Multimedia Systems

Information Processes & Technology:
Multimedia Systems

Characteristics of Multimedia Systems

Multimedia systems:

Multimedia systems are information systems that include combinations of the following media, including;

·  Text and numbers

o  Text is a meaningful string of characters; 7 bits per character; A = 65

o  Rules for using text:

§  Must be broken in paragraphs and easy to read

§  Have correct spelling and grammar

§  Have consistent formatting (size, font face, colour)

o  Serif fonts; Times New Roman; have curls – used mainly in newspapers (print)

o  Sans-serif fonts; Arial; don’t have curls – used for web display as it gives cleaner screen display.

·  Audio

o  Audio is digital sound; music, speech and sound effects

o  Audio should reflect and enhance presentation not be large to reduce loading time

o  Sampling converts sound waves into digital signals

§  Sampling rate (number of sample of wave)

§  Sampling size (number of bits used to represent each sample)

o  MP3, WMA, AAC are compressed audio formats

·  Images

o  Image resolution: number of pixels used to display an image in a given space.

o  Higher resolution image = better quality = more pixels = requires more storage space

o  Bitmap:

§  Composed of a matrix of pixels which can be controlled individually

§  Bit depth is the number of bits per pixel (the higher bit depth, the more colours possible)

§  To calculate file size (kB) of an uncompressed bitmap image:

o  Vector:

§  Composed of primitives (basic shapes)

§  Each line has mathematical coordinates for start and end points (but no points in between, which reduces file size)

§  Not suitable for photographs (no shading)

§  Can be resized without loss of quality

·  Animations

o  Creating the illusion of movement

o  Cell based – a sequence of images where each cell is slightly different to the previous cell and when played gives the illusion of movement

o  Path based – a character follows a drawn line across the background

·  Video

o  Combines image and sound data

o  To represent video in binary, each frame is represented as a bitmap = large file sizes

o  To calculate file size for video:

§  Calculate total frames (frames/sec × number of seconds)

§  Calculate size of each frame (Horizontal pixels × Vertical pixels × Bit depth)

§  Calculate total file size (frames × size of each frame = bits)

o  Buffering prevents delay when playing videos

·  Hyperlinks

o  A link that transports the user to other parts of the system; allowing them to freely explore areas of interest

o  Makes multimedia interactive

o  Anchor: transport user to another part of the same webpage

o  Link: transport user to a new webpage

Differences between print and multimedia:

·  [Resolution] Print has higher resolution (displayed in books, magazines) than multimedia (screen displays).

·  [Interactivity] Print is static = minimal interactivity. Multimedia is dynamic = designed for interactivity so user controls content (hypermedia, keyword searches, navigation buttons, site map, etc.)

·  [Distribution] Print is harder and more expensive to distribute (heavy). Multimedia is easier to distribute (stored on lightweight devices; cheaply transmitted via internet)

Distribution for print requires printing presses, ink, paper and willing publisher. Multimedia requires hardware, software and basic skills.

·  [Updating] Updates to print are not immediate (cannot be edited without reprinting). Updates to multimedia are immediate (e.g. online news).

Print tends to be more trusted (books checked by third parties) than multimedia.

Requirements of Multimedia Systems

The demands placed on hardware by multimedia systems:

·  Primary and secondary storage requirements as a result of:

o  Bit depth and colour representation:
Higher bit depth = larger RAM (frame buffer) and hard disk needed

o  Sampling rate for audio data:
More samples of original sound waves = larger hard disk and RAM needed to store it

·  Processing as a result of:

o  Video data and frame rate:
Video files are large files (containing thousands of individual frames and high quality audio). Therefore, need separate processor chip on video card to reduce processing strain on CPU when playing and editing video.

o  Image processing:
Morphing (smoothly transforming one image into a different image) and distorting (changing image from original shape by bending, twisting and stretching)

o  Animation processing:
Tweening (producing sequence of intermediate frames that alter the first key frame into the second)

·  Display devices as a result of:

o  Pixels and resolution:
High resolution images require high resolution screens (otherwise detail is lost)

Expertise required in the development of multimedia applications:

·  Content providers

o  Organisations that provide ready to use content for a fee (stock photographs, animations, video and text)

o  Individuals who can create original content to meet a specific need

·  System designers

o  Identify purpose of the system, decide feasibility, determine hardware and software and overall design

o  Leadership skills needed

·  Project mangers

o  Develop the project plan and ensure it is followed on time and on budget

o  Communication and negotiation skills needed

·  Those skilled in the collection and editing of:

o  Text – writers selected on ability and knowledge of subject matter

o  Graphics – illustrators and animators who use software to create figures

o  Audio – need technical skills to mix different digital audio clips and creativity to create sound effects

o  Video – camera operator, sound engineer, actors and director (who approves set design, costumes, camera angles, lighting, editing)

·  Those skilled in design and layout

o  Graphic designers improve the readability of multimedia by organising layout of screen, adjusting colour and size.

·  Those with technical skills to support the use of information technology being used

o  Multimedia delivered over internet relies on internet speed. Different levels of compression, lower resolution and streaming can ensure presentation delivered quickly

o  Data distributed on CD-ROM is compressed. Must ensure required codec is present on user computers

o  For databases, need person skilled in creating schemas, writing queries, organising back-up and securing the database.

Examples of Multimedia Systems

Education and training: (learner is engaged and progresses at their own pace)

·  Interactive educational games used to introduce reading and number skills to infants. They have large buttons, bright colours and a game style format.
Input collected by mouse. Distributed by CD-ROM.

·  Learning Management Systems allow online distribution of resources. When students log on, they complete an activity and are given results from their online test e.g. Moodle

·  Businesses use multimedia systems to train their staff for OHS and computer skills. Distributed online or CD-ROM.

·  Software companies produce multimedia tutorials to assist users to use their product
e.g. Internet Explorer 7 Quick Tour

Leisure and entertainment:

·  Using computers to communicate with friends (instant messaging, blogs, wiki, email and web cam)

·  Games – in PC, mobiles and game consoles

o  Online games allow thousands of players to interact when they log on to a virtual world (hosted by a powerful server)

o  Simulation games mimic real world situations through photo quality animation (requiring fast CPU, large RAM, video card and high screen resolution)

Information provision:

·  Information kiosks:
Touch screen and secured PC so users can make selections to filter content e.g. in shopping malls as a directory to provide location and information about each store

Virtual reality and simulations: (requiring fast CPU and video card)

·  Flight simulators - allow pilot to experience aircraft failure in a cost effective and safer way

·  Virtual reality used to treat people of extreme phobias; for instance, patient with fear of heights can be exposed to a virtual cliff

·  Virtual walkthroughs of new architectural designs (created by Computer Aided Design software). Allows analysis without construction. Virtual reality headsets produce a more realistic 3D walkthrough.

Advances in technology which are influencing multimedia development:

·  Increased storage capacity – multimedia can be stored with ease and at high resolutions (e.g. DVDs with more realistic images – high definition)

·  Increases in CPU processing power – high quality music and videos can be handled by modern CPU (e.g. jump to any point instantaneously during editing)

·  Improved resolution of capturing devices – such as digital camera’s and camcorders (better quality images and video capturing)

·  Improved resolution of displays – so displays are more realistic and of higher quality

·  Improved bandwidth allowing transmission of high quality multimedia – companies use online computer tutorials and home users enjoy online games and online newspapers with video

·  New codecs for handling compression of media while improving quality – highly interactive multimedia can be distributed on the web since file size is compressed

Displaying in Multimedia Systems

Hardware:

Screens:

·  Cathode Ray Tubes (VGA connector)

o  Beam of electrons glow on phosphor coated screen to create image

o  In decline because of new screens that are lighter in weight, use less desk space and have higher resolution

·  Liquid Crystal Display (DVI connector)

o  Electric current changes position of liquid crystals, creating the image

·  Plasma screens (DVI connector)

o  Heated gases emit U.V. light which glows on phosphor coated screen to create image

o  Used for large advertising displays and home theatre

·  Touch screens

o  Sensor panel detects electrical disturbances to determine where touch occurred

o  Used in ATMs, game consoles, tablet PC, information kiosk

o  Good for public areas – mouse and keyboard not damaged

o  LCD screens can be converted into touch screens

Digital Projection Devices:

·  Halogen light globe projects image onto screen

o  Either through a transparent image and then a lens (used in homes)

o  Or reflects light of a smaller image and then lens (cinemas)

Head up displays:

·  The display is superimposed on a transparent screen

·  User can view critical information without need to look down and refocus eyes

·  Used in military aircrafts so pilot can concentrate on real view and monitor functions

Head-sets:

·  Integrates a microphone and speaker into a single device worn on the head

·  Microphone close to mouth – amount of external noise low

·  User can immerse themselves with sound without interrupting others close by

·  Used in telephone systems and gaming

·  Virtual reality headsets add sensors to the users head, so when they move, the displayed image moves fluidly

Speakers and sound-systems:

·  Analog device converting alternating current into sound waves (electrical to sound)

·  The electromagnet vibrates rapidly back-and-forth, in turn making the speaker cone vibrate, compressing the air, creating sound waves

CD, DVD Players:

·  Stores digital data on spiral track composed of pits and lands

·  CDs have a single track; DVDs have more densely packed tracks

·  Read head generates laser beam which is reflected as fluctuations from the pits on the spinning disk. A sensor translates this into an electrical signal, representing the stored sequence of bits.

·  DVDs can be double sided and dual layered = large storage capacity = ideal for distributing multimedia

·  Quality of CD and DVD data is maintained after copying

Video tape players:

·  Stores analog data on long strip of magnetic tape wound on reels

·  Quality reduces after copying

Software:

Presentation software: (MS PowerPoint, Apple iWork Keynote, OpenOffice Impress)

·  Produces high quality multimedia presentations designed for group display

·  Slide shows (with animations, transitions, hypermedia)

Software for video processing: (Adobe Premiere, Windows Movie Maker, Corel VideoStudio)

·  Allows video to be captured, imported and edited (special effects, text overlays, transitions, cut and paste, etc.)

·  Compresses the original video source to a more efficient file size

Authoring software: (Articulate Quizmaker, NeoSoft NeoBook, Adobe Flash CS4)

·  create a multimedia production which incorporates several different types of media elements

Animation software: (CoffeeCup GIF Animator, Toon Boom Studio, Xara3D)

·  Create, edit and publish 2D and 3D animations

Web browsers: (Safari, Firefox, Internet Explorer)

·  Allow users to navigate and explore the web by viewing HTML documents and using search engines

HTML editors: (Notepad, Adobe Dreamweaver, MS FrontPage)

·  Create and edit HTML files

·  Dreamweaver: cascading style sheets - CSS (easier to apply consistent formatting); and cursors synchronised in split view and the design view (to allow code to be entered and the graphical editing of web pages)

·  Notepad: view and make minor edits to webpage source documents

Other Information Processes in Multimedia Systems

Analog to digital conversion:

·  To convert analog sound to a digital format we require an analog-to-digital converter (ADC). This function is normally built into a sound card.

·  An ADC is an electronic device that repeatedly samples the magnitude of the incoming electrical current and converts these samples to binary digital numbers.

Collecting:

·  Keyboard – collect text and numbers in digital format

·  Flatbed scanner – collect images, text and numbers from analog format

·  Digital camera – collect images in digital format

·  Microphone and sound card – collect audio from analog format

·  Video camera – collect audio and video

Processing:

Involves:

·  The integration of text and/or number, audio, image and/or video.

·  Compression and decompression of audio, video and images.

·  Hypermedia – the linking of different media to one another

Compression and decompression:

Compression:

·  Any of several techniques for reducing the number of bits needed to represent an item of digital data, either to save storage or to use less bandwidth when transmitting it.