IAudioLoudness interface

The IAudioLoudness interface provides access to a "loudness" compensation control. The client obtains a reference to the IAudioLoudness interface of a subunit by calling the IPart::Activate method with parameter refiid set to REFIID IID_IAudioLoudness. The call to IPart::Activate succeeds only if the subunit supports the IAudioLoudness interface. Only a subunit object that represents a hardware loudness control function will support this interface.

Most Windows audio adapter drivers support the Windows Driver Model (WDM) and use kernel-streaming (KS) properties to represent the hardware control parameters in subunits (referred to as KS nodes). The IAudioLoudness interface provides convenient access to the KSPROPERTY_AUDIO_LOUDNESS property of a subunit that has a subtype GUID value of KSNODETYPE_LOUDNESS. To obtain the subtype GUID of a subunit, call the IPart::GetSubType method. For more information about KS properties and KS node types, see the Windows DDK documentation.


The IAudioLoudness interface inherits from the IUnknown interface. IAudioLoudness also has these types of members:


The IAudioLoudness interface has these methods.


Gets the current state (enabled or disabled) of the loudness control.


Enables or disables the loudness control.



Minimum supported client

Windows Vista [desktop apps only]

Minimum supported server

Windows Server 2008 [desktop apps only]



See also

Core Audio Interfaces
DeviceTopology API