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IAudioSessionManager2::RegisterSessionNotification method (audiopolicy.h)

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The RegisterSessionNotification method registers the application to receive a notification when a session is created.

Syntax

HRESULT RegisterSessionNotification(
  IAudioSessionNotification *SessionNotification
);

Parameters

SessionNotification

A pointer to the application's implementation of the IAudioSessionNotification interface. If the method call succeeds, it calls the AddRef method on the application's IAudioSessionNotification interface.

Return value

If the method succeeds, it returns S_OK. If it fails, possible return codes include, but are not limited to, the values shown in the following table.

Return value Description
E_POINTER
 SessionNotification is NULL.
E_OUTOFMEMORY
 Internal object could not be created due to insufficient memory.

Remarks

The application can register to receive a notification when a session is created, through the methods of the IAudioSessionNotification interface. The application implements the IAudioSessionNotification interface. The methods defined in this interface receive callbacks from the system when a session is created. For example code that shows how to implement this interface, see

IAudioSessionNotification Interface.

To begin receiving notifications, the application calls the IAudioSessionManager2::RegisterSessionNotification method to register its IAudioSessionNotification interface. When the application no longer requires notifications, it calls the IAudioSessionManager2::UnregisterSessionNotification method to delete the registration.

Important

You must call IAudioSessionEnumerator::GetCount to begin receiving notifications. The session enumeration API discards new session notifications until the application has first retrieved the list of existing sessions. This is to prevent a race condition that can occur when a session notification arrives while the application using the session APIs is starting up. Calling GetCount triggers the enumeration API to begin sending session notifications.

Note  Make sure that the application initializes COM with Multithreaded Apartment (MTA) model by calling CoInitializeEx(NULL, COINIT_MULTITHREADED) in a non-UI thread. If MTA is not initialized, the application does not receive session notifications from the session manager. Threads that run the user interface of an application should be initialized apartment threading model.
 

Requirements

Requirement Value
Minimum supported client Windows 7 [desktop apps only]
Minimum supported server Windows Server 2008 R2 [desktop apps only]
Target Platform Windows
Header audiopolicy.h

See also

IAudioSessionManager2