A: It returns the meta tags in header format if the stream contains HTML data.
B: It gives you access to the context data that was used when opening the stream.
C: When working with streaming content this function will give you a list of chapters and sections and their corresponding stream location/jump points.
D: It gives information of the stream itself: in which mode the stream was openend, if
eof was hit, which filters are used and so on.