Constraint-based Approaches

• The author declares a set of relations between either instants (=, >, <) or intervals.

    Elastic Time Model:

• each multimedia object can also be associated with a minimum, a maximum and an optimal duration, either chosen by the author or automatically fixed by the authoring system depending on the nature of the object (text, image. video, etc.).
• first introduced in TemporalGlue and Firefly.
• For instance, the Company part of our example can be described by the Allen's relations given in Figure 8. The DelayGlob object is a fictive object (without content) which fixes the global duration of the Company part.

The aim of the temporal formatter(Figure 3):

• check the temporal consistency of this set.

• compute one solution.

• Algorithms used for these two phases are issued from either the temporal constraint satisfaction area or linear programming.

Expressive Power:

• Intuitive way of expression.

• Can easily capture the temporal information of multimedia documents.

Autoring Capabilities:

• Modifications of the scenario are made easier since the author has not to reconsider the whole structure but only to add or delete a relation.

Challenges:

• systems with good time performances.

• handling local interactions and unpredictable objects.