Compressing Sound

When publishing a Flash Movie (SWF) with sound embedded in it, Flash will compress the sound for better file size and try to retain the highest quality possible in the process. You can compress all the sounds in your file at once from the Flash tab in the Publish Settings, as shown in Figure 6.7. You can adjust both Event and Stream sounds by clicking their associated Set button.

Figure 6.7. In the Flash tab of the Publish Settings, you can control overall sound compression of your Flash file.

The best way to compress sound, especially if you have multiple tracks, is to compress them individually from the library. Compressing each sound individually gives you better control over both size and sound quality for each sound track.

To open the Sound Properties window from the library, select the sound file, then right-click (Ctrl+click on a Mac) and select Export Settings. You will see a window similar to Figure 6.8. Select the Compression drop-down for the different options of compression.

• Default This choice will use the Publish Settings of the file.

• ADPCM (Advanced Differential Pulse Code Modulation) This compression is here for one reason only: to be used in the Flash 3 or older players. This option has become obsolete because with the Flash 4 player or later, you can use MP3 compression. However, if you are creating content for older players, you may want to try this one out.

• MP3 This choice produces sounds of good quality and good compression and can be used in the Flash 4 player or later.

• Raw This is a great setting for CD media because of the high quality of the sound. But because it uses no compression, the size of your movie will increase a great deal as well.

• Speech This is a great choice for audio narration of your Flash file. Because this choice is designed for straight speech audio, it can often produce a better quality of compression and sound for narrations than MP3 compression.

Figure 6.8. The Sound Settings dialog box.

These settings can also be adjusted from the Sound Properties dialog box. To access this window, select the sound in the library and click the Properties button at the bottom of the library. You can test the sound from within the Sound Properties dialog box, as well as quickly and easily swap out instances of your sound track throughout your entire Flash file. To change the sound file, click the Import button and map to the replacement sound. After this is done, all instances of the sound will be replaced by your new sound. Following are the available formats to import:

• AIFF Similar to the WAV file, but created on Macs. Many Windows machines may have problems with these files.

• MP3 One of the most popular, and therefore readily available, sound file formats on the web. Excelling in both sound quality and small file size, MP3s work well within Flash. This format is also the only sound format that can be loaded into the Flash movie (SWF) at runtime.

• WAV WAV files, although larger than MP3s in file size, still maintain good sound quality and are a Windows sound format standard.

You have seen how to work with audio manually on the stage, but in the next section you learn how to work with sound in ActionScript.