Benefits
* A long period of silence in audio or a blank screen would mean a very small file. No audio data is wasted on silence or on simple tones and no visual data is wasted on a still screen or blackness.
* Although variable speed compressed files are difficult to stream continuously over most Internet connections, those that download the entire file before viewing are unaffected.
* More efficient processing means a better use of sound quality and file size.
* The format is ideal for audio recorded before the 60s/70s as the range of audio is usually much lower and can be compressed even smaller than expected with no perceivable quality loss. Smaller size means more files on your portable audio player, more hard drive space, or faster send over the Internet.
In terms of pure quality, variable encoding is usually far better than fixed but some variable encoding has a quality rating as well, allowing for much more lossy encoding. At low bitrates, this can be useful for spoken word audio as there are often pauses and silence between sentences.
So should I encode files Variable or Fixed?
Unless you need to stream files from your Web site or don't like having files turn out an unpredictable size, variable is strongly advised.
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