MiniDisc: Difference between revisions

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{{short description|Magneto-optical storage medium, mainly for audio (1992–2013)}}

{{Infobox media

{{About|the Sony storage format|other similarly-named formats and other uses of the term|Minidisc (disambiguation)}}

{{Use dmy dates|date=January 2020}}

{{Infobox storage medium

| name = MiniDisc

| logo = [[Image:MiniDiscLogo.svg|150px]]{{!}}class=skin-invert

| image = [[Image:Minidisc_Sony_MZ1TDK MiniDisc and Duracell Ultra M3 20070320.jpg|250px|]]

| caption =The SonyMiniDisc MZ1by MiniDisc playerTDK, the first to hitwith the[[AA marketbattery]] infor 1992.scale

| type = [[magnetoMagneto-optical disc]] disc

| encoding = [[ATRAC]], linear PCM ([[Minidisc#Hi-MD|with Hi-MD]])

| capacity = 60, 74, and 80 minutes

| capacity = 80 min (standard MiniDisc), up to 45 hours of audio (1GB capacity) ([[Minidisc#Hi-MD|with Hi-MD]])

| read = 780nm780 nm semiconductor laser diode

| write = magneticMagnetic field modulation

| standard =

| owner = [[Sony]]

| use = audioAudio storage, data storage ([[Minidisc#Hi-MD|with Hi-MD]])

| released = {{start date and age|1992|11}}<ref name="wb-minidisc-sony-mz-1">{{cite web|last=Woudenberg|first=Eric|title=Sony MZ-1|url=https://www.minidisc.org/part_Sony_MZ-1.html|access-date=2022-07-30}}</ref>

| extended from =

| discontinued = {{end date and age|2013|3}}

| extended to =

| extended from = [[Compact Cassette]], [[Compact disc]]

| extended to = [[MD Data]], [[Hi-MD]]

}}

{{optical disc authoring}}

[[File:Sony MZ-1 and a disc 20040221.jpg|thumb|The Sony MZ1, the first MiniDisc player, released in 1992.]]

'''MiniDisc''' ('''MD''') is a discontinued erasable [[magneto-optical]] disc-based [[data storage]] format offering a capacity of 60, 74, or 80 minutes of digitized [[sound|audio]].

:''See also IBM's [[VM (operating system)|VM]] operating system family, where '''minidisk''' refers to a logical unit of storage.

[[Sony]] announced the MiniDisc in September 1992 and released it in November<ref name="sony-end" /> of that year for sale in Japan and in December in Europe, North America, and other countries.<ref>{{cite web |url=http://www.sony.net/Fun/SH/1-21/h5.html |title=Sony history |access-date=1 June 2016 |archive-url=https://web.archive.org/web/20100625232554/http://www.sony.net/Fun/SH/1-21/h5.html |archive-date=25 June 2010 |url-status=dead}}</ref> The music format was based on [[ATRAC]] [[audio data compression]], Sony's own proprietary compression code. Its successor, [[Hi-MD]], would later introduce the option of [[linear PCM]] [[digital recording]] to meet audio quality comparable to that of a [[compact disc]]. MiniDiscs were very popular in Japan and found moderate success in Europe.<ref>{{cite web|url=http://www.trustedreviews.com/mp3/review/2008/04/08/Music-On-The-Move/p4 |title=Music on the Move: MiniDisc |first=Riyad |last=Emeran |date=8 April 2008 |archive-url=https://web.archive.org/web/20080513061754/http://www.trustedreviews.com/mp3/review/2008/04/08/Music-On-The-Move/p4 |archive-date=13 May 2008 |website=TrustedReviews}}</ref> Although it was designed to succeed the [[cassette tape]], it did not manage to supplant it globally.<ref>{{cite web | url=https://www.cnet.com/tech/mobile/sony-bids-farewell-to-the-minidisc/ | title=Sony bids farewell to the MiniDisc | archive-url=https://web.archive.org/web/20220509133417/https://www.cnet.com/tech/mobile/sony-bids-farewell-to-the-minidisc/ | archive-date=9 May 2022 | date=3 Feb 2013 | author=Lexy Savvides | website=CNET | url-status=live }}</ref>

A '''MiniDisc''' ('''MD''') is a [[magneto-optical]] disc-based [[data storage device]] initially intended for storage of up to 80 minutes of digitalized [[sound|audio]]. Today, in the form of [[MiniDisc#Hi-MD|Hi-MD]], it has developed into a general-purpose storage medium in addition to greatly expanding its audio roots.

By March 2011, Sony had sold 22 million MD players, but discontinued further development.<ref name="Nni20110707D07JFN01">{{Cite web |date=July 7, 2011 |title=Sony To Wind Up MiniDisc Walkman Shipments |url=http://e.nikkei.com/e/fr/tnks/Nni20110707D07JFN01.htm |url-status=dead |archive-url=https://web.archive.org/web/20110711122254/http://e.nikkei.com/e/fr/tnks/Nni20110707D07JFN01.htm |archive-date=Jul 11, 2011 |website=Nikkei.com}}</ref> Sony ceased manufacturing and sold the last of the players by March 2013.<ref>{{cite web |url=https://www.engadget.com/2013/02/01/sony-says-sayonara-to-minidisc-will-sell-its-last-players-in-ma/ |title=Sony says sayonara to MiniDisc, will sell its last players in March |publisher=Engadget.com |date=1 February 2013 |access-date=16 May 2016 |archive-date=20 May 2017 |archive-url=https://web.archive.org/web/20170520182126/https://www.engadget.com/2013/02/01/sony-says-sayonara-to-minidisc-will-sell-its-last-players-in-ma/ |url-status=live }}</ref> On January 23, 2025, Sony announced they would end the production of recordable MD media in February 2025.<ref>{{cite web|url=https://www.sony.jp/rec-media/info2/20250123.html?cpint=rec-media_sony_news-Sony%20News-ja_JP-responsivegrid_initial_middle_sonynews_1 |title= Notice regarding the end of production of Blu-ray Disc media, MiniDiscs for recording, MD data for recording, and MiniDV cassettes | publisher=Sony Storage Media Solutions Inc. | date=Jan 23, 2025}}</ref>

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.

== Market history ==

In 1983, just a year after the introduction of the [[compact disc]], [[Kees Schouhamer Immink]] and [[Joseph Braat]] presented the first experiments with erasable [[magneto-optical]] compact discs during the 73rd [[Audio Engineering Society|AES]] Convention in [[Eindhoven]].<ref>{{Cite journal

Along with [[Philips]] and [[Matsushita]] [[Digital Compact Cassette]] (DCC) system, the MiniDisc was targeted as a replacement for the [[Philips]] analogue [[Compact cassette|cassette]] audio tape system.

|journal=J. Audio Eng. Soc.

|volume=32

|date=1984

|title=Experiments Toward an Erasable Compact Disc

|author=K. Schouhamer Immink and J. Braat

|url=https://www.researchgate.net/publication/237764745

|pages=531–538

}}</ref> It took almost 10 years, however, before their idea was commercialized.

Sony's MiniDisc was one of two rival digital systems introduced in 1992 that were intended to replace the [[Philips]] [[Compact Cassette]] analog audio tape system: the other was the [[Digital Compact Cassette]] (DCC), created by [[Philips]] and [[Panasonic Corporation|Matsushita]] (now Panasonic). Sony had originally intended the [[Digital Audio Tape]] (DAT) to be the dominant home digital audio recording format, replacing the analog cassette. Because of technical delays, the DAT was not launched until 1989, and by then the [[U.S. dollar]] had fallen so far against the [[yen]] that the introductory DAT machine Sony had intended to market for about $400 in the late 1980s then had to retail for $800 or even $1,000 to break even, putting it out of reach of most users.

Despite enjoying a loyal niche (primarily musicians and audio enthusiasts), MiniDisc has met with only limited success. In Japan, it is still relatively popular, but it doesn't enjoy that 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.

TheRelegating companyDAT avoidedto theprofessional mistakeuse, thatSony itset hadto madework into come up with a simpler, more economical digital home format. By the [[1970s]]time Sony came up with the MiniDisc in late 1992, Philips had introduced a competing system, DCC, on a magnetic tape cassette. This created marketing confusion very similar to the [[BetamaxVideotape format war|videocassette format war]] videoof recordingthe system,late 1970s and thisearly time1980s. licensedSony thelicensed MD technology to other manufacturers, with [[JVC]], [[Sharp Corporation|Sharp]], [[Pioneer Corporation|Pioneer]], [[Panasonic]] and others all producing their own MD systemsproducts. MiniDiscHowever, technologynon-Sony wasmachines facedwere withnot newwidely competitionavailable fromin the compact discNorth consortiumAmerica, whileand thecompanies popularitysuch of traditionalas [[cassetteTechnics tape(brand)|Technics]] refusesand to[[Radio waneShack]] in certain quarters. MiniDisc is widely respected as being a very reliable format when it comestended to portable audio storage, such aspromote fieldDCC recordinginstead.

[[File:Pioneer MiniDisc car receiver MEM-P5500 crop.JPG|thumb|Pioneer MiniDisc [[vehicle audio|car receiver]]]]

Despite having a loyal customer base largely of musicians and audio enthusiasts,{{fact|date=September 2023}} the MiniDisc met with only limited success in the United States. It was very popular in Japan and parts of Asia, and relatively so in Europe during the 1990s and into the 2000s, but did not enjoy comparable sales success in other markets. Since then, recordable CDs, [[flash memory]] and HDD and solid-state-based [[digital audio player]]s such as [[iPod]]s have become increasingly popular as playback devices.

The initial lowslow uptake of MiniDisc was attributed to the small number of pre-recorded albums available on MD, as abecause relatively small number offew record labels embraced the format. The initial high cost of equipment and blank media was also a factor. Pre-recordedAdditionally, MDshome disappearedMiniDisc fromdecks thewere marketless ratherwidely suddenlyavailable, with most consumers instead connecting a portable MD device to their hi-fi system in theorder lateto 1990srecord.

MiniDisc technology was faced with new competition from the recordable compact disc ([[CD-R]]) when it became more affordable to consumers beginning around 1996. Initially, Sony believed that it would take around a decade for CD-R prices to become affordable – the cost of a typical blank CD-R disc was around $12 in 1994 – but CD-R prices fell much more rapidly than envisioned, to the point where CD-R blanks sank below $1 per disc by the late 1990s, compared to at least $2 for the cheapest 80-minute MiniDisc blanks.

== MD Data ==

[[MD Data]], a version for storing computer data was announced by Sony in [[1993]], but it never gained significant ground.

The biggest competition for MiniDisc came with the emergence of [[MP3 players]]. With the [[Rio PMP300|Diamond Rio player]] in 1998 and the [[Apple iPod]] in 2001, the mass market began to eschew physical media in favor of more convenient file-based systems.

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.

[[File:Sony mz rh1.jpg|thumb|Sony Hi-MD Recorder MZ-RH1, released 2006]]

The [[MiniDisc#Hi-MD|Hi-MD]] format, introduced in 2004, marked a return to the data storage arena with its 1GB 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.

By 2007, because of the waning popularity of the format and the increasing popularity of solid-state MP3 players, Sony was producing only one model, the [[Hi-MD]] MZ-RH1, available as the MZ-M200 in North America packaged with a Sony microphone and limited [[macOS]] software support.<ref>{{Cite web|url=http://www.minidisc.org/manuals/sony/Sony_MZ-RH1_user_manual.pdf|title=Sony MZ-RH1 User Manual}}</ref><ref>{{cite web|url=http://reviews.cnet.com/minidisc-players/sony-mz-m200-hi/1707-6492_7-32780518.html|title=Sony MZ-M200 Hi-MD Recorder with Stereo Microphone|website=[[CNET]]|date=5 December 2007}}</ref><ref>{{cite web|url=http://esupport.sony.com/US/perl/swu-download.pl?mdl=MZRH1&upd_id=2236&os_id=24|title=Hi-MD Music Transfer for Mac Ver.2.0|publisher=Sony|date=15 July 2006|access-date=9 December 2011|archive-date=11 May 2012|archive-url=https://web.archive.org/web/20120511002910/http://esupport.sony.com/US/perl/swu-download.pl?mdl=MZRH1&upd_id=2236&os_id=24|url-status=live}}</ref>

The MZ-RH1 allowed users to freely move uncompressed digital recordings back and forth from the MiniDisc to a computer without the copyright protection limitations previously imposed upon the NetMD series. This allowed the MiniDisc to better compete with HD recorders and MP3 players. However, most pro users like broadcasters and news reporters had already abandoned MiniDisc in favor of solid-state recorders, because of their extended recording time, open digital content sharing, high-quality digital recording capabilities and reliable, lightweight design.

==Design==

===Physical characteristics===

[[Image:Minidisc and Cartridge.jpg|thumb|Mindisc in cartridge (left), exposed minidisc (right) and protective cartridge holder (rear).]]

[[Image:Minidisclogo 32c.png|right|thumb|MiniDisc shutter]]

The disc is permanently housed in a cartridge (68 &times; 72 &times; 5 mm) with a sliding door, similar to the casing of 90 mm [[floppy disk]]ettes. 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 [[Compact Disc|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 [[Cross-Interleaved Reed-Solomon Coding|CIRC]] code, called Advanced Cross Interleaved Reed-Solomon Code (ACIRC) are employed.

On 7 July 2011, Sony announced that it would no longer ship MiniDisc Walkman products as of September 2011,<ref name="Nni20110707D07JFN01"/> effectively killing the format.<ref>{{cite web|url=https://www.theguardian.com/music/musicblog/2012/sep/24/sony-minidisc-20-years|title=MiniDisc, The Forgotten Format|publisher=The Guardian UK|date=24 September 2012 |first1=Joey |last1=Faulkner |url-status=live |archive-url= https://web.archive.org/web/20230604004940/https://www.theguardian.com/music/musicblog/2012/sep/24/sony-minidisc-20-years |archive-date= Jun 4, 2023 }}</ref>

===Differences from cassette and CDs===

MiniDiscs use rewritable magneto-optical storage to store the data. Unlike the [[Digital Compact Cassette]], or the (analogue) [[audio cassette|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. This means that MDs are only compatible to computers running Windows or Mac Operational Systems; it is not possible to use them with Linux or other opensource OS.

On 1 February 2013, Sony issued a press release on the Nikkei stock exchange that it would cease shipment of all MD devices, with last of the players to be sold in March 2013. However, it would continue to sell blank discs and offer repair services.<ref name="sony-end">{{cite news|

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. Defragmentation would require either two discs, or enough RAM to store the full contents of a MiniDisc, and computing power to rearrange the fragments so that each song is stored on the disc in one fragment only.

url=http://e.nikkei.com/e/fr/tnks/Nni20130131D3Z01N02.htm|

title=Sony To End Shipments of MiniDisc Players|

accessdate=4 February 2013|

newspaper=The Nikkei|

archive-date=16 February 2013|

archive-url=https://archive.today/20130216131953/http://e.nikkei.com/e/fr/tnks/Nni20130131D3Z01N02.htm|

url-status=live}}</ref> Other manufacturers continued to release MiniDisc players long after Sony stopped, with [[TEAC Corporation|TEAC]] & [[TASCAM]] producing new decks up until 2020 when both its consumer and professional products, TEAC MD-70CD and TASCAM MD-CD1MKIII, were discontinued.<ref>{{Cite web|url=http://s-mars.co.jp/end_of_md_deck/|title = Mdデッキ生産の終息について |website=株式会社 松本無線音響設備 |date= 2020-01-27 |url-status=live |archive-url=https://web.archive.org/web/20230625090500/http://s-mars.co.jp/end_of_md_deck/ |archive-date= Jun 25, 2023 }}</ref> In January 2025 Sony announced, that production of blank MiniDiscs (together [[BD-R]] and [[MiniDV]]) will be discontinued.<ref>{{Cite news |title=Sony no longer produces BD-R, MiniDiscs and MiniDV |last=Ernst |first=Nico |date=2025-01-25 |url=https://www.heise.de/en/news/Sony-no-longer-produces-BD-R-MiniDiscs-and-MiniDV-10256695.html |website=heise.de |archive-date=26 January 2025 |access-date=26 January 2025 |archive-url=https://web.archive.org/web/20250126151908/https://www.heise.de/en/news/Sony-no-longer-produces-BD-R-MiniDiscs-and-MiniDV-10256695.html |url-status=live }}</ref>

== Design ==

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.

=== Physical characteristics ===

===Compression===

[[ImageFile:MDWalkmanMemorex-minidisc.jpg|right|thumb|250px|MD[[Memorex]] WalkmanMini-Disc]]

The audio on a MiniDisc has traditionally been compressed using the [[ATRAC]] format ('''A'''daptive '''TR'''ansform '''A'''coustic '''C'''oding). 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 [[pulse-code modulation|PCM]] audio. In MiniDisc's latest progression, Hi-MD, uncompressed [[CD quality|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.

The disc is fixed in a cartridge (68×72×5&nbsp;mm) with a sliding door, similar to the casing of a 3.5" [[floppy disk]]. This shutter is opened automatically when inserted into a drive. MiniDiscs can either be blank or prerecorded. Recordable MiniDiscs use a magneto-optical system to write data: a laser below the disc heats a spot to its [[Curie point]], making the material in the disc susceptible to a magnetic field. A magnetic head above the disc then 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 [[magneto-optic Kerr effect]], the player senses the polarization of the reflected light as a 1 or a 0. Recordable MDs can be rerecorded repeatedly, with Sony claiming up to one million times. By May 2005, there were 60-minute, 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.

Sony's ATRAC codec differs from uncompressed PCM in that it is a [[Psychoacoustics|psychoacoustic]] [[Lossy data compression|lossy]] [[Audio data compression|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.

MiniDiscs use a mastering process and optical playback system that is very similar to CDs. The recorded signal of the premastered pits and of the recordable MD are also very similar. [[Eight-to-Fourteen Modulation]] (EFM) and a modification of CD's [[Cross-Interleaved Reed-Solomon Coding|CIRC]] code, called Advanced Cross Interleaved Reed-Solomon Code (ACIRC) are employed.

===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.

=== Differences from cassette and CDs ===

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.

[[File:Comparison disk storage.svg|thumb|Comparison of several forms of disk storage showing tracks; green denotes start and red denotes end. Some CD-R(W) and DVD-R(W)/DVD+R(W) recorders operate in ZCLV, CAA or CAV modes.]]

MiniDiscs use rewritable magneto-optical storage to store data. Unlike [[Digital Compact Cassette|DCC]] or the analog [[Compact Cassette]], MiniDisc 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 a PC with Sony's [[SonicStage]] V4.3 software and edited there. Transferring data from an MD unit to a non-Windows PC 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 use [[Mac OS X]]-compatible software. However, the Mac OS X-compatible software was still not compatible with legacy MD formats (SP, LP2, LP4). This means that an MD recorded on a legacy unit or in a legacy format still requires a Windows PC for faster than real-time transfers.

The beginning of the disc has a table of contents (TOC, the System File area), which stores the start positions of the various tracks, as well as metadata (title, artist) and free blocks. Unlike a conventional cassette, a recorded song does not need to be stored as one piece on the disc and can be scattered in fragments, similar to a hard drive. Early MiniDisc equipment had a fragment granularity of four seconds of audio. Fragments smaller than the granularity are not monitored, which may lead to the usable capacity of a disc shrinking over time. No means of defragmenting the disc is provided in consumer-grade equipment.

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 (computer)|fragmentation]].

All consumer-grade MiniDisc devices have a copy-protection scheme called the [[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, the last Hi-MD players can upload to PC a digitally recorded file which can be resaved as a [[WAV]] ([[PCM]]) file and thus replicated.

===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.

=== Audio data compression ===

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 [[Compact disc|CD]] players, as well as nano-model and video-capable [[iPod]]s via the latest firmware updates).

The digitally encoded audio signal on a MiniDisc has traditionally been [[Audio compression (data)|data-compressed]] using the [[ATRAC]] (Adaptive Transform Acoustic Coding) format.

ATRAC was devised to allow MiniDisc to have the same runtime as a CD. ATRAC reduces the 1.4&nbsp;Mbit/s of a CD to a 292&nbsp;kbit/s data stream,<ref name="wb-minidisc-bitrate">{{cite web|last=Woudenberg|first=Eric|title=MiniDisc FAQ: Audio Topics - What is the bit rate of the Minidisc's ATRAC audio after compression?|website=Minidisc Community Portal|url=https://www.minidisc.org/faq_sec_4.html#_q21|access-date=2022-07-30|archive-date=7 July 2022|archive-url=https://web.archive.org/web/20220707111557/https://minidisc.org/faq_sec_4.html#_q21|url-status=live}}</ref> roughly a 5:1 reduction. ATRAC was also used on nearly all flash memory [[Walkman]] devices until the 8 series.

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.

The ATRAC codec differs from uncompressed PCM in that it is a [[psychoacoustic]] [[lossy]] audio data reduction scheme. Like other lossy audio compression formats, it is intended to be acoustically transparent.

==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.

There have been four versions of ATRAC, each claimed by Sony to more accurately reflect the original audio. Early players are guaranteed to play later version ATRAC audio. Version&nbsp;1 could only be copied on consumer equipment three or four times before artifacts became objectionable, as the ATRAC on the recorder attempted to compress the already compressed data. By version&nbsp;4, the potential number of generations of copy had increased to around 15 to 20 depending on audio content.

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.

The latest versions of Sony's ATRAC are ATRAC3 and ATRAC3plus. Original ATRAC3 at 132&nbsp;kbit/s (also known as ATRAC-LP2 mode) was the format that was used by Sony's defunct Connect audio download store. ATRAC3plus was not used in order to retain backwards compatibility with earlier NetMD players.

Tracks recorded in LP2 or LP4 mode play back as silence on non-MDLP players.

In the MiniDisc's final iteration, Hi-MD, uncompressed [[CD-quality]] linear PCM audio recording and playback is offered, placing Hi-MD on par with CD-quality audio. Hi-MD also supports both ATRAC3 and ATRAC3plus at various bitrates.

===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&times; 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.

=== Anti-skip ===

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 Linux, *BSD, and so on. A free implementation, [[libnetmd]], is being developed, yet it cannot be used to upload music ([[As of 2005|as of December 2005]]).

MiniDisc has a feature that prevents disc skipping under all but the most extreme conditions. Older CD players had 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-analog converter at the standard rate of the format. The size of the buffer varies by model.

If a MiniDisc player is bumped, playback continues unimpeded while the laser repositions itself to continue reading data from the disc. This feature allows the player to stop the spindle motor for significant periods, increasing battery life.

==Hi-MD==

{{splitsection|Hi-MD}}

A buffer of at least six seconds is required on all MiniDisc players, whether portable or full-sized units. This ensures uninterrupted playback in the presence of file [[Fragmentation (computer)|fragmentation]].

[[Image:Sony Hi-MD front.jpg|right|thumb|250px|Sony Hi-MD disc, front view]]

[[Image:Sony Hi-MD back.jpg|right|thumb|250px|Sony Hi-MD disc, back view]]

[[Image:Sonymznhf800.JPG|right|thumb|250px|The Sony MZ-NHF800, a 2004 Hi-MD model.]]

=== Operation ===

In January 2004, Sony announced the '''Hi-MD''' media storage format.<ref>[http://news.sel.sony.com/en/press_room/consumer/portable_audio/walkman_players/release/8720.html Sony Introduces Hi-MD press release] </ref> With its release in later 2004 came the ability to use newly-developed, high-capacity 1-gigabyte Hi-MD discs, sporting the same dimensions as regular MiniDiscs.

[[File:Sony-MDS-JE780.jpg|thumb|MiniDisc Deck MDS-JE780 (2002–2005)<ref>{{Cite web |title=Sony MDS-JE780 Minidisc Deck Manual |url=https://www.hifiengine.com/manual_library/sony/mds-je780.shtml |url-status=live |archive-url=https://web.archive.org/web/20201003134556/https://www.hifiengine.com/manual_library/sony/mds-je780.shtml |archive-date=Oct 3, 2020 |access-date=30 May 2020 |website=HiFi Engine}}</ref>]]

[[File:Sony MiniDisc MD Recorder MDS-81.jpg|thumb|MiniDisc Recorder MDS-B1, normally used in [[Recording studio|recording or broadcast radio studios]].]]

[[File:Minidisc2.jpg|thumb|Detail view of the MZ-R30 MiniDisc recorder (Sony, 1996)]]

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 audio data, 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 physically erased, but are only marked as deleted. When a disc becomes full, the recorder can simply direct the data into sections where erased tracks reside. This can lead to fragmentation but unless many erasures and replacements are performed, the only likely problem is excessive searching, reducing battery life.

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 competing portable players such as most [[MP3]] players, fail to implement properly. Notable exceptions are [[CD]] players, as well as all recent [[iPod]]s.

The main features of Hi-MD include:

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 points out in the manual that the power should not be interrupted or the unit exposed to undue physical shock during this time.

* the ability to save non-audio data such as documents, videos and pictures

* longer playback and recording times per disc

* the ability to ''digitally'' transfer recordings to and from Hi-MD and computer.'' (Previously only one-way (lossy ATRAC) digital transfers were possible)''

* the ability to record in [[lossless]] [[lpcm|linear PCM]], offering [[CD]]-quality audio. This completely eliminates [[compression artifact]]s that occur when recording directly to [[audio data compression|lossy audio formats]] such as Sony's [[ATRAC]], or other formats like [[MP3]], [[Advanced Audio Coding|AAC]], [[Windows Media Audio|Windows Media Audio (WMA)]], [[Ogg Vorbis|Ogg Vorbis (ogg)]], etc. ''(Previously only recording to [[ATRAC]] [[lossy data compression|lossy codecs]] was possible).''

* the introduction of a new [[ATRAC]]3plus [[audio codec|codec]] with new Hi-LP and Hi-SP bitrates.

* compatibility (and enhanced capabilities) with standard MiniDiscs

=== Copy protection ===

Hi-MD offers the choice of several codecs for audio recording: '''PCM''', '''Hi-SP''' and '''Hi-LP''', each selectable on the Hi-MD Walkman itself. PCM is the highest quality mode, followed by Hi-SP (the default mode), then Hi-LP.

All MiniDisc recorders (except [[Professional audio|professional]] models) use the [[Serial Copy Management System|SCMS]] copy protection system which uses two [[bit]]s in the S/PDIF digital audio stream and on disc to differentiate between "protected" vs. "unprotected" audio, and between "original" vs. "copy":

* Recording digitally from a source marked "protected" and "original" (produced by a prerecorded MD or an MD that recorded an analogue input) was allowed, but the recorder would change the "original" bit to the "copy" state on the disc to prevent further copying of the copy. A CD imported via a digital connection does not have the SCMS bits (as the CD format predates SCMS), but the recording MD recorder treats any signal where the SCMS bits are missing as protected and original. The MD copy, therefore, cannot be further copied digitally.

* Recording digitally from a source marked "protected" and "copy" was not allowed: an error message would be shown on the display.

* Recording digitally from a source marked "unprotected" was also allowed; the "original/copy" marker was ignored and left unchanged.

Recording from an analogue source resulted in a disc marked "protected" and "original" allowing one further copy to be made (this contrasts with the SCMS on the [[Digital Compact Cassette]] where analogue recording was marked as "unprotected").

* ''PCM'' mode allows 94 minutes (1h:34min) of lossless CD-quality audio to be recorded to a 1GB Hi-MD disc ''(or 28 minutes on a standard 80-minute MiniDisc recorded in Hi-MD mode)''.

* ''Hi-SP'' allows seven hours and fifty-five minutes (7h:55m) of audio to be recorded on a 1GB Hi-MD ''(or 2h:20min on a standard 80-minute MiniDisc recorded in Hi-MD mode)''.

* ''Hi-LP'' allows 34 hours on a 1GB Hi-MD ''(or 10h:10min on a standard 80-minute MiniDisc recorded in Hi-MD mode''). <br />

In recorders that could be connected to a PC via [[USB]], it was possible to transfer audio from the PC to the MiniDisc recorder, but for many years it was not possible to transfer audio in the other direction. This restriction existed in both the SonicStage software and in the MiniDisc player itself. SonicStage V3.4 was the first version of the software where this restriction was removed, but it still required a MiniDisc recorder/player that also had the restriction removed. The Hi-MD model MZ-RH1 was the only such player available.

== Format extensions ==

Each of these codecs is available natively for recording on standalone Hi-MD devices. Additional bitrates are available with [[SonicStage]] software on the computer. Up to 45 hours of audio can be recorded per disc at the lowest-quality setting via SonicStage PC transfer.<br />

=== MD Data ===

{{Main|MD Data}}

MD Data, a format for storing computer data, was announced by Sony in 1993.<ref name=Byte199508>{{Cite web |date=August 1995 |title=Reviews / Sony's Mini-MO |url=http://www.byte.com/art/9508/sec11/art11.htm |url-status=dead |archive-url=https://web.archive.org/web/19961220103438/http://www.byte.com/art/9508/sec11/art11.htm |archive-date=December 20, 1996 |access-date=December 22, 2023 |website=[[Byte (magazine)|Byte]]}}</ref> Its media stored 140 MB<ref name=Byte199508/> and were generally incompatible with standard audio MiniDiscs.<ref>{{Cite web |title=MiniDisc MD-Data Product Table |url=https://www.minidisc.org/md_data_table.html |access-date=December 22, 2023 |website=The MiniDisc Community Portal |archive-date=22 December 2023 |archive-url=https://web.archive.org/web/20231222183757/https://www.minidisc.org/md_data_table.html |url-status=live }}</ref> MD Data cannot write to audio MDs, but only the considerably more expensive data blanks. It did see some success in a small number of multi-track recorders such as Sony's MDM-X4, Tascam's 564 (which could also record using standard audio MD discs, albeit only two tracks), and Yamaha's MD8, MD4, & MD4S.

All Hi-MD units have the ability to play back regular MiniDiscs. Most Hi-MD Walkmans also have the capability to record standard MiniDiscs in standard '''SP''', '''LP2''' and '''LP4''' codecs in ''MD mode'' (as opposed to ''Hi-MD mode''), ideal for creating discs intended to be played back in older ''(pre-Hi-MD)'' MiniDisc units.

=====Data andMD audioData2 on the same disc=====

In 1997, MD Data2 blanks were introduced with 650&nbsp;MB. They were only implemented in Sony's short-lived MD-based camcorder, the DCM-M1.

Hi-MD discs offer the ability to store computer files in addition to audio data. For example, a Hi-MD disc could have both school or work documents, pictures, videos, etc. as well as music (playable in a Hi-MD Walkman) if desired.

=== MDLP ===

When connected to a computer (via [[universal serial bus|USB]] cable), a Hi-MD [[Walkman]] is seen as standard [[usb mass storage|USB Mass Storage]] device, just like a [[usb flash drive|USB stick or external hard drive]]. On a Windows computer, a Hi-MD device is listed as "Removable Disk" in "My Computer". The disc has a [[file allocation table|FAT]] filesystem. Hi-MD units are powered by the USB bus when connected - just like USB sticks, they don't require additional power (and don't use their own battery power) when plugged in to a computer.

In 2000, Sony announced MDLP (MiniDisc Long Play), which added new recording modes based on the new codec ATRAC3. In addition to the standard, high-quality mode, now called SP, MDLP adds LP2 mode, which doubles the 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&nbsp;[[kbit/s]], and it uses separate stereo coding with discrete left and right channels. LP2 mode uses a bitrate of 132&nbsp;kbit/s and also uses separate stereo coding. The third mode, LP4, has a bitrate of 66&nbsp;kbit/s and uses [[joint stereo coding]]. The sound quality is noticeably degraded compared to the other two modes, but is sufficient for many uses.

Sony's [[SonicStage]] music management software is not needed to save and manipulate files on the discs; it is only required to get playable audio on and off the device; all files are manipulated using standard operating-system functions. However, when SonicStage software is active, the recorder is not treated as a data storage device - SonicStage "takes over" the management of the device.

Tracks recorded in LP2 or LP4 mode play back as silence on non-MDLP players.

When connected to a PC, "PC--MD" appears on the Hi-MD device's display to indicate the unit is connected in PC--MD mode. In PC--MD mode, pressing Play on the unit, for example, results in "PC--MD" flashing, indicating this function cannot be activated from the device when connected to the computer. It is essentially a slave to the computer in this mode. PC--MD status is constant as long as the unit is connected via USB cable (regardless of whether SonicStage is running or not).

=== NetMD ===

To play back Hi-MD audio data on the PC, [[SonicStage]] is needed. It can be done two ways:

[[File:Sony-MZ-N707-MD-Walkman.jpg|thumb|A NetMD Sony MiniDisc Recorder]]

# Launch SonicStage. Play audio from Hi-MD inside SonicStage. The audio is played back on the computer's PC speakers. SonicStage reads and decrypts the audio data straight from the Hi-MD disc.

Debuting in late 2001, '''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.

# transfer the audio data to the PC in SonicStage. Play the audio back from the PC's hard drive (instead of playing it back from the Hi-MD unit directly)

When transferring music in SP mode using NetMD with SonicStage, what is transferred is actually padded LP2. That is to say that the quality of the music is that of LP2 but recorded as SP.

Once the operation of transferring audio with SonicStage is completed, the audio itself can be saved in any number of ways (& audio formats). Saving audio in SonicStage in standard [[WAV]] format is a widely-accepted way to get the audio into many third-party applications like editors and sound analyzers. The user can then proceed to record CDs, edit the audio, archive to format of choice, etc.

NetMD is a proprietary protocol that initially required proprietary software such as [[SonicStage]]. A free [[*nix]] based implementation, libnetmd, has been developed. The library allows the user to upload SP files in full quality. In 2019, a programmer named Stefano Brilli compiled the linux-minidisc CLI into a web browser-based application,<ref>{{cite web|url=https://stefano.brilli.me/blog/web-minidisc/|title=The Web MiniDisc App|date=March 26, 2020|first=Stefano|last=Brilli |url-status=live |archive-url= https://web.archive.org/web/20230625050453/https://stefano.brilli.me/blog/web-minidisc/ |archive-date= Jun 25, 2023 }}</ref> allowing users to transfer music via USB on modern devices.<ref>{{cite news|url=https://www.techtelegraph.co.uk/remember-minidisc-heres-how-you-can-still-use-it-in-2020/|title=Remember MiniDisc? Here's How You Can Still Use It in 2020|date=July 25, 2020|work=TechTelegraph |url-status=deviated |archive-url=https://web.archive.org/web/20201219023141/https://www.techtelegraph.co.uk/remember-minidisc-heres-how-you-can-still-use-it-in-2020/ |archive-date= Dec 19, 2020 }}</ref>

=====Backward compatibility with standard MiniDiscs=====

Hi-MD units can play back standard MiniDiscs recorded in non-Hi-MD units, in addition to record on standard MiniDiscs and higher-capacity 1GB Hi-MD discs. There are two user-selectable operational modes on Hi-MD units (which Sony calls ''Disc Modes''): '''MD mode''' and '''Hi-MD mode'''.

=== Hi-MD ===

These are automatically selected whenever a disc with a recording on it is inserted. However, when a blank disc is inserted, the recorder will default to the user-selectable ''Disc Mode'' for any recordings made on it. The default Disc Mode on Hi-MD devices is ''Hi-MD mode'', but it can be changed to ''MD mode'' if desired.

{{Main|Hi-MD}}

Hi-MD is a further development of the MiniDisc format. Hi-MD media will not play on non-Hi-MD equipment, including NetMD players. The [[Hi-MD]] format, introduced in 2004, marked a return to the data storage arena with its 1&nbsp;GB discs and ability to act as a [[USB flash drive|USB drive]].<ref>{{Cite web|url=http://news.sel.sony.com/pressrelease/4270|title=Sony introduces Hi-MD Walkman digital music players |date=Jan 7, 2004 |website=Sony |archive-url=https://web.archive.org/web/20040201212250/http://news.sel.sony.com/pressrelease/4270 |archive-date=1 February 2004 }}</ref> Hi-MD units allow the recording and playback of audio and data on the same disc, and can write both audio and data to standard MiniDisc media – an 80-minute MiniDisc blank could be formatted to store 305&nbsp;MB of data.

== Recording and transfer modes ==

* ''MD mode'' is useful when intending to record on a standard MiniDisc using standard MD codecs for playback on devices that are not Hi-MD compatible. Data storage (and other benefits of ''Hi-MD mode'') cannot be used in MD mode.

Modes marked in green are available for recordings made on the player, while those marked in red are available for music transferred from a PC. Capacities are official Sony figures; real world figures are usually slightly higher. Native MP3 support was added in second-generation Hi-MD players in the spring of 2005.<ref>{{Cite web|url=http://bssc.sel.sony.com/BroadcastandBusiness/minisites/himd/index.shtml|title=Sony Business Solutions & Systems - Featured|date=15 April 2008|archive-url=https://web.archive.org/web/20080415133121/http://bssc.sel.sony.com/BroadcastandBusiness/minisites/himd/index.shtml |archive-date=15 April 2008 }}</ref> [[SonicStage]] version 3.4, released in Feb 2006,<ref>{{Cite web|url=http://www.sony.jp/products/overseas/contents/support/download/index.html|title=Overseas Model Customer Support|date=7 April 2006|archive-url=https://web.archive.org/web/20060407092514/http://www.sony.jp/products/overseas/contents/support/download/index.html |archive-date=7 April 2006 }}</ref> introduced ripping CDs in bitrates 320 and 352<ref>{{Cite web|url=https://www.sony.jp/products/overseas/contents/support/download/e_jeb_SS34ug.html|title=Overseas Model Customer Support|date=5 February 2006|archive-url=https://web.archive.org/web/20060205040106/https://www.sony.jp/products/overseas/contents/support/download/e_jeb_SS34ug.html |archive-date=5 February 2006 }}</ref> and added track transfer in ATRAC 192&nbsp;kbit/s to Hi-MD devices.

* ''Hi-MD mode'' is useful when the benefits of Hi-MD mode want to be used, such as increased capacity on standard MiniDiscs, new codec choices (PCM, Hi-SP, Hi-LP) and the ability to save data on the discs along with audio.

{| class="wikitable" style="margin:1em auto;"

Using ''Hi-MD mode'' with a standard 80-minute MiniDisc increases the disc's capacity from 177MB to 305MB. ''MD Mode'' is ignored when a 1GB Hi-MD is inserted; ''Hi-MD mode'' is always used with 1GB Hi-MD discs.

=====Sony removes restrictions=====

Since the release of [[SonicStage]] 3.4 (Sony's music-management program), virtually all computer audio transfer restrictions were removed. These plagued earlier versions of SonicStage for some time.'' (Sony actually started a big push to dispense with the [[Digital Rights Management|DRM]] restrictions with the release of SonicStage version 3.2. Version 3.4 dispensed with even more).''

A side-effect of this is that the wording in many Sony Hi-MD user's manuals regarding "transfer authorizations" don't apply to users using SonicStage versions 3.2 and later. The ability to transfer Hi-MD audio to (and from) computer is now essentially unrestricted, unlike previous versions of the software.

Some of these restrictions included:

* limited transfers of microphone and "line-in" recordings

* barring of digitally-sourced uploads (ie. recordings that were made from USB or digital optical input).

These restrictions had - in the past - severely impacted the utility and ease-of-use of Hi-MD.

One limit that still remains in current software is the inability to edit tracks transferred from SonicStage to the device. Attempting to add or erase track marks on-unit from tracks transferred through SonicStage will result in "NO EDIT" (or similar message) being flashed on the unit. No such editing restrictions exist when transferring via optical cable or via LINE-IN.

Sony mention this limitation in their manuals as necessary to prevent "loss of transfer authorization" on the edited tracks. Considering these transfer authorizations are gone now, it seems possible for Sony to get rid of this limitation as well - so that users may add & erase track marks on their Hi-MD units whenever they please, despite it being transferred from SonicStage.

The latest officially-downloadable release of SonicStage is SonicStage CP 4.3. It is available on the following Sony sites:

* [http://support.sony-europe.com/DNA/sonicstage/sstage_dl.asp?l=en Sony Europe]

=====Native support for MP3=====

In 2005 Sony released its second-generation Hi-MD devices offering native support for the popular [[MP3]] format (earlier, SonicStage would transcode MP3 files to ATRAC format before recording on the disc). Transcoding files to lossy formats always results in lower quality sound.

Sony's MP3 file support still means that the MP3s themselves had to go through [[SonicStage]] to be put on the device, and couldn't just be copied on the discs outside of SonicStage as you can with data files on Hi-MD (or Hi-MD-formatted MiniDisc media). SonicStage 'wraps' (encrypts) the MP3 files on the disc (as it does with all audio that's playable in a Hi-MD device). To many, the requirement of [[SonicStage]] for audio transfers has been a constant drawback.

At the release of the second-generation Hi-MD models in 2005, some controversy erupted. Some users argued that MP3 playback on the devices sounded dull; the treble seemed to be muffled in comparison to ATRAC-encoded files, which sounded 'brighter'. The results were consistent. The devices could be best described as having their MP3 playback crippled, angering many customers. Sony implemented a [[lowpass]] on MP3 playback, which could make MP3 sound dull in comparison to ATRAC. Some users believe this was done intentionally in hopes of fooling listeners into believing Sony's ATRAC was superior to MP3. Regardless of the intentions of Sony, the MP3 playback roll-off problem was notably absent with the release of a new model, the MZ-RH1 Walkman, in March 2006.

=====Hi-MD Photo=====

In 2005, Sony announced Hi-MD Photo.<ref>[http://www.sony.net/SonyInfo/News/Press/200503/05-013E/index.html Sony expands Hi-MD format by adopting direct MP3 playback]</ref>

The Sony MZ-DH10P Walkman was released to showcase the format. The unit offers a 1.3 megapixel digital camera and saves pictures to Hi-MD discs, but doesn't offer a microphone input to record live audio, as do most standard Hi-MD Walkmans. The unit was praised for its full-colour display and unique photo & music features, but met with limited market success.

=====Upload of 'legacy' MiniDiscs=====

In March 2006, Sony released the MZ-RH1 Hi-MD Walkman in Japan, which was later followed in other regions. With this unit, Sony enabled faster-than-realtime full digital transfers from standard MiniDiscs to the computer for the first time. Users with extensive MiniDisc collections, for example, could upload their recordings digitally faster than real-time via USB connection, just like Hi-MD recordings already offered.

One limitation is with transfers done from MiniDiscs recorded on NetMD devices. MiniDiscs that have had recordings transferred via USB from computer to the NetMD device cannot have those recordings uploaded to the computer digitally. However, NetMD live audio recordings (via MIC input) as well as LINE IN recordings can be transferred to the computer digitally with no restriction on the MZ-RH1.

These digital transfers of standard (pre-Hi-MD) MiniDiscs are in addition to the essentially unrestricted Hi-MD transfers already available since the online availability of [[SonicStage]] 3.4 (and later).

With the MZ-RH1, Sony made tangible speed improvements to the device over previous generations of Hi-MD recorders. The result being that the transfer times to and from computer are - under certain circumstances - cut in half over previous models, but still noticeably slower than flash memory and hard drive-based portables, because of the nature of the Hi-MD magneto-optical system.

=====Hi-MD selling points=====

Sony's Hi-MD models are widely-regarded for their high-quality recording, and are generally considered the highest quality recording devices in their price range.{{check}}

Hi-MD's strengths over most other [[digital audio player]]s and recorders on the marketplace include:

* [[gapless playback]]

* the ability to record in linear PCM at 16bits, 44.1KHz sampling rate (identical to CD with no lossy codecs being employed like WMA, MP3, AAC, ATRAC, etc)

* Connection flexibility; nearly all recorders offer MIC (microphone), digital OPTICAL and analogue LINE inputs.

* Recording the entire 20Hz-20KHz audible frequency range, making Hi-MD suitable for high-quality live audio capture of music in addition to voice. Most voice recorders have a limited frequency range, particularly when employing poor quality internal microphones

* high-quality low-noise components and circuit design<ref>[http://forums.minidisc.org/index.php?showtopic=16220 Hi-MD at Minidisc Community Forums]</ref> (low noise MIC pre-amps, LINE IN input)

* automatic gain control (AGC), manual level adjustment and level meters on all recorders

* high and low sensitivity microphone and variable AGC settings on all recorders with a MIC input

* on-unit disc editing such as track-marking, titling, combining, dividing and grouping tracks without the need for a computer

* USB connection for ''two-way'' digital transfers (computer-to-Walkman and Walkman-to-computer)

* Synchro record for synchronising the recording from optical digital inputs

*''SpeedControl'' - available on selected Hi-MD models - makes Hi-MD useful to musicians and language students by slowing down the audio without changing the pitch

* ''A-B Repeat'' allows a user to make a certain section of a track within a track repeat itself; (the user selects points A and B).

* Nearly all models include a remote control as a standard accessory and all Hi-MD Walkmans have the capability to accept a remote control.

[[Image:Sony Hi-MD inputs.jpg|right|thumb|250px|Sony Hi-MD output/inputs. From left to right;

standard headphone output with remote control connection,

MIC (microphone) input (with plug-in power),

LINE IN (OPT) for analogue LINE IN connections and digital OPTICAL connections. USB jack (hidden behind cover) for connection to computer. This is a typical example of the connection flexibility most Hi-MD units offer.]]

Audio can be transferred to the units without a computer via OPTICAL input, LINE IN via analogue cable and live audio via the MIC input. Optical inputs found on nearly all Hi-MD devices allow digital transfers from many [[Consumer Electronics|CE-devices]].

Transfers over digital optical cable typically maintain the high sound quality of the original by avoiding quality loss that comes from converting the digital audio to analogue form. The main difference between optical and USB transfers is that the optical transfer is real-time (ie. 1 hour of material takes one hour to transfer). Many non-computer (and computer) devices offer optical outputs that Hi-MD can record from with high quality.

In addition to digital optical input, recording via analogue sources is possible via the LINE input. On Hi-MD Walkmans, the same physical connector accepts both analogue and optical connections.

All Hi-MD (and older MD and NetMD) devices accept user-replaceable batteries, as opposed to a single non user-replaceable embedded battery popular on most digital audio players. This allows for easy battery switching when travelling and/or after extended recording or playback sessions. Several models accept the ubiquitous [[AA battery]].

=====Criticism=====

Criticisms of the Hi-MD format (nearly all apply to standard MiniDisc and NetMD, too):

; SonicStage : The requirement of [[Microsoft Windows]]-based [[SonicStage]] to transfer audio to and from the device when using the USB connection - and SonicStage's own peculiarities and limitations. When a Hi-MD unit records, audio information is encrypted by the device. When transferring content to or from the computer, the same applies, except SonicStage is used to decrypt and encrypt audio. Many argue audio should be able to be placed on the device in standard formats without a proprietary application needing to be installed to view and transfer Hi-MD-playable audio, much the same way as regular files can be placed on Hi-MD discs without encryption or obfuscation. If the encrypted audio data is damaged in any way (whether through normal operation of the unit or abuse) standard [[operating system]] disc-checking tools cannot be used to attempt to recover the audio due to its proprietary encrypted nature. Hi-MD recorders natively encrypt audio data regardless of any [[ATRAC]] or linear PCM codec recording choices, and regardless of recording source (microphone, optical or line-in). Similarly, files transferred from PC via SonicStage are natively encrypted (but not necessarily [[transcode]]d) regardless of source format ([[Advanced Audio Coding|AAC]], [[MP3]], [[WAV]]). Standard audio files such as [[MP3]], [[FLAC]], [[Ogg Vorbis]], [[Advanced Audio Coding|AAC]], [[Windows Media Audio|WMA]], etc. can be copied to a Hi-MD or Hi-MD formatted MiniDisc without the aid of SonicStage much the same way as pictures and documents are, but the files themselves will not be playable by the Hi-MD device natively (ie. without the aid of a computer).

; Disc-based limitations: Hi-MD units store non-audio information (such as start and end time of tracks) in the "system file" area of the disc. The system file is updated after any recording or edits on disc (like new recordings, moving track positions, adding tracks, removing tracks, track titling, etc). For example, recording and then pressing "stop" on the unit will result in the unit saving any in-memory audio data to disc - then updating the "system file" area of the disc. SYSTEM FILE WRITING is commonly seen on the display of a Hi-MD unit at this time (DATA SAVE may appear instead, when edited track names, disc name, artist names, etc. are being saved). In both cases, it is at this point the recorder spends several seconds updating the system file area of the disc. Sony warns not to shock the unit at this time or remove the power to the unit because the entire recording can be 'lost' if the system file area is not written to or updated properly. This is seen as a weakness of a disc-based format. To avert power-related problems when writing, the Hi-MD estimates whether the battery power is adequate in advance of any recording or editing taking place on the unit. "NotENOUGH POWER TO REC" and "NotENOUGH POWER TO EDIT" are two messages that may appear in the display when the recorder estimates the power to not be enough. Power-related problems are largely averted this way, but shocking the unit still may be an issue at this critical stage of writing.

; Mechanical noise: Hi-MD units are mechanical devices, and as such, emit a noise intermittently. A disc is read (or written to) in bursts. This means that when recording (for example), the audio data is fed to a memory buffer first, then written to disc as that memory buffer is filled. The audible manifestation of this is that a spinning motor noise is heard for a short period, followed by a far longer period of silence. Then some spinning whir again, then silence. The cycle is repeated. The same applies to playback, only differently: a disc is spun faster than required for normal playback (to fill the memory buffer), then stops spinning and the audio information is emptied (played back) from memory normally. As the memory buffer depletes, the disc spins up again, maintaining the fill of the memory buffer, only to spin down the disc again (into silence). The buffer memory allows the disc to spin down completely most of the time, conserving battery life. However, during live recording operations with a microphone, this can be a problem. If the microphone is directly connected to the unit (ie. directly connected to the MIC jack without a wire), or simply in close enough proximity with a fairly quiet background, this intermittent motor noise can be audibly present in the recording - if some basic precautions aren't taken. This contrasts with flash-based recorders with no moving parts for recording, who are able to record in silence with no self-noise. <!-- whoa whoa whoa, let's find an objective source for this. ''(In practice, unfortunately, too many flash recorders in Hi-MD's price range are simply poor recorders, chiefly due to poor component choice, lossy encoding methods, inadequate recording features and/or poor circuit design).'' -->

; Storage capacity: Relatively poor storage capacity (1GB per disc) compared to hard-drive and some recent flash-based digital audio players

; Slow transfer rates: When transferring audio (and data) to and from the computer. Hi-MD units offer far lower speeds than flash memory-based and hard drive-based devices.

; Miniaturization constraints: The larger size of Hi-MD units in comparison to some far smaller units available on the market today. Most of these smaller portable audio devices are [[flash memory]]-based units not limited in their miniaturization by the physical dimensions of a Hi-MD.

=====Marketing moves=====

In 2006, Sony positioned Hi-MD as a [[Digital Audio Tape|Digital Audio Tape (DAT)]] alternative, placing the MZ-M200 Hi-MD Walkman under the Pro Audio section of its "Broadcast & Business Solutions Company" website, alongside its [[flash memory]]-based recorder, the PCM-D1.<ref>[http://bssc.sel.sony.com/BroadcastandBusiness/DisplaySubCategory?m=0&p=10&sp=83 Product Listing]</ref> [[Digital Audio Tape|Digital Audio Tape (DAT)]] is a high-quality digital tape format that found a niche with musicians and studios, and is valued for its high-quality sound reproduction. DAT portables have commonly been used for field recording, but have gradually been replaced by solid-state and hard drive-based units like the [[Aaton]] [[Cantar]], the [[Zaxcom]] [[Deva]], and similar units from [[Fostex]] and [[Sound Devices]]. (Sony and Fostex ceased manufacturing DAT devices at the end of 2005, though parts and blank tapes should be available through 2010).

The MZ-M200 Walkman is Sony's MZ-RH1 with a powered stereo microphone included. The MZ-RH1 is targeted to a more general customer on Sony's consumer electronics sites and comes with no microphone bundle. The microphone is included to enable Hi-MD as a field recorder, and the higher price reflects the added value of the microphone.

Given the improvements in Hi-MD, such as linear PCM recording (offering truly CD-quality sound without lossy compression), as well as improvements in [[SonicStage]], MD users may hope that marketing efforts like this might see Hi-MD's use as a field recording tool grow.

While MD has been a reasonable success in Asia (particularly in Japan and Hong Kong), North America and Europe have leaned more often towards either flash or hard drive-based systems. For professional recording, many offer features such as professional [[XLR]] microphone inputs, among other pro-centric features. These units are typically significantly larger and heavier than a Hi-MD Walkman, often with reduced battery life and higher prices. It's for these reasons Hi-MD fills a niche for high-quality recording and editing purposes in a compact size - and still remains a quality playback device. Stealth recordists, in particular, continue to favour Hi-MD.

In 2006, Hi-MD Walkman models released were the MZ-RH1 & MZ-M200. These units were designed with a particular focus on ease-of-recording, and have received a positive reception from many recording enthusiasts.

== 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.

<center>

{| class="wikitable"

!rowspan=3|Name

!rowspan=3|Bitrate<br />(kbit/s)

!rowspan=3|Codec

!colspan=5|Availability and capacity (min)

Line 246 ⟶ 167:

!colspan=3|Hi-MD player

|-

!colspan=3|80 -minute disc

!80 -minute disc<br /> (HiMD formatted)

!1 GB Hi-MD disc

|-

Line 253 ⟶ 174:

|292

|ATRAC

| style="background:#bfb;"|80

|{{bgcolor-green}}|80

| style="background:#bfb;"|80

|{{bgcolor-green}}|80

| style="background:#bfb;"|80

|{{bgcolor-green}}|80

|n/a

|n/a

Line 262 ⟶ 183:

|146

|ATRAC

| style="background:#bfb;"|160

|{{bgcolor-green}}|160

| style="background:#bfb;"|160

|{{bgcolor-green}}|160

| style="background:#bfb;"|160

|{{bgcolor-green}}|160

|n/a

|n/a

Line 272 ⟶ 193:

|ATRAC3

|n/a

| style="background:#bfb;"|160

|{{bgcolor-green}}|160

| style="background:#bfb;"|160

|{{bgcolor-green}}|160

| style="background:#fbb;"|290

|{{bgcolor-red}}|290

| style="background:#fbb;"|990

|{{bgcolor-red}}|990

|-

! -–

|105

|ATRAC3

|n/a

| style="background:#fbb;"|127

|{{bgcolor-red}}|160

| style="background:#fbb;"|127

|{{bgcolor-red}}|160

| style="background:#fbb;"|370

|{{bgcolor-red}}|370

| style="background:#fbb;"|1250

|{{bgcolor-red}}|1250

|-

!LP4

Line 290 ⟶ 211:

|ATRAC3

|n/a

| style="background:#bfb;"|320

|{{bgcolor-green}}|320

| style="background:#bfb;"|320

|{{bgcolor-green}}|320

| style="background:#fbb;"|590

|{{bgcolor-red}}|590

| style="background:#fbb;"|1970

|{{bgcolor-red}}|1970

|-

! -–

|48

|ATRAC3plus

Line 301 ⟶ 222:

|n/a

|n/a

| style="background:#fbb;"|810

|{{bgcolor-red}}|810

| style="background:#fbb;"|2700

|{{bgcolor-red}}|2700

|-

!Hi-LP

Line 310 ⟶ 231:

|n/a

|n/a

| style="background:#bfb;"|610

|{{bgcolor-green}}|660

| style="background:#bfb;"|2040

|{{bgcolor-green}}|2040

|-

!Hi-SP

Line 319 ⟶ 240:

|n/a

|n/a

| style="background:#bfb;"|140

|{{bgcolor-green}}|160

| style="background:#bfb;"|475

|{{bgcolor-green}}|475

|-

!PCM

Line 328 ⟶ 249:

|n/a

|n/a

| style="background:#bfb;"|28

|{{bgcolor-green}}|28

| style="background:#bfb;"|94

|{{bgcolor-green}}|94

|}

</center>

==References See also ==

{{Portal|1990s}}

<references/>

* [[Capacitance Electronic Disc]] (SelectaVision) – an RCA-developed format that uses a disc inside a sleeve, like MD

* [[Fidelipac]]

* [[Universal Media Disc]] (UMD) – a similar Sony format, but read-only. Used on the [[PlayStation Portable]] handheld game console.

* [[Mini CD]]

* [[MiniDVD]]

* [[Mini Blu-ray]]

== References ==

==External links==

{{Reflist}}

* [http://bssc.sel.sony.com/BroadcastandBusiness/minisites/himd/index.shtml Sony Hi-MD page]

* [http://www.MiniDisc.org/ MiniDisc Community Portal]

* [http://www.minidisc.org/minidisc_faq.html MiniDisc.org FAQ]

* [http://forums.MiniDisc.org MiniDisc Forum]

* [http://www.audiotstation.com/forum Audio T-Board]

* [http://tuxmobil.org/player_linux_survey_sony.html Linux and Sony MiniDisc players]

== External links ==

{{Audio format}}

{{sister project auto}}

*[https://www.discogs.com/search/?format_exact=Minidisc List of artists with a Minidisc release – Discogs]

{{Audio formats}}

{{Music technology}}

{{Optical storage media}}

{{Sony Corp}}

[[Category:Audiovisual introductions in 1992]]

[[Category:Audio storage]]

[[Category:Consumer electronics]]

[[Category:Digital audio]]

[[Category:1991History introductionsof radio]]

[[Category:Sony products]]

[[Category:Discontinued media formats]]

[[cs:Minidisc]]

[[Category:Japanese inventions]]

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[[ja:ミニディスク]]

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