Video is composed of a series of still images called frames displayed in rapid succession to create the illusion of motion. It involves both visual and audio components. There are two main types of video - analogue and digital. Analogue video represents images and sound through continuous signals while digital video uses discrete numeric data. Common video file formats include .MP4, .AVI, .WMV and .MOV, each suited for different uses and applications.

1. Video

2. Introduction
 Video is a combination of image and audio. It
consists of a set of still images called frames
displayed to the user one after another at a specific
speed, known as the frame rate measured in number
of frames per second (fps), If displayed fast enough
our eye cannot distinguish the individual frames, but
because of persistence of vision merges the
individual frames with each other thereby creating an
illusion of motion. The frame rate should range
between 20 and 30 for perceiving smooth realistic
motion. Audio is added and synchronized with the
apparent movement of images. The recording and
editing of sound has long been in the domain of the
PC. Doing so with motion video has only recently
gained acceptance. This is because of the enormous

3. How Video Works?
 When light reflected from an object passes
through a video camera lens, that light is
converted into an electronic signal by a special
sensor called a charge-coupled device (CCD).
Top-quality broadcast cameras and even
camcorders may have as many as three CCDs
(one for each colour of red, green, and blue) to
enhance the resolution of the camera and the
quality of the image. It’s important to understand
the difference between analogue and digital
video.

4.  Analogue video has a resolution measured in the
number of horizontal scan lines (due to the nature of
early cathode-tube cameras), but each of those lines
represents continuous measurements of the colour
and brightness along the horizontal axis, in a linear
signal that is analogous to an audio signal. Digital
video signals consist of a discrete colour and
brightness (RGB) value for each pixel.

5.  Digitizing analogue video involves reading the
analogue signal and breaking it into separate
data packets. This process is similar to digitizing
audio, except that with video the vertical
resolution is limited to the number of horizontal
scan lines. For some multimedia projects you
may need to digitize legacy analogue video. The
following discussion will help you understand the
differences between analogue and digital video
and the old and new standards for horizontal
lines, aspect ratios, and interlacing.

6. Using Video
 Carefully planned, well-executed video clips can
make a dramatic difference in a multimedia project. A
clip of John F. Kennedy proclaiming “Ich bin ein
Berliner” in video and sound is more compelling than
a scrolling text field containing that same speech.
Before deciding whether to add video to your project,
however, it is essential to have an understanding of
the medium, its limitations, and its costs. This unit
provides a foundation to help you understand how
video works, the different formats and standards for
recording and playing video, and the differences
between computer and television video. The
equipment needed to shoot and edit video, as well
as tips for adding video to your project, are also

7.  Video standards and formats are still being refined as transport, storage, compression, and display
technologies take shape in laboratories and in the marketplace and while equipment and post-
processing evolves from its analogue beginnings to become fully digital, from capture to display.
Working with multimedia video today can be like a Mojave Desert camping trip: you may pitch your
tent on comfortable high ground and find that overnight the shifting sands have buried both your
approach and your investment. Of all the multimedia elements, video places the highest
performance demand on your computer or device—and its memory and storage.

8.  Consider that a high-quality colour still image on a
computer screen could require as much as a
megabyte or more of storage memory. Multiply this by
30—the number of times per second that the picture
is replaced to provide the appearance of motion—and
you would need at least 30 megabytes of storage to
play your video for one second, more than 1.8
gigabytes of storage for a minute, and 108 gigabytes
or more for an hour. Just moving all this picture data
from computer memory to the screen at that rate
would challenge the processing capability of a
supercomputer. Some of the hottest and most arcane
multimedia technologies and research efforts have
dealt with compressing digital video image data into
manageable streams of information. Compression
(and decompression), using special software called a
codec, allows a massive amount of imagery to be
squeezed into a comparatively small data file, which
can still deliver a good viewing experience on the
intended viewing platform during playback.

9. Broadcast Video Standards
 Digital broadcasting is very different from analogue.
The NTSC and PAL standards describe both
transmission of the signal and how the electrical
signal is converted into an image. In digital, there is
a separation between the subject of how data is to
be transmitted from tower to TV, and the subject of
what content that data might contain. While data
transmission is likely to be a fixed and consistent
affair, the content could vary from High Definition
video one hour, to SD multi-casting the next, and
even to non-video data casting. In the US, 8VSB
transmits the data, while MPEG-2 encodes pictures
and sound.

10. National Television System Committee
(NTSC)
 NISC is a television broadcasting system used in a
number of countries including Korea, Japan,
Canada, North America, parts of South America,
Mexico and the Caribbean islands. It is named after
the National Television Systems Committee, the
industry wide standardization body that created it.
The National Television Systems committee was set
up in 1940 by the Federal Communication
Commission in the United States to establish a
nationwide standard for black and white TV
transmission.

11. Phase Alternating Line (PAL)
 PAL, short for Phase Alternating Line, is the
analogue video format used in television
transmission in most of Europe (except France,
Bulgaria, Russia, Yugoslavia, and some other
countries in Eastern Europe, where SECAM is
used), Australia and some Asian, African, and
South American countries. PAL was developed in
Germany by Walter Bruch, and first introduced in
1967.

12.  The name “Phase Alternating Line” describes the
way that part of the colour information on the video
signal is reversed in phase with each line, which
automatically corrects phase errors in the
transmission of the signal. NTSC receivers have a
tint or hue control to perform the correction manually.
Some engineers jokingly expand NTSC to “Never
The Same Colour” while referring to PAL as “Perfect
At Last” or “Peace At Last”! However, the alternation
of colour information – Hanover bars – can lead to
picture grain on pictures with extreme phase errors.

13. Difference between NTSC and
PAL
 NTSC stands for National Television Standards
Committee. PAL stands for Phase Alternating
Line. NTSC is the standard broadcast format in
the United States, while PAL is the standard
broadcast format in Europe, Australia, and parts
of Asia.

14.  If you are an American who has tried to insert a
movie from Europe into your DVD player, you will
notice that the picture will be very scrambled and the
sound quality will be absolutely terrible. The vast
majority of DVD players that were manufactured for
the United States are not backwards compatible with
the PAL broadcast format.

15. Analogue Video
 In an analogue system, the output of the CCD is processed by
the camera into three channels of colour information and
synchronization pulses (sync) and the signals are recorded
onto magnetic tape. There are several video standards for
managing analogue CCD output, each dealing with the
amount of separation between the components—the more
separation of the colour information, the higher the quality of
the image (and the more expensive the equipment). If each
channel of colour information is transmitted as a separate
signal on its own conductor, the signal output is called
component (separate red, green, and blue channels), which is
the preferred method for higher-quality and professional video
work. Lower in quality is the signal that makes up Separate
Video (S-Video), using two channels that carry luminance and
chrominance information. The least separation (and thus the
lowest quality for a video signal) is composite, when all the
signals are mixed together and carried on a single cable as a
composite of the three colour channels and the sync signal.
The composite signal yields less-precise colour definition,

16. Digital Video
 In digital systems, the output of the CCD is digitized
by the camera into a sequence of single frames, and
the video and audio data are compressed before
being written to a tape (see Figure 5.3) or digitally
stored to disc or flash memory in one of several
proprietary and competing formats. Digital video data
formats, especially the codec used for compressing
and decompressing video (and audio) data, are
important; more about them later in this unit.

18. Formats of video files?
 .3GP: 3GP is a compression file format created by 3GPP (3rd
Generation Partnership Project), which is a basic version of
MPEG-4 part 14 (MP4) format. It is used to compress audio,
video, and other multimedia to save on disk space, bandwidth,
and data usage. It often creates files for use with cell phones.
There are different video players that can play this file format
videos on your computer, smartphone, or tablet. The .3GP or
.3G2 are the file extensions of the 3GP file format.
 .MP4: MP4 is a file format that was introduced in 1998, which
stands for MPEG-4 Part 14 and, it was agreed upon as a
standard by the MPEG. It is an audio and video compression
standard, commonly used to store video and audio as well as
store subtitles and still images. Like the MPEG-1 and MPEG-2
standards, MPEG-4 reduces the file size as much as possible
through codified methods for encoding audio and video. It
provides some features, such as DRM (Digital Rights
Management) support, various forms of interactivity, including
features for 3D rendering with VRML.

19.  .AVI: An AVI file is a sound and motion picture file, stands
for Audio Video Interleaved that is used for video files
under Microsoft Windows. The file size, 2 GB, is the
maximum file size of an AVI file. AVI files have the
extension .avi and need a special player to play the video
files that may be require downloading or may be included
with your Web browser.
 .WebM: WebM provides open video compression for
HTML5 videos that are based on the same video format,
which uses the MKV file extension. It is a container
format for audio and video data that is sponsored by
Google Inc. as a WebM Project. Under a BSD license, it
was put together to provide support and release WebM
content that led to available in the market to users for
free of cost. If any file has the WEBM file extension, it will
be a WebM Video file. As the format is used on HTML5
websites for video streaming, therefore, most web

20.  .MOV: MOV is a MPEG 4 video container file format introduced by Apple in 1998. It is
a format of Apple's Quicktime program. An algorithm, Apple's proprietary compression,
is used by MOV files, which can be opened with the help of using a video editor,
compatible video program, or QuickTime.
 .WMV: The WMV file extension is a video file format, which stands for Windows
Media Video and is developed by Microsoft. It is a compressed video file format that
supports different video codecs for streaming video over the Internet. The .WMV is the
file extension of the WMV file. It contains video encoded with one of Microsoft's WMV
proprietary codec and is the same as an. ASF file. Now WMV files can be played on
different player software. In 1999, it was introduced as a competitor of the RealVideo
format.
 .FLV: An FLV encoder tool is native to the Adobe Flash player, which is commonly
used to change audio and video into the FLV format. The .FLV is the file extension of
the FLV file.