Chapter6 VIDEO Multimedia

8/11/2019 Chapter6 VIDEO Multimedia

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Chapter 6

Video


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Overview

Using video.

How video works?

Broadcast video standards. Analog video.


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Overview

Digital video.

Video recording and tape formats.

Shooting and editing video. Optimizing video files for CD-ROM.


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Using Video

Video is an excellent tool for delivering

multimedia.

Video places the highest performance

demand on computer and its memory

and storage.

Digital video has replaced analog as the

method of choice for making and

delivering video for multimedia.


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Using Video

Digital video device produces excellent

finished products at a fraction of the

cost of analog.

Digital video eliminates the image-

degrading analog-to-digital conversion.

Many digital video sources exist, but

getting the rights can be difficult, time-consuming, and expensive.


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How Video Works

Light reflected from an object through

the cameras lens is converted into

electronic signal by charge-coupled

device (CCD).

This electronic signal contains three

channels of color information and

synchronization pulses (sync). Several video standards exist that deal

with the amount of separation between

the components of the signal.


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How Video Works

Analog video transfer methods

Componentvideo separates color andbrightness over three cables.

S-videoseparates color and brightness overtwo wires.

Compositevideo transmits the whole videosignal in a single cable.


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Broadcast Video Standards

National Television Standards Committee

(NTSC):

These standards define a method for

encoding information into electronic signalthat creates a television picture.

It has screen resolution of 525 horizontal

scan lines and a scan rate of 30 frames persecond.

United states, Canada, Mexico and Japan


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Phase Alternate Line (PAL)

PAL has a screen resolution of 625 horizontal lines and a scan rate of

25 frames per second.

Used in United Kingdom, Western Europe, Australia, South Africa,

China and South America.


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Sequential Color and Memory (SECAM):

SECAM has a screen resolution of 625 horizontal lines and is a 50 Hz

system.

SECAM differs from NTSC and PAL color systems in its basic

technology and broadcast method.

Used in France, Eastern Europe and few other countries


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Advanced Television Systems

Committee (ATSC) Digital Television

(DTV):

This digital standard provides TV stations withsufficient bandwidth to present four or five

Standard Television (STV) signals or one High

Definition TV (HDTV) signal.

This standard allows for transmission of data tocomputers and for new Advanced TV (ATV)

interactive services.


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Analog Video

Overscan and the safe title area:

Analog television sets remain the most

widely installed platforms for delivering and

viewing video. Overscanoccurs when an image is larger

than the standard TV screen.


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Analog Video

Overscan and the safe title area

(continued):

Underscan occurs when computer

monitors display a smaller image onpicture tube.

The safe title area is where the image will

not be affected by overscanning, even inthe worst conditions.


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.


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Analog Video

Video color:

Television sets use composite input.

Hence colors are less pure and less

accurate than computers using RGB

component.

NTSC television uses a limited color

palette and restricted luminance(brightness) levels and black levels.


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Analog Video

Video color (continued):

Some colors generated by a computer that

display fine on a RGB monitor may be

illegal for display on a NTSC TV. While producing a multimedia project,

consider whether it will be played on a

RGB monitor or a conventional television

set.


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Analog Video

Interlacingeffects:

In television, the electron beam makes two

passes on the screen while drawing a

single video frame. It first lays down all the odd-numbered

lines, and then all the even-numbered

lines, hence they are interlaced.

While capturing images from a video

signal, they can be filtered through a de-

interlacing filter provided by image-editing

applications.


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Analog Video

Text and titles for television and taking

care of analog tapes:

Titles for video productions can be created

with an analog character generator.

Computers can create titles digitally using

video and image-editing software.

New tapes should always be fast-forwarded to the end and then rewound, to

ensure even tape tension.


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Analog Video

Text and titles for television and taking

care of analog tapes:

Font for titles should be plain,san serif and

bold enough to be easily understood.

Do not kern tightly

When dealing with dark background, use

white or light color for text.


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Digital Video

Video clip stored on any mass-storagedevice can be played back on a

computers monitor without special

hardware.

Setting up a production environment for

making digital video, requires some

hardware specifications.

Some specifications include computer

with FireWire connection and cables,

fast processor, plenty of RAM, fast and

big hard disk.


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Digital Video Compression

Digital video compression schemes or

codecs is the algorithm used to

compress (code) a video for delivery.

The codec then decodes the

compressed video in real-time for fast

playback.

Streaming audio and video startsplayback as soon as enough data has

transferred to the users computer to

sustain this playback.


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Digital Video Compression

MPEG is a real-time video compression

algorithm.

MPEG-4 includes numerous multimedia

capabilities and is a preferred standard.

MPEG-7 (or Multimedia Content

Description Interface) integrates

information about motion videoelements with their use.


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Video Recording and Tape

Formats

Composite analog video.

Component analog video.

Composite digital.

Component digital.

ATSC digital TV.


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Composite Analog Video

Composite video combines the

luminance and chroma information from

the video signal.

Composite video produces lowest

quality video and is most susceptible to

generation loss.

Generation loss is the loss of qualitythat occurs while moving from original

footage to editing master to copy.


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Component Analog Video

Component video separates the luminanceand chroma information.

It improves the quality of the video and

decreases generation loss. In S-video, color and luminance information

are kept on two separate tracks (Y/C) to

improve the picture quality. Betacam is a new portable professional

video format which lays the signal on the

tape in three component channels.


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Composite Digital

Composite digital recording formats

combine the luminance and chroma

information.

They sample the incoming waveformsand encode the information in binary

(0/1) digital code.

It improves color and image resolutionand eliminates generation loss.


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Component Digital

Component digital formats add theadvantages of component signals to digital

recording.

D-1 component digital format is an

uncompressed format which has a very

high quality image.

It uses a 19 mm (3/4-inch) tape in order to

save data.

Several other digital component formats

are DCT, Digital Betacam, DV format,

DVCPRO, and DVCAM formats.


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ATSC Digital TV

These standards provide for digital STV

and HDTV recordings that can be

broadcast by digital TV transmitters to

digital TV receivers. ATSC standards also provide for

enhanced TV bringing the interactivity of

multimedia and the Web to broadcasttelevision.


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Shooting and Editing Video

Import video and sound at the highest

resolution and with the least amount of

compression possible.

Resolution should be reduced andfootage must be compressed later

according to the requirements.

A steady shooting platform shouldalways be used.


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Shooting and Editing Video

Good and even lighting is extremely

important.

Blue screen in digital video editing

applications is a popular technique formaking multimedia.

Wide panoramic shots and camera

motion should be avoided whenshooting for a small computer window

on CD-ROM or the Web.

O ti i i Vid Fil f CD


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Optimizing Video Files for CD-

ROM

CD-ROMs provide an excellent distribution

medium for computer-based video.

When preparing video for CD-ROM

distribution, interleave the audio track(s)with the video track. (flattening)

Key frames should be used every 10 to 15

frames and the size of the video windowmust be kept small.

The Sorenson codec is optimized for CD-

ROM playback.


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Summary

Digital video method is used for making

and delivering video for multimedia.

Charge-coupled device (CCD) converts

the light that has been reflected from anobject through the cameras lens.


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Summary

Various video standards are NTSC,

PAL, SECAM, and ATSC DTV.

Categories of video standards are

composite analog, component analog,composite digital, and component

digital.

Chapter6 VIDEO Multimedia

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