MP3Loader.as

// Author: Claus Wahlers
// License: Public Domain

// Dependencies:
// as3commons-bytecode-1.0-RC1.swc
// as3commons-lang-0.3.2.swc
// as3commons-logging-2.0.swc
// as3commons-reflect-1.3.4.swc
// as3swf.swc
// MinimalComps_0_9_9.swc

package
{
	import com.bit101.components.PushButton;
	
	import com.codeazur.as3swf.SWF;
	import com.codeazur.as3swf.SWFData;
	import com.codeazur.as3swf.data.SWFSymbol;
	import com.codeazur.as3swf.tags.TagDefineSound;
	import com.codeazur.as3swf.tags.TagDoABC;
	import com.codeazur.as3swf.tags.TagEnd;
	import com.codeazur.as3swf.tags.TagFileAttributes;
	import com.codeazur.as3swf.tags.TagShowFrame;
	import com.codeazur.as3swf.tags.TagSymbolClass;

	import org.as3commons.bytecode.abc.AbcFile;
	import org.as3commons.bytecode.emit.IAbcBuilder;
	import org.as3commons.bytecode.emit.IClassBuilder;
	import org.as3commons.bytecode.emit.IPackageBuilder;
	import org.as3commons.bytecode.emit.impl.AbcBuilder;
	import org.as3commons.bytecode.io.AbcSerializer;

	import flash.display.Loader;
	import flash.display.LoaderInfo;
	import flash.display.Sprite;
	import flash.display.StageAlign;
	import flash.display.StageScaleMode;
	import flash.events.Event;
	import flash.media.Sound;
	import flash.net.FileFilter;
	import flash.net.FileReference;
	import flash.utils.ByteArray;

	public class MP3FileRefLoader extends Sprite
	{
		private static const PACKAGENAME:String = "tmp";
		private static const CLASSNAME:String = "SoundClass";
		private static const QNAME:String = PACKAGENAME + "." + CLASSNAME;
		
		public function MP3FileRefLoader()
		{
			stage.align = StageAlign.TOP_LEFT;
			stage.scaleMode = StageScaleMode.NO_SCALE
			addChild(new PushButton(this, 10, 10, "Load MP3", function():void {
				var ref:FileReference = new FileReference();
				ref.addEventListener(Event.SELECT, function(e:Event):void { ref.load(); });
				ref.addEventListener(Event.COMPLETE, function(e:Event):void { loadBytes(ref.data); });
				ref.browse([new FileFilter("MP3 (*.mp3)", "*.mp3")]);
			}));
		}

		protected function loadBytes(mp3:ByteArray):void {
			// Wrap the MP3 with a SWF
			var swf:ByteArray = createSWFFromMP3(mp3);
			// Load the SWF with Loader::loadBytes()
			var loader:Loader = new Loader();
			loader.contentLoaderInfo.addEventListener(Event.INIT, initHandler);
			loader.loadBytes(swf);
		}

		protected function initHandler(e:Event):void {
			// Get the sound class definition
			var SoundClass:Class = LoaderInfo(e.currentTarget).applicationDomain.getDefinition(QNAME) as Class;
			// Instantiate the sound class
			var sound:Sound = new SoundClass() as Sound;
			// Play the sound
			sound.play();
		}

		protected function createSWFFromMP3(mp3:ByteArray):ByteArray
		{
			// Create an empty SWF
			// Defaults to v10, 550x400px, 50fps, one frame (works fine for us)
			var swf:SWF = new SWF();

			// Add FileAttributes tag
			// Defaults: as3 true, all other flags false (works fine for us)
			swf.tags.push(new TagFileAttributes());

			// Add DefineSound tag
			// The ID is 1, all other parameters are automatically
			// determined from the mp3 itself.
			swf.tags.push(TagDefineSound.createWithMP3(1, mp3));

			// Create and add DoABC tag
			// Contains the AS3 byte code for the class definition for the embedded sound:
			// package tmp {
			//    public dynamic class SoundClass extends flash.media.Sound {
			//    }
			// }
			var abcBuilder:IAbcBuilder = new AbcBuilder();
			var packageBuilder:IPackageBuilder = abcBuilder.definePackage(PACKAGENAME);
			var classBuilder:IClassBuilder = packageBuilder.defineClass(CLASSNAME, "flash.media.Sound");
			var abcFile:AbcFile = abcBuilder.build();
			var abcSerializer:AbcSerializer = new AbcSerializer();
			var abcBytes:ByteArray = abcSerializer.serializeAbcFile(abcFile);
			swf.tags.push(TagDoABC.create(abcBytes));

			// Add SymbolClass tag
			// Binds the sound class definition to the embedded sound
			var symbolClass:TagSymbolClass = new TagSymbolClass();
			symbolClass.symbols.push(SWFSymbol.create(1, QNAME));
			swf.tags.push(symbolClass);

			// Add ShowFrame tag
			swf.tags.push(new TagShowFrame());

			// Add End tag
			swf.tags.push(new TagEnd());

			// Publish the SWF
			var swfData:SWFData = new SWFData();
			swf.publish(swfData);

			return swfData;
		}
	}
}