RE: Conversion (Was: VideoBalun vs KAT5 ?)

[Keith Doxey]

There is nothing to be gained from Composite to S-Video or S-Video to
Composite conversion.

With the exception of an RF modulated signal, Composite is the lowest
quality signal and any attempt to separate to Luma and Chroma signals will
result in further loss of quality. A cheap PASSIVE filter cannot separate
the two signals properly. A special filter known as a "Comb
Filter" is
required and a decent digital comb filter is fairly expensive to build.

Once a composite signal gets into a TV it is passed trough a comb filter to
separate the various parts anyway. The filter inside the TV will almost
certainly be of higher quality than any external converter.

Converting S-Video to composite gives better results than composite to
S-Video but a passive converter is still not perfect. (Only two components
are required for a passive combiner).

Mark McCall has a KAT5 receiver with a "Modified" SCART lead that
I made
when I was over there. He is feeding the S-Video output of his PC via KAT5
to two receivers, one in his AV room where it is connected to his AV Amp as
S-Video and the other in the bedroom feeding a TV which does not support
S-Video. By fitting a resistor and capacitor inside the SCART plug the Luma
and Chroma signals are combined into a composite video signal. This gives a
perfectly acceptable picture on the TV. He could have used a second KAT5
transmitter to send the Composite output of the PC directly to the bedroom
TV.

Almost all S-Video equipment has a composite output as well. This will
provide better results than passive conversion of the S-Video output
because
it is in the manufacturers interests to make the quality as good as
possible. In short, if you have a TV capable of S-Video and a source with
S-Video out then use S-Video, otherwise use a composite output.

Highest quality is an RGB signal. RGB actually consists of 4 circuits Red,
Green, Blue, Sync and requires all 4 pairs in a CAT5 cable but does give
the
best quality. Converters are readily available to convert RGB to S-Video
which gives better results than the Composite output.

Component Video aka Y-Cr-Cb is midway between RGB and S-Video.

Most AV amps only support S-Video or Composite.
Most TV's have 1 RGB Scart and some S-Video inputs.
Until Digital TV, Consumer equipment rarely had RGB outputs but now there
are numerous devices such as SKY Digibox, ITV Digital, Games Consoles,
D2-MAC Satellite Receivers.

Keith



-----Original Message-----
From: Phil Harris [mailto:<a
href="/group/kat5-users/post?postID=rWGzDSCwzM6_9VYNp3eCy48qs3EjpAiQDLVfRh_yKIWjNEcnR-H4i3nIQUfwJfTsTP3WTktnfuh-E0BhGppJkhM">phillip.harris1@v...</a>]
Sent: 27 December 2001 12:55
To: <a
href="/group/kat5-users/post?postID=naf95Kj5l9hPVGB_67Z43IKMV1mVFrbfSCjbshceoHCDjiz9K4YymuIuouUIdhqMhMRjnq2sweRfudbXYXyhb4XqK7A">kat5-users@xxxxxxx</a>
Subject: RE: [KAT5] VideoBalun vs KAT5 ?


> you can see at this url :
> <a href="http://www.videocapturecard.com/videobalun1.ht";>http://www.videocapturecard.com/videobalun1.ht</a>>
ml

I have to say that I'm a little worried by the first statement on their
website which is ""Composite RCA to S-Video" and
"S-Video TO Composite
RCA" adapters. Our adapters have our special embedded micro-chip video
circuit that allow you to keep the color signal. Beware of pirated
imitations that hot wire the luminance and chrominance (Y/C) video
signals causing interference."

They seem to be implying that they have some form of circuit in there
which performs miracles without requiring external power which does
kinda worry me ... Such circuits are really fairly simple and don't need
hyping like this so I'm just a tad suspicious of companies that make
such "extreme" statements...

Phil



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