Some Video-Related Questions
Most of the buzz these days in video
has to do with the digital variety, high-definition or otherwise. But there’s still a
lot of analog video out there, and readers still have concerns. Here are a few:
RF video connection
I have read that connecting a video source to a TV via an
RF cable would have a maximum horizontal resolution of 330 lines, even if the source is a
DVD or SVHS cassette, and that the sound would be mono, even if both the set and the
source are capable of stereo. If that's the case, why would VCR manufacturers make
machines with only RF inputs and outputs?
You're correct on both technical counts, in my
experience. The resolution is equivalent to a good off-air signal, and is about the
maximum most TV tuners can handle. As for stereo, it would involve considerably more
complex circuitry in a VCR or disc player, and I imagine that manufacturers assume that
anybody interested in taking advantage of the higher performance available wouldn't be
using RF connections anyway. In fact, except perhaps for the very lowest models, it's very
unlikely that any manufacturer of VCRs -- or any video component -- would provide only RF
outputs today.
S-video override
My television has both S-video and RCA inputs for external
video sources. I have a hi-fi VCR hooked up to the line inputs, and I would like to feed
the output of my DVD player to the S-video jack. Whenever I hook up the S-video cable,
however, it overrides the VCR, which means every time I want to watch a DVD, I have to
reach around the back of the TV set and plug in the cable. When I'm done, I have to pull
the plug so my VCR setup works. Is there any way around this, short of buying a new TV
with a selectable S-video hookup?
There's no simple solution to your problem. True, there
are external switchers that would do what you want, but that tends to be a fairly
expensive way to go. From the fact that your set only has a single external input, I
gather it must have a few miles on it -- most newer sets have multiple inputs -- so you
may not really be seeing the benefit of the S-video connection anyway.
You can check this for yourself. Simply connect the DVD
player to the set by both its RCA output and its S-video output. As you plug and unplug
the S-video cable, you'll toggle back and forth between the two sorts of connection. If
the difference is subtle, you might be better off simply to use the RCA connections, in
which case your switching options become much easier and cheaper.
Aiming the dish
I am considering the purchase of a digital satellite
system. The product info indicates that I need an "unobstructed view to the
south." I live in an area with quite a few trees. I would mount the dish on the
rooftop, but there would still be some foliage in the way. How critical is the
unobstructed view to the image quality?
A little foliage may not be a problem; buildings and
mountains are another matter. The dish only needs a small window to see through, so it's
usually possible to position it so the signal is unobstructed. Also, the farther south you
are, the higher the dish has to be aimed, so it may well be that that angle plus the
height of your roof may be enough to clear the treetops.
Obstructions, incidentally, are more likely to interrupt
the picture than degrade its quality. The same is true of things like heavy rain.
How much resolution?
A couple of years ago I purchased a rear-projection
television with an advertised 1000 lines of horizontal resolution. I primarily view
digital satellite programming through a receiver that I understand produces a 480i signal.
A technician from the set's manufacturer informed me that the television should be able to
display a 720p but not a 1080i signal through the S-video input. Is this accurate? If not,
what is the theoretical best signal I will be able to display?
There are several misconceptions here. Your monitor, the
satellite system, and the DVD are all 480i devices. If a DTV receiver picks up a 720p
signal -- or a 1080i one, for that matter -- it will have to downconvert it to 480i for
display on that set. It might well have better horizontal resolution than your satellite
system or a DVD, but the number of scanning lines and the way they interlace will be the
same.
...Ian G. Masters
ian@mastersonaudio.com
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