he usado lo mismo que hay aquí
http://www.getid3.org/demo.basic.phps
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require_once('../getid3/getid3.php');
$getID3 = new getID3;
$ThisFileInfo = $getID3->analyze($filename);
getid3_lib::CopyTagsToComments($ThisFileInfo);
echo @$ThisFileInfo['playtime_string'];
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