Windows XP users may be having trouble with routines provided here and may (as above) only have access to "read" classes. The following very simplified "write" can be used for replacing Windows Media Player file tags, and with care and adjustments, can be used more generally.
<?php
define(_Title,"TIT2");
define(_Artist,"TPE1");
define(_Group,"TPE2");
define(_Album,"TALB");
define(_Genre,"TCON");
define(_TrackNo,"TRCK");
define(_Year,"TYER");
$frames = array(_Album=>"The Ultimate Experience",
_TrackNo=>"1",
_Title=>"All along the watchtower",
_Artist=>"Jimi Hendrix",
_Group=>"",
_Year=>"19xx",
_Genre=>"Rock");
function writeTags($mp3) {
$fl = file_get_contents($mp3);
$Header = substr($fl,0,10);
$tagLen = calcDecTagLen(substr($Header,6,4),$tagLen);
$music = substr($fl,$tagLen+10,-128);
$tagLen = 1024; $Header = substr($Header,0,6).setHexTagLen($tagLen);
file_put_contents($mp3,mkV2Tag($Header,$tagLen).$music.mkV1Tag());
}
function mkV2Tag($Hdr,$tagLen) {
Global $frames;
$null = chr(0);
$nl3 = $null.$null.$null; $out = "";
foreach($frames as $ky=>$val) {
$n=strlen($val)+1;
$out.= $ky.mkFrmLen($n).$nl3.$val;
}
return $Hdr.str_pad($out,$tagLen,$null);
}
function calcDecTagLen($word) {
$m = 1;
$int = 0;
for ($i=strlen($word)-1;$i>-1;$i--) {
$int +=$m*ord($word[$i]);
$m=$m*128;
}
return $int;
}
function mkFrmLen($int) {
$hx = "";
while ($int>0) {
$n = $int % 256;
$hx = chr($n).$hx;
$int=floor($int/256);
}
return str_pad($hx,4,chr(0),STR_PAD_LEFT);
}
function mkV1Tag() {
Global $frames;
$tagOut = "TAG".
adj($frames[_Title]).
adj($frames[_Artist]).
adj($frames[_Album]).
str_pad($frames[_Year],4).
str_pad(" ",29," ").
chr($frames[_TrackNo]).
chr($n);
return $tagOut;
}
function adj($str) {
return substr(str_pad($str,30,chr(0)),0,30);
}
writeTags("01-Cognac Blues.mp3");
?>
The setHexTagLen can be figured out from the calcDecTagLen but here's some sample code.
<?php
function setHexTagLen($int) {
$n = pow(128,3);
$intVar = $int;
$m = "";
for ($i=0;$i<4;$i++) {
$m .= chr(floor($intVar/$n));
$intVar = $intVar % $n;
$n=$n/128;
}
return $m;
}
?>