Appendix
1. What is a bitrate?
When MPEG audio files are encoded, they pack down data to a specific size. The bitrate determines this size. Say, for example, you encode at 128kbps. What MPegger will do is make it so that every second of audio can be stored in 128000 bits of data. Lower bitrates mean lower file sizes. However, as the bitrate decreases, MPegger must compress more data in to less space. To do so, it must keep removing data until it fits the file size. If the bitrate is too low, too much data may be removed, and you'll be able to hear the quality loss in the file. For CD quality audio, the best bitrates to use are probably from 112 to 160.
All in all, the higher the bitrate, the higher the quality, and the larger the file.
2. What is VBR?
VBR is short for Variable Bit Rate. What that means is that instead of staying one bitrate through the entire song, it tries to see how much compression is really needed for a specific piece of data. What this means is that complex parts of the song will take more size to keep the quality high, and simpler parts will take less to keep the size low. This can often result in files of the same size, but improved quality.
The problem with VBR is that it is new technology, and not fully accepted by all MP3 players. As of the publishing of this document, QuickTime does not yet support VBR playback.
3. Other MPEG audio resources
For those serious about learning about MPEG audio, the internet is a great place to start. There are a several web sites in particular which play small but important roles in the world of MPEG audio. Here are a couple of helpful web sites:
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