Intel High Definition Audio (IHDA) (also called HD Audio or development codename Azalia) is a specification for the audio sub-system of personal computers. It was released by Intel in 2004 as the successor to their AC'97 PC audio standard.[1]
Motherboards 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 or an external audio interface, as these provide additional features that are more oriented towards professional audio applications.
Like AC'97, HD Audio acts as a device driver, defining the architecture, link frame format, and programming interfaces used in the hardware of the host controller of the PCI bus and linking it to a codec used by a computer's software.[7] Configurations of the host controller (Chipset) are available from third-party suppliers, including Nvidia, VIA and AMD,[7] while codecs have also been provided by third-party suppliers including Realtek, Conexant, IDT, VIA, SigmaTel, Analog Devices and Cirrus Logic.[8][9] AMD's TRX40 chipset was introduced in 2019 for use with Ryzen "Threadripper" CPUs, which provided the Realtek ALC1220 chip instead of the HD Audio interface. As a result, a separate USB or PCIe audio device was required to integrate HD audio codecs on TRX40 motherboards.[10]
Limitations
As with the previous AC'97 standard, HD Audio does not specify handlers for the media buttons attached to headphone jacks (i.e., Play/Pause, Next, Previous, Volume up, Volume down).[citation needed]
Front panel connector
Computer motherboards often provide a connector to bring microphone and headphone signals to the computer's front panel. Intel provides a general specification for this process, but the signal assignments are different for both AC'97 and HD Audio headers.[11]
The pin assignments for the AC'97 and HD Audio connectors are:[11]: 21, 22
Pin
AC'97
HD Audio (HDA)
Signal
Description
Signal
Description
1
MIC
Audio, mono, in (mic. level)
Audio, left, in (biased, mic.level)
PORT 1L
Audio, left, port 1
2
AUD_GND
Ground
GND
Ground
3
MIC BIAS
Microphone bias
Audio, right, in (biased, mic. level)
PORT 1R
Audio, right, port 1
4
AUD_GND
Ground
PRESENCE#
HDA dongle/connector detection, active low
5
FP_OUT_R
Audio out, right, out (headphone-level capable), front panel
PORT 2R
Audio, right, port 2
6
FP_RETURN_R
Audio, right, return (when jack is unconnected), front panel
SENSE1_RETURN
Port 1 jack detection
7
AUD_5V
Power, +5 V
SENSE_SEND
Jack detection sense, resistance multiplexed
8
KEY
Not present, physical key
KEY
Not present, physical key
9
FP_OUT_L
Audio, left, out (headphone-level capable), front panel
PORT 2L
Audio, left, port 2
10
FP_RETURN_L
Audio, left, return (when jack is unconnected), front panel
SENSE2_RETURN
Port 2 jack detection
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.[11]: 20 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.[11]: 25
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 jumpers to short these pins if no front panel audio module is connected, so audio passes to the speakers.[11]: 21
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 10 kΩ pull-up resistor is attached to pin 4 (PRESENCE#). 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 SENSE1_RETURN (pin 6) and SENSE2_RETURN (pin 10) signals.[11]: 24
Intel warns that HDA dongles should be used with HDA motherboards:[11]: 19
It is strongly recommended that motherboard designers only use Intel HD Audio analog front panel dongles with the Intel HD Audio analog front panel header to ensure that the jack detection and dynamic retasking capability are preserved. Passive AC'97 analog front panel dongles (ones that leave the 5V Analog pin-7 line unconnected on the dongle) may be used with the Intel HD Audio analog front panel header. But note that the front panel jack detection and re-tasking functionality will be lost as the AC'97 jacks cannot support connection to the SENSE line. In addition, software must be aware that an AC'97 dongle is being used with an Intel HD Audio analog header since the software might need to dedicate codec ports that are connected to the header to meet the product's intended functionality.
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.[citation needed]
^"Universal Audio Architecture (UAA) High Definition Audio class driver version 1.0a available for Windows XP, Windows Server 2003, and Windows 2000". Microsoft. Retrieved September 19, 2022.
^. OpenSolaris. Archived from the original on April 26, 2008. Retrieved September 19, 2022.
^"Intel High Definition Audio bridge device driver". FreeBSD. January 25, 2012. Retrieved September 19, 2022.
^"Azalia — Generic High Definition Audio device". OpenBSD. March 15, 2012. Retrieved September 19, 2022.
Developer Education Resource: High Definition Audio for the Digital Home
January 12, 2023
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For the marketing term HD audio see High resolution audio Intel High Definition Audio IHDA also called HD Audio or development codename Azalia is a specification for the audio sub system of personal computers It was released by Intel in 2004 as the successor to their AC 97 PC audio standard 1 Realtek ALC 882 HD Audio Codec Contents 1 Features 2 Operating system support 3 Host controller 4 Limitations 5 Front panel connector 6 See also 7 References 8 External linksFeatures EditThe Intel High Definition Audio specification includes the following features 2 Up to 15 input and 15 output streams Up to 16 PCM audio channels per stream Sample resolutions of 8 32 bits Sample rates of 6 192 kHz Support for audio codecs e g ADC DAC modem codecs and vendor defined codecs Discoverable codec architecture Fine grained codec power control Audio jack detection sensing and retaskingMotherboards 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 or an external audio interface as these provide additional features that are more oriented towards professional audio applications Operating system support EditThe Service Pack 3 update to Windows XP 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 and XP Service Pack 2 3 macOS provides support for Intel HD Audio with its AppleHDA driver Several Linux operating systems also support HD Audio as well as OpenSolaris 4 FreeBSD 5 and OpenBSD 6 Host controller EditLike AC 97 HD Audio acts as a device driver defining the architecture link frame format and programming interfaces used in the hardware of the host controller of the PCI bus and linking it to a codec used by a computer s software 7 Configurations of the host controller Chipset are available from third party suppliers including Nvidia VIA and AMD 7 while codecs have also been provided by third party suppliers including Realtek Conexant IDT VIA SigmaTel Analog Devices and Cirrus Logic 8 9 AMD s TRX40 chipset was introduced in 2019 for use with Ryzen Threadripper CPUs which provided the Realtek ALC1220 chip instead of the HD Audio interface As a result a separate USB or PCIe audio device was required to integrate HD audio codecs on TRX40 motherboards 10 Limitations EditAs with the previous AC 97 standard HD Audio does not specify handlers for the media buttons attached to headphone jacks i e Play Pause Next Previous Volume up Volume down citation needed Front panel connector EditComputer motherboards often provide a connector to bring microphone and headphone signals to the computer s front panel Intel provides a general specification for this process but the signal assignments are different for both AC 97 and HD Audio headers 11 The pin assignments for the AC 97 and HD Audio connectors are 11 21 22 Pin AC 97 HD Audio HDA Signal Description Signal Description1 MIC Audio mono in mic level Audio left in biased mic level PORT 1L Audio left port 12 AUD GND Ground GND Ground3 MIC BIAS Microphone biasAudio right in biased mic level PORT 1R Audio right port 14 AUD GND Ground PRESENCE HDA dongle connector detection active low5 FP OUT R Audio out right out headphone level capable front panel PORT 2R Audio right port 26 FP RETURN R Audio right return when jack is unconnected front panel SENSE1 RETURN Port 1 jack detection7 AUD 5V Power 5 V SENSE SEND Jack detection sense resistance multiplexed8 KEY Not present physical key KEY Not present physical key9 FP OUT L Audio left out headphone level capable front panel PORT 2L Audio left port 210 FP RETURN L Audio left return when jack is unconnected front panel SENSE2 RETURN Port 2 jack detectionThe 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 11 20 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 11 25 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 jumpers to short these pins if no front panel audio module is connected so audio passes to the speakers 11 21 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 10 kW pull up resistor is attached to pin 4 PRESENCE When the HDA dongle is plugged in it pulls pin 4 to the ground with a 1 kW 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 SENSE1 RETURN pin 6 and SENSE2 RETURN pin 10 signals 11 24 Intel warns that HDA dongles should be used with HDA motherboards 11 19 It is strongly recommended that motherboard designers only use Intel HD Audio analog front panel dongles with the Intel HD Audio analog front panel header to ensure that the jack detection and dynamic retasking capability are preserved Passive AC 97 analog front panel dongles ones that leave the 5V Analog pin 7 line unconnected on the dongle may be used with the Intel HD Audio analog front panel header But note that the front panel jack detection and re tasking functionality will be lost as the AC 97 jacks cannot support connection to the SENSE line In addition software must be aware that an AC 97 dongle is being used with an Intel HD Audio analog header since the software might need to dedicate codec ports that are connected to the header to meet the product s intended functionality 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 citation needed See also EditSound chipReferences Edit Smith Tony 16 April 2004 Intel completes hi def audio spec The Register Retrieved 14 January 2014 High Definition Audio Specification 1 0a PDF Intel Corporation 2010 p 17 Universal Audio Architecture UAA High Definition Audio class driver version 1 0a available for Windows XP Windows Server 2003 and Windows 2000 Microsoft Retrieved September 19 2022 Open Sound System at OpenSolaris org OpenSolaris Archived from the original on April 26 2008 Retrieved September 19 2022 Intel High Definition Audio bridge device driver FreeBSD January 25 2012 Retrieved September 19 2022 Azalia Generic High Definition Audio device OpenBSD March 15 2012 Retrieved September 19 2022 a b AMD SB600 Product Information Page Advanced Micro Devices Retrieved September 19 2022 ALC888 7 1 2 Channel High Definition Audio Codec Realtek Archived from the original on April 25 2007 Retrieved September 22 2022 Conexant PC HD Audio Conexant Archived from the original on August 19 2013 Retrieved September 22 2022 Bonshor Gavin November 28 2019 The AMD TRX40 Motherboard Overview 12 New Motherboards Analyzed AnandTech Retrieved September 22 2022 a b c d e f g Intel Corporation February 2005 Front Panel I O Connectivity Design Guide PDF Version 1 3 pp 19 25 archived from the original PDF on 2011 05 11 retrieved 2011 11 04External links Edithttps 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 Motherboard Sound cards connectors pinout specifications Developer Education Resource High Definition Audio for the Digital Home Retrieved from https en wikipedia org w index php title Intel High Definition Audio amp oldid 1119126938, wikipedia, wiki, book, books, library,
