Developing multimedia applications with  JMF         T.G.Venkatesh      
15
  The JMF Time Model
•Media is any form of data that changes meaningfully with respect to time.
•Time class- represents a time instant
•Duration interface is implemented by classes that can compute and advertise the duration of the media they handle.
•For example Players and Processors extend Duration interface.
•Interface TimeBase - uncontrolled source of clock ticks
•Interface Clock - controlled source of clock ticks
•Clock can be stopped, restarted, rate can be adjusted.
•Analogy: crystal oscillator Vs digital clock.
Crystal
oscillator