[BC] Should We Now Wait on Digital-only TV?

[RichardBJohnson at comcast.net]

Sure they can. It's an essential part of converting
digital to analog. The digital is written to RAM in
a "scan converter." It is then independently read
out at the update rate for an analog modulator
signal. This modulates a RF carrier.

You need all this to get a TV signal anyway.

To get the correct aspect ratio, the scan
boundaries for the readout are adjusted.
These are just software variables, memory
starting and stopping locations. Although
the software wasn't free, the incremental
cost of obtaining the correct aspect-ratio
is zero.

This means that the picture is cropped. Ignore
the stuff you see on your digital TV when the
aspect-ratio is incorrect. For some reason,
they let the user muck with these.

With the scan converter modulator, the output
aspect ratio and the input aspect ratio are already
known and the output aspect ratio is a constant.

You will see circular circles correctly rendered.
However, many cameramen and/or their producers
don't have a clue about centering the action. They
assume that everybody can see everything to the
edges of the screen. This was never the case, even
with old B&W TV! I wish the modern crop of camera-
men (camera-PERSONS???) would take a course
or two before they hang out behind the lens.
We would have much better TV.

Note that cable TV is already doing the conversion
except they don't convert to NTSC, but QAM which
your "cable-ready" TV demodulates. Most cable
networks also transmit digital, but they don't tell
you about it, instead charging you for an extra
box.

FYI, at WJZ-TV a newbie cameraman would run
a camera in the studio alongside the on-air
camera. As he got better with his shots, he
would notice that his red-light was on more
often. That was the time that another would
start being trained.

--
Cheers,
Richard B. Johnson
Read about my book
http://www.LymanSchool.org


 -------------- Original message ----------------------
From: "W2XJ" <rameuser at tmo.blackberry.net>
> You should be able to do 4x3 center crop. 
> Paul Smith wrote:
> 
> My problem with the digital signal is the aspect ratio.  I know there are
> several ways to display it, but no matter what, they cant come up with a
> picture that looks natural aspect wise with a converter