High Definition Compatible Digital

HDCD ( High Definition Compatible Digital Short for ) is introduced in 1995 and patent protected technology for coding and decoding of audio data. It was developed between 1986 and 1991 from the audio engineers Keith Johnson and Michael Pflaumer.

The procedure

The method is intended for a higher quality sound with greater wealth of detail and better dynamics of digital audio recordings, especially on CD or DVD, make, thus reducing existing disadvantages, especially conventionally encoded discs according to the developers. The effect of a greater richness of detail is achieved according to the developers, inter alia, that the audio information is no longer as usual encoded with a resolution of 16 bit, but with an equivalent to about 20 bits. This is achieved by control signals are placed on a controller in the HDCD lowest bit of the PCM audio signal. This method is called in-band signaling. The HDCD controller controls an expander and can switch various modes of interpolation.


HDCD - capable devices are something of a rarity on the market for consumers. Therefore, the method has been designed from the outset so that HDCD - encoded audio signals are compatible with conventional display devices. Since the HDCD control signals are designed so that they occupy only the lowest bit, and that the loss of the useful signal when playing on non- HDCD - capable terminals is negligible even for a fraction of the total availability. Therefore, the maximum dynamic range of an HDCD signal is reduced only slightly when played on a non- HDCD - capable terminal. The compressed information signal is modeled using the optional peak - extension of a tape saturation curve so that any distortions are perceived less annoying to non- HDCD - enabled devices, as a conventionally -mastered CD that was overridden in the same volume.

There are CD players with built-in HDCD controller that output a corresponding decoded audio signal via the analog outputs, as well as ( pre-) amplifier with built-in HDCD controllers that the PCM signal on a PDIF or HDMI input can be obtained from any CD player or other source for PCM data. All DVD & BD players can play HDCDs.

The method has so far reached only a small market coverage. Currently are just about 5000 different HDCD -encoded CDs and DVDs will be available. In addition, usually the HDCD recordings appear only from already established and well-known artists.

The future

In September 2000, Microsoft bought the company Pacific Micro Sonics Inc., the Keith Johnson and Michael Pflaumer had founded in 1996 to improve the marketing of the proceedings to. Microsoft was the dissemination of decoder technology due to its market position and to entering into partnerships with handset manufacturers, which licensed the technology to increase. Meanwhile the audio / video receiver, digital -to-analog converter, sound processors, digital pre-amplifier with integrated HDCD decoder can be obtained. Microsoft is using the process in your own Windows Media Player for playback of digital audio formats.

The implementation of the system in recordings remains questionable. The newly developed Super Audio Compact Disc (SACD ) and DVD-Audio, which already have a significantly higher market share than HDCD -encoded CDs, provide even greater wealth of detail. The DVD-Audio and SACD store ( in different data formats ) the higher resolutions used in the production of 24-bit with at least 48 kHz. As it becomes clear that the buyers of high-quality sound recordings produced has turned to these formats (as of 2008), the days of the HDCD process on recordings appear to be numbered.