DataSource
Media source are varied in nature. So is the
media access protocol ( file, HTTP, HTTPS, FTP,
RTP, and RTSP ).
 We need an abstraction to hide the complexity
of media access protocol.
DataSource : encapsulates media location as
well as media access protocol
DataSource offers a simple connect protocol.
Connect, start, stop, and disconnect methods.
DataSource can be constructed from a
MediaLocator or URL.