Chapter 6

IT Essentials: PC Hardware and Software 1

Chapter 6

Multimedia

Capabilities


MultimediaMultimedia is a term typically used to mean the combination of

text, sound, and/or motion video. Multimedia has been described

as the addition of animated images, but typically it means one of

the following:

• Text and sound

• Text, sound, and still or animated graphic images

• Text, sound, and video images

• Video and sound

• Multiple display areas, images, or presentations presented

concurrently

• In live situations, the use of a speaker or actors and "props"

together with sound, images, and motion video


PC Requirements to Run Multimedia

The types of computer hardware and software necessary to

develop multimedia on the PC vary.

The minimum hardware requirements include:

• computer monitor

• video accelerator card

• sound adapter card with attached speakers.


Key Multimedia Components

• A microphone connected to a sound card to input sound.

• CD-ROMs and DVD players are used for input and output of

multimedia.

• A connection to the Internet via a network interface card or a

modem. Streaming of audio and video is very popular.

• Digital still pictures and video cameras connected to standard

computer ports or special card adapters.

• A video capture card

• MPEG hardware and Web based movie players are used to

play movies.

• Computer games via DVD or CD require specialized hardware.


The Video Card

• A video adapter (also called a display adapter or video board) is

an integrated circuit card in a computer that provides digital-to-

analog conversion, video RAM, and a video controller so that

data can be sent to a computer's display. In a few cases, the

video adapter is built in to the monitor. Today, almost all displays

and video adapters adhere to the standard Video Graphics Array

(VGA).

• In addition to VGA, most displays adhere to one or more

standards set by the Video Electronics Standards Association

(VESA). VESA defines how software can determine the

capability of a display. It also identifies resolutions setting beyond

those of VGA. These resolutions include 800 by 600, 1024 by

768, 1280 by 1024, and 1600 by 1200 pixels.


Display Characteristics

Displays use bits to describe color and how many colors can be

displayed

• The number of bits used to describe a pixel is called bit-depth

• VGA video is 256 colors or 8-bit bit-depth

• 24-bit bit-depth is known as true color

• Dot pitch is the size of an individual beam that gets through to

light up a point of phosphor on the screen measured in

millimeters with a typical display having a .28 mm dot-pitch

• The actual sharpness of a display image is measured in dots-

per-inch (dpi). The dots-per-inch is determined by a combination

of the screen resolution and the physical screen size.





Dot pitch is a diagonal distance between the same color phosphor dots. The smaller the dot pitch, the greater the potential image sharpness.



• On desktop computers, the display screen width relative to

height, known as the aspect ratio, is generally standardized at 4

to 3 (usually indicated as "4:3"). Screen sizes are measured in

either millimeters or inches diagonally from one corner to the

opposite corner. Common desktop screen sizes are 15-, 17-and

19-inch. Notebook screen sizes are somewhat smaller.

•The projection technology used by most displays is Cathode

Ray Tube (CRT) technology, which is similar to that used in most

television sets. CRT technology requires a certain distance from

the beam projection device to the screen in order to function.

Using other technologies, displays can be much thinner and are

known as flat-panel displays.


Media Formats

• Two data-compression standards are commonly used with

digitized video. These are the Joint Photographic Experts Group

(JPEG) and the Moving Picture Experts Group (MPEG)

compression standards.

Other Compression Standards

• Indeo compression standard, developed by Intel.

• Another compression/decompression (codec) standard

supported by Video for Windows is Cinepak. This standard uses

an AVI file format to produce 40:1 compression ratios and 30-

frames per second capture, at 320-by-200 resolution.


Media Compression

• JPEG provides enough compression to allow single-frame

digitized images to fit on disk drives, but full-motion pictures

were going to need much greater compression to be useful on

current technology. Therefore, the MPEG format was developed.

•MPEG has compression ratios up to 200:1, with high-quality

video and audio.

•The MPEG standard includes specifications for audio

compression and decompression in both MPEG1 and 2. MPEG1

supports a very near CD-quality stereo output, at data rates

between 128kbps and 256kbps. The MPEG 2 specification

supports CD-quality surround-sound (four-channel) output.


AGP Cards

• Newer Pentium systems were the first to include an advanced

Accelerated Graphics Port (AGP) interface for video graphics.

The figure below shows an AGP interface and its position on the

motherboard. The AGP interface is a variation of the PCI (see

Chapter 2) bus design that has been modified to handle the

intense data throughput associated with 3 dimensional graphics.


Video Capture Cards

• Video capture software is used to capture frames of television

video and convert them into digital formats that can be processed

by the system. One of the popular file formats for video is the

Microsoft Audio Visual Interface (AVI) format. Video capture

cards are responsible for converting video signals from different

sources into digital signals that can be manipulated by the

computer. As in the audio conversion process, the video card

samples the incoming video signal by feeding it through an A-to-

D (analog-to-digital) converter.

• One of the jobs of the video capture card is to convert the YUV

format into an RGB VGA-compatible signal. YUV is a video

encoding format that is different than RGB.


Video Card Installation

• After the video card has been installed and the monitor has

been connected to the video card and plugged into the power

outlet, it will be necessary to install the correct drivers for the

video card. The Windows 9x operating systems should detect the

video card, start the system with basic VGA video drivers, and

ask you if you want to install the manufacturer's video drivers.

• The Windows 2000 operating system is even more proactive. It

will detect the new video card, tell you that it has found the new

card, and then automatically load its video drivers. The only time

that you should need to be directly involved with the system's

video drivers is when PnP fails or the video card is not

recognized by the operating system.


Video Memory and Resolution

• Monitors are analog, not digital devices. In order for the monitor

to work, the digital information in the video memory must be

translated into analog form for export to the monitor screen. This

is the role of the Random Access Memory Digital-to-Analog

Converter (RAMDAC) chip. The RAMDAC chip reads the video

memory contents, converts it to analog, and sends it over a cable

to the video monitor. The quality of this chip impacts the quality

of the image, speed of the refresh rate, and maximum resolution

capability. Refresh rate refers to the number of times per second

that the video display screen can be redrawn.


Video Memory and Resolution

• The video chip set relies on video memory to render the image

requested. The basic element of every video image is a dot (or

pixel). Many dots comprise what you see displayed on the

monitor. Every dot has a location reserved in video memory. The

maximum number of dots, which can be displayed, relates to the

resolution.

•Resolution is expressed as a pair of numbers. Each pair of

numbers represents the maximum possible number of dots on a

horizontal and vertical axis. The basic VGA resolution is 640 by

480. The higher the resolution, the sharper and clearer the

image.


Sound Cards

• Audio is an integral component of the multimedia experience,

but for a PC to have audio capabilities, it requires the use of a

sound card.

• A sound card is a device (either in the form of an expansion

card or a chipset) that allows the computer to handle audio

information.

• Input – Sound cards can "capture" audio information from many different sources.

These sources include microphones, CD players, DAT, and MIDI devices.

• Processing – The processing capability of a sound card allows it convert audio

information in different formats as well as add effects to the sound data.

• Output – Simple sound card output devices include headphones and speakers

while more complicated devices consist of surround-sound digital theatre systems,

DAT and CD recorders, and other musical devices


Sound Cards

• Sound cards produce audio (synthesize) using three distinct

methods: Frequency Modulation (FM), Wavetable, and Musical

Instrument Digital Interface (MIDI).

• FM synthesis - creates waveforms that best match the

instrument playing.

• Wavetable - sound cards use actual digitized samples of

real instruments to reproduce audio.

• MIDI - is a combination of hardware and software that

allows the sound card to control actual musical instruments

and use these instruments to output the audio.


Sound Production and Quality

• The quality of a sound card is determined by its bit depth, sampling rate, and

feature set.

• Bit depth – Refers to the sample size and bus size of the sound card.

• Sampling rate – The rate at which the card can record audio information. Today's

16-bit sound cards are capable of sampling at 128kHz and beyond.

• Feature set – Includes additional features such as: 3-D audio co-processors,

device controllers, and digital output options.

• Sound cards can also act as device controllers that have built-in SCSI, RAID, or FireWire (IEEE 1394) controllers. Many higher-end sound cards also offer digital output ports such as Toslink (a fiber optic connector) and coaxial to allow connection to home theatre systems.


CD-ROMs

• CDs are 120mm in diameter, 1.2mm thick, and can store up to

800 MB of information.

• CD-ROM drives can be mounted internally in the computer or

as an external drive.

• They connect either directly to an external port on the computer

(such as USB, FireWire, or parallel) or to a controller installed in

one of the computer's expansion slots (usually SCSI).

• Common internal connections include IDE and SCSI.

• IDE communication cables are 40-pin ribbon cables that

connect to the drive and the motherboard.


CD-R and CD-RW

Currently there are two major types of CD recorders: CD-R and

CD-RW.

• CD-R – CD-R stands for Compact Disc - Recordable and was

the first of the two technologies conceived.

• CD-RW – CD-RW stands for Compact Disc - Rewritable.

• A CD drive that can write at 3000kb per second is shown as

having a 20x (or 20 times 150kb) write speed. A drive listed as

24x/40x has a write speed of 24x and a read speed of 40x.


CD Recording Formats

Chapter 6

Documents

video images video

pc hardware

video card

video cameras

video ram

video controller

withdigitized video

sound card