copyright © texas education agency, 2011. all rights reserved.1 computer maintenance multimedia

Copyright © Texas Education Agency, 2011. All rights reserved. 1

Computer Maintenance

Multimedia

How Multimedia Changed Computer Interface

IT: Computer Maintenance - Multimedia 2Copyright © Texas Education Agency, 2011. All rights reserved.

IT: Computer Maintenance - Multimedia 3

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

Copyright © Texas Education Agency, 2011. All rights reserved.


Summary Slide Continued

Video card How a video card works Troubleshooting a video card Choosing a video card

Virtual Reality



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.



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



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.



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

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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).



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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7The 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.

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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.



FM synthesisIn 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.



Digital SoundBefore 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.



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



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.



Choosing a soundcardWhen 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.



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.



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.)



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.

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3The 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.

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



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 avideo 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.



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.




The refresh 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.




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.




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.



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.



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?


copyright © texas education agency, 2011. all rights reserved.1 computer maintenance multimedia

Documents

digital sound

computer interface

computer graphics

digital data

sound capabilities

highquality sound

interactive multimedia

digital information