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One way of providing technological support for communities of teachers is to help participants to produce, structure and share information. As this information becomes more and more multimedia in nature, the challenge is to build multimedia authoring and publishing tools that meet requirements of the community. In this paper, we analyze these requirements and propose a multimedia authoring model and a generic platform on which specific community-oriented authoring tools can be realized. The main idea is to provide template-based authoring tools while keeping rich composition capabilities and smooth adaptability. It is based on a componentoriented approach integrating homogeneously logical, time and spatial structures. Templates are defined as constraints on these structures.

In this paper, we discuss the effect of the uncertainty in the duration of some multimedia objects on the quality of the presentation of multimedia scenarios. This uncertainty can be due to external factors such as the access delay over internet or the user interaction. An uncertain duration is often followed by a period of desynchronization during which the presentation deviates from the desired scenario. To solve this problem, we present in this paper a solution that integrates two complementary approaches which reduce the desynchronization and limit its propagation in the rest of the presentation. These approaches are non-blocking and use the flexibility in the duration of multimedia objects in order to resynchronize the presentation as rapidly as possible.

Authoring a multimedia document requires to specify both its spatial layout and its temporal organization, i.e. when and where objects such as pictures, texts and videos appear/disappear on /from the screen and when objects such as audios and videos start/end to play. In this paper, we present some benefits authors can gain when using an authoring tool in which constraints are used to specify these two kinds of information. We describe our experience in building Madeus, a constraint-based environment to design multimedia documents and we point out technical problems that still need to be solved to more completely satisfy author requirements.

This paper presents Smil‐Editor – an authoring environment to write multimedia documents encoded in SMIL. The main feature of Smil‐Editor is to strongly integrate the presentation view, in which the document is executed, with the editing process. In this view objects can be selected to perform a wide set of editing actions ranging from attributes setting to direct spatial or temporal editions. This way of editing a multimedia document is close to the well‐known WYSIWYG paradigm used by usual word‐processors. Moreover, in order to help the author to specify the temporal organisation of documents, Smil‐Editor provides an execution report displayed through a timeline view. This view also contains information which helps the author to understand why such execution occurred. These multiple and synchronised views aim at covering the various needs for authoring multimedia documents.