[mythtv-users] coax vs. composite
Jay R. Ashworth
jra at baylink.com
Mon May 15 14:43:50 EDT 2006
On Mon, May 15, 2006 at 03:04:08PM -0400, John Brooks wrote:
> When you say "coax" I assume you are referring to an RF signal with a
> TV signal modulated onto it. I mention this because "composite" video
> is normally carried on a co-axial cable.
>
> I see- I may have confused terms, then, because like Greg I conceive of
> composite as using RCA cable. My STB- a Motorola DCT2200- offers outputs in
> both coaxial form and RCA form.
Well, as Cory says, yes and no.
In both RCA and F connectors, the *connector* is coaxial, as is the
cable (usually). S-Video cables use non-coaxial connectors, but usualy
coaxial cable.
> "Composite" refers to a "baseband" or "video" signal of 1 volt peak-
> to-peak (nominally) running on a coax cable. With NTSC the color is
>
> So what is it that runs over RCA cables?
NTSC Composite, or 1/3 of a component (YPrPb) signal. Cory was using
"coax cable" in it's strictly technical sense, not in the home-theater
colloquialism which means "RG-59/U cable with an F connector at each
end". I commonly call those "RF cables" as do many others, though even
*that* can be misinterpreted as well, by a sufficiently determined
geek. :-)
> *grins* Like laws and sausage, eh? Fair enough. Part of the reason
> I asked was because beyond using just what looks good, I wanted to
> be able to change my recording profile to use a recording quality
> that would allow the most to come through without unnecessarily
> inflating the size of the transcoding. If you could clarify that
> one pont above, that would be really helpful!
The number one thing to do to reduce encoded space requirements is
*reduce video noise*. You do the math. RF amps, better shielded
cables...
Cheers,
-- jra
--
Jay R. Ashworth jra at baylink.com
Designer Baylink RFC 2100
Ashworth & Associates The Things I Think '87 e24
St Petersburg FL USA http://baylink.pitas.com +1 727 647 1274
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