IXAudio2EngineCallback: Client notification interface for engine events.
REMARKS: Contains methods to notify the client when certain events happen
in the XAudio2 engine. This interface should be implemented by
the client. XAudio2 will call these methods via the interface
pointer provided by the client when it calls XAudio2Create or
IXAudio2::Initialize.
IXAudio2EngineCallback: Client notification interface for engine events.
REMARKS: Contains methods to notify the client when certain events happen in the XAudio2 engine. This interface should be implemented by the client. XAudio2 will call these methods via the interface pointer provided by the client when it calls XAudio2Create or IXAudio2::Initialize.