hda

Hda commonly refers to High Definition Audio, a computer audio standard developed by Intel as Azalia and introduced in the mid-2000s to replace the older AC’97 specification. It defines both a hardware interface and a software model that enable a motherboard host controller to connect to an audio codec, providing higher fidelity, more channels, and advanced features for PC audio.

The architecture centers on a host controller, typically built into the chipset or system-on-chip, that communicates with a codec through a bidirectional digital interface. The codec handles the analog front end—converting microphone signals to digital data and digital audio to line-level and headphone outputs. HD Audio supports multiple channels (commonly 2 to 8) and can operate at sample rates up to 192 kHz with 24-bit resolution. A key feature is jack sensing and retasking, which allows the same physical jack to be reassigned for different functions (for example, microphone, line-out, or headphone) and supports dynamic power management to reduce energy use when audio devices are idle.

Software support is broad and multiplatform, with drivers available for Windows, Linux, and macOS. In Linux, HD Audio is managed through the ALSA and ASoC subsystems, while Windows provides native drivers and vendor-specific enhancements. Real-world implementations are common on consumer desktops and laptops, with codec manufacturers such as Realtek delivering the practical components that realize the HD Audio interface on most motherboards.

HD Audio marked a shift toward more flexible, higher-quality integrated audio in personal computers, complementing advances in multi-channel playback, headset and microphone support, and power-efficient operation.