Assuming you have successfully completed the previous tutorials I expect that I do not have to show you how to create buttons, import sounds, add graphics to sounds etc. In this tutorial we need to concetrate on the ActionScript that fades in/out the played sound.

Follow these steps to do this:

1.    Import a sound loop to you Flash Movie
2.    Give it a linkage ID ‘myTrack’
3.    Create to buttons. One with a plus sign inside and the other one with a minus sign inside. Place the on the stage like on the image 1.

4.    The plus button should have the instance name ‘fadeIn_btn’, the minus button ‘fadeOut_btn’.

The button should be placed on the layer ‘Content’. Above this layer, create a layer called ‘Actions’, select the first frame and open the Actions Panel (press F9). Paste the following code:

var mySound:Sound = new Sound();
mySound.attachSound("myTrack");
mySound.start();
var soundStarted:Boolean = true;
var lastPosition:Number = 0;
var id:Number;
fadeIn_btn.onRelease = fadeInSound;
function fadeInSound():Void {
    if (id) {
        clearInterval(id);
    }
    mySound.start(lastPosition);
    var volume = mySound.getVolume();
    id = setInterval(fadeIn, 10);
    function fadeIn():Void {
        mySound.setVolume(volume++);
        if (volume>=100) {
            clearInterval(id);
        }
    }
}
fadeOut_btn.onRelease = fadeOutSound;
function fadeOutSound():Void {
    if (id) {
        clearInterval(id);
    }
    var volume = mySound.getVolume();
    id = setInterval(fadeOut, 10);
    function fadeOut():Void {
        mySound.setVolume(volume–);
        if (volume<=0) {
            clearInterval(id);
            mySound.stop();
            lastPosition = Math.round(mySound.position/1000);
        }
    }
}