Intel High Definition Audio

Intel High Definition Audio (also called HD Audio or Azalia) is a specification for the audio sub-system of personal computers. It was released by Intel in 2004 as successor to their AC'97 PC audio standard. During development it had the codename "Azalia".

Features of the specification include:

However, as of 2008^[update], most audio hardware manufacturers did not implement the full specification, especially 32-bit sampling resolution.

Microsoft Windows XP SP3 and later Windows versions include a Universal Audio Architecture (UAA) class driver which supports audio devices built to the HD Audio specification. There are UAA drivers for Windows 2000 and Windows XP SP2 as well. OS X has full support with its AppleHDA driver. Linux also supports HD Audio controllers, as do the OpenSolaris,FreeBSD,NetBSD and OpenBSD operating systems.

Like AC'97, HD Audio is a specification that defines the architecture, link frame format, and programming interfaces used by the controller on the PCI bus and by the codec on the other side of the link. Implementations of the host controller are available from at least Intel, Nvidia, and AMD. Codecs which can be used with such controllers are available from many companies, including Realtek,Conexant (which bought out Analog Devices' SoundMAX division),Integrated Device Technology (IDT) (acquired from SigmaTel), VIA, Wolfson Microelectronics, and formerly C-Media.

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