Video Puzzlers
A couple of video questions from
readers this time.
Question 1
Roger in Australia wants to know if there are any signal
processors that can take a widescreen video signal and produce a simple pan-and-scan image
that will fill the standard-format TV screen.
No. And if there were, they would have to pick one area of
the screen -- dead center, most likely -- and reproduce only that. Those of us who are old
enough will remember this was how widescreen movies were first presented on TV, and
frequently when the hero and heroine were participating in a romantic two-shot, all you
could see were the tips of two noses and chins on either side of the screen, with a lot of
scenery in between.
The pan-and-scan process is a painstaking one, in which the
director has to evaluate every scene and every shot to decide what to include in the
narrower image, sometimes moving it within a shot (panning). Such artistic decisions would
be beyond a simple picture converter.
DVD technology does support something like that, but only
if specific instructions are embedded in the disc to tell the player what part of each
frame to display. There are players that can respond to those instructions, but mostly the
movie companies have been content either to issue separate widescreen and pan-and-scan
versions, or to put them separately on the two sides of a disc.
Question 2
Jim in Illinois says, "I have two digital camcorders,
from JVC and Sony, and both are capable of recording in the 16:9 widescreen mode, which I
prefer. Tapes from the JVC play back on my standard TV with the usual black bands at the
top and bottom. The picture is like that on Sony’s own LCD screen too, but when I
play a Sony-made tape on my TV, I get a squeezed picture to fill the 4:3 area. I would
like to view and make copies of my all my camcorder videos with the traditional black
bands but can't figure out how to do it."
There are two ways to achieve a widescreen picture with a
camcorder. The simplest uses the middle part of the image area, just like letterboxed
movies. The black bands are inherent in the picture, which is really a 4:3 image with
black stripes on the top and bottom. This will play without modification on a normal TV
set, and record on tape, black bands and all. That's the technique used in your JVC
camcorder. On a widescreen television in letterbox mode, the picture will be blown up to
fill most, or all of, the screen, but there is a sacrifice in vertical resolution, as
those black bands account for a significant number of the scanning lines.
The alternative, which is used in your Sony machine, is
called "anamorphic." The picture information is squeezed horizontally to fit in
a normal image area, but using all the available scanning lines (full vertical depth). On
playback, the picture is stretched to its original proportions. As long as the recoding
medium is capable of high enough resolution (and digital video is) and the camcorder's
pickup device has enough pixels (and Sony's do), there should be almost no sacrifice in
horizontal resolution, and none in vertical resolution. Trouble is, to view such images
properly you need a set specifically designed for that, and few are.
Until you're ready to buy such a monitor, you'll have to
stick to 4:3 when using the Sony, and use the JVC when you want widescreen images.
Question 3
A Florida video enthusiast says, "In the mid '80s, I
bought a VCR that is now nearing its end, and I'm seeking a replacement that offers some
of the same features. The main one is switchable digital noise reduction with a choice of
three levels. The DNR in my old machine was in the main video chain so it provided DNR for
any signal that the VCR processed, not just for recording and playback of VHS tapes. There
are a few current VCRs that include DNR, but it only affects tape recording and playback,
as far as I know. Do you know of any recorders that will do what I want?"
No, even though it does seem to be a useful feature. I
assume, however, that what's wearing out in your old VCR is the mechanism -- that's
usually the first thing to go -- so why not keep the old machine just for the noise
reduction. If you buy a new VCR, you can always pass its signal through the old one to
clean it up.
...Ian G. Masters
ian@mastersonaudio.com
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