MiniDisc

The Sony MZ1 MiniDisc player, the first to hit the market in 1992.
Media type:	Magneto-optical disc
Encoding:	ATRAC, linear PCM (with Hi-MD)
Capacity:	80 min (standard MiniDisc), up to 45 hours of audio (1 GB capacity) (with Hi-MD)
Read mechanism:	780 nm laser
Write mechanism:	Magnetic field modulation
Developed by:	Sony
Usage:	Audio storage, Data storage (with Hi-MD)

See also IBM's VM operating system family, where minidisk refers to a logical unit of storage.

A MiniDisc (MD) is a magneto-optical disc-based data storage device initially intended for storage of up to 80 minutes of digitalized 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. In computing, optical disc authoring, including CD authoring and DVD authoring, known often as burning, is the process of recording source material—video, audio or other data—onto an optical disc (compact disc or DVD). ... “Optical media” redirects here. ... It has been suggested that ISO image be merged into this article or section. ... This article does not cite any references or sources. ... Optical disc authoring software is computer software for authoring optical discs including CD-ROMs and DVDs. ... CD and DVD recorders for authoring optical discs such as CD-ROMs and DVDs have a history of various technologies. ... In optical disc authoring, there are multiple modes for recording, including Disc-At-Once, Track-At-Once, and Session-At-Once. ... Packet writing is an optical disc recording technology used to allow writeable CD and DVD media to be used in a similar manner to a floppy disk. ... Not to be confused with disk laser, a type of solid-state laser in a flat configuration. ... A compact disc or CD is an optical disc used to store digital data, originally developed for storing digital audio. ... The CD-ROM (an abbreviation for Compact Disc Read-Only Memory (ROM)) is a non-volatile optical data storage medium using the same physical format as audio compact discs, readable by a computer with a CD-ROM drive. ... This article does not cite any references or sources. ... Compact Disc ReWritable (CD-RW) is a rewritable optical disc format. ... Size comparison: A 12 cm Sony DVD+RW and a 19 cm Dixon Ticonderoga pencil. ... A DVD+R disc The title given to this article is incorrect due to technical limitations. ... DVD-D is a self-destructing disposable DVD format. ... DVD-R DL (Dual Layer) (Also Known as DVD-R9) is a derivative of the DVD-R format standard. ... This article or section does not cite any references or sources. ... DVD+R DL (Double Layer), also known as DVD+R9, is a derivative of the DVD+R format created by the DVD+RW Alliance. ... The title given to this article is incorrect due to technical limitations. ... This article or section does not cite its references or sources. ... JVC has announced they have gotten around to developing dual layered DVD-RW discs (DVD-RW DL). ... This article or section does not cite its references or sources. ... You can recognize a DVD-RAM immediately because visually there are lots of little rectangles distributed on the surface of the data carrier. ... A blank rewritable Blu-ray disc (a BD-RE) A Blu-ray Disc (also called BD) is a high-density optical disc format for the storage of digital information, including high-definition video. ... This article or section does not adequately cite its references or sources. ... HD-DVD disc HD DVD (for High Density Digital Versatile Disc) is a digital optical media format which is being developed as one standard for high-definition DVD. HD DVD is similar to the competing Blu-ray Disc, which also uses the same CD sized (120 mm diameter) optical data... HD DVD-R is the writable disc variant of HD DVD, and is now currently available with a single-layer capacity of 15GB. Currently, HD DVD-R has slower write speeds than the competing BD-R format (1–2x vs 1–4x) and lower storage capacity. ... An example of proposed HD DVD-RAM media. ... Ultra Density Optical (UDO) is a next-generation optical disc format designed for high-density storage of high-definition video and data. ... A UMD The Universal Media Disc (UMD) is an optical disc medium developed by Sony for use on the PlayStation Portable. ... It has been suggested that this article or section be merged into Holographic memory. ... Schematic representation of a cross-section through a 3D optical storage disc (yellow) along a data track (orange marks). ... Although research into optical data storage has been ongoing for many decades, the first popular system was CD-ROM, introduced in 1982, adapted to data storage (the CD-ROM format) with the 1985 Yellow Book, and re-adapted as the first mass market optical storage medium with CD-R and... The Rainbow Books are a collection of standards defining the allowed formats of Compact Discs. ... ISO 9660, a standard published by the International Organization for Standardization, defines a file system for CD-ROM media. ... Joliet is the name of an extension to the ISO 9660 file system. ... The Rock Ridge Interchange Protocol (RRIP, IEEE P1282) is an extension to the ISO 9660 volume format which adds POSIX file system semantics. ... The Rock Ridge Interchange Protocol (RRIP, IEEE P1282) is an extension to the ISO 9660 volume format which adds POSIX file system semantics. ... The El Torito Bootable CD Specification is an extension to the ISO 9660 CD-ROM specification. ... Overview Apple Macintosh computers use the HFS (or HFS+) file system on hard disks, mainly. ... The Universal Disk Format (UDF) is a format specification of a file system for storing files on optical media. ... The Mount Rainier logo Mount Rainier is a format for re-writable optical discs which provides for packet writing and defect management. ... Image File history File links This is a lossless scalable vector image. ... Download high resolution version (1360x985, 102 KB)An image of an Sony MZ1 Minidisc player and a disc. ... !!! Double article, please see also Magneto-optical drive !!! Magneto-Optical disc is an optical disc format that uses a combination of optical and magnetic technologies. ... Look up encoding in Wiktionary, the free dictionary. ... ATRAC (Adaptive TRansform Acoustic Coding) is a family of proprietary audio compression algorithms used to store information on MiniDiscs and other Sony-branded audio players. ... See also IBMs VM operating system family, where minidisk refers to a logical unit of storage. ... See also IBMs VM operating system family, where minidisk refers to a logical unit of storage. ... Sony Corporation ) is a Japanese multinational corporation and one of the worlds largest media conglomerates with revenue of $66. ... See also IBMs VM operating system family, where minidisk refers to a logical unit of storage. ... VM is an early and influential virtual machine operating system from IBM, apparently the first true virtual machine system. ... Magneto-optical disc A Magneto-optical disc and the numerous rectangles on its surface A magneto-optical drive is a kind of optical disc drive capable of writing and rewriting data upon magneto-optical discs. ... Many different consumer electronic devices can store data. ... Sound is a disturbance of mechanical energy that propagates through matter as a wave. ... See also IBMs VM operating system family, where minidisk refers to a logical unit of storage. ...

MiniDisc was announced by Sony in 1991 and introduced January 12, 1992. The music format was originally based exclusively on ATRAC audio compression. Recently, the option of linear PCM recording was introduced to attain truly CD-quality recordings. MiniDiscs are popular in Japan as a digital upgrade to cassette tapes, but have not been as popular world-wide. Sony Corporation ) is a Japanese multinational corporation and one of the worlds largest media conglomerates with revenue of $66. ... Year 1991 (MCMXCI) was a common year starting on Tuesday (link will display the 1991 Gregorian calendar). ... is the 12th day of the year in the Gregorian calendar. ... Year 1992 (MCMXCII) was a leap year starting on Wednesday (link will display full 1992 Gregorian calendar). ... ATRAC (Adaptive TRansform Acoustic Coding) is a family of proprietary audio compression algorithms used to store information on MiniDiscs and other Sony-branded audio players. ...

Market history

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. Philips HQ in Amsterdam Koninklijke Philips Electronics N.V. (Royal Philips Electronics N.V.), usually known as Philips, (Euronext: PHIA, NYSE: PHG) is one of the largest electronics companies in the world, founded and headquartered in the Netherlands. ... Logo for the Panasonic brand Matsushita Electric Industrial Co. ... Digital Compact Cassette (DCC) was a short-lived magnetic tape sound recording format introduced by Philips and Matsushita in late 1992. ... Philips HQ in Amsterdam Koninklijke Philips Electronics N.V. (Royal Philips Electronics N.V.), usually known as Philips, (Euronext: PHIA, NYSE: PHG) is one of the largest electronics companies in the world, founded and headquartered in the Netherlands. ... The Compact Cassette, often referred to as audio cassette, cassette tape, cassette, or simply tape, is a magnetic tape sound recording format. ...

Despite a loyal niche (primarily musicians and audio enthusiasts), MiniDisc has met with only limited success. In Japan, it is still relatively popular, but does not enjoy the same level of success in other major markets. Despite its popularity in Japan, flash memory and HDD-based audio players like Apple's iPod are becoming increasingly popular as playback devices. iPod is a brand of portable media player designed and marketed by Apple and launched in October 2001. ...

The company 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 1970s decade refers to the years from 1970 to 1979, also called The Seventies. ... Sonys Betamax is the 12. ... Victor Company of Japan, Limited ) (TYO: 6792 ), usually referred to as JVC, is an international consumer and professional electronics corporation based in Yokohama, Japan which was founded in 1927. ... Sharp Corporation ) (TYO: 6753 , LuxSE: SRP) is a Japanese electronics manufacturer, founded in 1912. ... Old Pioneer Logo (Until 1998) Pioneer Corporation ) (TYO: 6773 ) is a Japanese multinational corporation that specializes in digital entertainment products, based in Tokyo, Japan. ... Panasonic is an international brand name for Japanese electric products manufacturer Matsushita Electric Industrial Co. ... For the meaning of cassette in genetics, see cassette (genetics). ...

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 was also a factor. Pre-recorded MDs disappeared from the market rather suddenly in the late 1990s.

MD Data

MD Data, a version for storing computer data was announced by Sony in 1993, but it never gained significant ground. They were incompatible with standard audio MiniDiscs, this is often cited as being one of the main reasons behind the format's failure.^{[citation needed]} MD Data stands for minidisc-Data, and is a magneto-optical medium for storing computer data. ... Year 1993 (MCMXCIII) was a common year starting on Friday (link will display full 1993 Gregorian calendar). ...

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 and Yamaha's multitrack MD recorders, the MD4, MD4S and MD8.

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. See also IBMs VM operating system family, where minidisk refers to a logical unit of storage. ...

Design

Physical characteristics

Mindisc in cartridge (left), exposed minidisc (right) and protective cartridge holder (rear).

MiniDisc shutter

The disc is permanently housed in a cartridge (68 × 72 × 5 mm) with a sliding door, similar to the casing of 90 mm floppy diskettes. This shutter is opened automatically by a mechanism upon insertion; it cannot be opened manually by attempting to slide the shutter open, as you can on a 90 mm floppy disk. The audio discs can either be recordable (blank) or premastered. Recordable MiniDiscs use a magneto-optical system to record data. A laser heats one side of the disc to its Curie point, making the material in the disc susceptible to a magnetic field. A magnetic head on the other side of the disc alters the polarity of the heated area, recording the digital data onto the disk. Playback is accomplished with the laser alone: taking advantage of the Faraday effect, the player senses the polarisation of the reflected light and thus interprets a 1 or a 0. Recordable MDs can be recorded on repeatedly; Sony claims up to one million times. As of May 2005, there are 74 minute and 80 minute discs available. 60 minute blanks, which were widely-available in the early years of the format's introduction, were phased-out long ago and are rarely seen. Premastered MiniDiscs use a mastering process and optical playback system that is very similar to CDs, making them physically dissimilar to recordable discs. The recorded signal of the premastered pits and of the recordable MD are very similar to that of the CD. Eight-to-Fourteen Modulation (EFM) and a modification of CD's CIRC code, called Advanced Cross Interleaved Reed-Solomon Code (ACIRC) are employed. Image File history File linksMetadata Download high-resolution version (1024x768, 136 KB)By Richard Wheeler (Zephyris) 2007. ... Image File history File linksMetadata Download high-resolution version (1024x768, 136 KB)By Richard Wheeler (Zephyris) 2007. ... Image File history File links Minidisclogo_32c. ... Image File history File links Minidisclogo_32c. ... A floppy disk is a data storage device that is composed of a disk of thin, flexible (floppy) magnetic storage medium encased in a square or rectangular plastic shell. ... A floppy disk is a data storage device that is composed of a disk of thin, flexible (floppy) magnetic storage medium encased in a square or rectangular plastic shell. ... Magneto-optical disc A Magneto-optical disc and the numerous rectangles on its surface A magneto-optical drive is a kind of optical disc drive capable of writing and rewriting data upon magneto-optical discs. ... The Curie point is a term in physics and materials science, named after Pierre Curie (1859-1906), and refers to a characteristic property of a ferromagnetic material. ... In physics, the Faraday effect or Faraday rotation is a magneto-optical phenomenon, or an interaction between light and a magnetic field. ... A compact disc or CD is an optical disc used to store digital data, originally developed for storing digital audio. ... Eight-to-Fourteen Modulation (EFM) is an encoding technique used by CDs and MiniDiscs. ... This article does not cite its references or sources. ...

Differences from cassette and CDs

MiniDiscs use rewritable magneto-optical storage to store the data. Unlike the Digital Compact Cassette, or the (analog) compact audio cassette, the disc is a random-access medium, making seek time very fast. MiniDiscs can be edited very quickly even on portable machines. Tracks can be split, combined, moved or deleted with ease either on the player or uploaded to PC (only) with the latest version of Sony's PC based SonicStage V4.3 software and edited there. Transferring data from an MD unit to a non-Windows machine can only be done in real time, preferably via optical I/O, by connecting the audio out port of the MD to an available audio in port of the computer. With the release of the Hi-MD format, Sony began to release Macintosh compatible software. However, the Mac compatible software is still not compatible with legacy MD formats (SP, LP2, LP4). This means that using an MD recorded on a legacy unit or in a legacy format still requires a Windows machine for non-real time transfers. Digital Compact Cassette (DCC) was a short-lived magnetic tape sound recording format introduced by Philips and Matsushita in late 1992. ... For the meaning of cassette in genetics, see cassette (genetics). ...

At the beginning of the disc there is a table of contents (TOC, also known as "System File" area of the disc), which stores the start positions of the various tracks, as well as meta information (Title, Artist) about them and free blocks. Unlike the conventional cassette, a recorded song does not need to be stored as one piece on the disk, it can be stored in several fragments, similar to a hard drive. Early MiniDisc equipment had a fragment granularity of 4 seconds audio. Fragments smaller than the granularity are not kept track of, which may lead to the usable capacity of a disc actually shrinking. Also, no means of defragmenting the disc are provided in consumer grade equipment.

All consumer-grade MiniDisc devices feature a copy-protection scheme known as Serial Copy Management System. An unprotected disc or song can be copied without limit, but the copies can no longer be digitally copied. However as a concession to this the most recent Hi-MD players can upload to PC a Digitally Recorded file which can subsequently be resaved as a *.WAV (PCM) file and thus replicated. The Serial Copy Management System or SCMS was created in response to the digital audio tape (DAT) invention, in order to prevent DAT recorders from making second-generation or serial copies. ...

Compression

MD Walkman

The audio on a MiniDisc has traditionally been compressed using the ATRAC format (Adaptive TRansform Acoustic Coding). ATRAC was devised for MiniDisc so that the same amount of audio a CD can carry can fit on a disc far smaller than the CD. These days ATRAC is used on nearly all current Walkman devices, in addition to other formats. A CD, by contrast, contains uncompressed 16-bit stereo linear PCM audio. In MiniDisc's latest progression, Hi-MD, uncompressed CD-quality linear PCM audio recording and playback is offered in addition to ATRAC compression of varying bitrates—placing Hi-MD on par with uncompressed, CD-quality audio for the first time. SONY MD Walkman The source Japanese edition Photography person Lusheeta Photography day November, 2004 File links The following pages link to this file: Walkman MiniDisc Categories: GFDL images ... SONY MD Walkman The source Japanese edition Photography person Lusheeta Photography day November, 2004 File links The following pages link to this file: Walkman MiniDisc Categories: GFDL images ... ATRAC (Adaptive TRansform Acoustic Coding) is a family of proprietary audio compression algorithms used to store information on MiniDiscs and other Sony-branded audio players. ... Pulse-code modulation (PCM) is a digital representation of an analog signal where the magnitude of the signal is sampled regularly at uniform intervals, then quantized to a series of symbols in a digital (usually binary) code. ... A Compact Disc or CD is an optical disc used to store digital data, originally developed for storing digital audio. ...

Sony's ATRAC codec differs from uncompressed PCM in that it is a psychoacoustic lossy audio compression scheme, so decompression of the compressed signal will not yield the original signal, although the compressed signal may sound identical to the original to the listener. The latest version of Sony's ATRAC is ATRAC3plus. Original ATRAC3 at 132 kbit/s (also known as ATRAC-LP mode) is the format used by Sony's Connect audio download store. ATRAC3plus is not used in order to retain backwards compatibility with earlier NetMD players. Psychoacoustics is the study of subjective human perception of sounds. ... A lossy data compression method is one where compressing data and then decompressing it retrieves data that may well be different from the original, but is close enough to be useful in some way. ... Audio compression is a form of data compression designed to reduce the size of audio files. ...

Anti-skip

MiniDisc has a feature that prevents disc skipping under all but the most extreme conditions. Older CD players had once been a source of annoyance to users as they were prone to mistracking from vibration and shock. MiniDisc solved this problem by reading the data into a memory buffer at a higher speed than was required before being read out to the digital-to-analogue converter at the standard rate required by the format. The size of the buffer varies by model.

If the MiniDisc player were bumped, playback could continue unimpeded while the laser repositioned itself to continue reading data from the disc. This feature allows the player to stop the spindle motor for long periods, increasing battery life. The memory buffer concept introduced by MiniDisc was soon incorporated into portable CD players as well, and in Hard drive based Mp3 players like the iPod.^[1] A digital audio player (DAP) is a device that stores, organizes and plays digital music files. ... iPod is a brand of portable media player designed and marketed by Apple and launched in October 2001. ...

A buffer of at least ten seconds is required on all MiniDisc players, be they portable or stationary, full-sized units. This is needed to ensure uninterrupted playback in the presence of fragmentation.^{[citation needed]} In computer storage, there are three related uses of the term fragmentation: external fragmentation, internal fragmentation, and data fragmentation, all related to storage. ...

Operation

The data structure and operation of a MiniDisc is similar to that of a computer's hard disk drive. The bulk of the disc contains data pertaining to the music itself, and a small section contains the Table of Contents (TOC), providing the playback device with vital information about the number and location of tracks on the disc. Tracks and discs can be named. Tracks may easily be added, erased, combined and divided, and their preferred order of playback modified. Erased tracks are not actually erased at the time, but are marked so. When a disc becomes full, the recorder can simply slot track data into sections where erased tracks reside. This can lead to some fragmentation but unless many erasures and replacements are performed, the only likely problem is excessive searching, reducing battery life. Typical hard drives of the mid-1990s. ...

The data structure of the MiniDisc, where music is recorded in a single stream of bytes while the TOC contains pointers to track positions, allows for gapless playback of music, something which the majority of competing portable players, including most MP3 players, fail to implement properly. (Notable exceptions are CD players, as well as nano-model and video-capable iPods via the latest firmware updates.) Gapless playback is the seamless playback of digital audio formats. ... For other uses, see MP3 (disambiguation). ... A compact disc or CD is an optical disc used to store digital data, originally developed for storing digital audio. ... iPod is a brand of portable media player designed and marketed by Apple and launched in October 2001. ...

At the end of recording, after the "Stop" button has been pressed, the MiniDisc may continue to write music data for a few seconds from its memory buffers. During this time, it may display a message ("Data Save", on at least some models) and the case will not open. After the audio data is written out, the final step is to write the TOC track denoting the start and endpoints of the recorded data. Sony notes in the manual that one should not interrupt the power or expose the unit to undue physical shock during this period.

Format extensions

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. Year 2000 (MM) was a leap year starting on Saturday (link will display full 2000 Gregorian calendar). ...

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. In telecommunications and computing, bitrate (sometimes written bit rate, data rate or as a variable Rbit) is the number of bits that are conveyed or processed per unit of time. ... In telecommunications and computing, bit rate (sometimes written bitrate) is the frequency at which bits are passing a given (physical or metaphorical) point. It is quantified using the bit per second (bit/s) unit. ... Joint stereo, in audio engineering, is the technique of encoding stereo audio into a mid channel which is a full channel average of the combined left and right channels, with a side channel which has separation information on how to re-create two distinct stereo signals. ...

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-920) 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, yet it cannot be used to upload music (as of December 2005). SonicStage is the name for Sony software that is used for managing portable devices when they are plugged into a computer running Windows. ... 2005 is a common year starting on Saturday of the Gregorian calendar. ...

Hi-MD

Main article: Hi-MD

The Sony MZ1 MiniDisc player, the first to hit the market in 1992. ...

Recording modes

Modes marked in green are available for recordings made on the player, while those marked in red are only available for music downloaded from a PC. Capacities are official Sony figures; real world figures are usually slightly higher. Second generation Hi-MD players also support MP3 compression natively, in a multitude of bitrates. Recently, 352 kbit/s and 192 kbit/s ATRAC3plus have also been made available for 1st and 2nd generation Hi-MDs.

References

1. ^ http://www.ipodhacks.com/article.php?sid=1585

External links

• Sony Hi-MD page
• MiniDisc Community Portal
• MiniDisc.org FAQ
• MiniDisc Forum
• Audio T-Board
• Linux and Sony MiniDisc players