ID3 º¯Êý

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User Contributed Notes

jbwalker at telus dot net 15-Nov-2006 08:58
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");

#..........................................
#       WRITE ID3 TAGS (Write MP3 [v1, v2]
#..........................................
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);
    # Can use input Header for output but you may
    # wish to change the output filename for testing
        $tagLen = 1024; # or whatever you like >your actual
        $Header = substr($Header,0,6).setHexTagLen($tagLen);
        file_put_contents($mp3,mkV2Tag($Header,$tagLen).$music.mkV1Tag());
}
#   Create the V2 tag
function mkV2Tag($Hdr,$tagLen) {
    Global $frames;
    $null = chr(0);
    $nl3 = $null.$null.$null;            # 0 bytes for flags and encoding
    $out = "";
    foreach($frames as $ky=>$val) {
        $n=strlen($val)+1;
        $out.= $ky.mkFrmLen($n).$nl3.$val;
        }
    return $Hdr.str_pad($out,$tagLen,$null);
    }
#    Calculate Tag Length from bytes 6-10 of existing header
function calcDecTagLen($word) {
    $m = 1;
    $int = 0;
    for ($i=strlen($word)-1;$i>-1;$i--) {
        $int +=$m*ord($word[$i]);
        $m=$m*128;
        }
    return $int;
    }
#    Make the 4 byte frame length value for the V2tag
function mkFrmLen($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);
    }
#    Create the 128 byte V1 tag
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 $tagOut;
    }
#    Pad the header to 30 characters
function adj($str) {
    return substr(str_pad($str,30,chr(0)),0,30);
    }
   
#     This is a simple example for an mp3 in current folder   
    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;
}
?>
wmd at wazee dot org 11-Jul-2004 11:31
There are several highly developed id3 reader classes written in php that include id3v2 support, and support for other file formats (not just mpeg & id3). I recommend http://getid3.sourceforge.net/ as well as the id3 reader class integrated in the Zina is not Andromeda project (http://pancake.org/zina.html)