The need for multimedia information systems grows rapidly in a variety
of fields including business, manufacturing, education, CAD, CAE, medicine
etc. Due to the diverse nature of multimedia data, systems designed to
store, transport display and manage such data must have considerably
more functionality and capability than conventional information management
systems. Multimedia applications can be very complex as regards the number
of involved objects, transformations of the objects in the scope of an
application and relationships among them. These features become even more
salient with the advent and wide usage of the WWW as the main medium of
The issue of modeling, authoring, querying and rendering
Multimedia Documents (IMDs) has attracted significant research and
industrial efforts in the last years. In this book we present an integrated
framework for IMDs, results of our research work in the topic for several
years. The book aims at postrgaduate students and research scientists and
practitioners and the topics covered include:
Multimedia document models & standards
A review of the research efforts aiming at modeling the various aspects
of multimedia documents is provided as well as a substantial presentation
of current document standards (HYTIME, MHEG and SMIL).
Modeling of IMDs
The basis of the framework is a model for IMDs that covers widely
the issue of interaction and spatiotemporal composition. According to the
model an IDM is defined in terms of actors, events and scenario tuples.
The actors (video, sound, image, text, and buttons) represent the media
objects participating and their spatiotemporal transformations in order
to align to the presentation requirements. The events are the interaction
primitives and they may be atomic or complex. They are generated by user
actions, actorsí state changes or by the system. The basic constituent
of an IMD is the scenario, namely a set of scenario tuples. A tuple is
a fundamental entity of functionality in the scenario conveying information
about the event(s) that start (or stop) a set of synchronized media presentations.
Authoring & verification of IMDs
Based on this IMD model we develop an authoring methodology,
clearly identifying the stages of interaction and spatiotemporal presentation
specification. During the authoring process it is vital to provide to the
author verification facilities so as to review the document design and
thus avoid errors and improve the design quality. The verification has
to deal with the temporal and spatial dependencies and constraints of the
document. We propose a methodology for verification of the spatiotemporal
content of an IMD. A related issue is the ability of an author to query
an IMD as regards the spatiotemporal dependencies that are inherent to
it. There the requirement for efficiency is apparent. We have worked on
a spatiotemporal indexing scheme that processes efficiently queries with
intensive spatiotemporal content.
We present a scheme for managing IMDs that involve a large number of
interrelated objects. We propose an indexing scheme based on spatial indexing
techniques. Thus fast retrieval of queries regarding spatiotemporal queries
is feasible. Moreover spatial or temporal application layouts may be obtained.
The result of IMD specification under this approach is a declarative
script, which has to be executed whenever and IMD session is initiated.
The execution (rendering) of an IMD may be a complicated task due
the multitude of occurring events and the potentially large sets of different
presentation options. We developed two approaches for IMD rendering, one
that is based on a single-thread approach and another generic multi-threaded
architecture that detects and evaluates events that occur in the presentation
context and triggers the appropriate synchronized presentation actions.
Both schemes are implemented. The second presentes substantial potential
for WWW exploitation.