HDCD

(High Definition Compatible Digital) A digital processing technique that increases fidelity on audio CDs, developed by Keith Johnson and Michael "Pflash" Pflaumer. HDCD uses a 20-bit master instead of 16 bits and stores the additional data in a subchannel that is processed on HDCD-equipped players. The format remains compatible with the traditional audio CD, and non-HDCD players can play HDCD discs as if they were regular CDs. Because HDCD players have a higher quality digital filter, regular CDs may sound better.

Sold to Microsoft
Johnson, a recording engineer, and Pflaumer, inventor of the local area network TOPS, founded Pacific Microsonics, Inc. in 1996 to license the HDCD technology. In 2000, Microsoft acquired PMI to boost its strength in digital media, and the HDCD codec was later added to Windows Media Player, making it the first software player to support it. There are thousands of HDCD titles and numerous HDCD CD players on the market.