// declare a global variable
var s = 1;
// initiate sound
music = new Sound();
music.attachSound("backsound");
music.start(0, 999999);
// set the volume of the sound to zero
music.setVolume(0);
// set a variable named 'vol'
vol = 0;
// set another variable named 'fade', putting a setInterval function in it
fade = setInterval(fadeIn, 100);
// set the initial fade in function
function fadeIn() {
// fade the sound in with an increment of 3 in the variable 'vol'
vol += 3;
music.setVolume(vol);
// put an if condition to restrict the increment in volume after it reaches to 100
if (vol>=100) {
clearInterval(fade);
// create the 'step' variable
step = 1;
// create the 'fade' variable
Fade = 0;
}
}
// create the fade in and out function
// function executed on onEnterFrame
_root.onEnterFrame = function() {
// set fade out
if (Fade == 1) {
vol = vol-step;
if (vol<0) {
vol = 0;
}
music.setVolume(vol);
// set fade in
} else {
vol = vol+step;
if (vol>100) {
vol = 100;
}
music.setVolume(vol);
}
};

on (release) {
// set the function for variable value toggle
(_root.fade=!_root.fade) ? 0 : 1;
}

on (release) {

// set the function for variable value toggle

(_root.fade=!_root.fade) ? 0 : 1;

// put an if condition to tell the playhead to goto

// the frame from where the play button starts fading in

// as we have pressed the button to stop the sound

// we have already set the value of the variable s to 1

// thus the playhead moves to frame 2 where it starts fading

// the play button in and the stop button out 

if (_root.s == 1) {

tellTarget (this) {

gotoAndPlay(2);

// now you aobviously have to set the variable's value

// to 0, so that the next time you click the button

// the playhead moves to the 46th frame where the stop

// button starts fading in

_root.s = 0;

}

} else {

// else block executes when the varianle s is equal to 0

// when you click the button for the first time it sets the

// value of this variable to 0

// so the next time you click this button

// this else block executes

tellTarget (this) {

gotoAndPlay(46);

// now set the value of the var s to 1 again so that

// the next time this button is clicked the block with

// if condition can execute

_root.s = 1;

}

}

}