[AS 3] SoundMixer.computeSpectrum For Sound Spectrum Analyzer

I wanted to continue on with creating visuals for audio files and discovered the SoundMixer.computSpectrum class that will help in generating a full Spectrum Analyzer. I will post my .swf on another page as there aren’t any music playback controls in the movie.

View the demo here.

Here is the code for the bar:

package
{
	import flash.display.Sprite;
	public class SpectrumBar extends Sprite
	{
		private var xPos:Number;
		private var yPos:Number;
		private var rWidth:Number;
		private var rHeight:Number;
		private var color:uint;

		public function SpectrumBar(xPos:Number=0,yPos:Number=0,rWidth:Number=10,rHeight:Number=10,color:uint=0x336699)
		{
			this.graphics.beginFill(color);
			this.graphics.drawRect(xPos,yPos,rWidth,rHeight);
			this.graphics.endFill();
		}
	}
}

Here is the document class:

package
{
	import flash.display.Sprite;
	import flash.media.Sound;
	import flash.display.BitmapData;
	import flash.utils.ByteArray;
	import flash.media.SoundMixer;
	import flash.events.Event;
	import flash.net.URLRequest;
	import flash.system.ApplicationDomain;
	import flash.filters.BlurFilter;

	// resource: http://www.mikechambers.com/blog/2006/04/24/example-actionscript-3-computespectrum/

	public class SoundVisualizer extends Sprite
	{
		private var bytes:ByteArray;
		private var CHANNEL_LENGTH:uint = 256;

		//place in middle of screen
		var xVal:Number = stage.stageHeight;

		//evenly distribute
		var spacing:Number = stage.stageWidth / CHANNEL_LENGTH;

		private var barsArr:Array;
		var bar:SpectrumBar;

		public function SoundVisualizer()
		{
			var s:Sound = new Sound(new URLRequest("/path/to/music/file.mp3"));

			s.play();

			bytes = new ByteArray();
			barsArr = new Array();

			for(var ct:uint = 0; ct < CHANNEL_LENGTH; ct++)
            {
				var bar:SpectrumBar = new SpectrumBar(ct * spacing,xVal-1,spacing,stage.stageHeight, Math.random() * 0xffffff);
				barsArr.push(bar);
				addChild(bar);
            }

			addEventListener( Event.ENTER_FRAME, onEnterFrame );
		}

		private function onEnterFrame( event: Event ): void
		{
			SoundMixer.computeSpectrum(bytes, true, 0);

			var smooth:Number;
			var value:Number;

			graphics.clear();

			var color:Number;

			for(var i:int = 0; i < CHANNEL_LENGTH; i++)
			{
				//get the next byte
				value = bytes.readFloat();

				//normalize it to be a value between 0 and 256
				value = (value * CHANNEL_LENGTH) << 0;

				//figure out the color based on the value
				// color = 0xFF0000|(value << 8);
				color = Math.random() * 0xffffff;

				var bar:SpectrumBar = barsArr[i]; 

				var SpectrumChange:Number = (value/8) * -4;
				sizeBar(bar,SpectrumChange);
			}
		}

		private function sizeBar(bar:SpectrumBar, SpectrumChange:Number)
		{
			bar.y = SpectrumChange;
		}
	}
}