HDCD (High Definition Compatible Digital) is a digital encoding and decoding process for compact disc and DVD audio recording. The HDCD process manages to encode 20 bits of audio information into a conventional CD 16-bit channel, yielding a greater dynamic range and a more true-to-life sound when decoded. HDCD was developed by Keith Johnson and Pflash Pflaumer between 1986 and 1991, and made publicly available in 1995. Johnson and Pflaumer went on to found Pacific Microsonics, which was later acquired by Microsoft. Since 1995, more than 5,000 HDCD recordings have been released and more than 175 of those have been nominated for GRAMMY awards. An article in Wired Magazine hailed HDCD technology as "the greatest single advance in digital reproduction to date."
Audio chip manufacturers including Motorola, Sanyo, and Zoran have developed HDCD chips for audio products, such as CD and DVD players and receivers. HDCD-encoded media will play on machines that don't have the chip, and HDCD-equipped machines can play traditionally recorded media. Because the decoder chips include a high-precision digital filter, HDCD-equipped players will improve audio quality for even traditionally recorded CDs and DVDs. Conversely, because of the recording process, HDCD-encoded media will also sound better than traditionally CDs and DVDs on players that don't have the HDCD chip. Nevertheless, the best audio quality is yielded by HDCD-encoded media on an HDCD-equipped player.