MediaLisp -- A System Design forMultimedia Augmented Transition Network in Lisp

-- for CIS6931 Term Paper Assignment

March 2001

Yanli Sun (50%)Xiangyu Ye (50%)

Schools of Computer Science,Florida International University, Miami, FL.

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ABSTRACT

This paper presents a draft design of MediaLisp, a feasible approach to compose

multimedia presentations and to control the procedure of the presentation by using Lisp

based system. A multimedia presentation consists of a cluster of multimedia objects. Due

to the complexity of multimedia object, it is very difficult to describe the complex

temporal, structural and behavioral properties of a multimedia presentation and all

underlying objects by using conventional approaches.

Though Lisp language is very simple, it is expressing to meet the requirements for

describing temporal, structural and behavioral properties of multimedia objects and

presentations. Based on Lisp convention, MediaLisp provides an integrated system to

evaluate and process presentation. MediaLisp extends the semantics to define the

temporal, structural and behavioral properties of multimedia functionality by using MATN

semantic model and property set. The MediaLisp interpreter provides fundamental

functionality to control and synchronize media streams during the procedure of

presentation and servers as a framework over the component based hierarchy to manage

all multimedia related functional components.

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0. Introduction

Multimedia has gained significant popularity and extensive interest nowadays.

Unlike traditional information processing (text number ect), multimedia information is

very complex in nature and usually time-dependent. ations and to control the procedure

of the presentation by using Lisp based system. A multimedia presentation consists of a

cluster of multimedia objects. Due to the complexity of multimedia object, it is very

difficult to describe the complex temporal, structural and behavioral properties of a

multimedia presentation and all underlying objects by using conventional approaches.

Though Lisp language is very simple, it is expressing to meet the requirements for

describing temporal, structural and behavioral properties of multimedia objects and

presentations. Based on Lisp convention, MediaLisp provides an integrated system to

evaluate and process presentation. MediaLisp extends the semantics to define the

temporal, structural and behavioral properties of multimedia functionality by using MATN

semantic model and property set. The MediaLisp interpreter provides fundamental

functionality to control and synchronize media streams during the procedure of

presentation and servers as a framework over the component based hierarchy to manage

all multimedia related functional components.

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1. MATN Model

Multimedia Augmented Transition Network (MATN) is a variant of Augmented

Transition Network (ATN). This model is introduced by Shu-ching Chen in 1999. The

idea of MATN is to describe the behavior of multimedia streams by defining states and

transitions at the change (begin or end) of a stream.

MATN model is defined as follow:

- The building blocks:

MATN consists of nodes and arcs. Each node represents a state, and each arc

represents the transition of a state.

The states can have state names. A new state is created whenever there is any

change of media streams in the presentation. There are two situations for the change

of media streams: any media stream finishes to display; any new media stream joins

to display.

The arcs represent the time flow from one state to another. The arc labels

represent the media streams being displayed in the time duration between the states

the arc connects.

Figure-1 An MATN example

P P/X1 P/X2 P/X3 P/X4 P/X5X1 X2 X3 X4 X5

TimeInstant

TimeDuration d1 d2 d3 d4 d5

t1 t2 t4 t5 t6t3

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- The inputs:

The inputs for MATNs are modeled by multimedia input strings. A multimedia

input string consists of several input symbols and each of them represents the media

streams to be displayed at a time interval.

In a multimedia input string, the symbol “&” between media streams indicates

these two media streams are displayed concurrently. P/Xi denotes the state after Xi

has been read.

In the example shown in Figure 1, there are five occurrences of media stream

combinations at each time-duration:

• Duration d1: V1 & I1

• Duration d2: V1, T1, I1, & A1

• Duration d3: T2, I1 & A1

• Duration d4: V2, T2, I2 & A1

• Duration d5: V2 & A1

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2. Lisp Language

Lisp language was invented in late 1950’s as a formalism of reasoning about the use

of recursion equations as a model for computation. LISP stands for LISt Processing. Its

development history has often been associated with symbolic processing and with both

computer and human languages. A heterogeneous list data type has always been built into

the language in order to efficiently deal with arbitrary and changing models.

Besides its many other advantages, the following features caught our attention and

made us choose Lisp to represent MATN:

• Decoupled syntax from semantics:

Lisp defines a simple regular syntax that is used by default for reading programs.

It also provides a means to change that syntax, and an internal data representation for

programs that are not test based.

• Flexibility:

Lisp can be combined with other languages to produce wide variety of applications.

• Heterogeneity:

Lisp supports powerful data type (numeric, as well as heterogeneous objects),

polymorphic functions, logical pathnames, timing and date utilities, sophisticated

control structure.

• Object-oriented:

Lisp was the first ANSI standard to incorporate object oriented programming. It

has strong support of Meta Object Protocol (MOP).

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• Rapid prototyping:

Lisp is comprehensive. It supports modular design, supports interactive

development, debugging and update. Lisp is a very good vehicle for rapid

prototyping, which enables early review and discovery of problems.

• Database accessing support.

Now let’s move to the system design of MediaLisp.

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3. Multimedia Data Types in MediaLisp

Based on traditional lisp convention, MediaLisp achieves the functionality

concerning multimedia composition by extending a set of data types and corresponding

functions designated to describe and create multimedia objects. The following illustration

gives an overview of those data types:

Figure 2.1. Multimedia Data Types

In above figure, MultimediaObject, UnitMediaStream and CompositStream

are virtual data types used internally in MediaLisp. Though they are not reachable by

users, they do have semantic meanings and tightly related to internal implementation.

MediaStream, Delay, Sequence and Parallel are concrete data types used to

define media streams in multimedia representation.

Every data type has a property set that can be constructed at run-time and bound to

individual instances. There are two property types: system preserved property and user

MediaStream Delay

UnitMediaStream

Sequence Parallel

CompositMediaStream

MultimediaObject

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defined property. All the properties can be read and written at run time. The property set

functions as hash table and bound to individual media stream.

System preserved properties are properties whose names and values are defined by

MediaLisp system used to specify common features regarding to multimedia

representation, such as name, time duration and etc. Those properties can be recognized

by MediaLisp and used to retrieve the media stream and control its display

User defined properties can be any name-value pairs without name conflict with

system preserved properties. They are bound to the multimedia object to store

information used at run time. Users can feel free to use this feature to impose advanced

control features at run time.

3.1. Description of Multimedia Data Types:

3.1.1 ModiaStream:

The ModiaStream data structure severs as basic unit that represents a single media

stream within a multimedia representation. Each ModiaStream has a name within the

multimedia representation and a set of properties. In Media Lisp, the name of a

ModiaStream need to be distinct so that it can be referred by name.

The system preserved properties of ModiaStream are listed in following table:

System Preserved PropertiesName Type Description

Name String The name of

MediaType String

The media types, such as• Text• Video• Audio• Image

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• ect.

Duration IntegerThe number of basic time intervals. Thenegative value means the property needs to bedetermined at run time.

Location StringThis property tells the location to retrievethe media stream, it adopts Uniform ResourceLocation (URL) convention.

Priority Integer This value is used to determine the prioritiesamong media streams played in parallel.This value can be one of the predefined valued:

1. To be displayed exactly one time2. To be repeatedly displayed at least one

time3. To be repeatedly displayed any times

DisplayPolicy Integer

4.

Channel Integer

This value specifies the channel to physicallyload huge media objects (e.g. video stream). Itis assigned by system and is read-only. Usercan use this value to refer the run-timeproperties of the channel so as toprogrammatically control the display.

Player String

It allows users to specify their desired deviceto display the media stream. If this value isnot specified, MediaLisp can assign a properone according to MediaType property.

3.1.1.1. MediaStream Creation:

By using function Define to define a MediaStream object. The function interface is

as follows:

DefineCalling Convention:

(Define stream_name)Parameters:

Stream_name The name of the media stream. This value isNil, then MediaLisp would automatically assigna name

Return Value:The reference of the MediaStream Onject.

3.1.1.2. Temporal Relationship:For such objects, the time duration is calculated as follows:

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For non-looping object, the same value as it Duration property.

For looping object, if it is placed in a sub-net of MATN, the duration if the sub-net's

overall duration, otherwise is infinite.

3.1.2. Explicit Delay:

Sometimes, it's necessary for user to impose an explicit delay for some duration so as

to control (synchronize) the multimedia representation. For this purpose, we introduce the

Delay data type in MediaLisp.

The property set of such data type contains "Name" and "Duration" with regarding

system preserved properties.

Delay object can be created by the following clause:

DelayCalling Convention:

(Delay interval)Parameters:

Interval The number of unit time interval to wait forReturn Value:

The reference of the Delay object

3.1.3. Sequencing:

3.1.3.1. Semantics of Sequencing:

To describe a sequence of media streams, we adopt the operator <<<. A sequence is

a tuple of variable length surrounded by parenthesis with the first element is<<<. For

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example, to represent a sequential presentation of media streams x1, x2 and x3, we can

use: (<<< x1 x2 x3). Sequencing allows nested structures, each element can be

• A single media stream• A sequence of media streams• A parallel of media streams

The property set of Sequence contains "Name" and "Duration" with regarding

system preserved properties.

3.1.3.2. Temporal Relationship Regarding to Sequencing:

The time duration is the summation of all time duration of contained streams within

it. The temporal relationship among streams within a sequence can be obtained by simply

applying "meet" relationship sequentially over all contained media streams. For

example, given a sequence (<<< x1 x2 x3), then the time duration of the sequence is

1xτ + 2xτ + 3xτWhere 1xτ Duration of x1

2xτ Duration of x2

3xτ Duration of x3

The temporal relationship according to MATN:

x3x2x1

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3.1.4. Parallel(Concurrence):

3.1.4.1. Semantics of Sequencing:

To describe media streams played in parallel, we adopt the operator |||. A parallel

is a tuple of variable length surrounded by parenthesis with the first element is |||. For

example, to represent presentation of media streams x1, x2 and x3 palyed in parallel, we

can use: (||| x1 x2 x3). Parallel allows nested structures, such that each element

can be

• A single media stream• A sequence of media streams• A parallel of media streams

The property set of Parallel contains "Name" and "Duration" with regarding

system preserved properties.

3.1.4.2. Temporal Relationship Regarding to Parallel:

The time duration is the maximum all time duration among all contained streams

within it. The temporal relationship among streams within a sequence can be obtained by

simply applying "meet" relationship sequentially over all contained media streams. For

example, given a sequence (||| x1 x2 x3 x4 x5), then the time duration of the

sequence is

(max 1xτ 2xτ 3xτ 4xτ 5xτ )Where 1xτ Duration of x1

2xτ Duration of x2

3xτ Duration of x3

4xτ Duration of x4

5xτ Duration of x5

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The temporal relationship depends on the mutual relationship among all media

streams' duration. We can apply use Bucket-Sort algorithm to calculate the temporal

relationship as follows:

1. Calculate the number of all distinct time duration2. Construct a bucket according to duration in ascending order3. Put each media stream into the buckets in which the duration

values are less on equal to its duration4. For each bucket, combine all names of media streams inside

to build the multimedia string for an edge of MATM

For above example, suppose the time duration distributed as follows: 1xτ =5,

2xτ =3, 3xτ =7, 4xτ =7, 5xτ =5. The total number of distinct time duration is 3. The

buckets and the multimedia strings are shown as below:

Buckets Contents Multimedia String of MATN3 x1, x2, x3, x4, x5 x1&x2&x3&x4&x55 x1, x3, x4, x5 x1&x3&x4&x57 x3, x5 x3&x5

The corresponding MATN is drawn as follows:

x3&x5x1&x3&x4&x5x1&x2&x3&x4&x5

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3.2. Related API Functions:

In order to manipulate multimedia object, we define a small set of API functions

described as follows:

3.2.1. Query Name by Reference:

?Calling Convention:

(?stream_ref)Parameters:

stream_ref The reference of the media streamReturn Value:

The name of the media stream.

3.2.2. Getting Reference by Name:

?Calling Convention:

(? stream_name)Parameters:

Stream_name The name of the media streamReturn Value:

The reference of the media stream. Nil means no media streamexists under this name.

3.2.3. Property Query:

GetPropertyCalling Convention:

(GetProperty stream_ref property_name)(GetProperty stream_name property_name)

Parameters:Stream_nameOrStream_ref

The name or reference of the underlying mediastream

Property_name The name of the propertyReturn Value:

If the property exists, then return the corresponding value,otherwise return Nil.

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3.2.4. Property Update:

SetPropertyCalling Convention:

(SetProperty stream_name property_name property_value …)or(SetProperty stream_ref property_name property_value …)

Parameters:Stream_nameOrStream_ref

The name or reference of the underlying mediastream

Property_name The name of the propertyProperty_value The value of the underlying property

Return Value:None.

Description:For convenience, this function supports variable input. Theinput must contain exact integer number of "name-value" pairs.For example:(SetProperty stream_name name1 value1 name2 value2 name3 value3)

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4. Multimedia Representation Control

Except for functionality supported in general Lisp language, MediaLisp also

provides support for media stream branching and composing, as well as precise control

for multimedia presentation.

The MediaLisp maintains a set of system properties. Those properties can be used to

configure the behavior of the overall environment for the multimedia presentation. Dor

the sake of flexibility, a concept of Phase for fine-tuning of run-time behavior of one or a

group of media streams:

As in the MATN model, media stream branching occurs whenever user choice or

automatic choice based on condition table occurs. Media stream choice provides great

flexibility to deal with unpredictable situations in real life. We define three branching

functions for multimedia presentations, they are Case and Select.

4.1. System Property:

The are two types of system properties. They are defined by MediaLisp (thye are

recognizable by system) so as to describe and the control the runtime behavior of the

whole presentation. The set of system properties should contain at lease:

Name Type Description

Physical_Interval Number The physical time duration of unit timeinterval.The predefined error handling behavior1 Ignore error2 Prompt message3 End presentation

Error_Handling Integer

4 ……

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Accordingly, we define can use functions GetSProperty and SetSProperty to

access system properties:

4.1.1. System Property Query:

GetSPropertyCalling Convention:

(GetSProperty property_name)

Parameters:Property_name The name of the underlying system property

Return Value:If the property exists, then return the corresponding value,otherwise return Nil.

4.1.2. System Property Update:

SetSPropertyCalling Convention:

(SetSProperty property_name property_value …)or(SetSProperty stream_ref property_name property_value …)

Parameters:Property_name The name of the system propertyProperty_value The value of the underlying system property

Return Value:None.

Description:For convenience, this function supports variable input. Theinput must contain exact integer number of "name-value" pairs.For example:(SetSProperty name1 value1 name2 value2 name3 value3)

4.2. Phase:

The introduction of concept Phase provides detailed control over multimedia

presentation. A phase is a sub runtime environment under environment MediaLisp.

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Similarly, phase maintains a set of properties similar to system properties. Actually, the

runtime system can be treated as an implicit phase. If there is no phase specified,

MediaLisp uses system properties. Also, used can use any user defined phase properties

as long as there is no conflict with the preserved phase properties.

Whenever a phase is specified, MediaLisp uses the properties of the phase instead.

When a phase finishes, MediaLisp switches back to the default system properties to

control remaining presentation. The following table lists some basic phase properties:

Name Type DescriptionThe predefined error handling behavior1 Ignore error2 Prompt message3 End current phase

Error_Handling Integer

4 ……

4.2.1. Semantic of Phase Creation:

PhaseCalling Convention:

(Phase phase_name)Parameters:

Phase_name Optional. If it's not specified, the systemwill automatically assign an unique one.

Return Value:The reference of the phase

4.2.2. Phase Property Query:

GetPPropertyCalling Convention:

(GetPProperty phase_name Property_name)or(GetPProperty phase_ref Property_name)

Parameters:phase_name Name of the specific phasephase_ref Reference of the specific phaseProperty_name The name of the underlying system property

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Return Value:If the property exists, then return the corresponding value,otherwise return Nil.

4.2.3. Phase Property Update:

SetPPropertyCalling Convention:

(SetPProperty phase_name property_name property_value …)or(SetPProperty phase_ref property_name property_value …)

Parameters:phase_name Name of the specific phasephase_ref Reference of the specific phaseProperty_name The name of the phase propertyProperty_value The value of the underlying phase property

Return Value:None.

Description:For convenience, this function supports variable input. Theinput must contain exact integer number of "name-value" pairs.

4.3. Media Stream Branching

4.3.1. Case:

The Case function is similar to "switch" function in C++, its decisions are based on

integer value. Usually, the integer value should be the choice sequence number from a

user interactive choice. For this purpose, we also define ChoiceList data type to

describe user prompts.

4.3.1.1. Semantic of Case:

CaseCalling Convention:

(Case num stream1 stream2 …)Parameters:

Num The integer on which the decision should bebased at runtime

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Streami The corresponding media stream referenceReturn Value:

The reference of media stream (unit stream, parallel orsequence) that is determined by num at runtime.

Description:If there is no stream defined corresponding to the choicenumber, an exception will be passed to the phase or system.

4.3.2. ChoiceList:

A ChoiceList object is simply an array of prompt string. The sequence number

starts from 1. In MediaLisp, ChoiceList object triggers a dialog that shows all prompts

in order to user and returns the choice number. The semantics of ChoiceList is shown as

follows:

ChoiceListCalling Convention:

(ChoiceList prompt1 prompt2 prompt3 …)Parameters:

prompti The corresponding prompt string referenceReturn Value:

The reference of choice object

4.3.3. Select

An alternative of media stream branching is Select. Compared with Case, Select

provides much more flexible and detailed detail. This function can be used to serve

automatic decision-maker depending on various system or phase properties at run time.

The semantics of Select is shown as follows:

SelectCalling Convention:

(Select condition1 stream1 condition2 stream2 …)Parameters:

Conditioni The condition which should be of boolean datatype

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StreamI The media stream reference corresponding theunderlying condition

Return Value:The reference of choice object

The input parameter consists of a list of "boolean-stream" pairs. This function is

executed as follows: The MediaLisp evaluates the input list pair by pair from left to right.

If the condition is true, then return the corresponding media stream reference. If no

condition is true, then raises an exception and passes it the underlying phase of system.

To make sense, we can always put an explicit "true" condition (value T in Lisp) paired

with a stream reference to specify a default value.

4.3.4. Temporal Relationship in Media Branching

All media branching functions can be regarded as a specific media stream (can be

simple media stream, parallel or sequence of media streams) whose actual time duration

need to be determined at runtime. To keep track their actual time, we need to utilize MATN

model to describe and control the branching. The detailed technique concerning this issue

will be discussed in later section.

4.4. Presentation

After all media streams and their temporal and behavioral properties has been

defined, the work left is to bind all those information together and add them to the MATN

based execution tree implemented within MediaLisp. This job can be done by the

Present function call. The semantics of Present is listed as below:

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PresentCalling Convention:

(Present stream)or(Present phase stream)

Parameters:stream The reference of media streamphase The reference of underlying phase

Return Value:None.

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5. Comprehensive Examples

So far we have briefly discussed all necessary conventions about MediaLisp. In this

section, we will demonstrate MediaLisp to by an example.

5.1. Example1:

In this example, a bunch of multimedia objects of different types need to be

displayed time by time. They are listed in following table:

Object Type Start Time Duration Location

V1 Video 0 5 http://www.fiu.edu/vedio1.mpgT1 Text 0 5 C:\temp\text1.txtI1 Image 3 7 D:\iamges\image1.jpgA1 Audio 3 8 http://www.fiu.edu/a.auT2 Text 5 2 C:\temp\text2.txt

The corresponding MediaLisp script:

(Define "v1")(setproperty "v1" "Duration" 5

"Mediatype" "video""location" " http://www.fiu.edu/vedio1.mpg")

(Define "T1")(setproperty "T1" "Duration" 5

"Mediatype" "text""location" "C:\temp\text1.txt")

(Define "I1")(setproperty "I1" "Duration" 7

"Mediatype" "image""location" "D:\imges\image1.jpg")

(Define "A1")(setproperty "A1" "Duration" 8

"Mediatype" "audio""location" "http://www.fiu.edu/a.au ")

(Define "T2")(setproperty "T2" "Duration" 2

"Mediatype" "text""location" "C:\temp\text2.txt")

(setf x1 (||| (? "v1") (? "T1")))(setf x2 (<<< (delay 3) (||| ( (? "I1") (? "A1") ) )(setf x3 (<<< (delay 5) (? "T2") ))(present (||| x1 x2 x3) )

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5.2. Example2:

In this example, we use a sequence of images to simulate an animation. For each

image there are two versions of source files: compressed version and uncompressed

version. Suppose for jth image

Compressed version: http://www.fiu.edu/compress_i.jpgUncompressed version: http://www.fiu.edu/regular_i.jpg

Whether to use the compressed or uncompressed version, depends on the bandwith of the

system. Let N be the total number of images included in this animation, then the script is:

(setf ANI NIL)(setf i 1)(while (le N)

(setf x1 (define NIL))(setf x2 (define NIL))(setproperty x1 "duration" 1, "Mediatype" "image")(setproperty x2 "duration" 1, "Mediatype" "image")(setf s1 (+ "http://www.fiu.edu/" "compressed_" i "jpg"))(setf s1 (+ "http://www.fiu.edu/" "uncompressed_" i "jpg"))(setf unit (select (getSproperty "Bandwidth") x1 true x2))

(setf ANI (if (eq ANI NIL) unit (<<< ANI unit))))(present ANI)

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6. Issues Concerning MediaLisp Interpreter

To support multimedia related functionality, MediaLisp must provide:

• Multi-threaded execution and management support.

• Network communication ability

• Real-time management and synchronization.

• Intelligence to handle the semantic heterogeneity of multimedia

representation.

• The ability to display various multimedia objects via various devices.

So the in internal implementation of MediaLisp interpreter is much more complex than

common Lisp interpreters, it has four sub-systems that work together to process a

multimedia presentation. They are:

• General Lisp interpreter

• MediaLisp interpreter

• Real-time media presentation control sub-system

• Real-time media retrieval management sub-system

6.1. General Lisp Interpreter:

This part severs as common list interpreter that evaluates (interprets) instructions in

MediaLisp program except for those in MediaLisp extension. It manages all variables

and control flows. It also passes the MediaLisp instruction to MediaLisp Interpreter .

6.2. MediaLisp Interpreter:

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This interpreter is designed to evaluate MediaLisp instructions. It creates some extra

data structures will be created to hold all the media object's internal properties as well as

their mutual temporal and behavioral relationship, such as:

• Vector of unit media objects:

• Vector of phase objects (the outermost phase is the

• A MATN graph data structure whose edges are multimedia strings and nodes are

time stamps and choice markers.

The pointers (reference relationship) among those data structures will alos be built

up within this part.

6.3. Real-time media presentation control sub-system:

This sub-system plays a crucial role in multimedia representation. It serves as a

central coordinator to control (track and synchronize) the media retrieval, display and

error handling during realtime presentation based upon the MATN graph,

Starts from the start node of the MATN graph, the coordinator periodically (every unit

time interval) looks one more steps ahead to predict what to do next time interavl.

Before a multimedia object starts to display, it needs to initiates a pre-retrieval thread

to build up the network transmission channel, caches the whole object or its header

depending on the properties of the object. Whenever a choice is made, it can correctly

lead the media stream to the certain branch. It also manages media displayers and assign

different media objects to certain players.

A small knowledge needs to be involved to help making decision.

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7. Conclusion and Future Works

From the proposed draft design of MediaLisp in this paper, we have presented a

feasible approach to describe and control multimedia representations. By adopting the

MATN semantic model, this approach is expressive, flexible and convenient enough to

handle multimedia presentations.

Though Lisp was developed in 1950s, it has gained extensive interests in recent 10

years since its simplicity and flexibility. The semantics is very suitable to define tree-like

data structures. By extending Lisp with multimedia support, this approach can easily

describe all static and dynamic properties and conditions with respect to multimedia

presentation.

By adopting the MATN semantic model, MediaLisp can precisely control and keep

tracking of both static and dynamic temporal relationship among all multimedia objects

in a presentation. The ability to model dynamic temporal relationship as well as the

flexibility of scripting technique, MediaLisp can handle any complex situations

concerning multimedia presentation.

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8. Reference

[1]. Shu-Ching Chen, Mei-Ling Shyu, and R. L. Kashyap, "Augmented TransitionNetwork as a Semantic Model for Video Data," accepted for publication,International Journal of Networking and Information Systems, SpecialIssue on Video Data.

[2]. Sheng-Tun Li, Shu-Ching Chen, and Mei-Ling Shyu, "A Snapshot BrowsingModel for Distributed Surveillance Systems," accepted for publication,Journal of Applied Systems Studies, Special Issue on DistributedMultimedia Systems with Applications.

[3]. Sheng-Tun Li, Shu-Ching Chen, and Mei-Ling Shyu, "A Live TV-QualityDistant learning Multimedia Presentation System for Education," the34th Hawaii International Conference on System Sciences (HICSS-34), CD-ROM, IEEE Press, 9 pages, January 3-6, 2001, Maui, Hawaii.

[4]. Sheng-Tun Li, Shu-Ching Chen, and Mei-Ling Shyu, "A PresentationSemantic Model for Asynchronous Distance Learning Paradigm," ACMMultimedia 2000 Conference, pp. 404-406, October 30 - November 3, 2000,Los Angeles, California.

[5]. Mei-Ling Shyu and Shu-Ching Chen, "A Bayesian Network-Based ExpertQuery System for a Distributed Database System," IEEE InternationalConference on Systems, Man, and Cybernetics, Nashville, Tennessee, USA,pp. 2074-2079, October 8-11, 2000.

[6]. Shu-Ching Chen, Mei-Ling Shyu, and Naphtali Rishe, "ModelingInteractive Multimedia Presentation Systems Using Augmented TransitionNetworks," First International Workshop on Intelligent MultimediaComputing and Networking (IMMCN'2000), pp. 643-646, February 27-March3, 2000, Atlantic City, NJ, U.S.A.

[7]. Shu-Ching Chen, Srinivas Sista, Mei-Ling Shyu, and R. L. Kashyap,"Augmented Transition Networks as Video Browsing Models for MultimediaDatabases and Multimedia Information Systems," 11th IEEE InternationalConference on Tools with Artificial Intelligence (ICTAI'99), pp. 175-182, November 9-11, 1999, Chicago, IL, U.S.A.

[8]. Guy L. Steele, "Common Lisp the Language, 2nd Editio", Digital Press1990 paperbound ISBN 1-55558-041-6

[9]. Sean Luke, "Java for Lisp Programmers",at AAAI99 (the 1999 conferenceof the American Association for Artificial Intelligence).

[10]. Heiko Kirschke, "PERSISTENT LISP OBJECTS!", Version 2.09 of May 22,2000. "http://www.lisp.de/software/plob/Welcome.html"

[11]. http://www.elwoodcorp.com/alu/table/lisp.htm (March 2001).