Electronics Forum / Basics / February 2006

Composite video would refer to a complete NTSC/PAL/SECAM video signal,
including all colour and sync information which can be carried on a
single wire.

Component video would refer to separate red, green, and blue (or
perhaps other divisions), and perhaps a separate sync signal, all
carried on separate wires.

CMOS and TTL are technologies used to produce digital integrated
circuits.  Firewire is a digital communications bus.  It may be used
to carry digital data that represents a video signal.

This just highlights the fact that the term "format" is much-used (and
abused) to mean a whole LOT of different things in the video industry.
To some, "format" (esp. when talking about "digital" video) means the
same thing as what is also called "pixel format" or "addressability" (and
which is often ALSO mislabelled as "resolution"); to others, it's that
plus the specifics of the timing, or both of THOSE plus a specific
color encoding technique.  And so forth and so on.

Technically, "NTSC," "PAL," and "SECAM" refer to color encoding
methods, although these are also often used interchangeably with the
raster-scan standards most commonly used with each - i.e., "NTSC"
for the 525-line, 60 Hz field rate scanning standard ("525/60"),
and "PAL" or "SECAM" for 625/50.  "Composite" and "component"
have more to do with how the various parts of the video signal
(specifically, luminance and chrominance) are carried on the physical
interface, and "CMOS," "TTL" and "FireWire" are definitely various
classes/types of electrical interface ("CMOS" and "TTL" are actually
generic names for digital logic "families," which is a whole 'nother
problem). "S-Video" is, at a minimum, a specific connector standard,
although it's also often (mis-)used to refer to an interface with
separate luminance (Y) and chrominance (C) connections.

To really give you a complete answer would require a lot more space
than is available here; I will (at the risk of being accused of spamming)
point you to my book on the subject, "Display Interfaces: Fundamentals
& Standards," published by J. Wiley and Sons and available from
Amazon (among others), and possibly in your local engineering library.
Just so this doesn't appear to be QUITE as blatant a case of self-promotion,
there's also a very excellent text which covers quite a range of TV
standards, specifically, in great detail: "Digital Television Fundamentals,"
by Robin & Poulin, and published by McGraw-Hill.  (Despite the name,
it also contains quite a bit of information on the original analog broadcast
systems.

Bob M.