When you work in Cubase SX or other audio programs, you're dealing with uncompressed audio that can be turned into an audio CD. But other formats take advantage of compression, a data reduction process that makes audio files smaller without sacrificing too much quality. (This is not to be confused with level compression, a dynamics operation that works on the volume of file.) The advantages of a smaller digital file outweigh the slight compromise in sound for many situations, such as music for the Web, where small files mean quicker downloading.
Now that we've got music files in a state of near completion, let's examine the file formats available, and their uses in music production.
WAV or AIF
Wave and Audio Interchange File Format, or AIFF (herein abbreviated to their three-letter extension designations WAV and AIF), are the Windows and Mac file formats that deal in uncompressed, linear audio at a 16-bit/44.1 kHz resolution. Only these two types of files can be made directly into audio CDs that play in a DiscMan, boom box, car stereo, or high-end home-entertainment CD deck.
All other file formats employ a form of data compression (not to be confused with audio compression, a dynamic process) and can't be made into audio CDs without being converted to WAV or AIF (or SD2, but that's rarely encountered by home recordists). When you create and edit audio in Cubase SX or any other professional recording application, you're dealing in the WAV and AIF formats. A CD burner will write any type of file (including WAV) to a CD as data, but to create an audio CD, the file format must be WAV or AIF.
WMA
WMA is another lossy compression file format, developed by Microsoft, that rivals MP3. Its files are even smaller than MP3's, and at this writing, WMA is gaining popularity. It's difficult to make a qualitative judgment in the MP3-WMA rivalry, so if you're planning on creating music for the Web, you should encode your WAV files in both formats.
QuickTime
Developed by Apple Computer, QuickTime is a popular video format, but its audio engine is quite good, too, and has the distinct advantage of being able to stream as well as download. Although QuickTime is a popular audio and video player for the Mac, QuickTime for Windows is generally used in a video context.
RealAudio
RealNetworks' RealAudio is an audio-streaming format, which means the file doesn't need to download entirely onto your hard drive before it starts playing back. This offers two advantages: The file starts playing almost immediately, and you're not left with a huge file when the song completes because no data is being saved to your hard drive (except for a small „pointer“ file that directs your browser to the file's server location). Streaming also allows the server to prevent you from having a permanent copy of the music, which can be an advantage—at least to the distributor.
Tape
Tape is a linear format, and you must write data to it in real time. This might make it seem quaint and inefficient in the age of random access, but tape still has its place.
Digital Audio Tape
A few years ago, DAT (Digital Audio Tape) was the mixdown medium of choice for home musicians. It has been supplanted by cheap CD recorders, but there are still plenty of DAT machines and DAT tapes around. And they still sound great! If you find you have to record a file to DAT, you can use the S/PDIF jacks on your interface and the DAT deck for a straight digital transfer, or you can record/play back through the analog jacks. The only disadvantage with using the analog ports is that you have to watch your levels.
Cassette and Other Analog Tape
I don't know about you, but as much as I loathe the cassette medium for its sonic deficiencies, I still have several cassette decks in my house (and tons of tapes) that I won't throw out. Cassettes still have a foothold in the marketplace, as do other analog tape media such as open-reel quarter-inch tape. When you record to cassette, you should highly compress your signal, enough so that it slams the tape as hard as possible without causing the cassette deck's record-level meter to go into the red (actually, it's okay if the short, loud peaks go into the red momentarily). This yields the best signal-to-noise ratio on a medium that's very narrow with respect to noise floor and headroom. A hot signal with a narrow dynamic range is best for recording to cassettes.
