MULTIMEDIA TECHNOLOGY AND

APPLICATIONS

CHAPTER 7. MULTIMEDIA SOFTWARE DEVELOPMENT

TECHNOLOGY

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INTRODUCTION

Multimedia development is a project-based process.

Well-developed plan for multimedia product will save time money multiple modifications

The rule of thumb for development is 80% planning and 20% production.

80% planning + 20% production

SOFTWARE ENGINEERING DEFINED Software engineering is “multi-person

construction of multi-version software” What is the relationship between the size

of a program & the time it takes to develop it?

Real world software projects involve teams of developers

What’s the relationship between program size and the number of people involved? Is it linear (N developers == N time speedup)? Or is it exponential (N developers = NN

speedup)? How does multimedia affect the life cycle?

A SOFTWARE PROCESS REQUIRES RESOURCES…

What is the moral of the story (about project managers and resources)?

WATERFALL MODEL

Cascades from one stage to the next only after previous stage is complete

Gravity only allows the waterfall to go down; it’s very hard to swim upstream

RAPID PROTOTYPING MODEL A prototype is a partially developed product

that enables customers and developers to examine some aspect of a proposed system and decide if it is suitable for a finished product.

Allow time for prototypes and improved versions Multimedia authoring tools facilitate prototyping

SPIRAL MODEL

The spiral model is a software development process combining which elements of both design and prototyping-in-stages, in an effort to combine advantages of top-down and bottom-up concepts.

OBJECT-ORIENTED MODEL

The Object-Oriented paradigm assists the programmer to address the complexity of a problem domain by considering the problem not as a set of functions that can be performed but primarily as a set of related, interacting Objects.

Such as: Text, Audio, Video, Graphic, Image

Objects, Attributes, Operations Trends: Spiral model + Object-

oriented developing

Quiz!Quiz!

What are drawbacks of Waterfall Model? Can prototypes alleviate these drawbacks?

Why or why not? Why do many software development shops

prefer spiral models? How does multimedia affect the process? Does this discussion motivate you avoid

just hacking? Why or why not?

USER INTERFACE

System users often judge a system by its interface

A poorly designed interface can cause a user to make catastrophic errors

Poor user interface design is the reason why so many software systems are never used

USER CENTRED DESIGN

Software development should focus on the needs of users Understand your users Design software based on an understanding of the

users’ tasks Ensure users are involved in decision making

processes Design the user interface following guidelines for

good usability Have users work with and give their feedback

about prototypes, on-line help and draft user manuals

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THE IMPORTANCE OF FOCUSING ON USERS Reduced training and support costs Reduced time to learn the system Greater efficiency of use Reduced costs by only developing features that are

needed Reduced costs associated with changing the system

later Better prioritizing of work for iterative development Greater attractiveness of the system, so users will be

more willing to buy and use it

USABILITY VS. UTILITY

Does the system provide the raw capabilities to allow the user to achieve their goal? This is utility

Does the system allow the user to learn and to use the raw capabilities easily? This is usability

Both utility and usability are essential They must be measured in the context of particular

types of users

ASPECTS OF USABILITY Usability can be divided into separate

aspects: Learnability

The speed with which a new user can become proficient with the system

Efficiency of use How fast an expert user can do their work

Error handling The extent to which it prevents the user from making

errors, detects errors, and helps to correct errors Acceptability

The extent to which users like the system

DIFFERENT LEARNING CURVES

USABILITY PRINCIPLES

Do not rely only on usability guidelines – always test with users

Usability guidelines have exceptions; you can only be confident that a UI is good if you test it successfully with users

Base UI designs on users’ tasks Perform use case analysis to structure the UI

Ensure that the sequences of actions to achieve a task are as simple as possible

Reduce the amount of reading and manipulation the user has to do

Ensure the user does not have to navigate anywhere to do subsequent steps of a task

USABILITY PRINCIPLES

Ensure that the user always knows what he or she can and should do next

Ensure that the user can see what commands are available and are not available

Make the most important commands stand out Provide good feedback including effective

error messages Inform users of the progress of operations and of

their location as they navigate When something goes wrong explain the

situation in adequate detail and help the user to resolve the problem

USABILITY PRINCIPLES Ensure that the user can always get out, go

back or undo an action Ensure that all operations can be undone Ensure it is easy to navigate back to where the

user came from Ensure that response time is adequate

Users are very sensitive to slow response time They compare your system to others

Keep response time less than a second for most operations

Warn users of longer delays and inform them of progress

USABILITY PRINCIPLES

Use understandable encoding techniques Choose encoding techniques with care Use labels to ensure all encoding techniques are

fully understood by users Ensure that the UI’s appearance is

uncluttered Avoid displaying too much information Organize the information effectively

USABILITY PRINCIPLES

Consider the needs of different groups of users

Accommodate people from different locales and people with disabilities

Ensure that the system is usable by both beginners and experts

Provide all necessary help Organize help well Integrate help with the application Ensure that the help is accurate

USABILITY PRINCIPLES

Be consistent Use similar layouts and graphic designs

throughout your application Follow look-and-feel standards Consider mimicking other applications

SOME ENCODING TECHNIQUES

Text and fonts Icons Photographs Diagrams and abstract graphics Colors Grouping and bordering Spoken words Music Other sounds Animations and video Flashing

UI DESIGN PRINCIPLES UI design must take into account the

needs, experience and capabilities of system users

Users should be involved in the UI design process and UI designs should be refined through prototyping

There are cognitive factors, such as the size of short-term memory, which user interface designers must be aware of

UI DESIGN PRINCIPLES (CONTINUED) An interface should be based on user-oriented

terms and concepts rather than computer concepts

For example, a book-keeping system in a hospital should use terms such as patient profile, case record etc. rather than directories, file identifiers, etc.

The system should display an appropriate level of consistency

Commands and menus should have the same format, command punctuation should be similar, and so on

UI DESIGN PRINCIPLES (CONTINUED) The system should not surprise the user

If a command is executed in a known way (in some familiar context), a user should be able to predict the operation of comparable commands. E.g., ‘delete’ and ‘remove’ are somewhat synonymous in

the sense that they are both concerned with erasing something

The system should provide some resilience to user errors and allow the user to recover from errors

This might include an undo facilities, confirmation of destructive actions, 'soft' deletes, etc.

Some user guidance should be provided Help systems, on-line manuals, etc.

INFORMATION DISPLAY FACTORS Is user interested in precise information or

data relationships? How quickly do information values change?

Must a change be indicated immediately? Must user take some action in response to

a change? Is there a direct manipulation interface? Is the information textual or numeric? Are

relative values important?

DATA VISUALIZATION

Concerned with techniques for displaying large amounts of information

Visualization can reveal relationships between entities and trends in the data

Examples Weather information collected from a number of

sources The state of a telephone network A model of a molecule displayed in 3 dimensions

COLOR USE GUIDELINES

Don't use too many colors Use color coding to support user tasks Allow users to control color coding Design for monochrome then add color Use color coding consistently Avoid color pairings which clash Use color change to show status change Be aware that color displays are usually

lower resolution

USER GUIDANCE

A user guidance system is integrated with user interface to help users when they need information about the system or when they make mistakes

User guidance covers: System messages, including error messages Documentation provided for users On-line help

The help and message system may be integrated

ERROR MESSAGE DESIGN

Error message design is critically important. Poor error messages can mean that a user rejects the whole system

Messages should be polite, concise, consistent and constructive

The background and experience of users should be the determining factors in message design

USER DOCUMENTATION

As well as on-line information, paper documentation should be supplied with a system

Documentation should be designed for a range of users from inexperienced to experienced

As well as manuals, other easy-to-use documentation such as a quick reference card may be provided

USER INTERFACE DESIGN

Easy to learn? Easy to use? Easy to understand?

TYPICAL DESIGN ERRORS

Lack of Consistency Too much memorization No guidance / help No context sensitivity Poor response Unfriendly

GOLDEN RULES

Place the user in Control Reduce the user’s memory load Make the interface consistent

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