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What you should know about audio format


What you should know about audio format

An audio format is a medium for storing sound and music. 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.

Music is recorded and distributed using a variety of audio formats, some of which store additional information.

Timeline of audio format developments

1877 Phonograph cylinder
Mechanical analog; "hill-and-dale" grooves, vertical stylus motion

1883 Music roll
Mechanical digital (automated musical instruments)

1895 Gramophone record
Mechanical analog; lateral grooves, horizontal stylus motion

1898 Wire recording
Analog; magnetization; no "bias"

1925 Electrical cut record
Mechanical analog; electrically cut from amplified microphone signal, lateral grooves, horizontal stylus motion, discs at 7", 10", 12", most at 78 rpm

1930s Reel-to-Reel, Magnetic Tape
Analog; magnetization; "bias" dramatically increases linearity/fidelity, tape speed at 30 ips, later 15 ips with NAB equalization; refined speeds: 7½ ips, 3¾ ips, 1⅞ ips Electrical transcriptions Mechanical analog; electrically cut from amplified microphone signal, high fidelity sound, lateral or vertical grooves, horizontal or vertical stylus motion, most discs 16" at 33⅓ rpm

1948 Vinyl Record
Analog, with preemphasis and other equalization techniques (LP, RIAA); lateral grooves, horizontal stylus motion; discs at 7" (most 45 rpm), 10" and 12" (most 33⅓ rpm)

1957 Stereophonic Vinyl Record
Analog, with preemphasis and other equalization techniques. Combination lateral/vertical stylus motion with each channel encoded 45 degrees to the vertical.

1962 4-Track (Stereo-Pak)
Analog, 1⁄4-inch-wide (6.4 mm) tape, 3¾ in/s, endless loop cartridge.

1963 Compact Cassette
Analog, with bias, preemphasis, 0.15-inch-wide (3.8 mm) tape, 1⅞ in/s. 1970: introduced Dolby noise reduction.

1965 8-Track (Stereo-8)
Analog, ¼ inch wide tape, 3¾ in/s, endless loop cartridge.

1969 Microcassette
Analog, ⅛ inch wide tape, used generally for notetaking, mostly mono, some stereo. 2.4 cm/s or 1.2 cm/s.

1969 Minicassette
Analog, ⅛ inch wide tape, used generally for notetaking, 1.2 cm/s

1970 Quadraphonic 8-Track (Quad-8) (Q8)
Analog, ¼ inch wide tape, 3¾ in/s, 4 Channel Stereo, endless loop cartridge.

1971 Quadraphonic Vinyl Record (CD-4) (SQ Matrix)
Analog.

1975 Betamax
Digital Audio Dolby Stereo cinema surround sound

1976 Elcaset
Analog.

1978 Laserdisc
Digital.

1982 Compact Disc (CD-DA)
Digital. PCM

1985
Audio Interchange File Format (AIFF)

1985
Sound Designer (by Digidesign)

1986 High Definition Compatible Digital (HDCD)
Digital. Redbook compatible physical CD containing 20–24 bit information.

1987 Digital Audio Tape (DAT)
Digital.

1991 MiniDisc (MD)
Digital. Adaptive Transform Acoustic Coding (ATRAC)

1992 Digital Compact Cassette (DCC)
Digital, WAVEform (WAV), Dolby Digital surround cinema sound

1993
Digital Theatre System (DTS), Sony Dynamic Digital Sound (SDDS), MPEG-1 Audio Layer III

1997 DVD
Dolby Digital

1997 DTS-CD
DTS Audio

1997 Super Audio CD (SACD)
Direct Stream Digital
Windows Media Audio (WMA)
The True Audio Lossless Codec (TTA)

2000
Free Lossless Audio Codec (FLAC)

2001
Advanced audio coding (AAC)

2002
Ogg Vorbis

2003 DualDisc
Digital.

2004
Apple Lossless (ALE or ALAC)

2005 HD DVD
Dolby TrueHD, DTS-HD Master Audio
OggPCM

2006 Blu-ray Disc
Dolby TrueHD, DTS-HD Master Audio

2008 slotMusic
320kb/s MP3 on microSD or microSDHC


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