This presentation is on how video signals are organized and what are the three video frames. Images have been taken from internet.

1. Multimedia Technology (CS605C)
Sumanta Chakraborty
CSE, IEM

2.  Video Signals
 Video Frames

3.  A Video Signal contains a sequence of still images (frames).
 Actually, a video signal is the signal produced by the video
adapter that allows a display device, such as a
computer monitor, to display a picture.
 There are three types of video signals. That is, we can say
that video signals are organized in three categories:
1. Composite Video
2. S-Video
3. Component Video

4.  NTSC (National Television System Committee) is the name
given to the color television transmission standard used in
the U.S. Technically, NTSC is just a color modulation
scheme.
 PAL (Phase Alternation Line) is the color television
standard used in the most parts of Europe, including the UK
and Germany. Technically, PAL is also just a color
modulation scheme.
 SECAM (Sequentiel Couleur Avec Memoire, or Sequential
Color with Memory) is the color television transmission
standard used in France and some other countries. It is
similar to PAL but with some differences.

5.  Aspect ratio is the ratio of the width of the picture to the
height. Displays commonly have a 4:3 or 16:9 aspect ratio.
 Color bars are standard video test patterns used to check
whether a video system is calibrated correctly.

6.  The first analog video color format, which uses one channel
and a single cable (the audio tracks transmit in separate
channels and cables). All old analog TVs and many digital
TVs have composite video inputs.
 The original TV standard combined (Y) and both color
signals (U) and (V) into one channel, which uses one cable
and is known as "composite video”.
 Composite video was created when color was added to
black & white TV in 1954. Two color signals (U and V)
were multiplexed with the original monochrome signal (Y)
and transmitted in the same TV channel.

7.  It is one channel.
 Resolution is 480-576i.
 Composite video is usually in standard formats such as
NTSC, PAL, and SECAM and is often designated by
the CVBS, meaning "Color, Video, Blanking, and Sync."

8.  It is two-channel.
 Resolution is 480-576i.
 S-video was one of a number of enhancements in bringing
the signal from the video cassette player to TVs, and
separated video signal (luminance) and color signal
(chrominance).
 Produces sharper images.
 S-Video cables carry four or more wires wrapped together
in an insulated sleeve, with S-Video connectors at either
end.

9.  Component video is a video signal that has been split into
two or more components. In popular use, it refers to a type
of analog video information that is transmitted or stored as
three separate signals.
 Component video is a video signal that has been split into
two or more components. In popular use, it refers to a type
of analog video information that is transmitted or stored as
three separate signals.
 In component video, the luminance (Y) and two color
difference signals (U and V or I and Q) are separated into
three separate analog signals that can be transmitted over
three separate wires.

10.  3 channels.
 This combines with one or more color-carrying components,
termed ‘chroma’, that give only color information.
 No crosstalk between three channels.
 Component video is used in professional video production
and provides the best quality and the most accurate
reproduction of colors.

11.  Video frames are categorized into three frames based on
storing image information in the frames:
 I-Frame
 P-Frame
 B-Frame
I. I-Frame:
 Intra-coded Frame (Picture).
 Holds a complete image file – independent frame.
 Used as a reference frame to the other types of
frames.
 Periodic occurrences.
 Compression ratio: 10:1 to 20:1. That is, I-frames
take lots of space.

12. II. P-Frame:
 Predicted Frame (Picture).
 Holds only the changes in the image from the
previous frame.
 Not independent – constructed with previous I-frame
or previous P-frame. Used as a reference frame to
another P-frame or B-frame.
 Do not need to store the unchanging pixel
information in the P-frame.
 Compression ratio: 20:1 to 30:1. That is, P-frames
take less amount of space than I-frames.
 Also known as Delta frames.

13. III. B-Frame:
 Bidirectional Predicted Frame (Picture).
 Holds only the changes between the current frame
and both the preceding and following frames.
 Not independent – constructed with previous and
future frames (I-frame or P-frame). Never used as a
reference frame to other frames.
 Compression ratio: 30:1 to 50:1. That is, B-frames
are highly compressed.