Set the event callback function and user data that will be called when
collectpads has received an event originating from one of the collected
pads. If the event being processed is a serialized one, this callback is
called with pads STREAM_LOCK held, otherwise not. As this lock should be
held when calling a number of CollectPads functions, it should be acquired
if so (unusually) needed.
Set the event callback function and user data that will be called when collectpads has received an event originating from one of the collected pads. If the event being processed is a serialized one, this callback is called with pads STREAM_LOCK held, otherwise not. As this lock should be held when calling a number of CollectPads functions, it should be acquired if so (unusually) needed.
MT safe.