Transcript Class #3

Intro to Information Systems I
Multimedia and Communications
ISYS 101
Glenn Booker
ISYS 101
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Multimedia World
• Multimedia presentations go beyond the vugraph mode of presentation applications to
blend graphics, animation, video, and sound
• Metaphor becomes theater instead of a
podium presentation
• Many multimedia tools are designed for the
Web
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Interactivity
• A major feature of multimedia presentations
can be the use of interactive elements –
where the viewer chooses their path through
the presentation instead of seeing a fixed
series of events
• Normal web pages achieve interactivity
through hyperlinks
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Multimedia Hardware
• Basic input and output hardware for
multimedia include a CD-ROM or DVDROM drive, sound card, and speakers
(all now standard on personal computers)
• Optional equipment includes a microphone,
graphics tablet, digital camera, and a TV
video adapter
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Multimedia Hardware
• Faster video cards and 3-5 speakers instead
of just one or two (e.g. adding a subwoofer
or going for surround sound or theater-grade
THX sound) help too
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Multimedia Uses
• Multimedia is used increasingly for
– Computer based training (CBT) or education
(CBE)
– Livening up reference materials
(encyclopedias)
– Creating stand-alone sales or information
kiosks, playing a loop of information
– Even art is starting to use multimedia
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Big Files Need Compression
• Multimedia takes a lot more disk space than
text, so compression techniques are
important
• Algorithms are used to calculate how data
can be compressed – these algorithms are
called “codecs” (for compression/
decompression)
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Compression Types
• Compression techniques can be lossless or
lossy
– Lossless techniques retain every bit of original
data (literally!)
– Lossy techniques sacrifice some low level data
detail to produce higher levels of compression
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Graphics Compression Formats
• GIF (like “gift” without the ‘t’) allows a
maximum of 256 colors (8-bit), uses
lossless compression, and is often used for
simpler Web graphics
• JPEG allows up to 16.7 million colors
(24-bit), is lossy, and often used for photos
or other complex images on the Web
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Graphics Compression Formats
• PNG is a new format like GIF, but isn’t
proprietary (you have to pay royalties to be
able to create GIF images)
• Bitmap (BMP) is the Windows standard for
primitive graphics – is often without
compression, so bitmaps are huge
– A bitmap describes every pixel’s color
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Graphics Software
• Graphics software programs tend to fall into
three types for working with a single image
– Paint programs, which use bit-mapped or raster
graphics
– Drawing programs, which use vector graphics
– Image editors, for modifying existing photos
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Paint Programs
• Paint programs are designed to create
images at the pixel level
• Easy to create stuff this way, but harder to
edit, and harder to keep smooth
• Examples: Fractal Design Painter, Paint
Shop Pro, Corel Painter
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Drawing Programs
• Drawing programs use vector graphics –
each line is described by a math formula
• Draw and shape lines, then fill in colors and
textures among them
• Creates smoother images, which can be
scaled to any size
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Drawing Programs
• Saves documents in EPS format, which
some printers understand
– But EPS isn’t Web friendly
• Examples: Adobe Illustrator, Macromedia
Freehand, CorelDRAW
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Image Editors
• Image editors are for manipulating existing
pictures (e.g. photos)
• Allow you to resize, crop, merge and add
special effects to the images
• Examples: Adobe Photoshop and
PhotoDeluxe
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Moving Picture Software
• Programs for working with moving pictures
include:
– 3-D rendering programs, for adding 3-D effects
to graphics (lighting, shadows, etc.)
– Animation programs, for creating the illusion of
moving pictures through graphics
– Video editors, for creating and editing digital
videos
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3-D Rendering Programs
• Rendering programs account for specific
light sources, and determine shadows,
transparency, and other effects
• Used to require a supercomputer to do this
• Ray tracing is one technique they use
• Examples: Renderman, AutoCAD,
3D Studio MAX
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Animation Programs
• Animation is based on presenting still
images rapidly in succession
– A movie uses 24 frames per second
• Computer animation uses the same idea
with GIF images
• Some programs recognize background
images versus those elements which move
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Animation Programs
• Examples: Adobe LiveMotion, Macromedia
Flash, and Softimage XSI
• Some high end ($$$) programs combine
animation with 3D rendering, such as
Discreet combustion, Maya Complete, and
Newtek Lightwave
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Video Editors
• Video editors take input from a digital video
camera, and allow it to be rearranged, add
sound, etc.
• Examples: Adobe Premiere
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Video Formats
• Videos are usually in one of three formats
– MPEG is the standard for full motion video,
such as DVD’s
– QuickTime is an Apple standard for high
quality video and audio
– AVI (formally Video for Windows) tend to be
fairly low quality
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Streaming Video
• One way to get video across the Internet
quickly is to use streaming video
• A small bit of video is sent continuously to
the viewer
– Hence the viewer doesn’t need to download the
entire video before watching it
– But the viewer also never has a copy of the
video either
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Audio Software
• Audio software has improved to where most
professional recording studios don’t bother
with magnetic tape for recording – they use
computers instead
• Sound uses can range from simple
background music to original compositions
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Audio Formats
• Audio is digitized at 44.1 kHz for CD’s
• Raw audio files are very large, hence
compression is important
– MP3 is the most common format, can be
compressed up to 1/12th of original size
– AU format is used on Sun workstations
– WAV files are used in Windows, aren’t
compressed
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Audio Software
• Musical instruments use MIDI language to
speak to computers
• Audio applications include
– Notation programs to write music
– Recording and editing programs
– Mixers and synchronizers to coordinate many
musical parts into one piece
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Putting it all together
• Authoring software is used for assembling
multimedia presentations from all of its
parts (sound, graphics, video, animation)
• Uses a scripting language to coordinate
activities
• Example: Macromedia Director
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Virtual Environments
• Massive improvements in multimedia have
led to the concept of creating virtual
environments
• Hardware like head-mounted displays make
it possible to present a realistic fake
environment
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Virtual Formats
• VRML (Virtual Reality Modeling
Language) is a front-runner in providing a
virtual environment via the Internet
• Used for games, training, and data
visualization
• One common game environment is the
Multi-User Dungeon (MUD)
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Telecommunications
• Some aspects of computer networking
depend on the existing telecommunications
infrastructure
• Most home users use analog telephone lines
for their modem connection to the Internet
• Telecom is moving from analog signals on
copper wires to digital signals
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Telecommunications
• Analog wires can go up to T1 speed (1.5
Mb/s) or 24 voice signals
• Digital signals may be sent across fiber
optic cables, or beamed using microwaves
• Fiber optics can go up to T3 speed (43
Mb/s) or 672 voice signals using pulses of
light
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Telecom Standards
• Telecom standards are defined by the ITU, a
branch of the United Nations
• Telecom is a vital service for safety, so it is
heavily regulated to ensure service to
unprofitable regions
• Private or leased lines can be used for
communication too
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Modems
• Modems modulate and demodulate signals
• That converts a digital signal to analog, and
back again at the other end
• Modem speeds evolved from 300 bits/sec
(circa 1970’s) to the theoretical limit of
56,000 bps
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Modem Standards
• The current limit is defined by the V.90
standard (56 kbps)
• Earlier standards were V.34 (28.8 kbps) and
V.32 (14.4 kbps)
• Modems negotiate the fastest connection
both sides can handle
• Faxes can also be sent, generally at 9.6 kbps
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Need for Speed
• Bandwidth, or the speed at which data can
be sent and received, is critical for emerging
applications
– Video conferencing needs 10 Mbps
– High definition TV (HDTV) needs 11 Mbps
• Broadband refers to digital telecom at
speeds of 1.5 Mbps and up (T1 or better)
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Broadband Options
• ISDN is the most common broadband
service
– Basic ISDN goes up to 128 kbps
– Primary ISDN goes up to 1.5 Mbps (T1)
– Broadband ISDN doesn’t exist yet; claims up to
622 Mbps
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Broadband Options
• Digital Subscriber Lines (DSL) is still rare
– Some versions are asymmetric (you can have
much slower upload speed than download)
– Range from 128 kbps to 9.1 Mbps speeds
– Speed varies depending on how far you are
from the provider
• SONET is a future possibility; range from
52 Mbps to 1 Gbps
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Cable Modems
• Cable modems use coaxial cable from your
TV cable provider to feed Internet access
• Cable bandwidth is shared among the users
in the local area – more users online means
slower speeds for each user
• Speed can range from 100 kbps to over
2000 kbps
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Power Lines?
• Internet connections can be passed over
power lines too
• Still experimental
• Not likely to work in the US
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Phone, TV, and Internet Merge
• Some appliances can let a normal TV show
the Internet (WebTV)
• Phone service and Internet service can share
the same lines, and some computer
applications handle phone and fax functions
over normal phone lines
• The lines of distinction are blurring
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Computer Networking
• Networking allows computers to
communicate with each other, and share
resources (e.g. printers)
• Networks range in size from global to
consumer
• Networks are much faster than just using
telecom equipment
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Types of Networks
• A single building or group of buildings
might use a Local Area Network (LAN)
• Several related sets of facilities might use a
Metropolitan Area Network (MAN)
• Global corporations use a Wide Area
Network (WAN)
• Networks can be public or private
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Switching
• Networks control the flow of data using
switching
• Two major types of switching
– Circuit switching changes the circuit to produce
a physically direct connection; is very fast
– Packet switching sends packets of data which
get reassembled at the other end to produce the
message; is much cheaper than circuit
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Protocols
• Network protocols are the language spoken
across the network
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–
–
–
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TCP/IP is the language of the Internet
NetBEUI is a Windows networking protocol
AppleTalk is an Apple networking protocol
IPX is a Novell protocol
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Network Layers
• Networks function by taking data and
adding various pieces of information to it in
order to help it get to its destination
• The layers of the network describe what that
information is and how it is used
• The OSI reference model is the most
common system for networking
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Network Hardware
• Networks rely on each computer having a
network interface card (NIC) to allow them
to be connected to the network
– Like a modem allows connection to the Internet
• Most NIC’s are for Ethernet networks
• Ethernet speeds include 10, 100, and 1000
Mbps (the last one is Gigabit Ethernet)
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Network Hardware
• Most networks still use cables
–
–
–
–
Thick, thin, or 10base-T Ethernet cables
Token Ring cables
Coaxial cable
Fiber-optic cable
• Infrared and radio signals are used for
wireless networks
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Network Hardware
• Other network hardware might include:
– Switches, to control where data may go
– Router, to convert one language into another
– Hubs, to connect computers which speak the
same language (protocol)
– Bridges, to connect major parts of the network
together
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Network Terminology
• Every device on a network (computer,
printer, etc.) is a “node”
• Peer to peer networks work well for small
offices and home; allow sharing of files,
printers, and Internet connection
• Client/server networks use servers to
manage the network, and control access to
different nodes
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Network Operating System
• Normal operating systems routinely include
software to allow peer to peer networking
• Client/Server networks require a
networking operating system (NOS)
– Windows Servers (NT, 2000, etc.)
– Novell NetWare
– Unix
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Network Topology
• Network topology is the layout of a
network, like a street map to show where
roads go
• The “bus” topology connects everything
along a line (like a bus route) – good for
peer to peer networks
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Network Topology
• A “star” topology puts a hub in the middle,
and everything connects to it
• A “ring” topology passes information in a
circle, and every computer either passes it
along or uses it (e.g. IBM’s Token Ring)
• More complex topologies are variants on
these basic structures
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WAN Structure
• WAN’s are essentially a group of networks
which are connected by a “backbone”
(generally a very fast dedicated connection)
– Most use circuit switching, not packet
• Each local network connects to the WAN
via a POP (point of presence), similar to
how you connect to the Internet
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WAN Protocols
• Special protocols are used for WANs
– X.25 is for phone line connections, goes up to
64 kbps (like MAC machines)
– ATM (Asynchronous Transfer Mode) goes up
to 155 Mbps
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Why WAN?
• Most WANs are used for sharing files and
email across a large organization
• Some also handle transactions (e.g. credit
card authorization)
• Specific business-to-business transactions
can be done securely using Electronic Data
Interchange (EDI) standards
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