Next: Interaction Objects. Up: Combination Objects Previous: Structuring.


The issue of synchronization has always been one of the central problems of multimedia applications; it is therefore necessary for the MADE toolkit to offer a consistent solution to this issue.

The fundamental synchronization scheme used in MADE is called reference point synchronization. For each, so called, synchronizable MADE object a series of media specific reference points may be defined (for example, video frames, audio samples, etc.). Each reference point contains internal ``instructions'' for synchronization, references to other synchronizable objects that are to be synchronized with it, etc. Synchronizable objects are active objects; when they reach a reference point, synchronization is performed by exchanging messages with other active objects, waiting for their replies, etc. The reference point model has been greatly inspired by [3]; its details in the MADE environment are specified in [8]. Audio, video, and animation objects are obvious examples of synchronizable MADE objects. The MADE programmer may create new, application-specific synchronizable objects, too.

Based on this synchronization model, the MADE toolkit also includes a higher-level mechanism for time-based synchronization. This mechanism defines different types of schedulers which the application may use as building blocks for more complex time-based synchronization scenarios (see [8] for further details). These schedulers all assume the existence of a special synchronizable object within MADE, namely a timer. The approach of building time-based synchronization on the top of a more general mechanism, instead of considering it as a basic feature, allows the MADE library to be used in environments which do not necessarily offer real-time facilities.

Next: Interaction Objects. Up: Combination Objects Previous: Structuring.
Tue Jan 25 14:21:49 MET 1994