Laserdisc technology, using a transparent disc, was invented by David Paul Gregg in 1958 (and patented in 1961 and 1969). By 1969 Philips had developed a videodisc in reflective mode, which has great advantages over the transparent mode. MCA and Philips decided to join their efforts. They first publicly demonstrated the videodisc in 1972. LD was first available on the market, in Atlanta, on December 15, 1978, two years after the VHS VCR and five years before the CD, which is based on laserdisc technology. Philips produced the players and MCA the discs. The Philips/MCA cooperation was not successful, and discontinued after a few years. Several of the scientists responsible for the early research (Richard Wilkinson, Ray Deakin, and John Winslow) founded Optical Disc Corporation (now ODC Nimbus), and that company is still the world leader in optical disc mastering technology.