Java™ Media APIs: Cross-Platform Imaging, Media, and Visualization

Time—A Central Concept

Not surprisingly, after all it is called time-based media, time is a key concept in the JMF. Thus it is important that programmers who employ the API have a good understanding of the model of time that JMF uses.

JMF provides a layered model of time. At the bottom-most layer exists an exact representation of an instant in time at the nanosecond level. The next layers support the concept of a constantly ticking source of time: a clock. The highest layers support abstractions of time as being started or stopped and being in one of a number of potential states. These layers allow a programmer to exercise timing control (for example, alter play rate) as well as keep track of time-based processes at the level appropriate for ...