mm topic 1 - the development process 1 the definition given by the british computer society (bcs)...

MM Topic 1 - The Development Process

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The definition given by the British Computer Society (BCS) is:

“Multimedia is the presentation of information by a computer system using graphics, animation, sound & text.”

However this definition is now slightly out of date. What makes modern computer multimedia distinctive from older multimedia is that it is interactive. Interactivity is when the user responds to what is being displayed.


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Interactivity could involve:o Clicking on a hyperlink.o Selecting an option from a menu.o Playing and pausing a video clip.

A multimedia application is any presentation that uses a combination of different media elements AND allows the user to have some say in how they move through the presentation.

Interactivity means that a linear slide show where the user progresses through the screens in order, from start to finish without the opportunity to navigate, cannot be considered as a multimedia application.


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The stages in creating a multimedia application are exactly the same as those in software development:

Analysis

Design

Implementation

Testing

Documentation

Evaluation

Maintenance


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No matter what type of multimedia application, good planning is essential to ensure that a high quality product is created. The aim of the analysis stage is to produce a statement of what the client wants.

Multimedia applications are often developed in the context of large contracts worth millions of pounds. It is vital that the end product is not only high quality but a true reflection of what the client is paying for.


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In order to complete the analysis the development team will undertake a detailed process of fact-finding, gathering as much information as is possible.

There are many techniques used at this stage—interviewing clients, issuing questionnaires, observing people at work among others. Each method has its strengths and weaknesses and to obtain the most accurate specification a combination of approaches should be used.


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The questions the developers will ask are: Who? Where? Why? What? When? At this stage the developers are not interested in how the application is to be delivered; that is a concern for a later stage.

o The who will concern the personnel using the application. The level of expertise of users must be considered.

o Where should address the location an application will be used in. Will it be in a public area, for example?


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o When will force the client to think about the timescale for delivery of their application. If time is limited then less features may need to be included.

o Asking the client what they want helps them to understand exactly they type of product they want. This helps them and the development team identify the scope and boundaries of what is to be produced. Both will have to consider the budget that can be spent and the technology available.


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o Asking a client why they need something may force them to think about the reasons behind what they have asked for. They may want a web site with lots of animation, but if they cannot come up with a valid need for this then this part can be removed.

The analysis stage is iterative. It will be repeated until both client and developer are in agreement. This is particularly important because the client may be paying the developers a considerable amount of money. The solution should meet their wishes exactly, or as closely as possible.


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Once a clear idea of the type and nature of multimedia application has been agreed the development team then need to consider how this is to be put together. This does not involve heading to a computer—careful consideration is still needed.

There are three areas that must be designed:

o The HCI (Human Computer Interface).

o What each screen will look like.

o What media elements will be included.


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A common method at this stage is storyboarding.

Storyboards were first used in feature length cartoons made by Walt Disney studios in the 1930s. Later live action film directors began to use them. Directors would ask artists to sketch out what particular shots would look like before they were filmed. Here is a storyboard from an episode of The Simpsons:


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Using a storyboard saves time and money because if the director didn’t agree with the storyboard image they would decide to shoot the scene in a different way without having filmed the shot. In a film that uses lots of (expensive) special effects storyboards are essential if it is to be delivered on time and within budget.

Storyboards are also used widely in computer games development for similar reasons. Here is a sample games storyboard:


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A storyboard for a web page might look like this:

Company Logo

(scanned)

Welcome Message Banner(Blue background, white foreground,

Comic Sans MS size 48 bold)

About the company(Blue background, white text, Comic Sans MS, 14)

Link to news page

Link to images page

Link to guest book


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The storyboard can be shown to the development team so that they have an idea of what a page will look like, what fonts and colours to select and what navigation links to include.

They can also see where any elements such as sounds, videos and graphics are to be obtained from. This reduces searching times and may help avoid any copyright concerns.

The storyboard is also shown to the client for their approval. It is easier to make a change at this stage instead of producing an actual screen, only for the client to dislike it.


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Implementation is when the application is produced—similar to writing the program. You must consider the type of software you will use. This is, in part, determined by the type of application you are creating. There are four types of software available:

o Text Editors

o WYSIWYG (What You See is What You Get)

o Presentation Software

o Authoring Software


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Text Editors

A text editor is a simple program such as Notepad that lets you enter text.

At a simple level Notepad can be used for basic word processing—although this seldom happens as most computers have word processing programs with more features than a text editor.

Instead of word processing a text editor can be used to enter instructions for displaying a multimedia application.


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Text Editors

A common use of a text editor is in the creation of web pages where instructions in HTML (Hyper Text Mark-up Language) are entered.

When the text is entered the screen looks nothing like a web page—you must use a separate piece of software called a web browser (e.g. Microsoft Internet Explorer or Mozilla Firefox) that understands the instructions in HTML, translates them and displays the web page.


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Text EditorsHere is a web page written using a text editor:


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Text EditorsAnd here is the same page viewed using a web browser:


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Text Editors – Advantages

o Text editors are very simple programs that place very little demands upon a processor.

o Entering a programming language gives you greater flexibility over the media elements than using other techniques.

Text Editors – Disadvantages

o A programming language has to be learned.

o It is very difficult to visualise what a final page will look like.


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WYSIWYG

Pronounced ‘wizzywig’ this stands for What You See Is What You Get. A WYSIWIG program is one that lets the user view the application as it will finally be seen while it is being developed and edited.

Microsoft Publisher is an example of a WYSIWIG package.


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o It is ideal for beginners as no programming language needs to be learned, only how to use the software. o An application can be very easily edited compared to changing code in HTML.

WYSIWYG - Advantages

WYSIWYG - Disadvantages

o WYSIWIG software costs more than text editors.

o More RAM and a faster CPU are needed than for a text editor.

o WYSIWYG packages may not allow as detailed editing as coding with a text editor.


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WYSIWYG and Text Editors

While both have their advantages it is important to note that both will only be used for very simple multimedia applications. Neither would be used for professional applications with considerable interactivity.


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Authoring software

For powerful applications with greater degrees of interaction a different type of software is required. Tutorials on CD-ROMs and DVD-ROMs, information systems in public areas like kiosks and museums and some computer games are developed with authoring software. There are two ways that authoring packages can be used:

o Programming/adding scripts.

o Placing icons then adding instructions.


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Writing a program or script provides a great deal of flexibility in the application. Placing icons avoids the need to learn a programming language but allows fewer features to be included.

The most common examples of authoring software are Flash (used for animation and simple games), Dreamweaver (used for high-end web sites) and Director (for creating interactive guides), all made by Macromedia. Microsoft FrontPage, used for web site creation and management, is also an example.


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Presentation software

Presentation software is mainly used to generate applications that will be delivered to an audience such as slide shows.

Presentation software has fewer features than authoring packages as they create applications with less interaction – mostly hyperlinks.

Presentation software is easy to learn and less expensive than authoring packages. Microsoft PowerPoint is the most popular example in this field.


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Testing is done in a different way from testing a program but the intention is the same.

In the example of a web page all of the links would be tested to see if they took the user to the expected page. All links must work as pages can be rendered inaccessible if a link is broken. All links that return a user to an index page or home page must be working as clicking on the back button in the web browser to return to an original page is inefficient.

Typical users may also be asked to “beta test” the site. i.e try it out to see if they discover errors.


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Included with a multimedia application are the technical guide and user guide.

The technical guide is a complete guide to all aspects of the package. This will also include a statement of the hardware requirements needed to run the application.

A user guide should provide information on how to use the application and what to do if the user gets stuck. (This may comprise a tutorial and help section in electronic and/or paper form.)


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The evaluation stage is when the application is assessed against the requirements specification.

The use of storyboards is useful to see that each page looks the way it was designed to.


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Once a multimedia application has been developed it can then be distributed among users. If it is distributed via the internet (e.g. a web page) there are several issues to consider.

In order to view simple web pages you must have: an internet connection, a subscription to an ISP and a web browser.

A browser is a piece of software that enables pages to be translated from their own language (HTML) into the format the user sees when looking at a web site.


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The main browsers are:

o Microsoft Internet Explorer

o Apple Safari

o Netscape Navigator

o Mozilla Firefox

A browser is like a translator program—the HTML is like the source code and the page we view is the object code.

The browser checks there are no errors in the page and that all HTML rules—called protocols have been met. If everything is OK then the page will be displayed properly.


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When you open a web page you are downloading it to your computer. This is fine in most cases as web pages tend to be quite small in size.

However some web sites use complex multimedia content that means they take longer to open—some web sites include videos, games and sound clips. When multimedia content is built into a web page this is called embedded data.


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Embedded Data – Advantages

o Files are easier to manage if everything that is to be displayed on the page is included in the one file.

Embedded – Disadvantages

o Web pages with embedded data have a larger file size than those without embedded data.

o Not all data types (e.g. graphics saved as TIFFs) can be embedded.


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The alternative to embedding data is to provide a link to an other location where the data is held. Thus when the web page loads up it contains text and links or pointers to videos, graphics, sounds and animations that are stored separately.

You will need to download and install an extra piece of software (called a plug in) to view these media elements. A plug in works with the web browser to display certain types of data.


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Streaming is the process of watching video/listening to audio as it arrives rather than waiting for the whole file to download.

It is important to understand that most types of streaming are not the same as downloading files; if you download a file it is saved onto your hard disk and can be edited, forwarded or deleted.

Most streaming media files are copyright and once you exit a web page it is no longer on your computer. To access it again you would revisit the web site and the file would be restreamed.


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Codec is short for compressor - decompressor.

It is an algorithm (a set of rules or mathematical formulae) that reduces (compresses) the file size of a multimedia object such as a graphic or video clip, then restores its size (decompresses) when it needs to be displayed.

Codecs are needed to enable file sizes to be kept smaller and to be transmitted more quickly.


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There are several different ways that a file size can be reduced—some algorithms look for repeating data that needs only be stored once, other algorithms remove redundant data.

In order to access multimedia files either your hardware or software must have codecs built in. In the case of a PC that is receiving streamed files then the codecs are included as part of the media players. In the case of mobile telephones receiving video clips or radio broadcasts the codecs are embedded in microprocessors.


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Container Files

Sometimes applications contain several types of data e.g. a video clip contains both sound and moving images. Yet sounds and video are compressed in different ways: the sound may be stored as a wav file, the video as an MPEG.

A container file is a computer file format that can contain various types of data, compressed by means of standardized audio/video codecs.

The container file is used to identify and interleave the different data types.


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Container Files (continued)

Container files work by having an invisible area called a header. This header tells a computer what type of data is held in the file and which codecs to call up.- It also contains the synchronization information needed to play back the various streams together.

Simpler container formats can contain different types of audio codecs, while more advanced container formats can support multiple audio and video streams and features such as subtitles and chapter information

AVI and MP4 and MOV are examples of container files.


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Container Files – Advantages

The codec does not need to be downloaded with the file, thus saving storage space and transmission time

It is more convenient than storing and sending a series of separate compressed files. If audio and video are not grouped together they may not be in sync when played.