbb 10bbbbbb
			$newcharstring = chr ( ($charval >> 6) | 0xC0 );
			$newcharstring .= chr ( ($charval & 0x3F) | 0x80 );
		} elseif ($charval < 65536) {
			// 1110bbbb 10bbbbbb 10bbbbbb
			$newcharstring = chr ( ($charval >> 12) | 0xE0 );
			$newcharstring .= chr ( ($charval >> 6) | 0xC0 );
			$newcharstring .= chr ( ($charval & 0x3F) | 0x80 );
		} else {
			// 11110bbb 10bbbbbb 10bbbbbb 10bbbbbb
			$newcharstring = chr ( ($charval >> 18) | 0xF0 );
			$newcharstring .= chr ( ($charval >> 12) | 0xC0 );
			$newcharstring .= chr ( ($charval >> 6) | 0xC0 );
			$newcharstring .= chr ( ($charval & 0x3F) | 0x80 );
		}
		return $newcharstring;
	}
	
	// ISO-8859-1 => UTF-8
	static function iconv_fallback_iso88591_utf8($string, $bom = false) {
		if (function_exists ( 'utf8_encode' )) {
			return utf8_encode ( $string );
		}
		// utf8_encode() unavailable, use getID3()'s iconv_fallback() conversions (possibly PHP is compiled without XML support)
		$newcharstring = '';
		if ($bom) {
			$newcharstring .= "\xEF\xBB\xBF";
		}
		for($i = 0; $i < strlen ( $string ); $i ++) {
			$charval = ord ( $string {$i} );
			$newcharstring .= getid3_lib::iconv_fallback_int_utf8 ( $charval );
		}
		return $newcharstring;
	}
	
	// ISO-8859-1 => UTF-16BE
	static function iconv_fallback_iso88591_utf16be($string, $bom = false) {
		$newcharstring = '';
		if ($bom) {
			$newcharstring .= "\xFE\xFF";
		}
		for($i = 0; $i < strlen ( $string ); $i ++) {
			$newcharstring .= "\x00" . $string {$i};
		}
		return $newcharstring;
	}
	
	// ISO-8859-1 => UTF-16LE
	static function iconv_fallback_iso88591_utf16le($string, $bom = false) {
		$newcharstring = '';
		if ($bom) {
			$newcharstring .= "\xFF\xFE";
		}
		for($i = 0; $i < strlen ( $string ); $i ++) {
			$newcharstring .= $string {$i} . "\x00";
		}
		return $newcharstring;
	}
	
	// ISO-8859-1 => UTF-16LE (BOM)
	static function iconv_fallback_iso88591_utf16($string) {
		return getid3_lib::iconv_fallback_iso88591_utf16le ( $string, true );
	}
	
	// UTF-8 => ISO-8859-1
	static function iconv_fallback_utf8_iso88591($string) {
		if (function_exists ( 'utf8_decode' )) {
			return utf8_decode ( $string );
		}
		// utf8_decode() unavailable, use getID3()'s iconv_fallback() conversions (possibly PHP is compiled without XML support)
		$newcharstring = '';
		$offset = 0;
		$stringlength = strlen ( $string );
		while ( $offset < $stringlength ) {
			if ((ord ( $string {$offset} ) | 0x07) == 0xF7) {
				// 11110bbb 10bbbbbb 10bbbbbb 10bbbbbb
				$charval = ((ord ( $string {($offset + 0)} ) & 0x07) << 18) & ((ord ( $string {($offset + 1)} ) & 0x3F) << 12) & ((ord ( $string {($offset + 2)} ) & 0x3F) << 6) & (ord ( $string {($offset + 3)} ) & 0x3F);
				$offset += 4;
			} elseif ((ord ( $string {$offset} ) | 0x0F) == 0xEF) {
				// 1110bbbb 10bbbbbb 10bbbbbb
				$charval = ((ord ( $string {($offset + 0)} ) & 0x0F) << 12) & ((ord ( $string {($offset + 1)} ) & 0x3F) << 6) & (ord ( $string {($offset + 2)} ) & 0x3F);
				$offset += 3;
			} elseif ((ord ( $string {$offset} ) | 0x1F) == 0xDF) {
				// 110bbbbb 10bbbbbb
				$charval = ((ord ( $string {($offset + 0)} ) & 0x1F) << 6) & (ord ( $string {($offset + 1)} ) & 0x3F);
				$offset += 2;
			} elseif ((ord ( $string {$offset} ) | 0x7F) == 0x7F) {
				// 0bbbbbbb
				$charval = ord ( $string {$offset} );
				$offset += 1;
			} else {
				// error? throw some kind of warning here?
				$charval = false;
				$offset += 1;
			}
			if ($charval !== false) {
				$newcharstring .= (($charval < 256) ? chr ( $charval ) : '?');
			}
		}
		return $newcharstring;
	}
	
	// UTF-8 => UTF-16BE
	static function iconv_fallback_utf8_utf16be($string, $bom = false) {
		$newcharstring = '';
		if ($bom) {
			$newcharstring .= "\xFE\xFF";
		}
		$offset = 0;
		$stringlength = strlen ( $string );
		while ( $offset < $stringlength ) {
			if ((ord ( $string {$offset} ) | 0x07) == 0xF7) {
				// 11110bbb 10bbbbbb 10bbbbbb 10bbbbbb
				$charval = ((ord ( $string {($offset + 0)} ) & 0x07) << 18) & ((ord ( $string {($offset + 1)} ) & 0x3F) << 12) & ((ord ( $string {($offset + 2)} ) & 0x3F) << 6) & (ord ( $string {($offset + 3)} ) & 0x3F);
				$offset += 4;
			} elseif ((ord ( $string {$offset} ) | 0x0F) == 0xEF) {
				// 1110bbbb 10bbbbbb 10bbbbbb
				$charval = ((ord ( $string {($offset + 0)} ) & 0x0F) << 12) & ((ord ( $string {($offset + 1)} ) & 0x3F) << 6) & (ord ( $string {($offset + 2)} ) & 0x3F);
				$offset += 3;
			} elseif ((ord ( $string {$offset} ) | 0x1F) == 0xDF) {
				// 110bbbbb 10bbbbbb
				$charval = ((ord ( $string {($offset + 0)} ) & 0x1F) << 6) & (ord ( $string {($offset + 1)} ) & 0x3F);
				$offset += 2;
			} elseif ((ord ( $string {$offset} ) | 0x7F) == 0x7F) {
				// 0bbbbbbb
				$charval = ord ( $string {$offset} );
				$offset += 1;
			} else {
				// error? throw some kind of warning here?
				$charval = false;
				$offset += 1;
			}
			if ($charval !== false) {
				$newcharstring .= (($charval < 65536) ? getid3_lib::BigEndian2String ( $charval, 2 ) : "\x00" . '?');
			}
		}
		return $newcharstring;
	}
	
	// UTF-8 => UTF-16LE
	static function iconv_fallback_utf8_utf16le($string, $bom = false) {
		$newcharstring = '';
		if ($bom) {
			$newcharstring .= "\xFF\xFE";
		}
		$offset = 0;
		$stringlength = strlen ( $string );
		while ( $offset < $stringlength ) {
			if ((ord ( $string {$offset} ) | 0x07) == 0xF7) {
				// 11110bbb 10bbbbbb 10bbbbbb 10bbbbbb
				$charval = ((ord ( $string {($offset + 0)} ) & 0x07) << 18) & ((ord ( $string {($offset + 1)} ) & 0x3F) << 12) & ((ord ( $string {($offset + 2)} ) & 0x3F) << 6) & (ord ( $string {($offset + 3)} ) & 0x3F);
				$offset += 4;
			} elseif ((ord ( $string {$offset} ) | 0x0F) == 0xEF) {
				// 1110bbbb 10bbbbbb 10bbbbbb
				$charval = ((ord ( $string {($offset + 0)} ) & 0x0F) << 12) & ((ord ( $string {($offset + 1)} ) & 0x3F) << 6) & (ord ( $string {($offset + 2)} ) & 0x3F);
				$offset += 3;
			} elseif ((ord ( $string {$offset} ) | 0x1F) == 0xDF) {
				// 110bbbbb 10bbbbbb
				$charval = ((ord ( $string {($offset + 0)} ) & 0x1F) << 6) & (ord ( $string {($offset + 1)} ) & 0x3F);
				$offset += 2;
			} elseif ((ord ( $string {$offset} ) | 0x7F) == 0x7F) {
				// 0bbbbbbb
				$charval = ord ( $string {$offset} );
				$offset += 1;
			} else {
				// error? maybe throw some warning here?
				$charval = false;
				$offset += 1;
			}
			if ($charval !== false) {
				$newcharstring .= (($charval < 65536) ? getid3_lib::LittleEndian2String ( $charval, 2 ) : '?' . "\x00");
			}
		}
		return $newcharstring;
	}
	
	// UTF-8 => UTF-16LE (BOM)
	static function iconv_fallback_utf8_utf16($string) {
		return getid3_lib::iconv_fallback_utf8_utf16le ( $string, true );
	}
	
	// UTF-16BE => UTF-8
	static function iconv_fallback_utf16be_utf8($string) {
		if (substr ( $string, 0, 2 ) == "\xFE\xFF") {
			// strip BOM
			$string = substr ( $string, 2 );
		}
		$newcharstring = '';
		for($i = 0; $i < strlen ( $string ); $i += 2) {
			$charval = getid3_lib::BigEndian2Int ( substr ( $string, $i, 2 ) );
			$newcharstring .= getid3_lib::iconv_fallback_int_utf8 ( $charval );
		}
		return $newcharstring;
	}
	
	// UTF-16LE => UTF-8
	static function iconv_fallback_utf16le_utf8($string) {
		if (substr ( $string, 0, 2 ) == "\xFF\xFE") {
			// strip BOM
			$string = substr ( $string, 2 );
		}
		$newcharstring = '';
		for($i = 0; $i < strlen ( $string ); $i += 2) {
			$charval = getid3_lib::LittleEndian2Int ( substr ( $string, $i, 2 ) );
			$newcharstring .= getid3_lib::iconv_fallback_int_utf8 ( $charval );
		}
		return $newcharstring;
	}
	
	// UTF-16BE => ISO-8859-1
	static function iconv_fallback_utf16be_iso88591($string) {
		if (substr ( $string, 0, 2 ) == "\xFE\xFF") {
			// strip BOM
			$string = substr ( $string, 2 );
		}
		$newcharstring = '';
		for($i = 0; $i < strlen ( $string ); $i += 2) {
			$charval = getid3_lib::BigEndian2Int ( substr ( $string, $i, 2 ) );
			$newcharstring .= (($charval < 256) ? chr ( $charval ) : '?');
		}
		return $newcharstring;
	}
	
	// UTF-16LE => ISO-8859-1
	static function iconv_fallback_utf16le_iso88591($string) {
		if (substr ( $string, 0, 2 ) == "\xFF\xFE") {
			// strip BOM
			$string = substr ( $string, 2 );
		}
		$newcharstring = '';
		for($i = 0; $i < strlen ( $string ); $i += 2) {
			$charval = getid3_lib::LittleEndian2Int ( substr ( $string, $i, 2 ) );
			$newcharstring .= (($charval < 256) ? chr ( $charval ) : '?');
		}
		return $newcharstring;
	}
	
	// UTF-16 (BOM) => ISO-8859-1
	static function iconv_fallback_utf16_iso88591($string) {
		$bom = substr ( $string, 0, 2 );
		if ($bom == "\xFE\xFF") {
			return getid3_lib::iconv_fallback_utf16be_iso88591 ( substr ( $string, 2 ) );
		} elseif ($bom == "\xFF\xFE") {
			return getid3_lib::iconv_fallback_utf16le_iso88591 ( substr ( $string, 2 ) );
		}
		return $string;
	}
	
	// UTF-16 (BOM) => UTF-8
	static function iconv_fallback_utf16_utf8($string) {
		$bom = substr ( $string, 0, 2 );
		if ($bom == "\xFE\xFF") {
			return getid3_lib::iconv_fallback_utf16be_utf8 ( substr ( $string, 2 ) );
		} elseif ($bom == "\xFF\xFE") {
			return getid3_lib::iconv_fallback_utf16le_utf8 ( substr ( $string, 2 ) );
		}
		return $string;
	}
	
	static function iconv_fallback($in_charset, $out_charset, $string) {
		
		if ($in_charset == $out_charset) {
			return $string;
		}
		
		// iconv() availble
		if (function_exists ( 'iconv' )) {
			if (($converted_string = @iconv ( $in_charset, $out_charset . '//TRANSLIT', $string )) != false) {
				switch ($out_charset) {
					case 'ISO-8859-1' :
						$converted_string = rtrim ( $converted_string, "\x00" );
						break;
				}
				return $converted_string;
			}
			
			// iconv() may sometimes fail with "illegal character in input string" error message
			// and return an empty string, but returning the unconverted string is more useful
			return $string;
		}
		
		// iconv() not available
		static $ConversionFunctionList = array ();
		if (empty ( $ConversionFunctionList )) {
			$ConversionFunctionList ['ISO-8859-1'] ['UTF-8'] = 'iconv_fallback_iso88591_utf8';
			$ConversionFunctionList ['ISO-8859-1'] ['UTF-16'] = 'iconv_fallback_iso88591_utf16';
			$ConversionFunctionList ['ISO-8859-1'] ['UTF-16BE'] = 'iconv_fallback_iso88591_utf16be';
			$ConversionFunctionList ['ISO-8859-1'] ['UTF-16LE'] = 'iconv_fallback_iso88591_utf16le';
			$ConversionFunctionList ['UTF-8'] ['ISO-8859-1'] = 'iconv_fallback_utf8_iso88591';
			$ConversionFunctionList ['UTF-8'] ['UTF-16'] = 'iconv_fallback_utf8_utf16';
			$ConversionFunctionList ['UTF-8'] ['UTF-16BE'] = 'iconv_fallback_utf8_utf16be';
			$ConversionFunctionList ['UTF-8'] ['UTF-16LE'] = 'iconv_fallback_utf8_utf16le';
			$ConversionFunctionList ['UTF-16'] ['ISO-8859-1'] = 'iconv_fallback_utf16_iso88591';
			$ConversionFunctionList ['UTF-16'] ['UTF-8'] = 'iconv_fallback_utf16_utf8';
			$ConversionFunctionList ['UTF-16LE'] ['ISO-8859-1'] = 'iconv_fallback_utf16le_iso88591';
			$ConversionFunctionList ['UTF-16LE'] ['UTF-8'] = 'iconv_fallback_utf16le_utf8';
			$ConversionFunctionList ['UTF-16BE'] ['ISO-8859-1'] = 'iconv_fallback_utf16be_iso88591';
			$ConversionFunctionList ['UTF-16BE'] ['UTF-8'] = 'iconv_fallback_utf16be_utf8';
		}
		if (isset ( $ConversionFunctionList [strtoupper ( $in_charset )] [strtoupper ( $out_charset )] )) {
			$ConversionFunction = $ConversionFunctionList [strtoupper ( $in_charset )] [strtoupper ( $out_charset )];
			return getid3_lib::$ConversionFunction ( $string );
		}
		throw new Exception ( 'PHP does not have iconv() support - cannot convert from ' . $in_charset . ' to ' . $out_charset );
	}
	
	static function MultiByteCharString2HTML($string, $charset = 'ISO-8859-1') {
		$string = ( string ) $string; // in case trying to pass a numeric (float, int) string, would otherwise return an empty string
		$HTMLstring = '';
		
		switch ($charset) {
			case '1251' :
			case '1252' :
			case '866' :
			case '932' :
			case '936' :
			case '950' :
			case 'BIG5' :
			case 'BIG5-HKSCS' :
			case 'cp1251' :
			case 'cp1252' :
			case 'cp866' :
			case 'EUC-JP' :
			case 'EUCJP' :
			case 'GB2312' :
			case 'ibm866' :
			case 'ISO-8859-1' :
			case 'ISO-8859-15' :
			case 'ISO8859-1' :
			case 'ISO8859-15' :
			case 'KOI8-R' :
			case 'koi8-ru' :
			case 'koi8r' :
			case 'Shift_JIS' :
			case 'SJIS' :
			case 'win-1251' :
			case 'Windows-1251' :
			case 'Windows-1252' :
				$HTMLstring = htmlentities ( $string, ENT_COMPAT, $charset );
				break;
			
			case 'UTF-8' :
				$strlen = strlen ( $string );
				for($i = 0; $i < $strlen; $i ++) {
					$char_ord_val = ord ( $string {$i} );
					$charval = 0;
					if ($char_ord_val < 0x80) {
						$charval = $char_ord_val;
					} elseif ((($char_ord_val & 0xF0) >> 4) == 0x0F && $i + 3 < $strlen) {
						$charval = (($char_ord_val & 0x07) << 18);
						$charval += ((ord ( $string {++ $i} ) & 0x3F) << 12);
						$charval += ((ord ( $string {++ $i} ) & 0x3F) << 6);
						$charval += (ord ( $string {++ $i} ) & 0x3F);
					} elseif ((($char_ord_val & 0xE0) >> 5) == 0x07 && $i + 2 < $strlen) {
						$charval = (($char_ord_val & 0x0F) << 12);
						$charval += ((ord ( $string {++ $i} ) & 0x3F) << 6);
						$charval += (ord ( $string {++ $i} ) & 0x3F);
					} elseif ((($char_ord_val & 0xC0) >> 6) == 0x03 && $i + 1 < $strlen) {
						$charval = (($char_ord_val & 0x1F) << 6);
						$charval += (ord ( $string {++ $i} ) & 0x3F);
					}
					if (($charval >= 32) && ($charval <= 127)) {
						$HTMLstring .= htmlentities ( chr ( $charval ) );
					} else {
						$HTMLstring .= '&#' . $charval . ';';
					}
				}
				break;
			
			case 'UTF-16LE' :
				for($i = 0; $i < strlen ( $string ); $i += 2) {
					$charval = getid3_lib::LittleEndian2Int ( substr ( $string, $i, 2 ) );
					if (($charval >= 32) && ($charval <= 127)) {
						$HTMLstring .= chr ( $charval );
					} else {
						$HTMLstring .= '&#' . $charval . ';';
					}
				}
				break;
			
			case 'UTF-16BE' :
				for($i = 0; $i < strlen ( $string ); $i += 2) {
					$charval = getid3_lib::BigEndian2Int ( substr ( $string, $i, 2 ) );
					if (($charval >= 32) && ($charval <= 127)) {
						$HTMLstring .= chr ( $charval );
					} else {
						$HTMLstring .= '&#' . $charval . ';';
					}
				}
				break;
			
			default :
				$HTMLstring = 'ERROR: Character set "' . $charset . '" not supported in MultiByteCharString2HTML()';
				break;
		}
		return $HTMLstring;
	}
	
	static function RGADnameLookup($namecode) {
		static $RGADname = array ();
		if (empty ( $RGADname )) {
			$RGADname [0] = 'not set';
			$RGADname [1] = 'Track Gain Adjustment';
			$RGADname [2] = 'Album Gain Adjustment';
		}
		
		return (isset ( $RGADname [$namecode] ) ? $RGADname [$namecode] : '');
	}
	
	static function RGADoriginatorLookup($originatorcode) {
		static $RGADoriginator = array ();
		if (empty ( $RGADoriginator )) {
			$RGADoriginator [0] = 'unspecified';
			$RGADoriginator [1] = 'pre-set by artist/producer/mastering engineer';
			$RGADoriginator [2] = 'set by user';
			$RGADoriginator [3] = 'determined automatically';
		}
		
		return (isset ( $RGADoriginator [$originatorcode] ) ? $RGADoriginator [$originatorcode] : '');
	}
	
	static function RGADadjustmentLookup($rawadjustment, $signbit) {
		$adjustment = $rawadjustment / 10;
		if ($signbit == 1) {
			$adjustment *= - 1;
		}
		return ( float ) $adjustment;
	}
	
	static function RGADgainString($namecode, $originatorcode, $replaygain) {
		if ($replaygain < 0) {
			$signbit = '1';
		} else {
			$signbit = '0';
		}
		$storedreplaygain = intval ( round ( $replaygain * 10 ) );
		$gainstring = str_pad ( decbin ( $namecode ), 3, '0', STR_PAD_LEFT );
		$gainstring .= str_pad ( decbin ( $originatorcode ), 3, '0', STR_PAD_LEFT );
		$gainstring .= $signbit;
		$gainstring .= str_pad ( decbin ( $storedreplaygain ), 9, '0', STR_PAD_LEFT );
		
		return $gainstring;
	}
	
	static function RGADamplitude2dB($amplitude) {
		return 20 * log10 ( $amplitude );
	}
	
	static function GetDataImageSize($imgData, &$imageinfo) {
		static $tempdir = '';
		if (empty ( $tempdir )) {
			// yes this is ugly, feel free to suggest a better way
			require_once (dirname ( __FILE__ ) . '/getid3.php');
			$getid3_temp = new getID3 ();
			$tempdir = $getid3_temp->tempdir;
			unset ( $getid3_temp );
		}
		$GetDataImageSize = false;
		if (($tempfilename = tempnam ( $tempdir, 'gI3' )) != false) {
			if (is_writable ( $tempfilename ) && is_file ( $tempfilename ) && ($tmp = fopen ( $tempfilename, 'wb' ))) {
				fwrite ( $tmp, $imgData );
				fclose ( $tmp );
				$GetDataImageSize = @GetImageSize ( $tempfilename, $imageinfo );
			}
			unlink ( $tempfilename );
		}
		return $GetDataImageSize;
	}
	
	static function ImageTypesLookup($imagetypeid) {
		static $ImageTypesLookup = array ();
		if (empty ( $ImageTypesLookup )) {
			$ImageTypesLookup [1] = 'gif';
			$ImageTypesLookup [2] = 'jpeg';
			$ImageTypesLookup [3] = 'png';
			$ImageTypesLookup [4] = 'swf';
			$ImageTypesLookup [5] = 'psd';
			$ImageTypesLookup [6] = 'bmp';
			$ImageTypesLookup [7] = 'tiff (little-endian)';
			$ImageTypesLookup [8] = 'tiff (big-endian)';
			$ImageTypesLookup [9] = 'jpc';
			$ImageTypesLookup [10] = 'jp2';
			$ImageTypesLookup [11] = 'jpx';
			$ImageTypesLookup [12] = 'jb2';
			$ImageTypesLookup [13] = 'swc';
			$ImageTypesLookup [14] = 'iff';
		}
		return (isset ( $ImageTypesLookup [$imagetypeid] ) ? $ImageTypesLookup [$imagetypeid] : '');
	}
	
	static function CopyTagsToComments(&$ThisFileInfo) {
		
		// Copy all entries from ['tags'] into common ['comments']
		if (! empty ( $ThisFileInfo ['tags'] )) {
			foreach ( $ThisFileInfo ['tags'] as $tagtype => $tagarray ) {
				foreach ( $tagarray as $tagname => $tagdata ) {
					foreach ( $tagdata as $key => $value ) {
						if (! empty ( $value )) {
							if (empty ( $ThisFileInfo ['comments'] [$tagname] )) {
								
								// fall through and append value
							

							} elseif ($tagtype == 'id3v1') {
								
								$newvaluelength = strlen ( trim ( $value ) );
								foreach ( $ThisFileInfo ['comments'] [$tagname] as $existingkey => $existingvalue ) {
									$oldvaluelength = strlen ( trim ( $existingvalue ) );
									if (($newvaluelength <= $oldvaluelength) && (substr ( $existingvalue, 0, $newvaluelength ) == trim ( $value ))) {
										// new value is identical but shorter-than (or equal-length to) one already in comments - skip
										break 2;
									}
								}
							
							} elseif (! is_array ( $value )) {
								
								$newvaluelength = strlen ( trim ( $value ) );
								foreach ( $ThisFileInfo ['comments'] [$tagname] as $existingkey => $existingvalue ) {
									$oldvaluelength = strlen ( trim ( $existingvalue ) );
									if (($newvaluelength > $oldvaluelength) && (substr ( trim ( $value ), 0, strlen ( $existingvalue ) ) == $existingvalue)) {
										$ThisFileInfo ['comments'] [$tagname] [$existingkey] = trim ( $value );
										break 2;
									}
								}
							
							}
							if (is_array ( $value ) || empty ( $ThisFileInfo ['comments'] [$tagname] ) || ! in_array ( trim ( $value ), $ThisFileInfo ['comments'] [$tagname] )) {
								$value = (is_string ( $value ) ? trim ( $value ) : $value);
								$ThisFileInfo ['comments'] [$tagname] [] = $value;
							}
						}
					}
				}
			}
			
			// Copy to ['comments_html']
			foreach ( $ThisFileInfo ['comments'] as $field => $values ) {
				if ($field == 'picture') {
					// pictures can take up a lot of space, and we don't need multiple copies of them
					// let there be a single copy in [comments][picture], and not elsewhere
					continue;
				}
				foreach ( $values as $index => $value ) {
					if (is_array ( $value )) {
						$ThisFileInfo ['comments_html'] [$field] [$index] = $value;
					} else {
						$ThisFileInfo ['comments_html'] [$field] [$index] = str_replace ( '&#0;', '', getid3_lib::MultiByteCharString2HTML ( $value, $ThisFileInfo ['encoding'] ) );
					}
				}
			}
		}
		return true;
	}
	
	static function EmbeddedLookup($key, $begin, $end, $file, $name) {
		
		// Cached
		static $cache;
		if (isset ( $cache [$file] [$name] )) {
			return (isset ( $cache [$file] [$name] [$key] ) ? $cache [$file] [$name] [$key] : '');
		}
		
		// Init
		$keylength = strlen ( $key );
		$line_count = $end - $begin - 7;
		
		// Open php file
		$fp = fopen ( $file, 'r' );
		
		// Discard $begin lines
		for($i = 0; $i < ($begin + 3); $i ++) {
			fgets ( $fp, 1024 );
		}
		
		// Loop thru line
		while ( 0 < $line_count -- ) {
			
			// Read line
			$line = ltrim ( fgets ( $fp, 1024 ), "\t " );
			
			// METHOD A: only cache the matching key - less memory but slower on next lookup of not-previously-looked-up key
			//$keycheck = substr($line, 0, $keylength);
			//if ($key == $keycheck)  {
			//	$cache[$file][$name][$keycheck] = substr($line, $keylength + 1);
			//	break;
			//}
			

			// METHOD B: cache all keys in this lookup - more memory but faster on next lookup of not-previously-looked-up key
			//$cache[$file][$name][substr($line, 0, $keylength)] = trim(substr($line, $keylength + 1));
			$explodedLine = explode ( "\t", $line, 2 );
			$ThisKey = (isset ( $explodedLine [0] ) ? $explodedLine [0] : '');
			$ThisValue = (isset ( $explodedLine [1] ) ? $explodedLine [1] : '');
			$cache [$file] [$name] [$ThisKey] = trim ( $ThisValue );
		}
		
		// Close and return
		fclose ( $fp );
		return (isset ( $cache [$file] [$name] [$key] ) ? $cache [$file] [$name] [$key] : '');
	}
	
	static function IncludeDependency($filename, $sourcefile, $DieOnFailure = false) {
		global $GETID3_ERRORARRAY;
		
		if (file_exists ( $filename )) {
			if (include_once ($filename)) {
				return true;
			} else {
				$diemessage = basename ( $sourcefile ) . ' depends on ' . $filename . ', which has errors';
			}
		} else {
			$diemessage = basename ( $sourcefile ) . ' depends on ' . $filename . ', which is missing';
		}
		if ($DieOnFailure) {
			throw new Exception ( $diemessage );
		} else {
			$GETID3_ERRORARRAY [] = $diemessage;
		}
		return false;
	}
	
	public static function trimNullByte($string) {
		return trim ( $string, "\x00" );
	}

}