MiniDisc
A MiniDisc (MD) is a magneto-optical disc-based data storage device initially intended for storage of up to 80 minutes of digitized audio. Today, in the form of Hi-MD, it has developed into a general-purpose storage medium in addition to greatly expanding its audio roots.
MiniDisc was announced by Sony in 1991 and introduced January 12, 1992. The music format was originally based exclusively on ATRAC audio data compression, but the option of linear PCM recording was ultimately introduced to attain CD-quality recordings. MiniDiscs were popular in Japan and Asia as a digital upgrade from cassette tapes, but were not as popular elsewhere.
Along with Philips and Matsushita Digital Compact Cassette (DCC) system, the MiniDisc was targeted as a replacement for the Philips analog cassette audio tape system.
Despite having a loyal customer base (primarily musicians and audio enthusiasts), MiniDisc met with only limited success. It was relatively popular in Japan but did not enjoy the same level of success in other major markets. Despite its popularity in Japan, flash memory and HDD-based audio players have become increasingly popular as playback devices.
Sony avoided the mistake that it had made in the 1970s with the Betamax video recording system, and this time licensed the MD technology to other manufacturers, with JVC, Sharp, Pioneer, Panasonic and others all producing their own MD systems.
MiniDisc technology was faced with new competition from the recordable compact disc consortium, while the popularity of traditional cassette tape refuses to wane in certain quarters. MiniDisc is widely respected as being a very reliable format when it comes to portable audio storage, such as field recording.
The initial low uptake of MiniDisc was attributed to the small number of pre-recorded albums available on MD as a relatively small number of record labels embraced the format. The initial high cost of equipment and blank media was also a factor. Pre-recorded MDs disappeared from the market rather suddenly in the late 1990s.
Due to the waning popularity of the format and the increasing popularity of solid-state MP3 players, Sony now produces only one model, the MZ-RH1 (also available as the MZ-M200 in North America packaged with a Sony microphone and limited Macintosh software support.)
MD Data, a version for storing computer data, was announced by Sony in 1993 but never gained significant ground. Its media were incompatible with standard audio MiniDiscs, which has been cited as one of the main reasons behind the format's failure.
MD Data could not write to audio-MDs, only the considerably more expensive data blanks. In 1997, MD-Data2 blanks were introduced, which held 650 MB of data. They were only implemented in Sony's short-lived MD-based camcorder as well as a small number of MultiTrack Recorders; Sony's MDM-X4, Tascam's 564 (which could also record using standard MD-Audio discs, albeit only 2 tracks), and Yamaha's MD-8, MD-4, & MD4S.
The Hi-MD format, introduced in 2004, marked a return to the data storage arena with its 1 GB discs and ability to act as a USB drive. Hi-MD units allow the recording and playback of audio and data on the same disc in addition to compatibility with standard MiniDiscs.
MDLP
In 2000, Sony announced MDLP (MiniDisc Long Play), which added new recording modes based on a new codec called ATRAC3. In addition to the standard, high-quality mode, now called SP, MDLP adds LP2 mode, which allows twice as much recording time (160 minutes on an 80 minute disc) of good-quality stereo sound, and LP4, which allows four times more recording time (320 minutes on an 80 minute disc) of medium-quality stereo sound.
The bitrate of the standard SP mode is 292 kbit/s, and it uses separate stereo coding with discrete left and right channels. For most people the sound quality is indistinguishable from a CD. LP2 mode uses a bitrate of 132 kbit/s and also uses separate stereo coding. For most people the sound quality is almost as good as SP. The last mode, LP4 has a bitrate of 66 kbit/s and uses joint stereo coding. The sound quality is noticeably poorer than the first two modes, but is sufficient for many users.
Tracks recorded in LP2 or LP4 mode play back as silence on non-MDLP players.
NetMD
NetMD recorders allow music files to be transferred from a computer to a recorder (but not in the other direction) over a USB connection. In LP4 mode, speeds of up to 32× real-time are possible and three Sony NetMD recorders (MZ-N10, MZ-N910, and MZ-N920) are capable of speeds up to 64× real-time. NetMD recorders all support MDLP.
NetMD is a proprietary protocol, and it is currently impossible to use it without proprietary software, such as SonicStage. Thus, it cannot be used under non-Windows machines. A free -nix based implementation, libnetmd, is being developed, but it cannot be used to upload music (as of December 2005).
Hi-MD
Main article: Hi-MD
Hi-MD is the further development of the MiniDisc-format. It was introduced in 2004. Hi-MD media do not play on non Hi-MD equipment, including NetMD players.