MP3InfoUtil.getInfo("АДРЕС_АУДИО_ФАЙЛА");

MP3InfoUtil.addEventListener(MP3InfoEvent.COMPLETE, onMP3InfoComplete);

MP3InfoUtil.addEventListener(MP3InfoEvent.ERROR, onMP3InfoError);

...

public function onMP3InfoComplete(event:MP3InfoEvent):void

{

    trace("Длительность = " + event.info["lengthSeconds"]);   

}

 

public function onMP3InfoError(e:MP3InfoEvent):void{

    trace(e.info.message);

}