MiniDisc (MD) is an erasable magneto-optical disc-based data storage format offering a capacity of 60, 74, and later, 80 minutes of digitized audio.

Sony announced the MiniDisc in September 1992 and released it in November[2] of that year for sale in Japan and in December in Europe, North America, and other countries.

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.

By the time Sony came up with the MiniDisc in late 1992, Philips had introduced a competing system, DCC, on a magnetic tape cassette.

However, non-Sony machines were not widely available in North America, and companies such as Technics and Radio Shack tended to promote DCC instead.

Despite having a loyal customer base largely of musicians and audio enthusiasts,[citation needed] the MiniDisc met with only limited success in the United States.

Since then, recordable CDs, flash memory and HDD and solid-state-based digital audio players such as iPods have become increasingly popular as playback devices.

The slow uptake of MiniDisc was attributed to the small number of pre-recorded albums available on MD, because relatively few record labels embraced the format.

Additionally, home MiniDisc decks were less widely available, with most consumers instead connecting a portable MD device to their hi-fi system in order to record.

MiniDisc technology was faced with new competition from the recordable compact disc (CD-R) when it became more affordable to consumers beginning around 1996.

With the 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.

[10][11][12] 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.

On 7 July 2011, Sony announced that it would no longer ship MiniDisc Walkman products as of September 2011,[6] effectively killing the format.

[13] 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.

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.

Unlike DCC or the analog Compact Cassette, MiniDisc is a random-access medium, making seek time very fast.

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.

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, it can be scattered in fragments, similar to a hard drive.

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

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, but some listeners claim to be able to hear audible artifacts.

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.

In 2019, a programmer named Stefano Brilli compiled the linux-minidisc CLI into a web browser-based application,[20] allowing users to transfer music via USB on modern devices.

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.

[23] SonicStage version 3.4, released in Feb 2006,[24] introduced ripping CDs in bitrates 320 and 352[25] and added track transfer in ATRAC 192 kbit/s to Hi-MD devices.