If your Flash project contains any audio, there are some important technical details you need to consider. Quality is important, specifically sounds recorded in stereo at a 44.1 kHz sampling rate and 16-bit depth. When you develop a project for video output, it is always best to record at the highest quality whenever possible.
Working with Compressed Audio
In a situation where your sound file is relatively long, say five minutes or more, it may be best to convert it to a compressed format that Flash can import, such as MP3. Once you convert your audio file to a compressed format, the file size will be much easier to work with. Importing a compressed version of the sound into Flash also helps keep the movie file size manageable. Just make sure to retain a backup copy of the original high-quality sound file so you can reimport it into your Flash file for final export later.
Speaking of length, the actual running time of a half-hour television program is approximately 22 minutes. But working with a 22-minute Timeline in Flash is potentially problematic. At 30 frames per second, a 22-minute animation ends up being 39,600 frames long. Because Flash is not really capable of handling timelines of this length, instability can become a factor. To avoid crashing and the potential of a corrupt file, break up the audio into smaller chunks and import them into several different Flash files that you can later stitch together in your video editing program. I recommend that you work in smaller durations, somewhere between 30 and 60 seconds long.
There are a number of useful audio editing tools available to edit your sound files. My personal favorites are Sound Forge Audio Studio and Vegas, both from Sony. They run only in Windows. Adobe Audition is another choice for Windows users. For Mac users, there’s Soundtrack Pro from Apple. If you are on a budget, try Audacity, a very capable and open-source (free) audio editing tool available for Mac OS, Windows, and Linux.
When your animation is complete and you are ready to export it to video, delete the compressed sound files from the Flash movie. Export only the animation to your chosen video format and then import this video file, along with the original high-quality sound files, into your video editing program of choice, such as Adobe Premiere or Apple Final Cut Pro. This method not only keeps your FLA sizes to a minimum but also provides some editing flexibility because both sound and animation are maintained on separate tracks for further editing.
Synchronizing Animation with Sound
To sync your animation with the imported audio in Flash, you must embed the audio in the main Timeline. Select File > Import and locate the audio file on your hard drive. Once it’s imported, create a new layer on your main Timeline, select the first keyframe in this new layer, and locate the sound file in the Property inspector from the Sound pop-up menu.
By default, the sound behavior is set to Event. An Event sound plays in its entirety, independent of the Timeline, and does not ensure proper synchronization with the animation. You can change the behavior from Event to Stream by selecting the Sync pop-up menu in the Property inspector. When you set the sound to Stream, you will be able to grab the playhead and move it back and forth across the Timeline and hear the sound play. This is called scrubbing. Sound files, when set to Stream, are embedded in the Timeline and will be in sync with the animation that resides on the Timeline and any graphic symbols containing nested animation.