Once they appear in a keyframe, their data is simply referenced by later keyframes that use that sound and only changes to the sound are stored in subsequent keyframes. For streaming sounds, Flash portions out small chunks of the streamed sound and saves one of these chunks in each of the frames in the range of frames over which the sound is played. These sound chunks are reconstituted into a single audio stream as the movie plays. How compression affects streaming of sound Compression strategies for sound make streaming sound slightly different from streaming image data. Images are uncompressed once.
Sound needs to be uncompressed as fast as the sound plays, every time it plays.
Experimenting with different compression strategies for each of the sounds in your movie can help you make the choices between quality and performance that work best for the effects you want to achieve with sound. If sound is the most important feature of your movie sampling rates of 22 kHZ can be used but be aware that downloading sounds at high sampling rates can be very slow for the average 28.8 modem connection. Notice that the degree to which each setting affects file size displays underneath the Rate and Compression fields in the Sound Properties dialog box whenever you change either settings. The Test button in the Sound Properties dialog box lets you hear your sound with the rate and compression settings applied to it. Use these two features together to help guide you in making your rate and compression choices.