Core Audio Interfaces

This programming reference for the Core Audio SDK includes the following interfaces:

MMDevice API

The Windows Multimedia Device (MMDevice) API enables audio clients to discover audio endpoint devices, determine their capabilities, and create driver instances for those devices.Header file Mmdeviceapi.h defines the interfaces in the MMDevice API. For more information, see About MMDevice API.

The following table lists the MMDevice interfaces available with the Core Audio SDK for Windows Vista.

Interface	Description
IMMDevice	Represents an audio device.
IMMDeviceCollection	Represents a collection of audio devices.
IMMDeviceEnumerator	Provides methods for enumerating audio devices.
IMMEndpoint	Represents an audio endpoint device.
IMMNotificationClient	Provides notifications when an audio endpoint device is added or removed, when the state or properties of a device change, or when there is a change in the default role assigned to a device.

WASAPI

The Windows Audio Session API (WASAPI) enables client applications to manage the flow of audio data between the application and an audio endpoint device. Header files Audioclient.h and Audiopolicy.h define the WASAPI interfaces. For more information, see About WASAPI.

The following table lists the WASAPI interfaces available with the Core Audio SDK for Windows Vista and later.

Interface	Description
IActivateAudioInterfaceAsyncOperation	Represents an asynchronous operation activating a WASAPI interface and provides a method to retrieve the results of the activation. Applies beginning with Windows 8.
IActivateAudioInterfaceCompletionHandler	Provides a callback to indicate that activation of a WASAPI interface is complete. Applies beginning with Windows 8.
IAudioCaptureClient	Enables a client to read input data from a capture endpoint buffer.
IAudioClient	Enables a client to create and initialize an audio stream between an audio application and the audio engine or the hardware buffer of an audio endpoint device.
IAudioClock	Enables a client to monitor a stream's data rate and the current position in the stream.
IAudioClock2	Enables a client to get the current device position.
IAudioClockAdjustment	Enables a client to set the sample rate of a stream.
IAudioRenderClient	Enables a client to write output data to a rendering endpoint buffer.
IAudioSessionControl	Enables a client to configure the control parameters for an audio session and to monitor events in the session.
IAudioSessionControl2	Enables a client to get information about the audio session.
IAudioSessionManager	Enables a client to access the session controls and volume controls for both cross-process and process-specific audio sessions.
IAudioSessionManager2	Manages all submixes including enumeration and notification of submixes. It also provides support for ducking notifications.
IAudioSessionEnumerator	Enables a client to enumerate audio sessions.
IAudioStreamVolume	Enables a client to control and monitor the volume levels for all of the channels in an audio stream.
IChannelAudioVolume	Enables a client to control the volume levels for all of the channels in the audio session that the stream belongs to.
ISimpleAudioVolume	Enables a client to control the master volume level of an audio session.
IAudioSessionEvents	Provides notifications of session-related events such as changes in the volume level, display name, and session state.
IAudioSessionNotification	Sends notifications when session changes occur.
IAudioVolumeDuckNotification	Sends notifications about pending system ducking changes.

DeviceTopology API

The DeviceTopology API provides client applications with the ability to traverse the functional hardware topologies of audio rendering and capture devices. Header file Devicetopology.h defines the interfaces in the DeviceTopology API. For more information, see Device Topologies and DeviceTopology API.

The following table lists the DeviceTopology interfaces available with the Core Audio SDK for Windows Vista and later.

Interface	Description
IAudioAutoGainControl	Provides access to a hardware automatic gain control (AGC).
IAudioBass	Provides access to a hardware bass-level control.
IAudioChannelConfig	Provides access to a hardware channel-configuration control.
IAudioInputSelector	Provides access to a hardware multiplexer control (input selector).
IAudioLoudness	Provides access to a "loudness" compensation control.
IAudioMidrange	Provides access to a hardware midrange-level control.
IAudioMute	Provides access to a hardware mute control.
IAudioOutputSelector	Provides access to a hardware demultiplexer control (output selector).
IAudioPeakMeter	Provides access to a hardware peak-meter control.
IAudioTreble	Provides access to a hardware treble-level control.
IAudioVolumeLevel	Provides access to a hardware volume control.
IConnector	Represents a point of connection between components.
IControlInterface	Represents a control interface on a part (subunit or connector).
IDeviceSpecificProperty	Represents a device-specific property of a connector or subunit.
IDeviceTopology	Provides access to the topology of an audio device.
IKsFormatSupport	Provides information about the audio data formats that are supported by a software-configured I/O connection (typically a DMA channel) between the audio device and system memory.
IKsJackDescription	Provides information about the jacks or internal connectors that provide a physical connection between a device on an audio adapter and an external or internal endpoint device (for example, a microphone or CD player).
IKsJackDescription2	Provides convenient access to the KSPROPERTY_JACK_DESCRIPTION2 property of a connector to an endpoint device.
IKsJackSinkInformation	Provides information about the jack sink if the jack is supported by the hardware.
IPart	Represents a part (connector or subunit) of a device topology.
IPartsList	Represents a list of parts (connectors and subunits).
IPerChannelDbLevel	Represents a generic subunit control interface that provides per-channel control over the volume level, in decibels, of an audio stream or of a frequency band in an audio stream.
ISubunit	Represents a hardware subunit (for example, a volume-level control) that lies in the data path between a client and an audio endpoint device.
IControlChangeNotify	Provides notifications when the status of a part (connector or subunit) changes.

EndpointVolume API

The EndpointVolume API enables specialized clients to control and monitor the volume levels of audio endpoint devices. Header file Endpointvolume.h defines the interfaces in the EndpointVolume API. For more information, see EndpointVolume API .

The following table lists the EndpointVolume interfaces available with the Core Audio SDK for Windows Vista.

Interface	Description
IAudioEndpointVolume	Represents the volume controls on the audio stream to or from an audio endpoint device.
IAudioEndpointVolumeEx	Provides volume controls on the audio stream to or from a device endpoint.
IAudioMeterInformation	Represents a peak meter on the audio stream to or from an audio endpoint device.
IAudioEndpointVolumeCallback	Provides notifications when the volume level or muting state of an audio endpoint device changes.

Related topics

Programming Reference