Chapter 5:understanding Digital Video

technology By:

NOR HASHAHANA BT HJ GHAZALI 901025-03-6068

The Digital Age

• We live in a digital age• The world as we know changing, its going

digital • We can walk into Blockbuster Video and rent a

movie on DVD• DVD is a new storage medium that will hold

gigabytes of information on a single disc

• DVD are the latest in a series of advances in digital video technology

• DVD will replace VHS tapes, and someday is coming sooner than you might think

Digital Video, DV• Video n computers used to be two distinct

technologies • When the television and the computer were

each created, no one partipated they would one day merge

• Now you can surf the internet on your tv or use a computerized DVR or digital video recorder, to record hours and hours of programming without videotape.

• Video has evolved into digital video, DV.• Video cameras use CCDs, or change-coupled

devices, which are computer chips that convert the optical images into electrical impulses.

• Traditional video uses an analog signal, which is an electrical signal that fluctuates exactly like the original signal it is mimicking.

• Digital video converts the analog signal into binary from, which is represented by a series of zeroes and ones.

History of Digital Video• Digital video technology explode in the 1990s.• In the 1970s frame of analog video were converted into

digital firm and altered for special effects.• These digital video effects systems, DVEs were not

actually stored in memory.• Early 1980s, digital stil store devices (DDSs) were capable

of storing and recalling individual video frames.• In the mid 1980s, digital disc recorders (DDRs) were able

to both play back and record images at the same time.• All of these older technologies contributed to the

evolution of digital video.

Nonlinear Editing• Digital video was revolutionized on the Macintosh

computer platform with the advent of QuickTime, a type of software compression that shrinks the size of digital video files

• Avid technology was the company that pioneered the digital video, or nonlinear editing system.

• This new style of editing video on the computer was called nonlinear editing in the professional arena.

• As computer technology continued to evolved, the gap between nonlinear editing and desktop video began to decrease.

Linear Editing• Traditional video editing is called linear editing • In linear editing, the video program is editing

consecutively from beginning to end • One or more video decks play the original videotape

from the video cameras, and a second video deck records the selected shots onto the master, or editing, videotape

• The differences between linear editing and nonlinear editing can be clearly illustrated by using the analog of an audio cassette tape (linear) and an audio compact disc, CD (Non linear)

Advantages of Digital Video• Nonlinear editing, or digital video as it is

commonly called today, has several distinct advantages over linear editing

• Nonlinear editing is faster, changes are easier to make

• Therefore, editors have more creative freedom in arranging their shots

• Advantage of nonlinear is that it does not suffer from generation loss because the video signal is digital

The Video Signal & Standard• The video signal itself broken into two partsChrominance-is the color portion of the video

signalLuminance-is the black and white portion of

the video signalRGB-are the three additive primary color used

to construct a video image

The NTSC Video Standard• Video signal that broadcast in the united

states must adhere to a set of standards that was set forth by the NTSC, national television standard committee

• Other countries throughout the world use PAL (Phase Alternate Line)-UK, western Europe & Afrika or SECAM( Systeme Electronique Pour Couleur Avec Meoire)-France, Russia & Eastern Europe

File Size in Digital Video• Video pixel in a frame of digital video, contains

information• Standard 640x480 frame, there are over

300,000 pixels • There are three primary factors that

determine file saiz in digital video:Resolution Frame rate Color depth

• Creating digital video for :Internet –very small file sizesCD-ROMs-modarate file sizes Broadcast television- much larger sizes• There are typical standards used to create

digital video for broadcast, multimedia and the internet

Broadcast • ResolutionAnalog video camera- 640x480 pixelsDigital video camera-720-480 pixelsFull screen videoHDTV 2 resolution- 1280x720 pixels Video-72 dpi

Multimedia

• Multimedia are more flexible than they are for broadcast

• Computer with faster processors, faster CD-ROM drives and a lot slower systems

• Resolution-either 320x240 pixels(analog) or 360x260 pixels(digital)

• Frame rate-often 15 fps

Internet

• Can make digital video available as a downloadable movie-a copy of the entire digital video could be downloaded to the user computer

• Advantage-the user would have a copy of the digital video movie, remain on the user computer

• Resolution- 160x120 pixels(analog) or 180x120 pixels(digital)

• Frame rate- usually 8-bit color