Intel High Definition Audio (IHDA) (also called HD Audio or development codename Azalia) is a specification for the audio sub-system of

personal computer A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or te ...

s. It was released by

Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the developers of the x86 ser ...

in 2004 as the successor to their

AC'97 AC'97 (''Audio Codec '97;'' also MC'97 for ''Modem Codec '97'') is an audio codec standard developed by Intel Architecture Labs in 1997. The standard was used in motherboards, modems, and sound cards. The specification covers two types of compo ...

audio Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to: Sound *Audio signal, an electrical representation of sound *Audio frequency, a frequency in the audio spectrum * Digital audio, representation of sou ...

standard.

Features

The Intel High Definition Audio specification includes the following features: * Up to 15

input Input may refer to: Computing * Input (computer science), the act of entering data into a computer or data processing system * Information, any data entered into a computer or data processing system * Input device * Input method * Input port (disa ...

and 15 output streams * Up to 16

PCM Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals. It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications. In a PCM stream, the am ...

audio channels per stream * Sample resolutions of 8–32 bits * Sample rates of 6–192 kHz * Support for audio

codec A codec is a device or computer program that encodes or decodes a data stream or signal. ''Codec'' is a portmanteau of coder/decoder. In electronic communications, an endec is a device that acts as both an encoder and a decoder on a signal or ...

s (e.g., ADC, DAC),

modem A modulator-demodulator or modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by modulating one or more c ...

codecs, and vendor-defined codecs * Discoverable codec architecture * Fine-grained codec power-control *

Audio jack A phone connector, also known as phone jack, audio jack, headphone jack or jack plug, is a family of electrical connectors typically used for analog audio signals. A plug, the male connector, is inserted into the jack, the female connect ...

detection, sensing, and retasking

Motherboard A motherboard (also called mainboard, main circuit board, mb, mboard, backplane board, base board, system board, logic board (only in Apple computers) or mobo) is the main printed circuit board (PCB) in general-purpose computers and other expand ...

s typically do not have any more than eight built-in output channels (7.1 surround sound) and four input channels (back and front panel microphone inputs, and a back-panel stereo line-in). Users requiring more audio I/Os will typically opt for a

sound card A sound card (also known as an audio card) is an internal expansion card that provides input and output of audio signals to and from a computer under the control of computer programs. The term ''sound card'' is also applied to external audio ...

or an external

audio interface An audio interface is a piece of computer hardware that allows the input and output of audio signals to and from a host computer or recording device. Audio interfaces are closely related to computer sound cards, but whereas sound cards are opti ...

, as these provide additional features that are more oriented towards professional audio applications.

Operating system support

The Service Pack 3 update to

Windows XP Windows XP is a major release of Microsoft's Windows NT operating system. It was release to manufacturing, released to manufacturing on August 24, 2001, and later to retail on October 25, 2001. It is a direct upgrade to its predecessors, Wind ...

and all later versions of Windows included the Universal Audio Architecture (UAA) class driver, which supported audio devices built to HD Audio's specifications. Retrospective UAA drivers were also built for

Windows 2000 Windows 2000 is a major release of the Windows NT operating system developed by Microsoft and oriented towards businesses. It was the direct successor to Windows NT 4.0, and was released to manufacturing on December 15, 1999, and was offici ...

and XP Service Pack 2.

macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and la ...

provides support for Intel HD Audio with its AppleHDA driver. Several

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, whi ...

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...

s also support HD Audio, as well as

OpenSolaris OpenSolaris () is a discontinued open-source computer operating system based on Solaris and created by Sun Microsystems. It was also, perhaps confusingly, the name of a project initiated by Sun to build a developer and user community around t ...

FreeBSD FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular ...

, and

OpenBSD OpenBSD is a security-focused, free and open-source, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by forking NetBSD 1.0. According to the website, the OpenBSD project e ...

Host controller

Like AC'97, HD Audio acts as a device driver, defining the

architecture Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and constructing buildings ...

, link frame format, and

programming interface An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how ...

s used in the hardware of the host controller of the

PCI bus PCI may refer to: Business and economics * Payment card industry, businesses associated with debit, credit, and other payment cards ** Payment Card Industry Data Security Standard, a set of security requirements for credit card processors * Prov ...

and linking it to a codec used by a computer's software. Configurations of the host controller (Chipset) are available from third-party suppliers, including

Nvidia Nvidia CorporationOfficially written as NVIDIA and stylized in its logo as VIDIA with the lowercase "n" the same height as the uppercase "VIDIA"; formerly stylized as VIDIA with a large italicized lowercase "n" on products from the mid 1990s to ...

VIA Via or VIA may refer to the following: Science and technology * MOS Technology 6522, Versatile Interface Adapter * ''Via'' (moth), a genus of moths in the family Noctuidae * Via (electronics), a through-connection * VIA Technologies, a Taiwa ...

and AMD, while codecs have also been provided by third-party suppliers including

Realtek Realtek Semiconductor Corp () is a fabless semiconductor company situated in the Hsinchu Science Park, Hsinchu, Taiwan. Realtek was founded in October 1987 and subsequently listed on the Taiwan Stock Exchange in 1998. Realtek currently manufa ...

Conexant Conexant Systems, Inc. was an American-based software developer and fabless semiconductor company that developed technology for voice and audio processing, imaging and modems. The company began as a division of Rockwell International, before b ...

, IDT,

, SigmaTel,

Analog Devices Analog Devices, Inc. (ADI), also known simply as Analog, is an American multinational semiconductor company specializing in data conversion, signal processing and power management technology, headquartered in Wilmington, Massachusetts. The ...

and

Cirrus Logic Cirrus Logic Inc. is an American fabless semiconductor supplier that specializes in analog, mixed-signal, and audio DSP integrated circuits (ICs). Since 1998, the company's headquarters have been in Austin, Texas. The company's audio process ...

. AMD's

TRX40 This is an overview of chipsets sold under the AMD brand, manufactured before May 2004 by the company itself, before the adoption of open platform approach as well as chipsets manufactured by ATI Technologies after October 2006 as the completion ...

chipset was introduced in 2019 for use with

Ryzen Ryzen ( ) is a brand of multi-core x86-64 microprocessors designed and marketed by AMD for desktop, mobile, server, and embedded platforms based on the Zen microarchitecture. It consists of central processing units (CPUs) marketed for mainst ...

"Threadripper"

CPU A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, a ...

s, which provided the Realtek ALC1220 chip instead of the HD Audio interface. As a result, a separate USB or

PCIe PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe or PCI-e, is a high-speed serial computer expansion bus standard, designed to replace the older PCI, PCI-X and AGP bus standards. It is the common ...

audio device was required to integrate HD audio codecs on TRX40 motherboards.

Limitations

As with the previous AC'97 standard, HD Audio does not specify handlers for the media buttons attached to headphone

jack Jack may refer to: Places * Jack, Alabama, US, an unincorporated community * Jack, Missouri, US, an unincorporated community * Jack County, Texas, a county in Texas, USA People and fictional characters * Jack (given name), a male given name, ...

s (i.e., Play/Pause, Next, Previous, Volume up, Volume down).

Front panel connector

Computer motherboards often provide a connector to bring microphone and headphone signals to the computer's

front panel A front panel was used on early electronic computers to display and allow the alteration of the state of the machine's internal registers and memory. The front panel usually consisted of arrays of indicator lamps, digit and symbol displays, t ...

. Intel provides a general specification for this process, but the signal assignments are different for both AC'97 and HD Audio headers. The pin assignments for the AC'97 and HD Audio connectors are: The HD Audio 3.5 mm subminiature audio jack differed from connectors used in the AC'97 specification and in general audio equipment. The AC'97 used a regular 3.5 mm audio jack, which typically has 5 pins: one pin for ground, two pins for stereo signal, and two pins for the return signal. When no plug is connected, the two stereo signals are connected to their return pins. When a plug is inserted, the stereo signals contact the respective channels on the plug and are disconnected from the jack's return pins. The HD Audio 3.5 mm jack does not have the two return audio signals; instead, it has an isolated switch that senses the presence of a plug in the jack. In the AC'97 design, the audio output is sent to the jack by default. When a headphone is detected, the return signal pins for the speakers are disconnected, directing the audio to the headphone. The jack redirects the audio to the speakers if no headphone connection is detected. Similarly, the return pins ground the microphone jack connection if no microphone detected. As a result, most motherboards with AC'97 audio require two

jumper Jumper or Jumpers may refer to: Clothing *Jumper (sweater), a long-sleeve article of clothing; also called a top, pullover, or sweater **A waist-length top garment of dense wool, part of the Royal Navy uniform and the Uniforms of the United State ...

s to short these pins if no front panel audio module is connected, so audio passes to the speakers. In the HD Audio design, the codec sends the audio directly to the speakers if a plug is not inserted. When a plug is inserted, the isolated switch inside the jack informs the motherboard, and the codec sends audio to the headphones. A similar isolated switch is used to detect when a microphone has been plugged in. HD Audio can also sense the presence of an audio

dongle A dongle is a small piece of computer hardware that connects to a port on another device to provide it with additional functionality, or enable a pass-through to such a device that adds functionality. In computing, the term was initially synonym ...

. A 10 kΩ pull-up resistor is attached to pin 4 (). When the HDA dongle is plugged in, it pulls pin 4 to the ground with a 1 kΩ resistor. The motherboard can determine if a dongle is connected by examining the logic level on pin 4. If the motherboard does not detect a HDA dongle, it should ignore the (pin 6) and (pin 10) signals. Intel warns that HDA dongles should be used with HDA motherboards: The different signal assignments can cause trouble when AC'97 front-panel dongles are used with HDA motherboards and vice versa. An AC'97 dongle returns audio on pins 6 and 10 rather than digital plug sensing signals. Consequently, a loud audio passage may cause a HDA motherboard with a AC'97 dongle believe headphones and microphones are being plugged and unplugged hundreds of times per second. An AC'97 motherboard with an HDA dongle will route the AC'97 5 V audio supply (pin 7; silence) to the speakers instead of the desired left and right audio signals. To avoid this, some motherboards allow choosing between HDA and AC'97 front panels in the BIOS. Even though the actual audio hardware is HD Audio, the BIOS can be manipulated to allow the use of an AC'97 front panel. Likewise, some modern enclosures have both an "AC'97" and an "HDA" plug at the end of the front-panel audio cable.

References

External links

* https://web.archive.org/web/20121202194339/http://www.intel.com/design/chipsets/hdaudio.htm * https://web.archive.org/web/20110310072114/http://www.intel.com/standards/hdaudio
High Definition Audio Specification
1.0a (June 17, 2010)

{{PC sound standards Computer hardware standards High Definition Audio Sound cards