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. Features The Intel High Definition Audio specification includes the following features: 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 retasking 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. Operating system support The 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, Server 2003 and XP Service Pack 1/2. macOS provides support for Intel HD Audio with its AppleHDA driver. Several Linux operating systems also support HD Audio, as well as OpenSolaris, FreeBSD, and OpenBSD. Host controller 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. Configurations of the host controller (Chipset) are available from third-party suppliers, including Nvidia, VIA and AMD, while codecs have also been provided by third-party suppliers including Realtek, Conexant, IDT, VIA, SigmaTel, Analog Devices and Cirrus Logic. 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. 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). Front panel connector Computer motherboards often provide a connector to bring