Lesson8 Video

8/13/2019 Lesson8 Video

1/25

18-Jan-14 School of Science \ ComputerScience Dept. 1

Fundamental Concepts in Video

Lecturer

Dr. Aree Ali Mohammed

2012-20134thStage

[email protected]
mailto:[email protected]:[email protected]


2/25


Overview

What is digital video?

Video concepts

Analogue Video

Digital Video

File Size and Formats

Video Special Effects

Video Compression

Video H/S

Video Advantages and Disadvantages


3/25


What is Digital Video?

Digital video refers to the capturing, manipulation, and storage ofmoving images that can be displaced on computer screens.

This requires that the moving images be digitally handled by the

computer. The word digital refers to a system based on discontinuousevents, as opposed to analog, a continuous event.

Computers are digital systems; they do not process images the way thehuman eye does.

Advantages of Digital Video Ease of manipulation

Preservation of data

Internet (easy to store, retrieve, and publish)

Compression

Embedding in a web page


4/25


Video Concept Video is an excellent tool for delivering multimedia.

Video places the highest performance demand on computer and itsmemory and storage.

Digital video has replaced analog video as the method of choice formaking and delivering video for multimedia.


5/25


Digital video device produces excellent finished products at a fraction ofthe 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.

Video Concept


6/25


Analogue Video

Video information that is stored using television video signals,film, videotape or other non-computer media

Each frame is represented by a fluctuating voltage signal knownas an analogue wave form or composite video.


7/25


Analogue Video

Composite analogue video has all the video components:

brightness, colour and synchronization

Then combined into one signal for delivery

Example : traditional television Problems: colour blending, low clarity, high generation lost,

difficult to edit.

DIGITAL ANALOGUE


8/25


Digitizing Video

Digital video combines features of graphics and audio to createdynamic content for multimedia products.

Video is simply moving pictures.

Digitized video can be edited more easily. Digitized video files can be extremely large.


9/25


Digitizing Video

Digital video is often used to capture content from movies andtelevision to be used in multimedia.

A video source (video camera ,VCR, TV or videodisc) is connectedto a video capture card in a computer.

As the video source is played, the analog signal is sent to the videocard and converted into a digital file (including sound from thevideo).

VCR

Video Overlay BoardVideo Capture CardPC
http://www.cnn.com/2000/TECH/computing/09/20/vcr.graphics.card.idg/story.pc.tv.jpg


10/25


Analogue signal from VCRConverted to DIGITALby VIDEO CAPTURE CARD

The convertedsignal isentered inside acomputer

Signal is processedVideo is editedusing video editing

software software

Digitizing Video


11/25


Digital Video

Digital video is the digitisation of analogue video signals into numericalformat

It creates the illusion of full motion by displaying a rapid sequence ofchanging images on a display device.

Conversion from analogue to digital format requires the use on an ADC(Analogue to Digital Converter) A Digital to Analogue Converter (DAC) can be used to output digital

video on analogue equipment


12/25



There is an important consideration:

file size in digitized video which included

1. frame rate

2. image size

3. color depth.


13/25

18-Jan-14School of Science \ Computer

Science Dept. 13


1. Frame Rate

animation is an illusion caused by the rapid display ofstill images.

television and movies play at 30 fps but acceptableplayback can be achieved with 15 fps.


14/25


Science Dept. 14


2. Image Size

A standard full screen resolution is 640x480 pixels but to safe storingspace a video with 320x240 for a computer display is still acceptable.

New high-definition televisions (HDTV) are capable of resolutions upto 19201080p60,

1920 pixels per scan line by 1080 scan lines, progressive, at 60frames per second.
http://en.wikipedia.org/wiki/High-definition_televisionhttp://en.wikipedia.org/wiki/High-definition_television


15/25


Science Dept. 15


3. Color Depth

The quality of video is dependent on the color quality(related to the number of colors) for each bitmap in the

frame sequence.


16/25


Science Dept. 16

3. Color Depth

The color depth below 256 colors is poorer-quality image.

The frame rate to below 15 fps causes a noticeable and

distracting jerkiness that unacceptable. Changing the image size and compressing the file

therefore become primary ways of reducing file size.


24 bit 8 bit (256 colors)16 bit


17/25


Science Dept. 17

Special Effects

Transitions Such as fading, wiping, splatters, scrolling, stipple and many

more are available by simply dragging and dropping that

transition between the two video clips.


18/25


Science Dept. 18

Special Effects

Superimposing The ability to superimpose one clip over another is a valuable

technique.

The technique of green screening is identical except that the colorgreen is used for the screen and later digitally removed.

The blue screen and green screen superimposing are just two of thesuperimposing technique available.


19/25


Science Dept. 19

Video Compression

The video compression/decompression programs are used so that video can fit on asingle CD and the speed of transferring video from a CD to the computer can beincreased.

Let us say that a sequence of 25fps video is about 25MB.

CD-ROM transfer rate is calculated as follows: 1X= 150KB per second

10X=1.5 MB per second

100X= 15 MB per secondt

To overcome large video size, CODECS were developed.

Compresseswhen saved

CODEC

File format usedsuch as: Avi,

Mpeg, MovDecompresses

when needed fordisplay


20/25


Science Dept. 20

Video Hardware and Software

VCR

Video Overlay Board /

Video Capture Card

Video digital

Editing Software

MULTIMEDIA PC
http://www.cnn.com/2000/TECH/computing/09/20/vcr.graphics.card.idg/story.pc.tv.jpg


21/25


Science Dept. 21

Video Editing Software

Incorporating transitions such as dissolves, wipes and spin.

Superimposing titles and animating them, such as fly-in logo.

Applying special effects to various images, such as twisting, zooming,

rotating and distorting. Synchronizing sound with the video.

Apply filters that control color balance, brightness & contrast, blurring,distortions and morphing.


22/25


Science Dept. 22

Advantages of using Video

Captures interest

Increase retention Clarifies complex physical actions and relationships

Can incorporate other media


23/25


Science Dept. 23

Disadvantages of using Video

Is expensive to produce

Requires extensive memory and storage

Requires special equipment

Does not effectively illustrate abstract concepts andstatic situations


24/25


Science Dept. 24

Summary

Digital video method is used for making anddelivering video for multimedia.

Compression techniques help to reduce the file sizesto more manageable levels

Two types of compression lossless and lossy.

Standards for compression program are JPEG andMPEG.


25/25


Science Dept. 25

Group Discussion

Lesson8 Video

Documents

Transcript of Lesson8 Video