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Multimedia and Database Discussion Group
Multimedia Databases
Although computer vision and image processing
techniques improved significantly, the subjective user evaluation of video
and image data as well as unsatisfactory object recognition methods made it necessary
incorporation of fuzzy, uncertain, and imprecise data in multimedia
databases. The multimedia database systems have to enable information for an
attribute at different levels of uncertainty and support querying with fuzzy
and crisp values independent of how data is stored in the database. We have
developed a conceptual database model for multimedia database applications
using ExIFO2 data model [15] and used Fuzzy Object Oriented Model
(FOOD) as the logical model. This multimedia database is applied for videos
of soccer games [3]. Multimedia Networking
The data whether stored in the database or not has
to be transmitted over networks shared by many users. The congestion of the
network and the compressed video data affect the quality of presentations
drastically. Especially, the loss of a frame does not only affect the display
of the frame, it also affects the display of the dependent frames. We have
proposed a Probe-loss utilization streaming (PLUS) mechanism to reduce the
loss of high priority frames [2]. For an MPEG video stream, I frames have the
highest priority and B frames have the lowest priority. The status of the
network is probed with B frames and I frames are protected in a better
way by reducing the congestion caused by the system. We have built a client
server middleware design strategy for streaming multimedia presentations [1]. Interactive Multimedia
Presentation Management
The user interactions are core elements of
multimedia presentations. The loss and delay of the data over networks complicates
the synchronization if user interactions that change the course of the
presentations are enabled. The event-based or constraint-based
synchronization models provide powerful mechanism to handle synchronization
in distributed systems. However, the interactions like skip and backward
usually complicates the synchronization and the specification of the
synchronization. We have proposed a rule-based synchronization model based on
Event-Condition-Action (ECA) rules [10, 14]. These rules can be specified by
a rule definition language or can be extracted from SMIL expressions [12].
The necessary constraints or rules for user interactions are automatically
extracted by the system and may be updated by the author. Model Checking
One major question is whether the specified
multimedia presentation is correct or not. A synchronization specification
may yield different results on different presentation tools. It is important
whether the presentation is actually played correctly by the synchronization
model. The specification properties have also to be checked based on the
synchronization model. The multimedia systems are usually tested by
simulation or by conducting experiments. Nevertheless, in these cases it is
not possible to cover all cases and sometimes mistakes can be costly. We
eventually applied model checking techniques on multimedia synchronization.
The synchronization rules are converted to PROMELA language and the
properties are verified by the SPIN model checker [4,11].
Consequently, the author is guaranteed to develop correct presentations. Video Processing
Most of the multimedia research is devoted on
video. The video data challenges researchers in compression, information
retrieval, and transmission and led many research areas. We have developed a
novel video application to spatially browse recorded video data [5]. The
users are allowed to perform pan left and right, tilt up and down, and zoom
in and out, if the necessary information can be extracted from various
portions of the video. This requires high resolution sprite (mosaic)
generation, reduction of blurring in the sprite, fast motion estimation and
compressed domain processing to decrease processing cost [6, 7, 8, 9]. We
have developed a tool named as VideoCruise to
spatially browse videos [5]. We have tested this tool for distance education
application. We have integrated video browsing tool, synchronization model
for user interactions and PLUS under a multimedia system. |