Setting Individual Compression
By default, Flash exports all a movie's sounds in MP3 format, in 16 Kbps mono. This setting is guaranteed to get you good compression but average fidelity.
It is possibleand encouragedto set the compression and output format of each sound individually. That way, feature sounds can be compressed less (and will sound better), while background ones can be compressed more. This helps balance file size with reproduction quality.
To individually set the optimization setting for a particular sound, open the Library by clicking Window, Library. Select the sound and choose Properties from the Options menu. Notice the drop-down list, set to Default. It has four options:
DefaultThis exports the sound according to the movie's global setting.
ADPCMThis option should be used for 8- or 16-bit sound data. Higher sample rates result in better quality but bigger SWF files.
MP3Again, the higher the bit rate is, the better the output is. This includes a Quality option that determines how long the compressor takes to operate on the sound. Fast is acceptable for most cases.
RawThis option applies no compression.
Although Flash offers ADPCM and MP3 compression, MP3 is preferred. MP3 reduces the size of sounds by a factor of 10 to 14 without an audible loss of quality, making it a good choice for Web streaming and playback.
However, if you plan to export your movie to SWF 3 or earlier, ADPCM is the only option. It is still acceptable, but it doesn't have the high compression ratio of MP3.
The global sound settings for the current movie can be changed using the File, Publish, Flash tab.