AUTOMATIC TEMPORAL LAYOUT MECHANISMS REVISITED
BY,
CECILIA BUCHANAN AND POLLE T.ZELLWEGER
PRESENTED BY,
SOUMYA JAYARAM
INTENT OF THE PAPER
•Multimedia document systems should provide mechanisms for automatically
producing temporal layouts for documents.
• By automatically producing temporal layouts for documents the advantage is
that it makes it easier for authors to create and modify the multimedia
documents.
INTRODUCTION
• A traditional static document has a spatial layout that specifies where objects
in the document appear.
• Multimedia documents incorporate time, they also require a temporal layout or
schedule that specifies when events in the document occur like audio, video,
and animations.
• Document formatting systems allow authors to specify the content, such as text
and figures, separately from formatting directives, such as justification,
centering, line and paragraph leading and figure placement.
REQUIREMENTS FOR AUTOMATIC TEMPORAL FORMATTING
• The automatic formatter must support media components that have a rich set of
capabilities.
• Must have a method for explicitly representing temporal relationships
among media components.
• It must provide a powerful temporal algorithms.
MEDIA COMPONENTS
• Media components are the data that will be presented in documents.
• Granularity: Deals with the amount of internal structure the media component
makes accessible to the system.
• Events: Mark points in time during a media component’s presentation, and they
can be classified as either predictable or unpredictable.
• Unpredictable events: They mark times during the presentation of a media
component that cannot be determined in advance.
• Durations. Durations provide a formatter with information on the lengths of time
required to prepare and present media data.
TEMPORAL RELATIONSHIPS
• Temporal relationships describe how media components should be combined
temporally to produce a multimedia document.
• The temporal relationships serve both as input to a temporal formatter and as
an explicit record of the author’s intentions.
• For the purposes of temporal formatting, temporal relationships have four
primary attributes: granularity, temporal relation types, flexibility, and
flexibility metrics. Of secondary importance are the temporal aspects of the
document’s behavior and spatial specifications.
ENVIRONMENTAL SPECIFICATIONS
• An environmental specification consists of two parts:
Workstation and Network specifications
• Workstation specifications describe the capabilities of the target workstations upon
which a document may be presented, such as available multimedia hardware
devices and restrictions on the simultaneous utilization of these resources.
• Network specifications describe the characteristics of the networks over which
media components or multimedia documents may be transported, such as quality
of service, transport costs or connection delays, and network connectivity.
AUTOMATIC TEMPORAL FORMATTERS
• An automatic temporal formatter processes a document’s temporal and
environmental specifications to produce a temporal layout that indicates when
events in a document should occur.
• It begins by attempting to position media components without considering the
flexibility of their durations and temporal relationships.
• If the initial temporal layout is consistent with the document’s temporal
specification, the formatter is done. Otherwise, the temporal formatter attempts
to eliminate temporal mismatches by using the flexibility built into the temporal
specification to perturb the layout.
ARCHITECTURAL SCHEMA OF AUTOMATIC TEMPORAL FORMATTER
COMPILE TIME ALGORITHMS
Linear algorithm: A formatter can position entire media components using topological
sort, a that but cannot handle any form of flexibility.
Polynomial algorithm: This is a limited form of continuously adjustable durations
which are specified as a minimum and maximum value. The allpairs-shortest path is an example.
Advantage of this algorithm : Help authors locate errors by providing immediate
feedback when an editing operation introduces a
temporal mismatch.
FIREFLY’S HYBRID TEMPORAL FORMATTER
• Firefly was designed to increase the expressive power of multimedia documents
and to make them easier to create and maintain.
• Firefly supports media items with fine granularity, predictable and unpredictable
durations, continuous adjustability, and flexibility metrics.
• Temporal constraints are ordering relations (with all optional parameters) that
can be placed between pairs of events in one or more media items.
• Flexibility and flexibility metrics on constraints are not supported.
• Behavior specification in Firefly is handled via ordered operation lists, which can
be associated with any event.
FIREFLY’S GRAPH NOTATION
TEMPORAL FORMATTING ALGORITHM
Firefly’s compile time formatter
Firefly’s runtime formatter
FIRFLY REVISITED
• Firefly was reimplemented in C++ under the Windows operating system as part of
an effort to transfer this technology to the commercial sector.
• Unifying Durations and Temporal Constraints: Firefly treats media item durations
and temporal constraints differently even though both specify the elapsed time
between events. The most significant difference was that flexibility was supported
for media durations, but not for temporal constraints.
• Visual Representation: Firefly’s weakest component is the graph notation used in
its document editor.
CONCLUSION
•This article was proposed to analyze automatic temporal formatters that existed
in 1993
• The goal was to provide a tool with which we and others could assess their
expressive power, their ease of use, and their efficiency.
• At present, our framework treats environmental and spatial specifications as being
of secondary importance.
• We note that more of the recent systems provide hybrid schedulers that combine
the advantages of compile time and runtime temporal formatting. This advance in
capabilities benefits both authors and readers.
THANK YOU