Flash Levels

A single timeline can often limit the capabilities of a designer, as Flash movies often grow larger than the single timeline in which it is created. The movie symbol often succeeds at allowing the developer to utilize independent elements, but sometimes even these symbols become limiting.

A way to solve this problem is build into Flash: Flash has the capability to load additional movies into a main movie by using ActionScript.

The ActionScript command for loading a movie is:

LoadMovieNum("yourMovie.swf", Level);

The file "yourMovie.swf" is obviously replaced by the name of your valid SWF file, but the Level field is completed by adding a number (a level) to this field.

Let's take a second to talk about this Level for a bit. Think of Level numbers a little like the layers on your timeline. Objects located at the top of the timeline appear "above" objects located at the bottom. This Level attribute determines the location of the loaded movie: the higher the number, the further "above" the other levels objects appear.

Your main movie level is considered to be Level 0 (_level0). Level 0 defines the stage size, the frame rate and background color for all the levels loaded above it. The levels loaded above Level 0 are transparent: background colors do not apply. However, all buttons and symbols are active on all layers. A button on Level 0 can interact with a movie on Level 1 and so on.

When you wish to load a movie, you use the LoadMovieNum ActionScript command and set the parameters accordingly. So, if I have my movie root with background imaging on Level 0, lets assume I have an audio SWF and an interactive menu SWF I want to load. I would use the following commands:

LoadMovieNum("audio.swf", 1);
LoadMovieNum("menu.swf", 2);

From a user perspective, they are seeing one movie, but you have segmented it into more manageable pieces.

If you wanted to use the buttons in the menu.swf file (on Level 2) to alter the timeline of the movie on Level 0, you can simply call the level and frame name or number like this:

on (release){
     _level0.gotoAndPlay("intro");
   }

This tells Flash that when the user releases the mouse button, play the frame named "intro" on Level 0. Named movie symbols, named text fields (Flash MX), frames and scenes can all be given instructions from different levels. How cool is that!

Why would you want to do this?

You could be saying to yourself, "Yeah, that's cool. I can load Flash movies into Flash movies. Well, so what? What is it good for?"

Wow. Glad you asked.

We are going to use a real world example to illustrate the power of this tool. Recently, wecreated a multimedia presentation for a client that was to stream off a CD. They are incorporating video clips, voice over audio, soundtrack audio and tons of high quality graphics. The Flash FLA file was 313MB, and when Flash finally created the self contained .exe file, the compiled version was about 200MB. This size file stores well on a CD, but does not stream easy as one complete unit. The viewer of this program would have to wait in upwards of six minutes for the disk to auto run and play after the CD was inserted. Not a realistic solution.

So, what we did is we broke this project into about six reusable parts and eighteen miscellaneous SWF files. The Level 0 file, which is the background images, mini "Welcome Video" and welcome animation starts the program. This file is 800kb, spins up fine and is used as the EXE to start the AutoRun. This movie stops and then loads a Level 1 Audio track, a Level 2 Menu Button Tree, and a Level 3 Text layer. Each of these files is about 25kb.

Then, after the user clicks "Start the Presentation", the Level 3 Text layer is replaced by the first movie segment. The current level unloads, and the new video SWF starts to load. The video segment, at about 10MB in size, comes in quickly (about 3 seconds to load off CD with 40X speed CD Drive) and starts playing. When this ends, it is replaced by a new animation SWF. The video SWF unloads and the new animation SWF (about 3.5MB) loads. This takes about 1 second to come in.

As we move through the program, the same layer is loading and unloading different SWF elements. Notice that the Level 1 Audio track still plays its merry loop and the Level 2 Menu Buttons still controls the entire movie, but they don't load with each new element. All the background images on Level 0 stay intact as well. They don't need to continually reload with each new element, dramatically shaving load times and file sizes.

On this project, we broke the program into bits of no more than 10MB and the user experiences little or no lag using an average CD Drive. Now, instead of a huge long wait, the viewing audience gets the program delivered in chunks, as they need it.

This example could translate to a web project you are working on. If you have a huge site or presentation you wish to display using Flash, using the LoadMovieNum command allows your user to control download times by only receiving the files they want. A complete site download may take 5 minutes at a slow connection, but if you create the site using several different movie elements, your user may have the main portal loaded in 15 seconds. Then, if they click on the About You link, only that movie loads. Again, by loading in chunks, you shave load times way down.

LoadMovieNum is a powerful tool for the intermediate and advanced ActionScript programmer. Experiment with it and let us know how you do! Have fun!