HD audio - technical definition

(1) See also HD Radio.

(2) (High Definition audio) The latest digital audio formats supported by Blu-ray, such as Dolby Digital Plus, Dolby TrueHD and DTS-HD (see Dolby Digital and DTS).

The term may occasionally refer to DVD-Audio and SACD, both of which are audio-only, high-resolution formats with limited success in the market (see DVD-Audio and SACD).

(3) (High Definition Audio) A specification for building audio and modem functions on a PC motherboard. Introduced in 2004 by Intel and superseding AC'97, HD Audio provides 32-bit, 192kHz audio with eight channels (7.1), enabling it to support DVD-A and Dolby Digital and DTS multichannel surround formats. It supports a 16-element array microphone and automatic jack retasking, the latter enabling both a speaker or microphone to be plugged into the same port. HD Audio also supports multiple, independent audio streams for sending audio to different rooms in the house.

Controller and Codec
Like AC'97, HD Audio is made up of a controller connected to analog/digital codecs by a 5-wire TDM interface called "HD Audio Link." The two subsystems separate the digital controller, which is built into the PC chipset, from the analog circuits, which can be in a chip on the motherboard, a riser card or cabled close to the I/O connectors.

For international certification (homologation), modem codecs are often placed on riser cards, which can be easily interchanged. See AC'97 and riser card.