Trying to access the first instance of an array in Actionscript 3 - arrays

Question

I am trying to do deat detection in actionscript 3. My idea is to create an array of dots (MovieClips) on the x axis which represents the frequency spectrum, SoundMixer.computeSpectrum(bytes, true, 0); is set to true. How do I access the first dot instance of my array. I then want to check it's highest value on each current frame and and measure it against the last value. I think I need to set a threshold and when the value is within the threshold call that a beat....I'm lost, can anybody point me in the right direction..
Thanks in advance.
var snd: Sound = new Sound();
var req: URLRequest = new URLRequest("mySong.mp3");
snd.load(req);
var channel: SoundChannel;
channel = snd.play();
addEventListener(Event.ENTER_FRAME, onEnterFrame);
snd.addEventListener(Event.SOUND_COMPLETE, onPlaybackComplete);
const CHANNEL_LENGTH: int = 256;
const BUFFER_LENGTH: int = 512;
var dot:Dot;
dot.cacheAsBitmap = true;
var myArray:Array = new Array();
var bytes:ByteArray = new ByteArray();
function onEnterFrame(event: Event): void
{
SoundMixer.computeSpectrum(bytes, true, 0);
for (var i:int = 0; i < CHANNEL_LENGTH; i+=8) // channel_length = 256
{
var sampleValue:Number = bytes.readFloat();
dot = new Dot();
dot.x = i * 2;
dot.y = sampleValue * 250; //50 + (i * 30)
addChild(dot);
myArray.push(dot);
}
}

Answer 1

I am not sure what excetly you are going to do.
But if you want to do a sound spectrum visualizer, I think your direction is right.
I follow what you do and get result like this: (http://www.imageupload.co.uk/5M3n) Those dots will dance with the music
just move dot.cacheAsBitmap = true; after dot = new Dot(); or you can remove it.
and in Dot class, don't forget to dispose itself after some time.
But actually I dont need to use myArray at all.
Here is my code:
import flash.events.Event;
var snd: Sound = new Sound();
var req: URLRequest = new URLRequest("mySong.mp3");
snd.load(req);
var channel: SoundChannel;
channel = snd.play();
addEventListener(Event.ENTER_FRAME, onEnterFrame);
snd.addEventListener(Event.SOUND_COMPLETE, onPlaybackComplete);
const CHANNEL_LENGTH: int = 256;
const BUFFER_LENGTH: int = 512;
var dot:Dot;
var myArray:Array;
var bytes:ByteArray = new ByteArray();
function onEnterFrame(event: Event): void
{
SoundMixer.computeSpectrum(bytes, true, 0);
myArray = [];
for (var i:int = 0; i < CHANNEL_LENGTH; i+=8) // channel_length = 256
{
var sampleValue:Number = bytes.readFloat();
dot = new Dot();
dot.cacheAsBitmap = true;
dot.x = i * 2;
dot.y = sampleValue * stage.StageHeight;
addChild(dot);
myArray.push(dot);
}
var firstElement:Dot = myArray.length>0?myArray[0]:null;
if(firstElement)
{
handleWithFirstElement(firstElement);
}
}
function onPlaybackComplete(e:Event):void
{
removeEventListener(Event.ENTER_FRAME, onEnterFrame);
}
function handleWithFirstElement(ele:Dot):void
{
//your code
}
And in Dot class:
flash.utils.setTimeout(this.parent.removeChild, 100, this);
// Run this just after added on Stage