IAudioAutoGainControl interface

The IAudioAutoGainControl interface provides access to a hardware automatic gain control (AGC). The client obtains a reference to the IAudioAutoGainControl interface of a subunit by calling the IPart::Activate method with parameter refiid set to REFIID IID_IAudioAutoGainControl. The call to IPart::Activate succeeds only if the subunit supports the IAudioAutoGainControl interface. Only a subunit object that represents a hardware AGC 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 IAudioAutoGainControl interface provides convenient access to the KSPROPERTY_AUDIO_AGC property of a subunit that has a subtype GUID value of KSNODETYPE_AGC. 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 IAudioAutoGainControl interface inherits from the IUnknown interface. IAudioAutoGainControl also has these types of members:


The IAudioAutoGainControl interface has these methods.


Gets the current state (enabled or disabled) of the AGC.


Enables or disables the AGC.



Minimum supported client

Windows Vista [desktop apps only]

Minimum supported server

Windows Server 2008 [desktop apps only]



See also

Core Audio Interfaces
DeviceTopology API