Release / Format

This field describes which medium a release is distributed on. Normally a release will be distributed on multiple media with different catalog numbers and barcodes; each should be a separate release.

The values may be:

Name			Date of creation	Rarity*	Details
Compact Disc			1982	Widespread	PCM, Available in 120mm and 80mm formats.
	Copy Control CD		2001	Common?	Copy Control CDs went out of favor by the end of 2006
	Data CD
	DTS CD		1992	Very Rare	a.k.a. 5.1 Music Disc — DTS Audio
	Enhanced CD		1995	Common? Rare?	a.k.a E-CD, CD-Extra, CD-Plus & CD+ -- combines music and data tracks
	HDCD		1995	Rare?	High Definition Compatible Digital. Enhanced sound recording compatible with the standard Audio CD. In 2000 there were over 4000 releases available, in 2008 there were about 4000 releases. [1]
	Mixed Mode CD
	CD-R		1995	Common?	Record-able CD
	8cm CD		1987
	Blu-spec CD		2008	Common	PCM
	Minimax CD
	SHM-CD		2007	Common	(English) (Super High Material CD) PCM. The first re-issues on SHM-CD were released 21 November 2007
	HQCD		2008
	CD+G		1985	Rare	Audio CD with Graphics, usually used for karaoke
		8cm CD+G
Vinyl			1948/1957/1971	Common	Vinyl / Quad Vinyl. A simple evolution of gramophone record: Analog, with pre-emphasis and other equalization techniques (LP, RIAA). Lateral grooves, horizontal stylus motion. Monaural were created in 1948, then stereo vinyl came later in 1957 and Quad in 1971: analog, with pre-emphasis and other equalization techniques. Combination lateral/vertical stylus motion with each channel encoded 45 degrees to the vertical.
	7" Vinyl			Common	17 cm
	10" Vinyl				25 cm
	12" Vinyl			Common	30 cm
	Flexi-disc		1962	Common?	Phonosheet, Sonosheet, Soundsheet
		7" Flexi-disc		Common?	17 cm
Digital Media				Widespread	All born-digital releases, in any file format
Cassette			1963	Common?	Analog, with bias, preemphasis, 1/8 inch wide tape, 17/8 inches/sec. 1970: introduced Dolby noise reduction.
	Microcassette		1969	Rare	Analog, 1/8 inch wide tape, mostly mono, some stereo. 2.4 cm/s or 1.2 cm/s.
DVD
	DVD-Audio		1999	Rare? Common?	DVD-Audio products were delayed until mid 2000
	DVD-Video		1996	Widespread	First available in Japan by November, on March 1997 in US and later established in Europe by 1998
SACD			1999	Rare	Super Audio CD. Intended as successor to CD; generally regarded as a failure except by audiophiles.
	Hybrid SACD			Rare	SACD which also contains audio playable in normal CD players
		Hybrid SACD (CD layer)
		Hybrid SACD (SACD layer)
	SHM-SACD		2010	Rare	SACD manufactured using the SHM manufacturing process. First CDs were released 23 June 2010
DualDisc			2003	Common?	An audio cd on one side (though not redbook), and a dvd on the other side
	DualDisc (CD side)
	DualDisc (DVD-Video side)
	DualDisc (DVD-Audio side)
MiniDisc			1991	Common	ATRAC
Blu-ray			2006	Common
	Blu-ray-R
HD-DVD			2005	Rare?	Abandoned by 2008. Last known release(s) were in 2010 although in HD-DVD-R format
VCD			1993	Rare	Video CD. Digital format, precursor to DVD
	SVCD		2000	Rare? Common?	Super Video CD. Chinese-developed alternative to DVD-Video; intended as successor to VCD; didn't succeed.
CDV			1987	Rare	CD Video. Mixed analog/digital video/audio format; began to disappear by 1991
UMD			2004	Rare	Universal Media Disk. a proprietary format used only by the PlayStation Portable; some movies were released on it
Shellac			1921	Common?	Phonogram record made with shellac instead of vinyl
	7" Shellac				17 cm
	10" Shellac				25 cm
	12" Shellac				30 cm
Acetate				Rare?	Phonogram record made with acetate instead of vinyl
	7" Acetate				17 cm
	10" Acetate				25 cm
	12" Acetate				30 cm
SD card			?	?
	slotMusic		2008	Common?	A type of microSD memory card developed by SanDisk preloaded with music in DRM-free MP3 format and other content. The current selection of songs comes from EMI Music, Sony BMG, Universal Music Group, and Warner Music Group.
Other				Rare	Use for formats not otherwise listed
	Betamax		1975	Common?	'Dolby Stereo' cinema surround sound.
	Cartridge		1962	Rare?	4 track (in 1962) / 8 track (in 1965) / Quad 8 track (in 1970) -- Analog, 1/4 inch wide tape, 3 3/4 inches/sec, endless loop cartridge. Quad: 4 Channel Stereo.
		HiPac	1971		Successor of PlayTape. Introduced August 1971 in Japan only. Discontinued 1973.
		PlayTape	1966
	CED		1981	Very Rare	Capacitance Electronic Disc
	DAT		1987	Rare
	DCC		1992	Very Rare	Digital Compact Cassette
	DVDplus		1999	Rare
		DVDplus (CD side)
		DVDplus (DVD-Video side)
		DVDplus (DVD-Audio side)
	Edison Diamond Disc		1912	Rare
	Floppy Disk		1971	Rare?
		3.5" Floppy Disk	1981		double-sided, high-density (HD) "1.44 MB" disks became available 1986
		5.25" Floppy Disk	1976
		Zip Disk	1994		Fell out of favor during the early 2000s
	LaserDisc		1978	Rare?
		8" LaserDisc
		12" LaserDisc
	Music Card			Common?	Card with a digital download code printed on it
	Pathé disc		1905	Rare
	Piano roll		1883	Very Rare	Mechanical digital
	Playbutton		2011	Rare?	Badge with a pin for attaching to clothes officially launched February 2011. Has buttons to control playback (no shuffle though), volume and choosing from 7 preset equalizers. A headphone jack is used for listening and charging the lithium-ion battery. Music is stored in WAV or Ogg Vorbis format on 256MB flash memory disallowing modification or transferring to other media.
	Reel-to-reel		1930s	Rare	Analog; magnetization; "bias" dramatically increases linearity/fidelity
	Tefifon		1936	Rare	Primarily used in Germany in the 1950s. Marketed for a very short time by Western Electric in the US under the name "Westrex". Production discontinued in 1965.
	USB Flash Drive		2004	Common?	2004 was earliest use as a music format
	VHD		1983	Rare
	VHS		197X	Common
	VinylDisc		2007	Rare?	It is made from two fused layers; the silver layer contains the digital information (either in CD or DVD format) and the upper layer has a record groove, meaning it can be played on any record-player.
	Wax Cylinder		1877	Very Rare	Mechanical analog; "hill-and-dale" grooves, vertical stylus motion

(*) Rarity is just a rough indication of availability as consumer products - values are: "Very Rare", "Rare", "Common" and "Widespread".

Other items from the list I'm not sure how to fit in

Name	Date of creation	Rarity	Details	Map to
Wire recording	1898	Rare	Analog; magnetization; no "bias"	Other
4 tracks/8 tracks/multitracks recording	?	Very Rare?	This is not in itself a physical format (may be performed on a variety of equipments, from tape based equipment to digital equipment and hard disks). Likely to be only available in studios, as professional equipments.	Other
Elcaset	1976	Rare	A short lived cassette format.	Cassette
Gramophone record	1895	Common	Mechanical analog; lateral grooves, horizontal stylus motion. The terms LP record (LP, 33, or 33-1/3 rpm record), EP, 16-2/3 rpm record (16), 45 rpm record (45), and 78 rpm record (78) refers to specific types of gramophone records	Vinyl

Partial list of digital audio formats

1985 Audio Interchange File Format (AIFF)
1985 Sound Designer (by Digidesign)
1992 WAVEform (WAV)
1992 Dolby Digital surround cinema sound (AC-3)
1992 Adaptive Transform Acoustic Coding (ATRAC)
1993 MPEG-1 Audio Layer II (MP2)
1993 Digital Theatre System (DTS)
1993 Sony Dynamic Digital Sound (SDDS)
1995 MP3
1999 Windows Media Audio (WMA)
1999 The True Audio Lossless Codec (TTA)
2000 Free Lossless Audio Codec (FLAC)
2001 Advanced audio coding (AAC)
2002 Ogg Vorbis
2004 Apple Lossless (ALE or ALAC)
2012 Opus

More information

The original ticket that led to our implementation is 2565
Mailing list discussion is here
Wikipedia has a list of Audio Formats
https://musicbrainz.org/statistics/formats -- How many of each format are used, with links to lists of them.