If the movie you are exporting contains sound, this will also be included in the exported movie file.
These audio export options determine the size of the exported file and its sound quality:
Format. The sound 'format' is a combination of the sampling rate and whether it is in mono or stereo. The higher the sampling rate the better the quality but the larger the exported movie file. Selecting mono instead of stereo will decrease the movie size but only include one channel of sound instead of two.
MP3 Compression. This option greatly decreases the size of movies exported with sound. It should only be unchecked if you are experiencing problems with BB FlashBack while exporting movies.
Note: BB FlashBack uses a redistribution of the open-source LAME MP3 codec: www.mp3dev.org .