Bits & Bytes

Archive for the ‘Actionscript’ Category

Graphing Sound Data Visualizations in Actionscript 3.0

This program demonstrates how to retrieve and graph a set of samples of sound data. To see the program run, left-click the box above.

The code begins with three lines to output the click instructions. The next three lines create a Sound object, load an mp3 file, and set a callback for when the sound finishes playing. Then we create a ByteArray to store the sound data and set the StartSound() function as a callback for left-clicks.

The rest of the code consists of functions. The StartSound() function begins playing the sound and sets the callback function StartFrame() to get called for every frame of the animation. The SoundFinished() function stops StartFrame() from receiving messages after the sound is finished playing.

The function StartFrame() retrieves the sound data and graphs it. It begins with a call to the static function computeSpectrum() that returns 512 sound samples, 256 for each channel, in the ByteArray qSignal. Next, it clears the old graphics and sets the line style to a green line of width 1 pixel, and calls DrawSignal() twice, once for each channel.

Finally, the DrawSignal() function graphs each of the 256 sound samples. The graph is centered at the y-value dCenterY and the amplitude is scaled by 50 pixels. The scaling means that the samples, which range between -1 and 1, are scaled to the range -50 to 50. We begin each graph with a call to moveTo() so that no line is written from the previous position.

// Output the initial instructions to user
var qInstructions:TextField = new TextField();
qInstructions.text = "Click To Play";

var qSound:Sound = new Sound(); 
qSound.load(new URLRequest(""));
qSound.addEventListener(Event.SOUND_COMPLETE, SoundFinished);

var qSignal:ByteArray = new ByteArray();

stage.addEventListener(MouseEvent.CLICK, StartSound);

function StartSound(e:Event):void {
	var qSoundChannel:SoundChannel =;
	addEventListener(Event.ENTER_FRAME, StartFrame);

function SoundFinished(e:Event):void { 
	removeEventListener(Event.ENTER_FRAME, StartFrame); 

function StartFrame(e:Event):void {
	// Get the data for the left and right channels
	SoundMixer.computeSpectrum(qSignal, false, 0);
	graphics.lineStyle(1, 0x00FF00);
	// Graph the left channel on the top
	// Graph the right channel on the bottom

function DrawSignal(dCenterY:Number):void {
	graphics.moveTo(0, dCenterY + 50*qSignal.readFloat());
	for (var i:int = 1; i < 256; i++) { 
		graphics.lineTo(i, dCenterY + 50*qSignal.readFloat()); 

Loading and Playing a Sound File in Actionscript 3.0

This program loads an mp3 file and plays it. The entire program is given below and the compiled SWF is shown above. To hear the file play, left-click the window above.

The code begins with three lines that tell the user to click the screen. Then we create a String for the URL, which could also be a local file. Next, we set our function as the callback for mouse clicks. Inside the function OnClick(), we create a Sound object, load the sound file, and then play it.

// Output the initial instructions to user
var qInstructions:TextField = new TextField();
qInstructions.text = "Click To Play";

const ksXoaXDotNet:String = "";

// Play the mp3 when the screen is clicked
stage.addEventListener(MouseEvent.CLICK, OnClick);

function OnClick(e:MouseEvent): void {
	var qSound:Sound = new Sound();
	qSound.load(new URLRequest(ksXoaXDotNet));;

Saving a Screen Capture to a JPEG Image File in Actionscript 3.0

The program below demostrates how to capture an image of the stage and save it as a jpg image. We have drawn a yellow circle give the image capture something more interesting to render. To save the jpg image, just left-click the box above and select a location to save the image in.

The program for this jpg image capture is shown below. Additionally, you will need the JPGEncoder file which you can get here: To use the source file, select Edit->Preferences->Actionscript->Actionscript 3.0 Settings . . . and add the folder where you put “mikechambers-as3corelib-release.93-8-g24c6c16\mikechambers-as3corelib-24c6c16\src” to the src paths. Then you should be able to compile and execute the Actionscript code.

In this program, we import the JPGEncoder class and then draw a filled yellow circle on the stage. Next, we register an event listener to call the function SaveJPG() to save the image when a left-click occurs; Actionscript requires that file-saving code be contained in a user-initiated function.

Inside the callback, we create a BitmapData object that is the size of our stage and draw the stage into it. Then we create the encoder and call encode() to put the jpg data into a ByteArray. Finally, we create a FileReference object and save the jpg data.

import com.adobe.images.JPGEncoder;

// Draw a circle on the staqe
graphics.drawCircle(160, 120, 100);

stage.addEventListener(MouseEvent.CLICK, SaveJPG);

function SaveJPG(e:MouseEvent):void {
	// Store the image capture of stage in a BitmapData Object
	var qImageData:BitmapData = new BitmapData(320, 240);
	// Set the encoding to high-quality
	var qEncoder:JPGEncoder = new JPGEncoder(100);
	var qBytes:ByteArray = qEncoder.encode(qImageData);
	var qFile:FileReference = new FileReference();, "YellowCircle.jpg");

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