Encoding

Both formats use a form of "lossy" compression. This means that neither format will sound exactly like a CD it was recorded from. Although some audio engineers tell you that the average person won't notice some of the "missing" frequencies, tests have shown that while individuals cannot pinpoint an exact flaw they do notice things have changed. But Sony continues to improve on ATRAC. The latest revisions of ATRAC (3.5+) have come close to and in many professional opinions equal the quality of the audio CD.

The specifics of each can get pretty hairy and confusing so I won't go into them here. Suffice it to say both do well in an ear-by-ear test using the maximum bitrates of 320 Kbps for MP3s and 285.3 Kbps for MiniDisc.

With pop, pop-country, rock, or hip hop, most people won't notice anything, as these genres tend to be heavily produced with effects filters, sound compressors, and the like. You will notice that MiniDisc has a slight edge in music that has greater dynamic range, such as classical, jazz, and operettas.

Storage

While the main point of contention is sound quality, however, it's not the only one. With MiniDiscs you're limited to the size of the MiniDisc medium (either 74 minute or 80 minutes discs). With the use of additional compression via the LP modes on newer MiniDisc players, you can almost quadruple your storage.

With MP3s you get more choice and flexibility. Hard drive MP3 players offer seemingly endless amounts of space with 6GB, and up to 20GB on some models. Flash memory MP3 players are the most limiting with the highest CF media card at 1GB. The best solution is the CD/MP3 hybrid players that allow MP3s to be burned onto a CD-R/W disc. CD/MP3 hybrids also play regular audio CD as well.

Hardware

Many MiniDisc players allow you to record from a variety of line-in sources, including a microphone if you wish to do something like dictation. MP3 players usually only allow you to hook up directly to a computer to transfer music or delete files. This means to use an MP3 player you need to own a computer, while a MiniDisc only requires an audio source like a CD player, home stereo, or microphone.

Music sharing

MP3s are essentially just computer files you can copy, share, or even send as attachments through email. MiniDiscs, on the other hand, are limited by a couple of factors.

Although you can copy music from one MiniDisc player to another it's usually only in analog format. This means the quality is degraded, similar to dubbing a cassette tape. Secondly, Sony implemented SCMS (Serial Copy Management System) in the MiniDisc. This is just a fancy acronym for copy protection.

To prevent people from unauthorized copying, SCMS is encoded on a MiniDisc any time you copy from a digital source. SCMS thwarts transferring music from one MiniDisc to another digital source, such as DAT or another MiniDisc. The only way to get around SCMS is to use more sophisticated and expensive home- and professional-grade MiniDisc decks plus a digital format converter that will remove the SCMS signal.