Compact disc
Compact disc (CD) is a digital optical disc data storage format that was co-developed by Philips and Sony and released in 1982. The format was originally developed to store and play only sound recordings (CD-DA) but was later adapted for storage of data (CD-ROM). Several other formats were further derived from these, including write-once audio and data storage (CD-R), rewritable media (CD-RW), Video Compact Disc (VCD), Super Video Compact Disc (SVCD), Photo CD, PictureCD, CD-i, and Enhanced Music CD. The first commercially available audio CD player, the Sony CDP-101, was released October 1982 in Japan.
Kees Schouhamer Immink
After the CD standard was set in 1980, Immink and his co-workers conducted pioneering experiments with magneto-optical audio recording on pre-grooved discs. They also found a simple method to extend the analog videodisc standard with digital sound. The new systems were brought to market as MiniDisc and CD Video. Laserdisc’s fabricated after 1984 have digitally encoded sound signals.