OT: Composite/Component [was Re: [mythtv-users] Re: Image quality, what effects it?]

[Jay R. Ashworth]

On Tue, Aug 10, 2004 at 07:16:03PM -0400, David George wrote:
> Answer in simple terms below:

Simple, but not necessarily *accurate*.

> Dr NoName wrote:
> >ok, stupid question:
> >
> >what's the difference between composite and component?
> >
> Composite is a single cable with RCA connectors.  Component has three 
> cables labeled Y, Pr, Pb (the connectors are usually, if not always, 
> green, red, and blue) also using RCA connectors.

I dunno, on most of *my* equipment, they're BNC connectors.

:-)

> >My TV has only one set of (red, white, yellow) inputs
> >for (left, right, video). What's that one called?
> >  
> >
> Composite.  The composite video signal is on the cable that plugs into 
> the yellow connector.  Your right and left audio go through the red and 
> white connectors.

One step more complicated answer:

Composite video is the black-and-white (or monochrome) signal, and the
3.58MHz color subcarrier signal, all going through one cable, usually
with a yellow RCA (Phono) plug on consumer equipment.

S-Video is kind of a low-rent version of component, which preceded it
on consumer equipment: the color subcarrier signal is kept separate on
all the wires, which permits the removal of the filter usually
necessary to keep it out of the luminance (or monochrom) signal -- this
gets you better sharpness, and less color crawl.  It commonly moves
around on 4-pin mini-DIN connectors on consumer gear (and 7-pin locking
ones on pro-gear).

Component usually refers, as David says, to a three-cable video system
where the luminance and the I and Q components (as they're called in
pro circles (ok, Pr and Pb aren't *exactly* I and Q, but they're close
enough for NTSC ;-)) travel on three separate cables; about the only
place you currently find that on consumer gear is on "progressive" DVD
players and upscale monitors (and scan-doublers).

Component originated on Sony Betacam professional recorders, originally
as a deck-to-deck dubbing format (as, incidentally, did S-video; the
pro version derives from the old U-matic dub cable format, which was
4-wire split multiplexed chrominance, but at the 729kHz on-tape
subcarrier frequency).

At the moment, so far as I'm aware, there are no consumer grade capture
cards, and certainly nothing with a tuner on it, which do Y-Pr-Pb
component input.  You have to get up to things like the Matrox
DigiSuite (and possibly RtX) cards to get that.

Ok, I think it's time for someone to snipe at me now for trying to be
informative.  ;-)

Cheers,
-- jra
-- 
Jay R. Ashworth                                                jra at baylink.com
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	"You know: I'm a fan of photosynthesis as much as the next guy,
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