Windows Audio Architecture

This topic provided a high level summary of the Windows 10/11 audio architecture.

Windows 10/11 Audio Stack Diagram

This diagram provides a summary of the major elements of the Windows 10/11 audio stack.

APIs

Top level APIs

The top level APIs are used for application development. These APIs are in currently in use and supported.

• XAML MediaElement class(C#, VB, C++)
• HTML Audio object and Video object<tags> (used by websites and Windows Web Apps)
• Windows.Media.Capture namespace (C#, VB, C++)
• Microsoft Media Foundation (C++)

These older APIs are deprecated.

• DirectShow
• DirectSound
• PlaySound
• Windows.Media.MediaControl

Low level APIs

These lower level APIs are recommended for audio streaming.

• WASAPI (High performance, but more complicated)
• IXAudio2 (Typically used for games)
• MIDI

This lower level API is recommended for enumeration.

• Windows.Devices.Enumeration

These APIs are not recommended for Windows applications.

• About MMDevice API (replaced by Windows.Devices.Enumeration)
• DeviceTopology API
• EndpointVolume API

Audio Engine

The audio engine consists of two related components, the Audio Device Graph (audiodg.exe), which loads the Audio Engine (audioeng.dll).

The audio engine:

• Mixes and processes audio streams. For more information about how the audio engine uses buffers to transfer audio, see Understanding the WaveRT Port Driver.
• Loads Audio Processing Objects (APOs), which are H/W-specific plugins that process the audio signal. For more information about APOs, see Windows Audio Processing Objects.

Audio Service (audiosrv.dll)

The audio service:

• Is used to setup and control audio streams.
• Implements Windows policies for background audio playback, ducking, etc.

Audio Endpoint Builder (audioendpointbuilder.exe)

The Audio Endpoint Builder (audioendpointbuilder.exe):

• Is used to discover new audio devices and create software audio endpoints. For more information about the algorithm that is used, see Audio Endpoint Builder Algorithm.

Audio Drivers

Audio drivers:

• Follow the port-miniport model. For more information, see WDM Audio Terminology and Developing a WaveRT Miniport Driver.
• Allow the audio stack to render and capture audio from several audio devices, including: integrated speakers and microphones, headsets/headphones, USB devices, Bluetooth devices, HDMI, etc.
• The port-miniport model corresponds to the Advanced Linux Sound Architecture ALSA
• For information on sample driver code, see Sample Audio Drivers.

Hardware

The audio hardware that is present on any given device varies but can include:

• Audio Codec
• DSP (optional)
• Integrated speakers, microphone, etc
• External devices: USB audio devices, Bluetooth audio devices, HDMI audio, etc.
• Signal processing can also be implemented in the H/W (e.g. the codec or the DSP), instead of or in addition to the APOs.