Preload of MP3 files from XML

Question

Hey guys,
I've almost finished my flash website for a friend and just want to add a simple MP3 player.
I have the following code which reads an XML file and loads the mp3s referred to in it and plays them... this is all cool...(i've removed the bits for the buttons as i didnt think they were relevant)
what I really really want to be able to do is buffer the MP3 files so that they begin playing when 1/2 loaded or similar (ideally preload 1/2 of track 1, play track 1, when track 1 loading is complete start preloading track 2 etc.)
I just cant work out how to do it...
Any advice would be very gratefully received!
var my_songs:XMLList;
var my_total:Number;
var my_sound:Sound;
var my_channel:SoundChannel;
var current_song:Number = 0;
var song_position:Number;
var song_paused:Boolean;
var myXMLLoader:URLLoader = new URLLoader();
myXMLLoader.load(new URLRequest("playlist.xml"));
myXMLLoader.addEventListener(Event.COMPLETE, processXML);
function processXML(e:Event):void {
var myXML:XML = new XML(e.target.data);
my_songs = myXML.SONG;
my_total = my_songs.length();
playSong(0); // Simply remove this line to stop automatic playback.
myXMLLoader.removeEventListener(Event.COMPLETE, processXML);
myXMLLoader = null;
function playSong(mySong:Number):void{
var myTitle = my_songs[mySong].@TITLE;
var myArtist = my_songs[mySong].@ARTIST;
var info = myTitle+" - "+myArtist;
var myURL = my_songs[mySong].@URL;
title_txt.text = info;
if (my_channel){
my_channel.stop();
my_channel.removeEventListener(Event.SOUND_COMPLETE, onNext);
my_sound = new Sound();
my_sound.load(new URLRequest(myURL));
my_channel = my_sound.play();
my_channel.addEventListener(Event.SOUND_COMPLETE, onNext);

Answer 1

thanks for the help but I now have another error :*(
slightly different error:
ArgumentError: Error #2068: Invalid sound.
at flash.media::Sound/play()
at mp3_fla::MainTimeline/MP3_LOADING()[mp3_fla.MainTimeline::frame1:47]
line 47 is "my_channel = my_sound.play();"
var my_songs:XMLList;
var my_total:Number;
var my_sound:Sound=new Sound();
var my_channel:SoundChannel;
var current_song:Number = 0;
var song_position:Number;
var song_paused:Boolean;
var myXMLLoader:URLLoader = new URLLoader();
myXMLLoader.load(new URLRequest("playlist.xml"));
myXMLLoader.addEventListener(Event.COMPLETE, processXML);
function processXML(e:Event):void {
var myXML:XML = new XML(e.target.data);
my_songs = myXML.SONG;
my_total = my_songs.length();
playSong(0); // Simply remove this line to stop automatic playback.
myXMLLoader.removeEventListener(Event.COMPLETE, processXML);
myXMLLoader = null;
function playSong(mySong:Number):void{
var myTitle = my_songs[mySong].@TITLE;
var myArtist = my_songs[mySong].@ARTIST;
var info = myTitle+" - "+myArtist;
var myURL = my_songs[mySong].@URL;
title_txt.text = info;
if (my_channel){
my_channel.stop();
my_channel.removeEventListener(Event.SOUND_COMPLETE, onNext);
//my_sound = new Sound();
my_sound.load(new URLRequest(myURL));
this.loaderInfo.addEventListener(
  ProgressEvent.PROGRESS, MP3_LOADING
var alreadyStarted:Boolean=false;
function MP3_LOADING(e:ProgressEvent):void {
  var loaded:Number =e.bytesLoaded;
var total:Number=e.bytesTotal;
  bytes.text=int(loaded*100/total)+"%";
if(loaded*2>=total&&!alreadyStarted){
alreadyStarted=true;
my_channel = my_sound.play();
my_channel.addEventListener(Event.SOUND_COMPLETE, onNext);
next_btn.addEventListener(MouseEvent.CLICK, onNext);
function onNext(e:Event):void{ //This used to have MouseEvent, change it to Event.
current_song++;
if (current_song>=my_total){
current_song=0;
playSong(current_song);
prev_btn.addEventListener(MouseEvent.CLICK, onPrev);
function onPrev(e:MouseEvent):void{
current_song--;
if (current_song<0){
current_song = my_total-1;
playSong(current_song);
pause_btn.addEventListener(MouseEvent.CLICK, onPause);
function onPause(e:MouseEvent):void{
if (my_channel){
song_position = my_channel.position;
my_channel.stop();
song_paused=true;
play_btn.addEventListener(MouseEvent.CLICK, onPlay);
function onPlay(e:MouseEvent):void{
if (song_paused){
my_channel = my_sound.play(song_position);
song_paused=false;
} else if (!my_channel){
playSong(current_song);