By Keith Jack
Although there are many
variations and implementation
techniques, video signals are just
a way of transferring visual
information from one point to
another. The information may be
from a VCR, DVD player, broadcast
channel, cable television, satellite
system, the Internet, or one of
many other sources.
Invariably, video information must be transferred from
one device to another. It could be from a satellite
set-top box or DVD player to a television — or it could be
from one chip to another inside the satellite set-top box
or television. Although it seems simple, there are many
different requirements and, therefore, many different
ways of doing it.
Until a few years ago, most consumer video equipment
supported only analog video. Digital video was confined
to professional applications, such as video editing.
The average consumer now uses digital video every
day, thanks to continually falling costs. This trend has
led to the development of DVD players and recorders,
digital set-top boxes, digital television (DTV), portable
video players, and the ability to use the Internet for
streaming video data.
Initially, video contained only Y or grayscale (also
called black-and-white) information.
While color broadcasts were being developed,
attempts were made to transmit color video using
analog RGB (Red, Green, Blue) data. However, this