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Hands-On: Flash MX 2004 Publishing

Exercise 43: Make the Bandwidth Profiler Work for You

  1. Open the file "BuildPreloader.fla" that you worked on earlier. Do a Test Movie.
  2. As the exported .swf file plays, select View > Bandwidth Profiler [Ctrl] + [B], and then choose Frame by Frame Graph, and then Download Settings > 56K (4.7KB/s) all from the same View menu. Finally choose View > Simulate Download. (This option is only available in the Flash Player while you are testing.)
  3. The Bandwidth Profiler provides information while the movie plays, letting you view a graph from the data.

    4. Screen shot of the Bandwidth Profiler in action.

  4. Look at the first section of data, called Movie. This information is mostly a recap of the settings you can change in your source movie. Notice two more values whose numbers will vary: Size and Preload. (Later on you'll try to optimize this file).
    5. Note : Preload displays how many frames must "preload" (and how long that takes) before the movie will start playing. These estimates are based on the modem settings.
  5. Custom Download Settings The Bandwidth Profiler WindowSelect the View > Download Settings > Customize… and notice the different modem settings listed. You can customize the three User Settings if you wish.
  6. Select View > Show Streaming. The movie will start over, and you'll see a green progress bar move across the top of the graph. Try different modem rates to see how it affects the graph.
  7. Look at the View menu; if it has the Frame by Frame Graph selected, the graph shows a vertical bar for the file size of each frame's contents. A tall bar means a frame has more data than a shorter bar. The red horizontal line represents the sustained data transfer rate the current bit rate can maintain.
    The Bandwidth Profiler Window
  8. So in other words, if a frame's bar is higher than the red line, Flash may need to pause at that frame while it downloads. And, this may be the reason to have a Preloader movie load first.

Points to Ponder:

  • For your information, just because a vertical line is above the red line doesn't necessarily mean playback will pause at that frame.
  • The Bandwidth Profiler Window When it's possible, Flash MX 2004 will start to download frames before they are encountered. Since some frames have no changes viewed onscreen, Flash MX 2004 can start to download frames from later in the movie.
  • Frames that have no visual changes don't take long to download; therefore, Flash MX 2004 can concentrate on downloading future frames. This behavior is a form of advance streaming.
  • The Bandwidth Profiler has an option to show such streaming in a graph similar to the Frame by Frame graph. Select View > Streaming Graph, and you'll still see each frame's vertical box in an alternating light and dark gray box presentation.

 
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