Sound Object, SharedObject

 By: Ben Partch » On: September 17th, 2007

Okay so the client wants to add a background sound to their web page. You have advised against this but they still want you to do it. Whats the best way?

<embed src="audio_file.wav" autostart="true" loop="true" volume="100" hidden="true"><noembed><bgsound src="audio_file.wav"></noembed>

No, no no…
There are a few issues with the above, but mostly you know there needs to be an off button, and you do not want users to have to turn the sound off every time they come back to the site.

The best way (or at least the way I would do it) is with Flash by using a SharedObject (a flash cookie) to remember if the user has pressed the stop button.

Things you are going to need to follow along with this tutorial:

• A basic understanding of Flash/AS/HTML
• Flash software
• A small audio file

Example:

Here is what we are going to make:

As you can see the main part of this article is not a pretty flash player, it’s the SharedObject. We are going to use it to store the users decision to turn off the sound (which is what I would assume most people will do) when they visit this page. Once you have clicked stop then it will not play again until you delete the SharedObject from your hard drive. If you have clicked stop, go ahead and refresh the page, you will not hear the sound again.

If you want to delete the SO it is stored at:

Win:
C:\Documents and Settings\[Your_Username]\Application Data\Macromedia\Flash Player\#SharedObjects

Mac:
/Users/[Your_Username]/Library/Preferences/Macromedia/Flash Player

Linux:
~/.macromedia

Okay, so on with how to make it. The first thing we need to do is prepare our flash document. Most of this is going to be accomplished with Actionscript so the first part of this is creating and naming a few symbols.

The Steps:

1. Open Flash and create a new file. Size it to 100 width x 70 height (or whatever) just make it big enough to create a couple of small buttons. Then save (file + save/ctrl + shift + s) it to your hard drive give it a name
2. Next use the tools (rectangle, oval…) to create a shape for your button
3. With the shape you made selected on the stage press F8
4. In the dialog box that appears select movieclip and give it a name of button click OK
5. Now in the properties inspector give it an instance name of play_but
6. Open the library (window > Library) and drag another instance of the button MC from the library to the stage in the properties inspector give it an instance name of stop_but
7. In the timeline name that layer buttons and lock it
8. Goto (file > import > import to library), browse to the audio file you wish to import, and select it. Open the library (window > library) right click this audio file, select linkage then in the dialog box that appears select “Export for Actionscript” then give it an Identifier name of my_audio and click OK
9. Create a new layer in the timeline and name it “actions”

The Actionscript

Create the sound object:

Now open the actions panel (window > actions) and with the empty keyframe of the actions layer selected, type the following.

var my_snd_obj:Sound = new Sound();

The above actionscript creates a sound object and stores it in a variable named my_snd_obj. You can name this variable anything you like, though check flash help for reserved names.

Attach the library sound file to the sound object:

my_snd_obj.attachSound("my_audio");

The above line attaches the sound my_audio to the sound object my_snd_obj. The name my_audio is the linkage Identifier you gave the sound back in step 8. Now that we have attached the sound to the my_snd_obj variable we can use that variable name to manipulate the sound.

For example:

my_snd_obj.setVolume(15);

Would set the volume of the sound to 15 out of 100.

Now the SharedObject

var my_so:SharedObject = SharedObject.getLocal("userPref");

The above declares a SharedObject and assigns it to a variable named my_so. Then looks for it on the users computer, if it does not exist it creates it and names it userPref. Though currently it’s value is undefined.

Now the real action begins:

if (my_so.data.stopped == undefined) {
	my_snd_obj.start(0, 1000);
} else {
	my_snd_obj.stop();
}

The above says: if the userPref SharedObject we created a minute ago has a data property with an attribute of stopped who’s value is undefined then go ahead and play the my_audio sound from the beginning looping it 1000 times, else if the data property’s attribute does have a value then stop the audio before it plays.

This works because if the user has NOT pushed the stop button then the SharedObject’s data property attribute (stopped) has no value.

Now for some more action:

stop_but.onRelease = function() {
	my_so.data.stopped = 1;
	my_snd_obj.stop();
};

The above function targets the stop_but movieclip symbol you created earlier. If clicked it sets the SharedObjects data property attribute to 1 and stops the my_audio sound.

A side note:

It is important to note that the data property MUST have a attribute name. It will not work if you attempt to assign a value directly to the data property itself.

my_so.data = 1;

Will not work.

my_so.data.attributeName = 1;

Will work because you are assigning the value to the attributeName and not the data property itself. You can name it anything you like, though check flash help for reserved names.

The extras:

Then you need to add an action for the play button should the user decide they want to hear the audio after all.

play_but.onRelease = function() {
	if (my_so.data.stopped == !undefined) {
		my_so.clear();
		my_snd_obj.start(0, 1000);
	}
};

If the SharedObject’s data property has an attribute value that is NOT undefined (meaning it exists and has a value) delete it, and start playing the audio again. This prevents the audio from starting again while it is already playing.

That is pretty much it. There are obviously many more uses for a SharedObject, this is just one example. I will try to come up with some other examples in the future. In the meantime, if you have any questions, opinions on this article or an alltogether better way to do it feel free to post it in the comments below.

Download the Flash 8 source file here (.fla}

Credits: jazz.mp3: Flash Kit

This article was posted in: the Tutorials category. If you have an opinion about this article, you can contact Ben Partch, or leave a comment below. You can also follow comments made by others via the RSS 2.0 feed.

5 Responses to “Sound Object, SharedObject”

1. Dave McNally  Says:
   September 17th, 2007 at 10:37 pm

   Cool Tutorial!

   Gave me an excuse to open up flash once more. Will come in handy if a client ever insists on using some flash music for a project.

   It was easy to understand and worked a treat.

   Thanks

2. jack  Says:
   November 26th, 2007 at 10:57 am

   Although it should be clear, apparently I still made a mistake, so I tried downloading the sourcefile, but the link is broken?

3. Ben Partch  Says:
   November 26th, 2007 at 12:05 pm

   Hey Jack

   Sorry about that. It should be working now.

4. jack  Says:
   November 27th, 2007 at 4:15 am

   Thanks for the fix, this made my crappy day, less crappier !

5. Ben Partch  Says:
   November 27th, 2007 at 12:04 pm

   Glad to hear it Jack! Thanks for visiting my site.