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1


Computer Maintenance

Multimedia


How Multimedia Changed
Computer Interface

IT: Computer Maintenance
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Multimedia

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IT: Computer Maintenance
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Multimedia

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Summary Slide


Multimedia


The history of multimedia


Sound Card


How a sound card works


MIDI, FM synthesis, Digital sound


3D audio


MP3 music


Choosing a sound card

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Multimedia

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Summary Slide
Continued


Video card


How a video card works


Troubleshooting a video card


Choosing a video card


Virtual Reality

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IT: Computer Maintenance
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Multimedia

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Multimedia

Any computer
-
delivered electronic system that
allows the user to control, combine, and manipulate
different types of media, such as text, sound, video,
computer graphics, and animation. Interactive
multimedia

integrate computer, memory storage,
digital (binary) data, telephone, television, and other
information technologies.

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Multimedia

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History of Multimedia


1905


First jukebox is released


1906


First animated cartoon film is produced


1907


Bell &Howell develop a film projection
system


1914


The camera is invented


1928


Television sets in households


1948


Cable TV is installed

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History of Multimedia
(cont.)


1967


Prerecorded movies on videotape sold
for home TV sets


1979


In Japan, the first cellular phone network


1985


The first CD
-
ROM can store 270,000
pages of text


1995


A CD
-
ROM can carry a full
-
length
feature film


The original IBM PC had no sound or video.


Multimedia is now an integral part of the web.


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Multimedia

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Sound Cards


None of the multimedia
that enhances the use
of the PC could exist
without sound
capabilities.


The sound card allows
a computer to play and
record high
-
quality
sound.

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How a Soundcard Works

A soundcard receives a
sound in analog signal,
sometimes more than one
signal at a time.

A ROM chip, or in newer
designs, rewritable
memory, contains the
instructions for handling
the digital signal.

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2

3

The ADC sends the binary
information to a chip, called
a digital signal processor
(DSP).

4

The signals go to an
analog
-
to
-
digital converter
(ADC) chip where the chip
changes the analog signal
to digital data (0’s and 1’s).

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Soundcard (cont.)

The DSP sends the
compressed data to the PC’s
main processor, which in turn
sends the data to a hard drive
to be stored, typically as a
.WAV or .MP3 file.

The DSP decompresses the
data on the fly and sends it to a
digital
-
to
-
analog converter chip,
which translates the digital
information to a constantly
wavering electrical current.

To play a recorded sound, the
CPU fetches the file
containing the compressed
signal replication of the sound
from a hard drive or CD
-
ROM,
and sends it to the DSP.

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The analog current is amplified;
then the stronger current powers
an electromagnet that’s part of
the speaker, causing the
speaker's cone to vibrate,
recreating the sound.

8

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MIDI

Whereas some types of sounds are
straightforward recordings, such as those
contained in .WAV files, musical instrument
digital interface (MIDI) sound was developed
to conserve disk space by saving only
instructions on how to play music on
electronic versions of various musical
instruments, not recording the actual sounds.
Many musicians use MIDI to compose music
on a computer.


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FM synthesis

In FM synthesis, the DSP tells an FM
synthesis chip to produce the note. The
chip stores the characteristics of different
musical instruments in a collection of
mathematical descriptions called
algorithms. By combining the DSP
instructions with the algorithm, the chips
synthesize a facsimile of the actual
instrument playing the note.

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Digital Sound

Before a sound track is recorded, Dolby
Digital B


also known as AC3 and used
in many DVD movies


encodes soft,
treble sounds so they will be recorded
louder than they actually are.

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3D Audio


3D Audio effects sounds detected by
the ear


The interaural intensity difference is
detected because the sound is louder to the
ear nearer to the source


The interaural time difference occurs
because the sound reaches one ear sooner
than the other

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MP3


MP3 is a form of audio compression
adapted from the MPEG format for
compressed video.


MP3 compresses the original sound by
filtering out differences in the sound
signal that the human ear cannot
detect.

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Choosing a soundcard

When choosing a soundcard you should

consider the following:


MIDI support to ensure the sounds
often found in games and presentation
packages can be generated.


FM Synthesis to produce MIDI sound.


Sound Blaster compatibility ensures
that the sound card will work with most
programs and operating systems.

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Choosing a soundcard

(cont.)


Sampling size and rate of a sound card
determine the quality of the sound
produced. 16
-
bit sampling size and a
44.1 kHz sampling rate are good.


Full
-
duplex sound cards can send and
receive sounds at the same time,
allowing conversation over the Internet.


Multi
-
speaker capability can support up
to five speakers, which can enhance
the sound capabilities of the computer.

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Upgrading may allow you to add memory
to your sound car,d which allows you to
increase the capabilities of the sound
card. Sound cards usually contain enough
memory for most programs, including
games, so you will only need to add
memory if you plan to compose or sample
music.


Choosing a soundcard

(cont.)

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Video card

A video card generates the text and
images that appear on the display
area of the monitor
.

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How a Video Card Works

A camera and microphone
capture the picture and
sounds of a video, and send
those analog signals to a
video
-
capture adapter card.

A compression or
decompression chip or
software reduces the amount
of data needed to re
-
create
the video signals
.

1

2

3

The combined audio and
video elements of the signal
are sent to a digital
-
to
-
analog
converter, which translates
binary data into analog
signals that go to the screen
and speakers.

4

On the video
-
capture
adapter card, an analog
-
to
-
digital converter chip
converts the wavering
analog video and audio
signals to a digital pattern.

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Video Card (cont.)

A PC at a remote location
receives the digital signals,
decompresses them, and
converts them to the analog
signals needed to control the
display and audio playback.

Motion Pictures Expert Group
(MPEG) compression records
only key frames and then
predicts what the missing frames
look like by comparing the
changes in the key frames.

Advanced forms of
compressing use a sampling
process to cut down on the
amount of data that must be
recorded or transmitted.

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Lossy

compression saves
time and memory without
any discernible change in
the image.

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Troubleshooting a

video card


If your monitor is not displaying
information due to a malfunctioning
video card, test your monitor on another
computer first.


Also, ensure that the video card is
installed in the correct expansion slot.
Some computers require that the video
card be plugged into a specific slot in
the computer.

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Choosing a video card



The
resolution

determines the amount of
information displayed on the screen and is
measured by the number of horizontal and
vertical pixels. The video card and monitor must
be able to use the same resolution.



The
Color depth


the video card determines
the number of colors a monitor can display.

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Choosing a video card


The r
efresh rate

determines the speed that
information is redrawn on the screen; it is
measured in hertz (Hz). The video card and
monitor must be able to use the same refresh
rate.



Always ensure that you are using the correct
and most up
-
to
-
date driver for your video
card.

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Choosing a video card


Memory


a video card uses memory
chips to store the information it displays
on the screen.



You can add memory chips to a video
card to increase its capabilities. Adding
memory chips can

increase the
resolution and color depth the video
card can display.

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Choosing a video card


Graphics Processing Unit


The GPU allows the
video card to display information on the screen
without using the CPU, which can improve the
computer

s performance.



Built
-
in Video Port


Many system boards come
with a built
-
in video port. To upgrade the video
capabilities you must disable the port on the
system board and then install a new video card in
an expansion slot.

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Virtual Reality


Virtual reality can deliver the ultimate
multimedia experience.



Using 3D animation and sound, virtual
reality takes you through exotic worlds,
futuristic shoot
-
outs, and flying aircraft that
yaw, pitch, and roll.


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28

Review


What is multimedia?


List some important historical events that contributed to
the development of multimedia.


List some features you should look for when purchasing
a sound card.


Briefly explain how a sound card works.


Briefly explain how a video card works.


List some features you should look for when purchasing
a video card.


What is virtual reality?

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