Compression settings in Flash

It is always best to import the best quality sound into Flash^® and not anything less. Let Flash^® do the work of compression. Generally the best quality sounds are in 44Khz Stereo 16 bit format. This is CD quality sound. If you import a sound that is formatted in 22Khz mono 8 bit, you can never "upgrade" to better quality in Flash^®. The source file or imported file properties (1) are shown in the Sound Properties window.

There are 4 choices for compression as shown below (2). The compression for all the sounds can be set globally or individually. In this example, we will set compression for the individual sound file. When you double click on the sound in the library, in this case "trans", the Sound Properties dialog box opens as shown here in the diagram.



Default uses the compression default setting found in the Publish Settings dialog box at the time of export. You need not worry about this setting if you are using individual compression settings.

The Raw setting exports the sound with no compression. Use this setting when your Flash^® movie will run off a CD or hard drive or from anywhere where file size is not an issue and quality is everything.

ADPCM is a setting that makes use of the number of bits in the sound and registers fewer samples of the sound. This results in the decrease in file size and of course lower fidelity. Use this setting if for any reason you wish to reach audiences that do not have the Flash 4^® or later plugin.

MP3 compression generally yields the best results. Here you can select from several bit rates. You can also choose to output your sound in stereo if you choose any bit rate higher than 16kbps. Once you choose your setting, you will see the expected size of the sound file at output shown below (3). As for the Quality setting (4), you should always use Fast when running your movie on the web; however use Best if you are running your movie from a hard drive or CD.



As always, you should test your sounds with various settings to get the best result to fit your project. Keep in mind the connection speed at which your audience will view and hear your work. You will always need to maintain a balance between file size and variety or fidelity. For this reason, it is best to plan your entire project from the beginning with sound in mind, if sound is to play a part in your project (as it should!).

When setting your sound compression, you will notice, especially with experience, that certain sounds compress very well. Those sounds contain low frequencies. Any low frequency sounds, such as bass sounds, compress very well because compression largely cuts out higher frequencies. Therefore, the fidelity of high frequency sounds such as that of the hi-hat or cymbal in a drum set will be dramatically affected. With that in mind you should plan out the type of sounds you will use from the start of your project.