An audio format is a medium for sound recording and reproduction. The term is applied to both the physical recording media and the recording formats of the audio content—in computer science it is often limited to the audio file format, but its wider use usually refers to the physical method used to store the data. Note on the use of analog compared to digital in this list; the definition of digital used here for early formats is that which is represented using discrete values rather than fluctuating variables. A piano roll is digital as it has discrete values, that being a hole for each key, unlike a phonograph record which is analog with a fluctuating groove.
Music is recorded and distributed using a variety of audio formats, some of which store additional information.
Earliest device known to record sound, invented by Édouard-Léon Scott de Martinville. While this device was capable of recording sound waves, they couldn't be played back.
Analog, the Ediphone and subsequent wax cylinders used in Edison's other product lines continued to be sold up until 1929 when the Edison Manufacturing Company folded.
Mechanical analog; vertical groove, vertical stylus motion - made from Bakelite or china clay
Blue Amberol cylinder record
Mechanical analog; vertical groove, vertical stylus motion - made from blue celluloid with plaster of paris core - 160rpm standard - 200 threads per inch
Analog; magnetization; AC "bias" dramatically increases linearity/fidelity, tape speed at 30 ips, later 15 ips and other refined speeds: 7+1⁄2 ips, 3+3⁄4 ips, 1+7⁄8 ips
Mechanical analog; electrically cut from amplified microphone signal, high fidelity sound, lateral or vertical groove, horizontal or vertical stylus motion, most discs 16" at 33+1⁄3 rpm
Analog, medium consisting of a thin, plastic belt 3.5" wide that was placed on a cylinder and rotated like a tank tread, developed by the Dictaphone company in 1947
Analog, with preemphasis and other equalization techniques (LP, RIAA); lateral groove, horizontal stylus motion; discs 7", 10" and 12" at 33+1⁄3 rpm, 1st LP Columbia ML 4001 Milstein, Mendelssohn Violin Concerto
Electro–mechanical analog, vinyl belt housed in a cassette, used an embossing technique using a stylus to imprint the information, was the first thing to resemble a modern audio cassette
Analog, with pre-emphasis and other equalization techniques. Combination lateral/vertical stylus motion with each channel encoded 45 degrees to the vertical
Dictet
Analog, 1⁄4 tape, 2.48 in/s, (3" reels housed 5.875 × 3 × .4375 inch cassette), developed by the Dictaphone Corp
Analog, 1⁄4 inch wide tape (stereo & mono), 3+3⁄4 in/s & 1.875 in/s, one of the first attempts to offer reel-to-reel tape recording quality in a convenient format for the consumer market
Analog, 1⁄4 inch wide tape in cartridge, 7+1⁄2 in/s & 15 in/s, Introduced in 1959 by Collins Radio, the cart tape format was designed for use by radio broadcasters to play commercials, bumpers and announcements
1⁄4 inch wide tape housed in a transparent cartridge measuring 2.6 × 2.9 × 1.9 inches, tape was stored on two reels residing atop one another, keeping the cartridge compact
A cartridge format for embedding and easy handling usual 3-inch-tape-reels with 1⁄4 inch tape, compatible to reel-to-reel audio recording in 3+3⁄4 ips.
This audio format famously caused controversy among recording companies when released due to the potential of perfect digital copies to increase piracy[2]
Digital, 1⁄8 inch wide tape, 1+7⁄8 in/s, introduced by Philips and Matsushita in late 1992, marketed as the successor to the standard analog compact cassette
^Demetris, Jordan (1990-01-01). "The challenge of introducing digital audio tape technology into consumer markets". Technology in Society. 12 (1): 91–100. doi:10.1016/0160-791X(90)90031-7. ISSN0160-791X.