Sound Duration, problems

Hello!

I am crating a MP3 Player, and i have one problem to fix. When i use the my_sound.duration (where my_sound is var my_sound:Sound = new Sound(); ), the duration only shows correcty when i use the onLoad method. Exemple:

var my_sound:Sound = new Sound();
my_sound.loadSound (“my file.mp3”, true);
my_sound.onLoad = function() {
duration_txt.text = my_sound.duration;
}

But, i dont want wait the music complete loaded to show the duration, but when the music starts show the duration.

I cant use the id3.LEN on my file. The other soluction is put the duration information in a XML file and later show in the Flash, but i want somethig ease, more dinamic.

So, have soluction to my problem or i have to say the duration of the Music.

Thanks

Ps: Sorry for my English