Wednesday, July 21, 2010

Multimedia Notes - Good Ones

“Multimedia Systems”

Ø Characteristics of multimedia systems: Multimedia means the use of different media to present a message or to entertain. Multimedia systems are information systems that combine a variety of different media types. In computer terms, Multimedia applies to software that can different forms of information and it has only become a possibility due to development of powerful and inexpensive computers that have the ability to record and play sound, display millions of colours and record and playback video.

· Multimedia systems as information systems that include combinations of the following media –

Text, hypertext, numbers – test is any sequence of symbols that have meaning such as keyboard symbols and in multimedia text allows the users to read and review the information at their own speed. Hypertext is text presented in such a way that when selected it links to new information. Hypertext makes multimedia interactive as it allows the user to obtain new information in any direct order which doesn’t have to be linear. Numbers like text are used to display information and often used for exact, accurate information.

Audio – sound is digitised by measuring its pitch and volume thus audio can either be in waveform or MIDI (Musical Instrument Digital Interface) format which uses a digital version of sounds to create music.

Images and/or animations – an image is the fundamental part of multimedia presentation as they contain a wide range of graphical information like graphs, drawings, pictures, icons etc. The hypertext images when used to provide navigation links, images are classified as hypermedia which is any display object that links to new information. An animation is a moving graphic like video and the basic principle of animation (on movie screens, TV and VDUs) is the persistence of vision.

Video – or moving images are similar to animation. Both video and animation add enormous appeal to a multimedia system. Video and animation are complex data types for information systems to handle since huge amounts of data needs to move between storage devices (both primary and secondary) and the display device fast enough to create smooth motion effects. Often data must be processed before it can be displayed.

Ø The differences between print and multimedia including:

· Different modes of display – print (static) media is limited to hard copy such as books, newspapers, magazines and posters. However multimedia (dynamic media) can be implemented for computer use, wireless pocket PCs, PC/TV combinations and other diverse applications. Once a book is published it cannot change thus its static but multimedia can be updated and distributed easily. In static media, changes have to be reprinted which is time-consuming, only one user can view it at one time, it can’t have sound and requires some imagination. Multimedia however has many advantages as its dynamic, changes can be immediately updated and put on website, allows multiple views at same time, has sound and interactive animations, is interactive through hypertext and hypermedia, but requires hardware and software. Print is limited to hardcopy mode while multimedia has multiple modes and print is presented in a linear or sequential way but multimedia is presented in non-linear and hierarchical way.

· Interactivity and involvement of participants in multimedia systems – the interactive nature of multimedia is another difference from static media. Interactivity means that the user is able to make an immediate response to what is happening and modify the process. Effectively, there is a dialogue between the user and the computer or communications device and the data access and transfer can be non-linear.

Ø The demands placed on hardware by multimedia systems, including – the audio and video/animation component of a multimedia require the greatest amount of storage space and processing. Thus a high level CPU is required plus high resolution (at least 1024 x 768) for multimedia applications. Text, numbers and hypertext is usually stored as ASCII or ANSI codes as they need little space and processing.

· Primary and secondary storage capacity as a result of:

Bit depth and the representation of colour data – the bit depth describes the number of data bits needed to store each pixel in an image. This sets the number of possible colours for each pixel. The bit depth controls the number of possible colours for each pixel. A display system with a bit depth of 1 could only store a 0 or a 1 for each pixel. If 1 represented white and 0 represented black, then every pixel on the screen would be either black or white. With a bit depth of 24, the colours that could be displayed are 16777216, thus a higher bit depth of 24 (true colour) represents true colour data.

Sampling rates for audio data – sound and other analog data is generally represented as transverse wave and converted to digital form by a process called sampling. The sampling size is the number of bits used to store each sample from the analog wave. A higher sample size results in increased accuracy but higher data storage requirements. The sampling rate is the number of samples or slices taken of the analog wave in a second. The higher the sampling rate, the better the representation of the initial analog signal.

· Processing as a result of:

Video data and frame rates – processing video files requires special hardware and software to enable it to be recorded and played back. Piped video is the simplest method of displaying video footage on computer screen. A frame is a single image in a video or sequence and frame rate is the speed with which video frames are displayed on the screen. Video is shown at a certain speed so that observer’s perception of movement is one of smooth motion. The PAL (phase alternate line) displays a frame rate of 25 frames per second and current PCs cannot sustain a transfer rate between primary and secondary storage of 1,500 Mb per minute, thus compression, decreased colour depth and decreased resolution are used to process video data. Digital video editing software allows digital video to be manipulated either by an insertion or deletion of a scene and can be stored on digital media like hard disk drive, CD, DVD or tape.

Image processing, including morphing and distorting - when an image undergoes a process of metamorphosis and changes slowly from on image to a completely different one is called morphing where image is changed pixel by pixel. Warping or distorting is another animation technique where an image is gradually distorted by changing its pixels either by stretching or resizing so image results in a different form eg. Changing your picture so you have very large ears. Image processing is an aspect of video work that demands processing power and morphing and warping are the primary types.

Animation processing – is the process of displaying a series of drawn images in quick succession, creating the effect of movement. Each drawing is a frame. Animation is based on the principle of persistence of vision thus animation seeks to create an illusion of smooth movement. Computers have made the task of animation easier via 2 methods: Cel-based animation is an animation technique where each individual frame is stored separately into a memory page and creates a separate picture for each frame with only small changes between the frames. This types of animation gives the animator complete control over every frame in the animation but is time and space consuming. Path-based animation is an animation technique in which the only part of the frame that changes is the moving object. The animator describes the path or movement of every object and the system then creates the animation frames with each object drawn in its correct position. The generation of scenes in-between by path-based animations is called tweening as animator only defines the starting and end point and the path to be taken, so tweening occurs. Thus path-based relies on system to create animations much faster with less storage requiring but animator doesn’t have much control.

· Display devices as a result of:

Pixels and resolution – a pixel is a single picture element which is the smallest controllable element on a graphics screen. A typical home VDU PC contains more than 600,000 pixels and each individual pixel’s colour and brightness is set by the computer to create an image that is displayed. The resolution is a measure of the quality or detail present in a displayed image. It’s usually described as the number of pixels across and down the screen (e.g. 640 x 480 was considered HIRES (high resolution before but is now LORES with 12000 x 860 now considered HIRES). High and low resolution describes graphic images and graphic display systems. The more pixels that can be displayed by a screen, the better the image quality or resolution.

Ø The variety of fields of expertise required in the development of multimedia applications including: a number of different skills are required for the development of a good quality multimedia application such as –

· Content providers – are people who provide material such as video footage, audio tracks, competitions and other materials. They’re experts in the subject matter of the application and ensure its technical accuracy.

· System designers and project mangers – are basically the people who plan and design the system. They’re responsible for the overall design, development and completion of the application. They require leadership skills as well as technical knowledge about systems development.

· Those skilled in the collection and editing of each of the media types – collection and editing of media types is an area that requires particular expertise. Depending upon the intended delivery mode, eg. CD or Internet, collectors/editors are required to consider issues such as bandwidth and data transfer requirements, screen resolution and memory and processor demands to ensure the chosen media mode is sufficient to meet the application’s purpose.

· Those skilled in design and layout – are required to ensure that the presentation of the application, screen layout, keyboard commands, flow of information and other such areas produce an ergonomically sound interactive application which meets its design goals.

· Those with technical skills with the information technology being used – are required to assist developers and users of a computer system with questions relating to hardware and software maintenance, usage and repair and so on. In terms of development of multimedia systems, such skills would involve selecting, installing and configuring appropriate hardware and software.

Examples Of Multimedia Systems:

Ø The major areas of multimedia use, including:

· Education and training: multimedia systems designed for teaching/learning – multimedia is excellent for educational purposes as it uses different methods of display whereas animations provide changing scenes , text and subtitles assist the students who are hearing impaired and sound can assist those with sight disabilities. Multimedia offers education at an individual level with desired speed and convenience. Students can be trained via the Internet through multimedia terminals at home. Multimedia education is thus interactive assistance in developing student’s skills by educating and informing them. Its components are: Data and Information (text, images and video that combine to produce structured activities the user views as information, more emphasis will be on text-based information), Participants (teachers and students, parents and siblings, they will also be using the system), IT (high resolution VDU, audio speakers, CD/DVD drive, sufficient RAM and reasonably fast processor, keyboard and mouse for children’s click n drag, headphones) and Relationships (the direct user, the students who are also the participants, will control the path taken through applications as they select from the interactive menu via a mouse or keyboard and use the multimedia CD to their own need, speed and preference).

· Leisure and entertainment: multimedia systems like computer games and other leisure activities – electronic games, 3D adventure games, sporting games and interactive movies have become extremely popular forms of multimedia applications due to their high level of interactivity. The new generation of games provide ingenious levels of interactivity and realism to captivate the user thus they based mainly on animations and videos rather than text due to their entertainment purposes. The components are: Data and information (realistic videos, animations and sounds with limited text), Participants (game players, ordinary people of all ages and abilities, more likely to be children and teenagers), IT (peripherals such as joystick, mouse, keyboard and track-pad, high resolution VDUs, high quality audio speakers, CD and DVD drive) and Relationship (the participants are also the players who play the games for leisure using a joystick etc and make their own choices via navigational and hidden hypermedia).

· Information: multimedia systems that provide information such as an information kiosk- multimedia has been used to provide guidance through the use of information centres in locations like museums, airports, rail stations etc. They’re aimed at quickly providing very basic information. An information kiosk allows the user to obtain specific information without asking a stranger like location details, product availability, arrivals and departures are all examples of information that can presented in this format. Its components are: Data and information (text with graphics and signs to provide basic information, audio to give directions, simple navigational options with little text, hypermedia to provide basic details), Participants (general public who happen to visit an information kiosk, travellers, tourists etc.), IT (touch screen for ease of using multimedia computer, trackball built into the system, display terminals including high resolution VDUs and monitors, laser screens) and Relationships (the general public is also the participant as they use hypermedia via touch screens to obtain basic information).

· Virtual realities and simulations such as flight simulator – simulation is designed to duplicate real situations so user can gain valuable training and experience from using the system. It represents the behaviour of physical or abstract systems to help pilots and drivers to deal with various real-life situations in a safe environment. Virtual reality is a computer-generated artificial reality that projects a person into a sensation of 3 dimensional space, it convinces the user that they are part of a real situation. Components are: Data and information (audio and video to represent situations, in a VR – a 3D video headset will allow user to feel the reality) Participants (simulation – pilots and specialists to further knowledge and training, VR- ordinary people who play games etc), IT (high resolution VDUs, simulator – keyboard and controls to interact with the flight’s cockpit, VR - joystick, mouse and keyboard) and Relationships (both participants are also the users as they interact with the system via a keyboard or joystick).

· Combined areas such as educational games – this is where multimedia applications provide leisure as well as educational games that seek to interact with the student and make learning fun. Games such a building blocks by using times table is 1such example. In this multimedia, text will be limited but animation and video will be emphasised to make learning fun and interactive. The data and information (limited text, animation, audio and video), Participants (students, teachers) IT (joystick, mouse, high resolution VDUs etc).

Ø Advances in technology which are influencing multimedia including:

· World Wide Web and communication speed and capacity – appearing in 1993, www was the first method of sharing and linking text documents over the Internet, it was the 1st widely available hypertext system that could be used by people with totally different computer systems. It has made it extremely easy for large number of people to access multimedia systems stored as a series of linked webpages. Continued improvement in communication speed (or bandwidth) through technologies such as cable, ADSL and satellite have made the presentation of multimedia content via Internet a viable option. It has overcome the slow download speeds particularly for pages with graphic, sound and video. With an advanced ADSL connection, these data types can be downloaded within seconds and have improved communication capacity.

· CD-ROM speed – this stands for compact disk-read only memory and is an optical disk format that is used to hold pre-recorded text, graphics and sounds which can be run many times by purchaser. Before it had a single speed drive with the ability to access data at 150Kb p/sec. Through improved technology its now possible to purchase drives that are 40 or 60 times faster and the faster the drive spins, the more quickly it is able to deliver information to the processor. This improvement effectively began the multimedia revolution due to the sudden availability of high capacity random access data storage offering better quality animations.

· Digital Video Disc – this is what DVD originally stood for but now it stands for digital versatile disc. The enormous storage capacity of a DVD means that a single disc can store an entire movie, with extra scenes, multi- language options etc. A DVD can store anything from an encyclopaedia, interactive and far realistic games, complete training systems and complex simulations. Its biggest advantage over CD-ROM is greater storage capacity allowing up to 17Gb of data to be stored in contrast which is 28 CDs in every DVD. Increased storage means increased flexibility for multimedia developers, so it’ll replace CD-ROM and VHS.

Displaying In Multimedia Systems:

Ø Hardware for creating and displaying multimedia, including:

· Screens: CRT displays, LCD displays and touch screens – A CRT is the most commonly used graphic display device. A Cathode Ray Tube is a sealed vacuum chamber that can fire and accurately focus beams of electrons on a chemically coated screen. A LCD (liquid crystal display) is an electro-optical device used to display digits, characters or images that uses transistors and a complex chemical solution to display each pixel. LCDs use a thin layer of liquid crystal material that changes electrical properties when electric current is applied, thus light is either blocked or allowed to pass through. Each area of the screen that represents a pixel can be individually affected. LCDs are smaller in size and weight with considerable savings in power, more clarity and resolution than CRTs but are more expensive. A touch screen is a computer display screen that is sensitive t human touch, allowing a user to interact by touching pictures or words on screen. They are used in information kiosks, in computer-based training services, and in systems designed to help impaired individuals with difficulty using a mouse or keyboard.

· Projection devices – this allows the projection of video and graphic images onto a screen. It produces an electronic image onto another medium. They were once very expensive and only worked in very dark rooms though still expensive, the projectors can display very bright light and clear high-resolution images in broad daylight. They’re now common in sporting and mass entertainment events or classroom teachers. It contains a chip with up to 500,000 mirrors which can individually controlled. By shining a bright light onto the chip while supplying its electrical circuits with a TV signal (from a camera, VCR or computer) the chip is able to create an image that can be projected onto a screen.

· Speakers, sound systems – sound has become an important part of a multimedia presentation as PCs are sold with high quality speakers. Sound special effects, particularly those giving ‘3D’ sounds are now common in computer games. The sound cards in most multimedia PCs can also play and create both MIDI and waveform files. Speakers provide the cheapest and easiest output device for audio but the quality matters. A sound card is needed for digital audio output and convert binary data into information by producing a digitised sound.

· CD-ROM –

· Video – a suitable video card to receive and translate the video data into a form that can be displayed on the scree is called a piped video method.

· Head-up displays and head sets – virtual reality often uses a headset to give the wearer a 3D image and stereo sound. It removes all the other outside distractions so that the user’s senses of sight and sound are totally dominated by the artificial sound. Two VDUs are used in the headset, each giving the user a slightly different perspective view of the same scene. When the brain combines the 2 images, a realistic 3D view is created. Head up displays are smaller, less intrusive version of the headset developed for use by pilots.

Ø Software for creating and displaying multimedia, including:

· Presentation software – these use graphics and data/information from other software to communicate and make presentations of data to others assisting users in making automated slide presentations. The PowerPoint is an example of presentation software. Modern presentation software allow the creation of a professional looking multimedia with just a few clicks and these presentations They can incorporate text, numbers, images, audio, animation and video and allow relatively fast generation of a series of linked screens. They can be viewed using a standard monitor, data projector for a large group, hard copies of slides and transparencies and hard copies of paper handouts.

· Application software such as word processors with sound notes and video – application software is a computer program used for a specific task. They allow you to add the elements of multimedia into just about any document. Programs like Word (used to produce word processed documents), and Adobe Photoshop (used to generate complicated graphical images) can be used to generate content that can be incorporated into a multimedia project. Digital video editing packages for computer systems allow user to create transitions, titles and sound, and to record sound and video clips but are expensive with high quality. Video or sound can even be imported by some word processing software. Specialist multimedia application software like Windows Media Player or Real Jukebox allows sound and video files to be displayed.

· Authoring software – these multimedia software are new that incorporate many features of stand-alone applications. They allow users to create multimedia using both static and dynamic media and records the final product onto CD, DVD, tape, a computer hard drive or other electronic media. Authoring software allows the user to sequence and time the occurrence of events determining which graphics, sound, text and video files are to be utilised at any given point in the final product and allows creator to determine the level of user interaction. Examples include Macromedia Authorware and Adobe Acrobat.

· Animation software – this software eases the burden of drawing the hundreds of cells or frames required for even a simple animation. There’s a wide range of animation software available each with weaknesses and strengths, but the majority provide the tools to produce an animation using 1 of the different animation techniques, including traditional frame-by-frame, path-based, morphing or warping eg. GIFAnimator. Programming languages eg Consumption++ and Java are used to create high quality professional multimedia applications.

· Web browsers and HTML editors – these are known as scripting software packages that allow the development of quite sophisticated multimedia applications. A web browser is software that allows you to browse through and view the thousands of websites that exist on WWW such as Internet Explorer. Editors allow the generation of pages on the Web and range from simple text-based programs which require coding of HTML to WYSIWYG systems like Macromedia Dreamweaver which allow coding to be generated without direct user intervention. HTML (Hypertext Markup Language) is the language or code that is written on pages on the Web. Web browsers and HTML editors assist users in creating and editing multimedia material for the WWW and for locating and viewing material on the Web.

Other information processes in Multimedia systems:

Ø Processing: involves the manipulation of data as collected data is imported into multimedia software which use compression techniques to minimise data transfer rates, bandwidth and storage requirements.

· The integration of text and/or number, audio, image and/or video – multimedia by definition consists of information presented in various forms including text, numbers, audio, images and video. Thus integration occurs in multimedia where items of data from a range of forms of information are combined together leading to increased storage requirements. The solution of course is compression to reduce redundant data.

· Compression and decompression of audio, video and images – the 3 data types are compressed to reduce their file size thus the storage capacity and the processing required. In compressing a file, processing occurs when the multimedia is moved from a secondary storage (like hard disk or CD-ROM) into the system RAM. Because multimedia contains enormous amounts of data, processing is an elemental part of creation.

· Hypermedia as the linking of different media to another – hypermedia is often utilised in multimedia and refers to the linking of data types. Eg. Clicking on a particular object may cause additional text to be displayed, or the user to ‘jump’ to a different section of the program, or cause a video clip to play. The term ‘hyper’ refers to a link between elements of the program and so hypertext for instance is text that links to new information.

Ø Organising presentations using different storyboard layouts, including: a storyboard is an illustrated scene-by-scene layout of the multimedia presentation showing the sequence of events and navigational links:

· Linear – the user moves sequentially through the multimedia presentation where only options are back and forward. It’s ideal for testing presentations where 1 task must be finished before moving on to next one.

· Hierarchical – this allows the user to choose from multiple options. The information is presented in a linear format but the user can choose which direction to take allowing them to explore more in detail. It’s ideal for information or leisure related tasks where at each stage, multiple options are provided.

· Non-linear – allows the freedom to move in any direction within the structure at any time. They choose any path without significant restriction. Ideal for content presentations like multimedia encyclopaedia.

· A combination of these – composite layout is where each of the 3 structures are combined. It includes a linear, non-linear and hierarchical structure.

Ø Storing and retrieving:

· The different file formats use to store different types of data – images, audio and video can be stored in a wide variety of formats. For text and numbers: ASCII, RTF (Rich Text Format), TXT and DOC are available. For images: JPEG (Joint Photographic Experts Group) compresses images, GIF (Graphics Interchange Format) compresses images, BMP (Bit Map) uncompressed bit-mapped file format that increases size and HTML is a text based language used to create documents on web for images, text, audio and video. For audio: WAV (wave file) uncompressed sound format with large sizes but very common, MIDI (Musical Instrument Digital Interface) has small file size and is common, MP3 (MPEG Audio Layer 3) compresses file size greatly with high quality and easy to create and QuickTime which supports both wav and MIDI but uncompressed. For video: QuickTime which supports multiple file formats but has poor compression creating larger files, MPEG (Motion Pictures Experts Group) has very high compression and is standard for moving images and AVI (Audio Video Interleave) is the standard for digital video and common format but large size.

· Compression and decompression – compression reduces the quantity of data in a file by a variety of methods. Audio files are compressed to reduce their storage space and transmission time and popular format is MPEG-1 audio layer 3 or MP3 – it uses lossy compression technique with little loss of quality. Video compression is achieved by use of codec a compression/decompression algorithm which is the method used to compress and then restore a data file. A number of video codes are in use including MPEG-1, -2 and -3 created by the Moving Pictures Expert Group. Image compression involves minimising the size in bytes of a file without degrading the quality of the image to an unacceptable level. This reduction in file allows more information to be stored in a given amount of disk or memory space, it also reduces the time required for information to be sent over Internet. Compression schemes can be lossless (where the decompressed data is identical to the original data with nothing lost in transaction such as GIF) and lossy (where the decompressed data is slightly different from the original eg. JPEG and MPEG-1). Decompression, or the expansion of a compressed file, is only possible if a lossless compression scheme is utilised. So it’s only possible to expand a compressed file format to the original data set if the compression algorithm doesn’t discard information in the original compression process.

Ø Collecting: for multimedia requires the digitisation of data presented in another form:

· Text and numbers in digital format – for use on computer, data needs to be converted into binary numbers – digitisation – which is done by coding. ASCII is a standard 7bit code that represents 128 letters, numbers and punctuations as a 7bit binary number with 0s and 1s.

· Audio, video and images in analog format – these three data types in the real world are referred to as analog data and fill the physical environment that surrounds us. They have continuous values and an analog signal is an electrical signal in the form of a wave. Analog or real world data must be converted to digital for processing by a computer after collecting it as digital data represents the computer world.

· Methods for digitising analog data – audio is digitised via sampling where regular measurements are taken of the sound. Video data is displayed by the piped video system where a video card receives and translates the video data in a form that can be displayed over the screen. Capturing full motion video requires a video capture card to digitise the signal before storing on disk for later editing. Analog video data also undergoes the sampling process where a video digitiser measures and records signals that represent colours and light intensities where in contrast to audio sampling, the quantity of data that the video digitiser handles is considerably larger. Digitising an image involves converting it into bit patterns within a computer’s memory which can be edited, manipulated and improved. Optical scanners and video digitisers convert images into bit patterns by making many measurements of the signal coming. An optical scanner is a digitising device that shines an intense beam of light at a paper document. The light detectors inside the scanner measured the intensities and colours of the reflected light and analog to digital converters then turn these measurements into digital bit patterns that can be stored for later use.

Issues related to multimedia systems:

Ø Copyright: the acknowledgment of source data and the ease with which digital data can be modified – Copyright is the ownership of intellectual property. It is illegal to copy or reproduce a multimedia work without the express permission of the author. The particular issue with computer programs is that they’re relatively easy to copy and modify digital data with the appropriate tools. This becomes an ethical issue for users who have the technology to break copyright and avoid detection. The author of a saleable item has the right to expect a just a reward for their efforts. Another aspect of this is the need for the developer to fully acknowledge all sources that they use. E.g. if a multimedia encyclopaedia developer produced a program without acknowledging external sources of information and images, then they’re contravening copyright laws. When original work is produced using published sources, the author, URL address, date of publication, publisher, etc should be acknowledged. The digital data in multimedia is easy to locate copy and edit.

Ø Appropriate use of the Internet and the widespread application of new developments on it such as live video data – appropriate use of Internet and other multimedia contents involves the issues of ethics and moral behaviour. As communications technology improves and new uses of Internet appear, like netbanking, there are many opportunities of misuse and abuse. Materials can be easily copied and presented as original work without acknowledging. In using the Internet, ethical considerations such as privacy need to be addressed as it’s a common practice for people and organisations to set up video cameras and streamline video on Internet. People captured on video may not want to be displayed worldwide on personal screens. The placement of pornographic images and other disturbing materials within the reach of young people browsing the Internet raises legal and ethical issues, as does the presence of flashing hyperlinks indiscriminately tempting Internet users of all ages to visit casino websites.

Ø The merging of radio, television, communications and the Internet with the increase and improvements in digitisation – the increasing usage of digitisation due to digital convergence where content can be stored as a digital file rather than the more traditional analog form in multimedia has merged communications via radio, TV telephones, computers, the Internet and other modes into one. Web-TV allows the TV to act as a monitor connected to Internet; telephony is also possible with Internet using a sound card, microphone, PC and Internet to communicate as audio-conferencing. Desktop radio broadcasting is available on the Internet and audio and video files are available as streaming audio/video allowing you to listen or view video while it is being downloaded for playing at a later stage. Streaming technology has allowed the development of online broadcasting and WebTV.

Ø The integrity of the original source data in educational and other multimedia systems – data integrity is the accuracy, consistency, currency and reliability of the data. The integrity of data becomes more important as amount of information on Internet increases. Sometimes browsers will be unaware that the information on a website is dated if site hasn’t been updated. Publishing on the Internet is less formal and can be done by anyone with appropriate technology so data can be anything pretending to be fact. Integrity and accuracy is vital in a multimedia application designed to educate. An educational multimedia should provide a bibliography and identify its sources so that the accuracy of its information can be checked. The publishers of the Encyclopaedia Britannica, who have print, CR-ROM, and online versions of their world-renowned reference materials available, could choose to use data from questionable sources but don’t instead they ensure the integrity of their product. However, overtime the accuracy of their factual information diminishes which is why they reproduce yearly editions. If the aim is information, such as a multimedia kiosk, then integrity will be judged by ease of use and honesty where accuracy is important but the need to check for sources is rarely an issue. If the aim of multimedia is entertainment, then factual accuracy isn’t important but integrity is judged by speed, reliability and variety of the games. In a training simulation (and VR), integrity will be judged by how closely the simulations match reality and to what extent its presents the users with a realistic experience otherwise it’ll be of little value.

Saturday, July 17, 2010

IPT Notes Backup {2010}

GLOSSARY


Word

Definition

TPS

An information system that collects, stores, modifies and retrieves the daily transactions of an organisation

Controlled Process

A controlled process is a process that must support an organisations operations

Rapid response

The turn around time from the input of the transaction to the production of the output.

Batch processing

A Transaction Processing method that collect transaction data as a group, or batch and process it later

Real-time processing

A TP method that processes data immediately

Concurrency

A property of a transaction processing system that ensures two users cannot change the same data at the same time

Atomicity

A property of a TPS that ensure that all of the steps involved in a transaction are completed successfully as a group

TPM

Software that allows transaction processing application programs to run efficiently

Data validation

The checking of the accuracy of the data before it is processed into information

Manual transaction (MTS)

Business systems that operate without the use of machines

Users

Pinky is an idiot. Users are people who use the system directly

Participants

People who use the system indirectly

Reservation systems

They are used to set aside certain items for a product of a customer to use at a future time

POS terminal

They send inventory data to a central computer when the sale is made

EFTPOS

Electronic Funds Transfer At Point Of Sale. A way of paying for things electronically

Library loan system

Used to keep track of items borrowed from the library

Database

An organised collection of data

Hierarchical Database

Data organised in a series of levels

Network D/B

Organises data as a series of nodes linked by branches

Good data placement

A database that is designed to access patterns of data and to place frequently accessed data together

Short transaction

Self explanatory

Real-time backup

Processing that is characterised by continuous operations with downtime kept to a minimum.

High normalisation

Redundant information that is kept to a minimum whenever possible to increase the speed of updates

Historical data

Data that is rarely referenced into a separate database

Master file

Contains information about an organisations business situation.

Transaction file

A collection of transaction records.

Work file

A temporary file in the system used during the processing

Program file

Contains instructions for the processing of data.

Consolidated

Data that is organised using consistent naming conventions, measurements, attributes and semantics

Subject oriented data

A large amount of data stored across an organisation.

Read only data

Data that has been moved to the data warehouse and cannot be changed unless the data was correctly

Backup

Another copy of the data that could be used to rebuild the system

Journal

A journal maintains an audit trail of transactions and database changes.

Checkpoint

A suspension of all processing to synchronise its files and journals. All transactions in progress are completed, and the journal entries are updated. The DBMS then writes a special record to the transaction file. This record is called the ‘checkpoint record’

Recovery manager

A program that restores the database to a correct condition and restarts the transaction processing

Backward recovery

Used to back out or undo unwanted changes to the database.

Forward recovery

Starts with a backup copy of the database.

Magnetic tape

Magnetic tape is often used as a backup medium. It is a very long, thin strip of plastic coated with a thin layer of magnetic material

Sequential access

This is a form of access that starts at the beginning of the tape and reads from one reel to another

Grandfather-father-son backup

This is a backup procedure that refers to at least three generations of backup master files. The most recent backup is the son, the second last is the father, and the oldest is the grandfather

Partial backup

Partial backups occur when only parts of the master file backup.

Direct access

Direct access occurs when data is accessed without accessing previous data items.

MICR

Magnetic Ink Character Recognition systems are used to read account numbers on cheques.

ATM

Automatic Teller Machines are used for common banking transactions

Barcode reader

Used in retail industries at point of sale to collect product information.

On screen forms

On-screen forms are created for computerised data entry purposes to populate fields in a database.

Web forms

Used by users that wish to purchase items over the internet

DSS

Used to assist people in making decisions and providing information, models and analysis tubes.

Data mining

Used to find relationships and patters in the data stored in a database

Automation of jobs

The use of information technology to perform tasks once performed by people.

Bias

Data that is unfairly skewed or gives too much weight to a particular result

Data security

The use of a series of safeguards to protect the data

Data accuracy

The extent to which data is free from errors

Data integrity

The reliability of data. Involves the accuracy, currency, and relevance of data

Downtime

The total period that a service or component is not operational within an agreed service time


INFORMATION SYSTEMS AND DATABASES
Information systems:
Information systems perform a set of information processes requiring participants,
data/information and IT.
Created to provide access to information for an organisation or individual.
Data is head in a database and access is achieved using a DBMS.
Characteristics of information systems:
− Organisation of data into information.
− Analysing the information to give knowledge.

Purpose of information systems:
Transaction
processing
systems [TPSs]
Collect, store, modify and retrieve the daily transactions of an organisation.
− Batch processing collects the transaction data and processes it later.
− Real-time processing is processed immediately.
Examples: POS terminal, processing credit card payments, tracking receipts of
materials from suppliers.
Decision support
systems [DSSs]
Assist people to make decisions by providing information, models and analysis
tools.
Examples: system that analyses the stock market and helps the user to make
decisions about buying and selling shares.
Expert systems Provide information and solve problems that would otherwise require a person
experienced in that field. It asks a number of questions and compares their
answers to a knowledge base
Examples: system that help doctors diagnose infectious blood diseases and
prescribe antibiotics. Patient’s medical details are compared to its knowledge
base.
Solutions are not always correct, up to the user to accept or reject solution.
Management
information
systems [MISs]
Provide information for the organisation’s managers. Presents basic facts about
the performance of the organisation.
Examples: Execute Information Systems (EIS) provides information on
strategic issues.
Office
automation
systems
Provide people with effective ways to complete administrative tasks in an
organisation. Uses a range of software and communication technology.

Examples of database information systems
Information systems that uses a database. Databases are accessed by a database management
system [DBMS]. INFORMATION SYSTEMS AND DATABASES
• School database: information about teachers, students, classrooms and subjects.

Environment

− The school community (students, staff, parents)
− The educational services offered by the school/
− The flow of information between the school and authorities.
− The hardware and software.
− Any organisation, business or individual that receives information generated by the
school database administration systems or supplies data for the system.
Purpose
− To maintain the efficient operation of the school, its personnel, fiancés, resources and
administrative tasks.
− To provide information on student enrolments, subject selections and assessments for
both school staff and educational authorities.
Data / information
Information on people, resources and processes eg…
− Equipment registers; Finance and purchase orders; GST records; Library resources and
loans; Staff information; Student marks and grades; Student personal and academic
information; Timetables and room allocations.
− Most data stored on an administration computer network in the school office and library
and some on individual staffroom computers.
Participants
− School office and library staff who use the system.
− Teachers who add class information into the system.
− Students who search the library catalogue.
− Everyone in the school is likely to be a system participant at some stage.
Information Processes
C O A S P T D
− Collecting: through enrolment forms, marking of class rolls, payment of fess, recording
results in class mark books, library loans and returns and administrative tasks.
− Organising and storing: a number of different databases that deal with student and
staff information, resources of various types and finances.
− Analysing and processing: creating class lists, student reports, financial reports,
purchase orders, receipts and over due book lists.
− Transmitting and receiving: some data are transmitted to and received from
educational authorities e.g. BOS.
− Displaying: input and output data are displayed on VDUs and printouts.
Information
Technology
− Computers (data entry, access and in staffrooms)
− Barcodes readers (library loans and returns).
− A student inquiry and loan/circulation network.
− Software: OASIS office network administration system, motorised mark book,
spreadsheet application.
INFORMATION SYSTEMS AND DATABASES
• RTA: information on automobiles.

Environment

− All drivers, driving instructors, driver examiners.
− Vehicle owners, vehicle inspectors.
− RTA services eg registration and licensing.
− Flow of information between the RTA and the NSW Department of Transport.
− Police and courts
− Hardware and software.
Purpose
− To manage the registration all the drivers and motor vehicles in NSW.
− To send out vehicle registration payments requests.
− To provide statistical information on drivers and vehicles to the government and
registration information to other authorities.
Data / information
− Driver personal details, payment details.
− Driver licence number, license type and classification, driving history.
− Vehicle identification number, make and model.
− Vehicle owner details, registration number, payment details.
− Vehicle inspection record, insurance details; GST records.
All available to authorise RTA employees at any motor registry and vehicle inspection
station anywhere in the state.
Participants
− Data entry operators, inspectors, counter staff and administration officers at RTA
offices.
− Motor registries and motor vehicle inspection stations.
− Police Department Traffic Branch.
Information Processes
C O A S P T D
− Collecting: through registration application forms, licence applications, renewals,
vehicle inspection and driving test results.
− Organising and storing: a number of different databases that deal with drivers,
vehicle information and finances.
− Analysing: producing statistics on registered vehicles and licensed drivers.
− Processing: vehicle registration and licence renewal forms are sent out.
− Transmitting and receiving: data on vehicles and drivers are transmitted to the Police
and other authorities when requires.
− Displaying: input and output data are displayed on VDUs and printouts.
Information
Technology
− Computers – keyboards and monitors (data entry and display terminals)
− EFTPOS machines (credit / debit card payments)
− Barcode scanners (registration notice payments).
− Networking between the computers (in office / building and links to a state WAN) INFORMATION SYSTEMS AND DATABASES
• Video stores: information on borrowers and videos

Environment

− Customers and staff
− Suppliers
− Entertainment and other services supplied by the store.
− The flow of information between the store and its head office.
− Hardware and software.
Purp
ose
− To keep accurate records of the stock (rental and sales).
− To collect data for further analysis by store management.
Data / information
− Customer details (current loans and overdue items).
− Video rental title records (items in stock and on loan)
− Saleable items records (videos, snack foods).
− Rental and/or sale figures for each item.
− GST records.
Most available to store staff, some may be available to customers through inquiry
terminals.
Participants
− Staff who check out videos and other products
− Staff who process returns.
− Staff who authorise orders for new stock.
− Head managers who use the data provided by the system for inclusion management
and planning reports.
Information Processes
C O A S P T D
− Collecting: through membership applications, sale items and rental videos passed
over the scanner, and new products that arrive at the store.
− Organising and storing: in product and customer databases.
− Analysing: producing statistics on video rentals, sales, delinquency rates (non-return
of videos) and store income.
− Processing: products are sold, rented, returned or arrive as new products. Video
rental or return, customer’s record is updated.
− Transmitting and receiving: all data is transmitted to the head office.
− Displaying: input and output data are displayed on VDUs and printouts.
Information
Technology
− Computers – keyboards and monitors (enter details of a new rental customer)
− Barcode scanners (database input devices).
− WAN link from the head office (to update database when there’s new video rental
titles).
− Customer inquiry terminals – touch screen and web like interfaces.
− Database management and sakes software.
− Network communication software. INFORMATION SYSTEMS AND DATABASES
Organisation methods
Process of arranging, representing and formatting data.
Database: an organised collection of data.
Non-Computer Methods:
− Telephone book
− Dictionary
− Recipe book
Computer-based Methods:
− Flat-file systems
− Database management systems
− Hypermedia
May be sorted: Alphabetically; numerically; chronologically; By Category, etc.
Non-computer and computer-based methods:
Computer based methods Non-computer based methods
− Easily edited.
− Large storage.
− Fast retrieval.
− Display options.
− Easily searched through.
− Many people can access it at once.
− Backup storage can be easily kept.
− Access to data can be restricted
− Sorting of data is flexible over a range of
fields
− Convenient to obtain information.
− Easily, inexpensively organise data.
− Do not need a computer or computer skills.
− Easier to keep secure therefore, remain more
private.
− Data is more difficult to use for other
purposes.

Databases
Database: a large storage of information. As an information system, a database allows the
effective manipulation of information it contains through a Data Management System (DBMS).
File: A block of data. A file in a database is divided into a set of related records.
Record: Collection of facts about one specific entry in a database. A record is divided into one or
more related fields.
Field: Specific category of data in a database. Data items in a field are made up of characters.
Character: Smallest unit of data people can use e.g. letters, numbers and special symbols.
Key: Fields that are used to sort and retrieve information. Usually, each key holds a unique item
that applies to only one record. Key is used when records are sorted, not all data has to be read
or retrieved.
− Primary key: a single or compound key that must have a value cannot be empty.
− Secondary key: a field that contains useful items of data often used in searches, not always
unique.
Types of keys
− Foreign key: an attribute of a table that is a primary key of another table. INFORMATION SYSTEMS AND DATABASES
Flat-file databases:
- Organises data into a single table.
- Simple to create and organize
- Inexpensive
- Data for the whole database is contained in
a single file
- Managed by programs called file managers
- Consists of fields, records and files
- High level of data redundancy
- Access is often sequential, slower access




Relational databases:
- Organises data using a series of related
tables.
- Provide a method of storing data based on
multiple databases linked together by
common keys. The keys provide the facility
to build up huge databases without necessary
duplicating information (data redundancy) –
the data is shared.
- Draws information from one or more
additional files as well as the current file
- Needs a Primary Key / Link (Unique key
field)
- Organisation of data involves a schema.

Relationships are built between the tables of the relational database to provide a flexible way of
manipulating and combing data.

Schema
- A data definition for a database.
- An organised plan of the entire database, showing how and where the data is found, description
of the data, data’s logical relationships.

Relational database: defines the entities, attributes and relationships.
Entity: A specific thing about which information is collected and stored.
Attribute: Defined property of an entity (fields).
Relationship: The way the entities related to each other. There are three ways:

Types of relationships
One-to one: when each record in the first entity is related to exactly one record in the sconed
entity.
One-to-many: when one record in the first entity is related to many records in the second entity,
but any record in the second entity only relates to one record in the first entity.
Many-to-many: when each record in the first entity is related to many records in the second
entity, and each entity in the second entity is related to many records in the first entity.

INFORMATION SYSTEMS AND DATABASES
Views of data for different purposes:
• Tables: an organisation of data into columns (attributes) and rows (tuples).
• Forms: used to view, enter and change data in a table.

Data modelling
Process of identifying entities, the relationships between those entities and the attributes of those
entities. Used to develop a schema for the database.

Data dictionaries: a comprehensive description of each field (attribute) in the database. It
contains information about the characteristics of each item entered in the database eg field name,
field size, data type and field description.

Field name Name of the field, e.g. surname
Data type kind of data that can be stored in the field
Alphanumeric data: alphabet, numbers and symbols.
Numeric data: numbers and numerically related symbols.
Boolean or logical data: composed of true / false or yes / no.
Data date: displayed as dd / mm / yy or mm / dd / yy.
Time date: in the form hh / mm.
Field size Number of characters allowed in each field, e.g. 50
Description Specifies the contents of the field, e.g. surname of student

A data dictionary consists of metadata – data about data. Provides a common ground for people
working on a project at the same time. This reduces data redundancy – the undesirable
duplication of data within a database.

Schematic Diagrams:
Graphical tools that help define the database. A common schematic diagram is an entity-
relationship diagram [ERD]; it’s a graphical method of identifying the entities and showing the
relationships between them, helps to determine the data to be included and excluded from the
database.

Normalisation:
Process of studying the conceptual schema for a database and organising it into a group of tables
in the most efficient way, that is, the production of a relational schema which minimizes data
redundancy.
The degree of normalisation has been defined in terms of forms such as: INFORMATION SYSTEMS AND DATABASES

- First Norm First [1NF]: (basic level of normalisation) moving data items into separate tables
where the data in each table is a similar type.
- Domain/key normal form [DKNF]: (final level of normalisation) a key uniquely identifies each
row in a table. A domain is set of permissible values for each attribute.

Hypermedia and Hypertext:
Hypermedia is the storage of information using a set of documents that may contain text,
numbers images, audio and video. Each document is independent and information is retrieved
using hypertext.
Hypertext: a system where documents can be cross-linked in such a way that you can navigate
from one document to the next by clicking on a link. A link / hyperlink allows the electronic
connection.
Node: a computer that has the destination of the link.

Links
Links between nodes in a hyper document have no structure. They are associated with anchors
and bookmarks – smaller parts of the nodes.

Uniform resource locator [URL]
Address of a file or resource on the Web.
http://www.smh.com.au/crossword.html


Parts of the URL:
- Protocol: transfer method used to access a particular resource on the Web ‘http://’ [hypertext
transfer protocol].
- Domain name: address of the specific computer where resource is located (can be replaced by
IP number).
- File path: the full path to the file to be retrieved.

HTML [hypertext mark-up language]:
A set of special instructions that indicate how parts of document will be displayed and navigated.
Viewed in a web browser. HTML editor specialises in writing HTML code. HTML tags are metadata
(information about data).

Protocol Domain name File Path INFORMATION SYSTEMS AND DATABASES
Tools for organising hypermedia:
Storyboard: a series of frames, each representing a different action or screen image. Used to
organise hypermedia. Consists of navigation paths, information and graphics. Popular because
simple to construct, easy to read and can be modified at every stage.
Layouts:
− Linear: sequential path.
− Hierarchical: sequential path in top-down design.
− Non-linear: no structure.
− Combination: a blending of the layouts above.

Web page creation software: allows the creating of web pages without having to use HTML.
The required HTML tags are inserted automatically by the software. Web pages can be viewed in
HTML form or seen on the web browser.

Storage and retrieval
Database management system: application software that allows the entry, manipulation and
storage of data in a database format. Used for secure and efficient storage and retrieval of
information of a database.
- Reduces data redundancy
- Backup and recovery capabilities

Methods of accessing data
Sequential access - Data is accessed in a sequence. Accesses data in the order it was stored.
Does not require the exact location of the data item, and it’s much slower than direct access.
Example: accessing data stored on magnetic tape.
Direct access - Data is access without accessing previous data items. Data is stored in a
particular storage location based on algorithm. Algorithm is used to calculate the approximate
location of the data – if data not found at this location, computer searches through successive
locations until data is accessed.
Indexed access: when direct access involves the use of an index (a table that has information
about the location of the data). Data is accessed by referring to the index and obtaining its exact
location. Requires more processing time to search the index and to maintain the index.
Example: storing data on a disk and the logical location of data within a database.



INFORMATION SYSTEMS AND DATABASES
Storage mediums:
- Magnetic tape: store large amount of data inexpensively, used for backup. Uses sequential
access – all bits of data are organised in a strict sequence. Erasable, reusable and durable way of
storing data
- Removable cartridge: a HDD encased in a cartridge. Fast, not as fast as HDD, use direct
access. E.g. Zip disks 100-250Mb, Jaz disks 2 GB.
- Hard disk: uses direct access.
- Optical disc: data is read and written using laser technology, uses direct access. Eg CDs
650mb, DVD 4.7 GB – 17Gb. Writable CDs have an extra, non-reflective layer that the laser can
modify.

Encryption and decryption:
− Process of encoding data, involving manipulations of bit patterns.
− Decryption: process of decoding.
− Most effective way to achieve data security during data transmission.
− Data encoded  transmitted  data decoded.
− Problem: to find a method that is difficult to decode but also practical to use.

Asymmetric encryption: requires a public key for encryption (before transmission) and a
private key for decryption (received message).
Types of
encryption
Symmetric encryption: requires the same key for encryption and decryption e.g. Data
Encryption Standard [DES].

• Selecting data from a relational database using SQL commands:
Query: search of a database for records that meet a certain condition.
Constructed form: .
Method for constructing a query is query by example [QBE]: requires user to enter the criteria
against a field.
Relational query: search of a database involves two or more entities.
Operators
Relational operators: (= , <> , < , > , <= , >=) indicates relationship between two
expressions.
Wildcard characters: (* number of characters, ? one character) represent unknown characters.
Logical operators: used to combine queries so that a search is carried out on one or more fields.
- AND: requires both first and second query to be true.
- OR: requires either the first or the second query to be true.
- NOT: exact opposite. INFORMATION SYSTEMS AND DATABASES
Structure Query Language [SQL]
Query language: specialised language designed to search a database.
SQL: a query language used to access and manipulate data in a relational database. Variations to
SQL are developed by specific DBMSs eg ANSI SQL, standard SQL.
SQL statements contain keywords that are used to perform a particular task.
Must use correct syntax: keywords – uppercase, fields separated by commas, entity and attribute
are separated by full stop, search criteria or data item enclosed in double quotes.

Keyword Values Description
SELECT Field(s) Data to be displayed.
FROM Table(s) Source of data.
WHERE Criteria Query.
ORDER BY Field(s) Order in which fields to be displayed.

Tools for hypermedia search and retrieval:
Retrieving data in hypermedia involves using search engines.
Search engines: database of indexed websites that can be searched using keywords.
Works by sending out a search robot, crawler or spider to fetch as many documents as possible.
Another program, called an indexer, then reads these documents and creates an index based on
the words contained in each document.
Directories: lists of Web sites organised into categories.
Search robot: program that access Web sties and gathers information for search engine indexes.

Other information processes
A report is the formatted and organized presentation of data.
A form is used to enter, view and edit data.

Reporting on relevant information in a database:
Report: formatted and organised presentation of data eg mailing labels, invoices, sales
summaries and telephone lists.

Issues related to information systems and databases
Privacy & Security:
Database systems usually have security measures in place to prevent both unauthorised access to
the system and corruption of the data stored. This introduces the concern about security.
− Data may get into the wrong hands. May become damaged or deleted accidentally or
intentionally. INFORMATION SYSTEMS AND DATABASES
− Incorrect data may be entered.
− Validation of data:
- Format of data
- Accuracy of data and reliability of sources. Data is protected by copyright regardless of
where it is obtained. Data should be acknowledged or permission sought from the owner
before the information can be used in publication.
− Ownership and control of data is an ethical issue
− Restrictions on the level of access – password protection: personal objects, biometric devices.
Data encryption and firewall (used on the Internet or network to verify and authenticate all
incoming data).
− Closed circuits. Monitoring by camera and logs.
− Data encryption.
− Dial back modems to registered phone numbers.
− Backup of data.
− Firewalls and Virus Protection.

Accuracy of data and the reliability of data sources:
Data integrity can be maintained by ensuring that the database is able to resist:
− User mistakes.
− System malfunctions.
− Deliberate or accidental alteration.
Data validation checks the accuracy and appropriateness at the data entry stage.
Data bias occurs in the way the data is collected, captured and manipulated.
Data captures in a machine readable form will less likely be biased
Data transcribed by the operator from a non-machine readable form will like be biased.
Rejection and editing of some collected data can cause data to be biased and unreliable.
Access to data, ownership and control of data:
Freedom of Information Act 1982:
The rights of individuals to privacy and control of information concerning personal details need to
be considered. However the existence of a store of information concerning individuals can, in
some cases, be beneficial to society in general.
− Unwanted names on mailing list
− The sale of mailing lists
− Loss of control of information
− Information on individuals needs to be accurate
− Surveillance information held on computers controlled by government agencies
− Tracing missing persons INFORMATION SYSTEMS AND DATABASES
− Assistance in the apprehension of tax evaders
− Assistance on the apprehension of social security benefit cheats
− Ability to determine bad creditors
− Availability of research data
− Emergency access to medical records
− Monitoring of visits to doctors.

Data warehousing and data mining:
Data warehousing: collection of data designed to support management decision-making.
Development of data warehouse includes development of systems to extract data from operating
systems plus installation of a warehouse database system that provides managers flexible access
to the data.
Data mining: use of software that looks for hidden patterns in warehoused data.