Unit 4 and 5

Fundamentals of Multimedia, Chapter 3

UNIT- IV

• FILE FORMATS•INPUT & OUTPUT DEVICES

• STORAGE TECHNIQUES

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File FormatsDifferent applications (programs) store data in different formats. Applications support some file formats and not others.

File formats appear as a (usually) 3 letter suffix or “extension” after the name of the file, e.g., .psd, .doc, .jpg, .pct, .tif, .gif, .ppt, etc.

GIF• GIF standard (Graphics Interchange Format):

Limited to 8-bit (256) color images only, which, while producing acceptable color images, is best suited for images with few distinctive colors .

• GIF standard supports interlacing — successive display of pixels in widely-spaced rows by a 4-pass display process.

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GIF• For the standard specification, the general file format of a GIF file is as

in following fig.

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JPEG• JPEG (Joint Photographic Experts Group): The most important

current standard for image compression (.jpg, .jpeg, .jpe).

• The human vision system has some specific limitations and JPEG takes advantage of these to achieve high rates of compression.

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A photo of a flower compressed with successively more lossy compression ratios from left to right.

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Fig. 3.17: JPEG image with low quality specified by user.

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PNG• PNG format: standing for Portable Network Graphics — meant to

supersede the GIF standard, and extends it in important ways.

• Special features of PNG files include:

1. Support for up to 48 bits of color information — a large increase.

2. Files may contain gamma-correction information for correct display of color images, as well as alpha-channel information for such uses as control of transparency.

3. The display progressively displays pixels in a 2-dimensional fashion by showing a few pixels at a time over seven passes through each 8 8 block of an image.

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TIFF• TIFF: stands for Tagged Image File Format.

• The support for attachment of additional information (referred to as “tags”) provides a great deal of flexibility.

1. The most important tag is a format signifier: what type of compression etc. is in use in the stored image.

2. TIFF can store many different types of image: 1-bit, grayscale, 8-bit color, 24-bit RGB, etc.

3. TIFF was originally a lossless format but now a new JPEG tag allows one to opt for JPEG compression.

4. The TIFF format was developed by the Aldus Corporation in the 1980's and was later supported by Microsoft.

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Input and Output Devices

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• An input device one that, together with appropriate software, transforms informationinformation from the user into datadata that the computer application can process.

• Choice and method of use of an input device should contribute positively to usabilityusability of the system

• The usability of an input device depends greatly on the provision of appropriate feedbackfeedback

I/O Devices: Input

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• 3D tracker3D tracker– Relays position and orientation to a receiver. Replaces mouse where

desk space is limited (e.g., laptops)

• JoystickJoystick– Small stick, movable in any direction in a fixed socket.

• MouseMouse– continuous input device. Buttons for discrete input. Relative device.

• Trackball Trackball (a.k.a. “dead mouse”)– Rotatable ball in fixed socket

• TabletTablet– used with stylus or puck. Absolute device

• MoleMole (a.k.a. “foot mouse”)

Pointing devices: cursor control

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Pointing devices

• DatagloveDataglove– Communicates hand and finger position to an application. Used

for manipulating virtual objects

• Touch-sensitive screenTouch-sensitive screen– Special screen that detects the position of a finger touching it.

• Light penLight pen– Location found by beam passing through screen during refresh

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Choosing appropriate input devices

• Matching devices with workwork– The particular manipulations needed to accomplish a piece of work need

to be analyzed– Natural mappings between use, feedback, meaning of result and user’s

mental model are needed

• Matching devices with usersusers– e.g., eye and head input for the physically disabled

• Matching devices with environment of useenvironment of use– space– relation to other concurrent tasks etc.,

Types of Storage

• Magnetic Disk Storage

• Optical Disks– Magneto-optical– CD-ROM– CD-R– CD-RW– DVD-ROM

• Magnetic Tape Storage

Magnetic Disk Storage

• Data represented as magnetic spots– Magnetized spot = 1– Absence of a magnetized spot = 0

• Read– Converts the magnetized data to electrical

impulses

• Write– Converts electrical impulses to magnetized spots

on disk

High-Capacity Portable Disks

• Larger files

• Portable

• High-capacity– 120 / 200 MB– Can read and write standard diskettes– Ex: Superdisk

• Zip disk– 250 MB– not compatible with 3 ½ inch diskettes

Hard Disk

• Various sizes

• Portability– Generally non-portable– Removable hard disks available for PC

• Rigid platter coated with metallic substance

Disk DriveRead / Write Operation

• Disks rotate

• Access arm moves read/write head

• Read / write operation begins and continues until complete

• Data is transferred to/from memory

Redundant Array of Independent Disks

Optical Disk

• Greater capacity than other portable media

• Process– Laser writes on metallic material spread over the

surface of disk– Heat from laser produces pits on disk surface– Reading – laser picks up light reflections from the pits

• Technology– ROM– WORM

MOMagneto-optical

• Hybrid

• High-volume capacity

• Written multiple times

• Process– Laser melts a microscopic spot– Magnet aligns crystals– Reading – laser picks up light reflection from crystals

CD-ROMCompact Disk Read-Only Memory

• High capacity portable

• Read multiple times

• Cannot record

• Capacity – up to 680 MB (450 standard 3 ½ inch diskettes)

• Used for software distribution

CD-RCompact Disc-Recordable

• High capacity

• Portable

• Write once

• Read multiple times– CD-R drive– CD-ROM drive

CR-RWCompact Disk-Rewritable

• High capacity

• Portable

• Read multiple times

• Record multiple times

• Some compatibility problems reading CD-RW disks on CD-ROM drives

DVD-ROMDigital Versatile Disk

• Larger capacity than CD-ROM– Standard – Up to 4.7 GB, 7 times more than CD-ROM– Double layers – 8.5 GB– Double-sided – 17 GB

• Data is packed more densely

• Read multiple times, Cannot record

• Can read CD-ROM disks

• Benefits– Full-length movies– Audio quality comparable to audio compact disks– High-volume business data

• Expected to replace CD-ROM in the near future

DVD-ROMDigital Versatile Disk

UNIT 5

• Multimedia Authoring

• Hypertext

• Hypermedia

• Distributed Multimedia

Multimedia Authoring Tools

• Multimedia authoring tools provide the important framework that Multimedia designers require to organises and edit the various elements of a multimedia projects including, Video, Sound, Animation, Graphics and Text.

• Authoring tools are used for designing interactivity and User Interface.

Multimedia Authoring Tools II

• There are three general categories of Multimedia authoring tools.

• These are:

– Card or page-based tools

– Icon-based tools

– Time-based tools

Multimedia Authoring Tools III

• Card - or Paged based tools– Are systems that are based on a book

or a page metaphor. This means that the way the elements are organized are similar to pages of a book or a card file.

– E.g. Hypercard

Multimedia Authoring Tools III

• Card - or Paged based tools– Are systems that are based on a

book or a page metaphor. This means that the way the elements are organized are similar to pages of a book or a card file.

– E.g. Hypercard

Multimedia Authoring Tools IV

• Icon-Based Tools– These authoring tools multimedia

elements are organised as objects in a structural framework. The programme typically displays flow diagram of activities along branching paths

– E.g Macromedia Authorware

Multimedia Authoring Tools V

• Time-Based Tools– These authoring systems view the

development of a multimedia package as organising objects along a time line. Sequentially organised frames are then played back to the user.

– E.g Macromedia Director

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HYPERTEXT and HYPERMEDIA

Hypertext• Hypertext is a system of storing images,

text, and other computer files that allows direct links to related text, images, sound, and other data.

• Hypertext is the main basis of operation for the web.

Hypermedia• Hypermedia is an updated extension of text

in hypertext.

• It is the connection between hypertext and multimedia.

• Hypermedia documents contain links to other pieces of text, sound, images, movies, and other forms of media.

How Hypertext is Different From Hypermedia

• Like regular text, hypertext can be edited, stored, searched or read. Unlike regular text, it can also contain connections to other documents.

• Hypermedia documents are like hypertext, except that they also contain links to other forms of media like movies, sound, and images.

Uses of Hypermedia/Hypertext

• As an educational tool

• As a way of navigating the internet.

• A way of organizing content in a database.

• As a way of allowing users with disabilities to learn.

• Entertainment.

• Making online purchases.

• Not just for the internet. Can be used in other applications such as dictionaries, encyclopedias, databases, and presentations.

Distributed Multimedia

What is Distributed Multimedia? Large quantities of distributed data Typically streamed out One or many receivers of the data Run over general purpose infrastructure Data is time sensitive, but not necessarily real

• A simple architecture of DMMS

Four Phases Encoding Storage (not always required) Transport Decoding

Distributed Multimedia, cont.

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