HSC IPT - Multimedia Notes PDF

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HSC IPT Option Topic: Multimedia (HSC Mark 94)
Still relevant to new 2020 syllabus...

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Information Processes and Technology - Multimedia MULTI MULTIMEDIA MEDIA MEDIA:: M MEEDIA CONTAIN CONTAINII NG THRE THREEE OR MORE TYPES OF MEDIA Types of Media • Text, hypertext and numbers o Text – letters, numbers and other characters whose meaning and format is not specified § Has no meaning until a person reads and interprets it § Written using a word processor o Hypertext – allows the user to navigate through a multimedia product by crosslinking documents, allowing interactivity in multimedia products such as the World Wide Web § Hyperlink – highlighted item that allows the electronic connection § Author must specify the location of the information accessed by each link, which can be of a different media type o Numbers – predefined numerals whose meaning and format are specified, and used for calculations o File Formats § ASCII (American Standard Code for Information Interchange) • Standard format for storing text and numerical data • Most applications store data in ASCII format • Used in conjunction with most keyboards § RTF (Rich Text Format) • Standard developed by MS to specify text format in documents § HTML (Hypertext Markup Language) • Used to create documents for the web • Uses a set of special instructions (tags and classes) to indicate how parts of the file is to be displayed § PDF (Portable Document Format) • Used to distribute electronic versions of printed material • Accurately describes the layout of pages and can include single vector images, or interactive elements such as hyperlinks • Audio o Sound that is digitised, meaning is determined by listening and interpreting the sounds, often used to explain concepts, reinforce selections and provide special effects o Amplitude = loudness o Frequency = pitch o Sampling rate – how many samples are taken per second o Sampling size – how many bits per sample o Mono/stereo – one or two channels of audio o Calculating file size § sample rate * sample size * time (in seconds) * number of channels o File Formats § MP3 (MPEG-1 Audio Layer 3) • Lossy compression, removes the sounds that would not be noticed by most people • Format for electronic distribution of commercial music files § WAV (Waveform Audio Format) • Lossy, lossless or no compression • Can store 8-bit or 16-bit sound • Metafile format for MS § WMA (Windows Media Audio) • Lossy compression • MS format designed to compete against the MP3 format § MIDI (Musical Instrument Digital Interface) • Lossless or no compression • Standard connection between computers and electronical musical instruments and synthesisers o Quality of sound depends on synthesiser • Specifies each note, tone and perhaps instrument o Less storage as it only contains note information instead of audio samples

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Meaning is determined by looking and interpreting it, used to create interest and provide information Pixel – a tiny dot that makes up a part of the screen Resolution – total number of pixels on a screen Bitmap graphics § Data for each pixel is stored as a bit in memory § Produces good quality images where shading and details are needed § Resolution is lost when they are transformed by resizing or stretched • Aliasing – staircase pattern created when enlarging each pixel Vector graphics § Made by using functions and equations which define shapes, curves and lines with characteristics such as position, line width, pattern § Coordinated positions change according to the mathematical expressions Calculating File Sizes § Resolution (horizontal*vertical) * colours (2^depth) * tones (2^depth) / 8(bytes)*1024(kBs) File Formats § JPEG (Joint Photographics Expert Group) • Lossy compression • Used to compress photos and continuous tone images, by grouping similar colours together which are almost impossible to detect with the human eye • Supports up to 24-bit true colours (16.7 million colours) and 8-bit greyscale • Compression ratio of 100:1 § GIF (Graphics Interchange Format) • Lossless compression, often used for banners and logos on the web and line-art drawings • Supports only 8-bit depths (256 colours) • Compression ratio of 2:1 § PNG (Portable Network Graphics) • Lossless compression, used in web compression • Supports up to 48-bit true colour and 16-bit greyscale • Includes a variable transparency alpha channel so graphics can have semi-transparent shadows § BMP (Bitmap) • Lossless compression, used primarily for MS Windows • Supports up to 24-bit depths (16.7 million colours) • Files are usually compressed and uses run length encoding (RLE) § TIF (Tagged Image File Format) • Lossless compression • Standard format for storing professional quality images • Can contain many other embedded image files (including vector images) • Supports up to 48-bit depth

Video and Animation o Video – real movement is captured in frames and replayed in rapid succession o Animation – series of still frames (cells) are presented in rapid succession to create the illusion of movement o Can present information more effectively than text or image o Cell-based animation involves drawing and displaying individual frames which are stored separately and loaded onto a graphics page of primary memory o Path-based animation – displaying the movement of objects onto a fixed background in a particular sequence or path, where the pixels in the background do not change, only those for the moving object which saves memory and processing time § Tweening – generating immediate frames between two objects § Morphing – smooth change between two images, transforming the shape, size and colour of one image into another, creating the effect of merging one image into another § Warping – transforming or distorting a portion of the image o Calculating File Size § image file size * frames per second * time (in seconds)

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File formats § MPEG (Motion Picture Expert Group) • Lossy compression, achieves a high compression ratio • A family of formats for compressed video • Only stores changes from one video frame to another instead of data for each pixel in each frame • Supports a large variety of resolutions and frame rates § MOV (QuickTime, QT) • Lossy compression • Format developed by Apple and was used to develop the current MP4 standard • Can store interactive media § AVI (Audio Video Interleave) • Lossy compression • Older format created by MS and IBM § WMV (Windows Media Video) • Lossy compression • MS format used for streaming video data § SWF (Small Web Format, Shockwave Flash) • Lossy, lossless or no compression • Flexible metafile format used tor vector images, animation, video, and other interactive elements • Requires a Flash player on the end user’s computer

Hardware Dem Demaand ndss of Multime Multimedia dia Sys Systems tems • Large primary storage (RAM) for high quality audio, HD images, video and animation • Fast processing CPUs to process large amounts of data • High resolution capturing and display devices • Large removeable storage for backup • High bandwidth transmitting devices for larger capacity to transmit a large amount of data per second Pri Print nt VS Multi Multimedia media Print (Newspaper) • Only has text and images à not interactive • Easily damaged or lost • Hard to share • Not environmentally friendly (deforestation for paper) • Difficult to update in real time • Hard to search for specific information or find archives • Does not internet or devices to view

Multimedia (Online newspaper) • Can include all types of media à interactive • Backups online • Easily shared through social media or printed for distribution only when necessary • Immediate updates • Easy to search for specific information or find archives • Requires internet and devices to view

Modes of Displa Displayy • Monitors o CRT Monitor § Images are produced by firing a beam of electrons onto the inside of the screen which is coated with phosphor starting from the upper left corner, moving left to right and top to bottom in a zigzag pattern called a raster scan § Raster scan is REFRESHED or repeated to maintain the image produced as the phosphor only displays colour for a short time. Non-interlaced monitors refresh up to 72 times per second. Interlaced monitors scan odd lines then repeat with even lines but this causes the monitor to flicker o LCD monitor § The cooled liquid crystals is placed between two polarising sheets of glass which polarise light at different angles so that one pane blocks vertically vibrating waves of light and the other blocks horizontally vibrating waves of light § Electricity passes through the liquid crystals turning it "on" and "off" by twisting and untwisting the liquid crystal structure. When the crystals are switched off or twisted, light is rotated by the crystal and can flow through the polarising glass and light up a sub pixel (RGB)

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Information Processes and Technology - Multimedia Plasma Monitor § Each subpixel is an individual plasma lamp that is switched on and off electronically using plasma § Each lamp of a pixel is coated using a different phosphor to produce different colours when exposed to light or electrons in electricity § Allows for thinner screen and faster switching of colours § Expensive, heavier and more fragile, uses more electricity to change colours of pixels, lamps can burn out after an image is exposed for too long o LED Monitor § Uses an array of light-emitting diodes placed behind an LCD display and the light diffuser is used to form a uniform amount of light across the screen § Opacity of a pixel is controlled through and electric field which applies a portion of light for pixel that needs to be displayed o Touchscreens § Uses a matrix of infrared light beams that shine horizontally and vertically across the screen § When the user uses a finger to touch the screen, the matrix is disrupted and the light beams that are broken do not travel to the other side of the screen and allows the device to calculate the position of the user’s finger § Allows input of data by detecting touch while the display is being used, but does not allow for fine precision of input Printers – a device that represents data on paper, producing a hard copy o Impact printers – make image on paper using some sort of physical contact o Non-impact – make image using some other method (laser and inkjet) o Quality of output is called resolution o Dot matrix printer § Cheap § Ink was wet after printing § Low resolution § Loud o Inkjet printer § Ink head sprays fine droplets of ink onto paper § Quieter § Higher resolution § Printer and cartridges are cheap but only print up to 200 pages each o Laser printer § Laser attracts powdered ink onto paper § Highest quality printer § Cartridges can print up to 1500 pages per cartridge but is expensive o Plotter § Large scale printer that is used for architectural or digital designs § High quality drawings such as maps, charts and building plans Speakers – outputs sound o Audio is converted and stored as digital data through devices such as a microphone o Voice synthesis – artificial production of human speech o A coil attached to a diaphragm is placed in a magnetic field created by a circular magnet § Coil is located between the poles in the ring magnet and connected to the output of an amplifier which provides AC current • Change direction at same frequency as the sound • Magnitude in proportion to the amplitude of the sound § When current flows through the coil, the motor effect causes the coil and diaphragm to move up and down, vibrating to create sound waves when connecter to a paper cone o

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Projection Devices o Data projectors § Data projection panel – device that can be used together with a standard overhead projector, which uses translucent LCD technology to display images, in which light passes through the image and the image is projected onto a surface § Data projectors can also be used to project videos and images on to the wall by taking video signals directly from a computer • Data projectors are more versatile than projection panels, although more expensive Virtual reality o Head-up displays § A transparent miniaturised technology that projects information or other data at eye level, allowing users to see both the display and their surroundings while keeping their heads up § Used in cars – projector is embedded into the dashboard, projecting transparent images which bounces off a series of mirrors that magnify and flip the image to allow the data to be readable § Other applications – the display is projected onto the surface of glasses, so users can see the display overlaying reality, does not interfere with forward vision (e.g. military uses with pilots) o Headsets § Integrates a microphone and speaker into a single device, often used in conjunction with telephone systems • The closer the microphone is to the user’s mouth, the less external noise interference is captured • Allows users to immerse themselves in audio without distracting others • Can be found in VR systems, gaming (as sound effects and music can disturb others), office environments where employees in a room need to call other people (customer service)

Sto Storag rag ragee Dev Devices ices • Primary storage o Random Access Memory (RAM) – read/write memory that is temporary and volatile, will be lost when power is lost o Read Only Memory (ROM) – memory that is fixed by the developers during manufacture and cannot be edited or deleted, is not lost when power is lost o Cache Memory - speeds up access to frequently used instructions or commands, rather than accessing from RAM • Secondary Storage (refer to Information Systems notes) o Floppy disk o Hard drive o CD and DVD Org Organi ani anisin sin singg Mu Multi lti ltimedi medi mediaa (refer to Information Systems notes) • Storyboards • Hypermedia using nodes and links

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Information Processes and Technology - Multimedia Collectin Collectingg Devices • Scanners o Handheld scanners – enters text and images that are less than a page wide, scanner is passed over the document o Flatbed scanners – document remains flat and stationary during scanning, similar to a small photocopier § Row of the image is scanned by flashing RGB lights and the content of the CCD is converted from analogue to digital and onto the scanner’s main processor and storage chips § Scan head is attached to a stabilising par and moved using a stepping motor attached to a belt and pulling system, where number of movements made by stepping motor determines vertical resolution of the image § Image is sent to computer via interface cable whilst scanning is in progress o Overhead scanners – documents are placed faced up on scanning bed and small overhead tower moves across page • Digital Camera o Input devices that capture and store images in digital formats o Includes a storage medium such as memory card, hard disk drive, floppy disk, etc. o Photos are limited by amount of memory and quality of lens o ADV: inexpensive and fast as no film processing is required o ADV: easy to compress into JPEG format for simple multimedia usage • Digital Video Camera o Used to create videos in analogue and digital forms o Video capture card – converts analogue into digital by interpreting each frame of the video as bitmapped images and compressing clips by analysing and storing the changes between consecutive frames o ADV: uses a compressed digital format (e.g. MPEG) for greater storage and can be directly transferred to computer

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Video Cassette Recorder (VCR) o Used to select footage from existing videotapes Composite Video System (CVS) o Sends all video information to a computer using a single signal o Professional video quality uses a signal for colour and a signal for brightness Frame Grabber o Captures and digitises images from a video and displays frames at around 30fps Microphones o Input device that captures sound o Sound card – transforms sound from microphone into audio, can support MIDI sequences

Impor Importance tance of Inter Interactivi activi activity ty • Allows user to choose the sequence and content of information, choosing their topics of interest instead of following a predetermined path • Ease of use à users can easily go back and forth between pages • User has full control of their experience • Not content heavy and easy to find specific information due to navigation system Peopl Peoplee in Multi Multimedi medi mediaa • Content providers o Provide the material for the multimedia product, and do not necessarily need technical skills for software or hardware • System designers o Plans and organises the hardware and software required for the presentation o May act as project manager or provide technical support • Project manager o Organises the scheduling of various components of the product o Provides overall supervision of the components and ensures that all components are delivered on time • Technical staff o Variety of artists and technicians who edit the media into appropriate formats for the final document § Includes layout and design personnel who work to develop an overall theme and look of the product o May also include content providers or be a completely separate group • NOTE: people may be multiskilled and work in different aspects of the multimedia product, which requires detailed project plans

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Information Processes and Technology - Multimedia Areas of M Multim ultim ultimedia edia Us Usee • Education and training o Incorporation of multiple media types maintains the user’s interest o Interactive nature allows user to control pace of learning and review misunderstood concepts o Computer-based training (CBT) § Allows user to learn information at their own pace § Designed by experts in their fields and designed to cater for different rates of learning § Interactivity is the basis for individuals to progress through the system § Usually contains some form of assessment to determine whether an individual is ready for the next level • Leisure and entertainment o Computer games provide a high level of interactivity o Responses of the user determine the game being played o Sequence of actions may be limited by the game designer or have a large range of possibilities o Often time restricted and have complex animation, level and amount of text is limited o High resolution images, audio, animation and video o Often uses alternatives to the keyboard, such as a joystick, or mouse for input o Technological advancements have made some computer games more realistic • Information o User controls when, how and what information is displayed o Interactive nature allows user to search using keywords to find specific information o E.g. Multimedia encyclopaedia o E.g. Information kiosk § Allow people to use a touch screen and select information about an organisation or service § Displays information depending on the selections of the user § Usually provides information about items, locations of items or a map to a particular product or service § Large navigation buttons with few options • Virtual reality and simulations o Virtual reality – use of computer modelling and simulation to enable a person to interact with an artificial environment o Immerses the user in an environment that simulates reality through the use of interactive devices § Devices such as goggles, head-up displays, gloves or body suits o Users wear helmets with a screen for each eye to view animated images of a simulated environment o Motion sensors detect user’s movements and adjusts views to create the illusion of interaction and reality o E.g. Flight simulators § Used to train pilots using external effects such as changing weather conditions § Requires high resolution images and ability to control different aspects of the system § Different scenarios and reactions must be carefully modelled to be as realistic as possible § ADV: ‘crashing’ a flight simulator is cheaper than crashing a real plane § DISADV: requires a lot of physical room and inv...