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
Around 1976, Philips and Sony showed prototypes of digital audio disc players, which were based on optical videodisc technology. In the interview by Tekla Perry for the IEEE Spectrum, May 2017, Immink explains that he got involved in the CD project at the end of 1979 when Sony and Philips had decided to jointly settle one design. Both Philips and Sony had shown prototype CD players to the press in 1978. The team at Philips, he says, "needed someone to do measurements of the two competing systems, the quality, how they coped with scratches, how they coped with imperfections of the disc. My job with the LaserDisc was finished, so I said, 'Sure, I could do it.'" Both Philips and Sony had come up with different rules for translating digital audio data to sequences of pits and lands. After a lot of experimentation, Immink improved the playing time by thirty percent by inventing a code that could better cope with the servo systems. The encoding system Immink devised came to be called Eight-to-fourteen modulation (EFM).