HSC Information Processing and Technology/Multimedia Systems

Multimedia Systems will probably be the easiest and most intuitive part of any IPT exam, because while you may have never know any thing about the system development cycle and the seven information processes before you began IPT, you would have known what resolution was, and what a bitmap was, etcetera.

Characteristics of a Multimedia System
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.

Text, Hypertext and Numbers
Text 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.

Fonts
This is the style of which text appears. It defines the appearance of text through size, thickness, style and format.

Hypertext
Text that contains links to other sections of a multimedia program

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.

Storage in MP3 Format
lossy format

Images
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.

Bitmapped Graphics
Bit-mapped graphics treat each pixel on the screen individually and represents this by bits in memory. They produce good quality images where shading and detail are needed. However, when transformed (resized or stretched), bit-mapped graphics become ragged and suffer loss of resolution. Enlarging each pixel in a bit-mapped image graphic creates staircase pattern called aliasing. Bit-mapped images require large amounts of storage. They are often stored in compressed formats, such as GIF and JPEG.

Vector Graphics
Vector graphics are made up of objects, such as a straight line, a curve or a shape. Each object is defined by its characteristics, such as position, line width, and pattern. These characteristics are stored as mathematical expressions and displayed on the screen as pixels. Some common formats include CGM, EPS and WMF.

Video
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.

Print and Multimedia
The differences between print and multimedia including:

Modes of Display
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 combination 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
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.

The Demands Placed on Hardware by Multimedia Systems
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

 * 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 Demands

 * 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 - 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 e.g. 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 type 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 the 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 required, but the animator doesn’t have much control.

Display demands

 * 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 1200 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.

Expertise
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 managers – 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, e.g. 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.

Education and Training
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
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 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 Reality and Simulation
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). the earth is flat

Combined Areas
This is where multimedia applications provide leisure as well as educational value through games that seek to interact with the student and make learning fun. Games such as building blocks by using times table is one such 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.).

The Worldwide Web
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.

Optical Discs

 * 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. CD-RW or Compact Disk Re-writable allows the content stored on the disk to be overwritten and deleted as needed
 * 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 will replace CD-ROM and VHS for most applications.

Screens
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 to 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 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.

Heads-Up Displays
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.

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
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 e.g. GIFAnimator. Programming languages e.g. Consumption++ and Java are used to create high quality professional multimedia applications.

Web Browsers/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.

Collecting

 * 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.

Organising Multimedia Presentations
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.

Processing for a Multimedia System
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.

Data Integration or Hypermedia
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
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.

Compression methods can be categorised into two categories: lossy, where some of the original data is lost in compression, and lossless, where no data is lost in compression.

Hypermedia
Hypermedia is the linking of multiple mediums to each other. Hypermedia is often utilized in multimedia and refers to the linking of data types. For example, activating a particular object on a website may cause additional text to be displayed, cause the user to ‘jump’ to a different section of the program, or to 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.

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 e.g. 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.

==Issues Related to Multimedia Systems==

Copyright
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.

Appropriate use of the Internet
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.

Merging Technologies
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.

Data Integrity of Source Data
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 Encyclopædia 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.