IBasicAudio Interface (Compact 2013)

3/26/2014

This interface is an interface that supports the filter graph's audio component. It allows access to volume and balance functionality.

The Volume property is a value between -10,000 and 0 representing a set of logarithmic steps. Not all devices support 10,000 distinguishable steps.

The Balance property is a value between -10,000 and 10,000:

• A value of -10,000 indicates that the right speaker is disabled and the left speaker is receiving an audio signal.
• A value of 0 indicates that both speakers are receiving equivalent audio signals.
• A value of 10,000 indicates that the left speaker is disabled and the right speaker is receiving an audio signal.

When to Implement

The audio renderer filter supplied with DirectShow implements this interface. It is also implemented by the filter graph manager (by means of a plug-in distributor) to pass method calls from the application to the audio renderer filter's implementation of the interface.

Implement this interface if you are writing a replacement audio renderer filter or a replacement DirectShow plug-in distributor. You can use the CBasicAudio Class class, which handles the IDispatch implementation for Automation, to help implement this interface.

When to Use

When the filter graph manager exposes this interface, it is used by applications that need to control the properties of the audio renderer filter.

Applications should not use the interface exposed by the audio renderer directly.

When the audio renderer filter exposes this interface, it is used by plug-in distributors, such as the DirectShow plug-in distributor, which pass calls from the application.

Methods in Vtable Order

The following tables show the methods that appear in the Vtable beneath the standard COM methods inherited from IUnknown.

IDispatch method	Description
IDispatch::GetTypeInfoCount	Determines whether there is type information available for this dispinterface.
IDispatch::GetTypeInfo	Retrieves the type information for this dispinterface if GetTypeInfoCount returned successfully.
IDispatch::GetIDsOfNames	Converts text names of properties and methods (including arguments) to their corresponding DISPIDs.
IDispatch::Invoke	Calls a method or accesses a property in this dispinterface if given a DISPID and any other necessary parameters.

IBasicAudio method	Description
IBasicAudio::put_Volume	Sets the volume (amplitude) of the audio signal.
IBasicAudio::get_Volume	Retrieves the volume (amplitude) of the audio signal.
IBasicAudio::put_Balance	Sets the balance for the audio signal.
IBasicAudio::get_Balance	Retrieves the balance for the audio signal.

Requirements

Header	dshow.h
Library	Strmiids.lib

See Also

Reference

DirectShow Interfaces