Working with embedded sounds

Flash Player 9 and later, Adobe AIR 1.0 and later

Using embedded sounds, instead of loading sound from an external file, is most useful for small sounds that are used as indicators within your application’s user interface, such as sounds that play when buttons are clicked.

When you embed a sound file in your application, the size of the resulting SWF file increases by the size of the sound file. In other words, embedding large sound files in your application can increase the size of your SWF file to an undesirable size.

The exact method of embedding a sound file into your application’s SWF file varies according to your development environment.

Using an embedded sound file in Flash

The Flash authoring tool lets you import sounds in a number of sound formats and store them as symbols in the Library. You can then assign them to frames in the timeline or to the frames of a button state, use them with Behaviors, or use them directly in ActionScript code. This section describes how to use embedded sounds in ActionScript code with the Flash authoring tool. For information about the other ways to use embedded sounds in Flash, see “Importing Sounds” in Using Flash.

To embed a sound file using the Flash authoring tool:

  1. Select File > Import > Import to Library, and then select a sound file and import it.

  2. Right-click the name of the imported file in the Library panel, and select Properties. Click the Export for ActionScript checkbox.

  3. In the Class field, enter a name to use when referring to this embedded sound in ActionScript. By default, it will use the name of the sound file in this field. If the filename includes a period, as in the name “DrumSound.mp3”, you must change it to something like “DrumSound”; ActionScript does not allow a period character in a class name. The Base Class field should still show

  4. Click OK. You might see a dialog box saying that a definition for this class could not be found in the classpath. Click OK and continue. If you entered a class name that doesn’t match the name of any of the classes in your application’s classpath, a new class that inherits from the class is automatically generated for you.

  5. To use the embedded sound, you reference the class name for that sound in ActionScript. For example, the following code starts by creating a new instance of the automatically generated DrumSound class:

    var drum:DrumSound = new DrumSound(); 
    var channel:SoundChannel =;

    DrumSound is a subclass of the class so it inherits the Sound class’s methods and properties, including the play() method as shown above.

Using an embedded sound file in Flex

There are many ways to embed sound assets in a Flex application, including:

  • Using the [Embed] metadata tag in a script

  • Using the @Embed directive in MXML to assign an embedded asset as a property of a component like a Button or a SoundEffect.

  • Using the @Embed directive within a CSS file

This section describes the first option: how to embed sounds in ActionScript code within a Flex application using the [Embed] metadata tag.

To embed an asset in ActionScript code, use the [Embed] metadata tag.

Place the sound file in the main source folder or another folder that is in your project’s build path. When the compiler encounters an Embed metadata tag, it creates the embedded asset class for you. You can access the class through a variable of data type Class that you declare immediately after the [Embed] metadata tag.

The following code embeds a sound named smallSound.mp3 and uses a variable named soundClass to store a reference to the embedded asset class associated with that sound. The code then creates an instance of the embedded asset class, casts it as an instance of the Sound class, and calls the play() method on that instance:

    import flash.display.Sprite; 
    public class EmbeddedSoundExample extends Sprite 
        public var soundClass:Class; 
        public function EmbeddedSoundExample() 
            var smallSound:Sound = new soundClass() as Sound; 

To use the embedded sound to set a property of a Flex component, it should be cast as an instance of the mx.core.SoundAsset class instead of as an instance of the Sound class. For a similar example that uses the SoundAsset class see “Embedded asset classes” in Learning ActionScript 3.0.