Transcript Multimedia Communication

Multimedia Communication
Multimedia Storage
CP586 © Peter Lo 2003
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Types of Media
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Magnetic Media
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Optical Media
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Suitable for dynamic data that often changes. Used in
most cheap portable floppy disks an hard disk drives.
Optical media such as the CD has a long life span and
high storage capacity. Fast data access times.
Analogue Media
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Videodisk is the general term for disks used to store
analogue data.
CP586 © Peter Lo 2003
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The Evolution of Storage
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Storage began as a series of punch cards.
Eventually secondary storage devices and hard
disks were required to store data.
Magnetic media was used to store data.
Advances in optical technology lead to the
development of CD ROM and DVD technology.
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Compact Disk
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A CD is a polished metal platter capable of storing
digital information and is used in the music
industry to store digital recordings.
CD’s are read-only, which means that once the
data has been recorded onto them, they can only
be read, or played.
The standard for most CD-ROMs is 24 or 32
speed (24 times per second).
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Compact Disk Read Only Memory
(CD ROM)
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A CD ROM can store up to 1GB, although the
most common size is approx 630MB.
A single CD-ROM has the storage capacity of 700
floppy disks, enough memory to store about
300,000 lines of text.
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DVD
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Short for digital versatile disc or digital video disc,
a new type of optical technology that holds a
minimum of 4.7GB (gigabytes), enough for a
full-length movie.
Many experts believe that DVD disks, called
DVD-ROMs, will eventually replace CD-ROMs,
as well as VHS video cassettes and laser discs.
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DVD Specifications
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The DVD specification supports disks with capacities of
from 4.7GB to 17GB and access rates of 600KBps to 1.3
MBPS.
DVD drives are backward-compatible with CD-ROMs.
DVD players can play a CD-ROM, CD-I disks, and video
CDs, as well as new DVD-ROMs.
DVD is 5” or 12 cm in diameter.
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DVD Specifications
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With DVD, information is contained in pits which
are about half the size of CD pits and the tracks
are therefore twice as close together.
DVD can store 7 to 14 times that of a CD.
Up to 8 different language soundtracks and 32
different language subtitles can exist on one DVD.
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DVD Features
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Multiple camera angles. (Eg. 007)
Parental Lock or rating control.
Multi-aspect ratio : Letter box or wide screen.
Interactive movie plots. (Eg. Blade)
Multiple Soundtracks and sub titles.
Additional footage and voiceovers.
CP586 © Peter Lo 2003
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(Write Once Read Many Times)
WORM
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This technology allows you to write data to a disk
a single time.
However, after that the data is permanent and can
only be read many times.
Unlike CD-ROMs, there is no single standard for
WORM disks. As a result you need the same
hardware to read and write.
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Tape
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A magnetically coated strip of plastic on which
data can be encoded.
In the computing industry tapes are primarily used
for backup because information has to be accessed
sequentially rather than randomly.
Tape drives are now available for PC’s at a
relatively inexpensive cost. (DAT)
CP586 © Peter Lo 2003
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Removable Hard Disk
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Often HDD are enclosed in plastic or metal
cartridges so that they can be removed like floppy
disks.
The storage capacity of a typical removable hard
disk can range from 60MB to 2GB, much more
than the capacity of floppy disks.
CP586 © Peter Lo 2003
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Iomega Zip Drive
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Iomega Zip drive uses a low-cost, flexiblemagnetic-media technology that gives it a decided
price advantage over drives that use SyQuest and
magneto-optical technology.
A Zip disk is light and easy to carry.
However, these disks are fairly slow and do not
compare to the read performance of a CD ROM.
The Zip Plus can hold 250MB.
CP586 © Peter Lo 2003
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Iomega Jaz Drive
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A removable disk drive developed by Iomega
Corporation.
The Jaz drive has a 12-ms average seek time and a
transfer rate of 5.5Mbps. The removable cartridges
hold 1GB of data.
The fast data rates and large storage capacity make
it a viable alternative for backup storage as well as
everyday use.
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