Laserdisc
The Laserdisc was an optical video disc medium released in 1978 in various countries, but mostly a failure except in Japan. Its laser-read technology was similar to what was later used in more-successful media including the CD and DVD.
Laserdiscs are larger than CDs or DVDs in physical size, but have a lower information density. Three encoding formats were used: CAV (Constant Angular Velocity or Standard Play), supporting 30 minutes of video per side; CLV (Constant Linear Velocity or Extended Play), supporting 60 minutes per side; and CAA (Constant Angular Acceleration), used in later discs. The discs were double-sided, with some players able to play both sides without manual flipping, and others requiring a turnover as with vinyl records.
Laserdiscs were used for computer games and karaoke discs as well as their primary use as a video medium.
