HOME
TOPICS
SEARCH
ABOUT ME
MAIL
BLOG
The broadcasters who send you that glorious video might decide to cut corners electronically.
|
| technofile
Al Fasoldt's reviews and commentaries, continuously available online since 1983
T e c h n o f i l e
HDTV's little flaw might drive you batty
Sept. 30, 2007
By Al Fasoldt
Copyright © 2007, Al Fasoldt
Copyright © 2007, The Post-Standard
As good as high-definition TV is, it's got a small problem no one seems to want to talk about.
All TV broadcasts and cable-delivered signals will have to switch to HDTV by Feb. 17, 2009.
Manufacturers have been helping prepare consumers for the changeover -- and boosting their own sales, of course -- by
coming up with HDTV models that seem to get cheaper every time you look at the ads.
By Thanksgiving, the traditional start of the holiday shopping season, you should be able to buy a
good small-screen HDTV for $150 or less. Even now, HDTVs with large LCD displays are available for prices that would
hardly have made a down payment on such a set two years ago.
(Walmart, for example, is now selling Polaroid's excellent 46-inch LCD HDTV for $1,398. It's a
1080p model that can even function as a giant, high-quality computer monitor. I bought one as soon as I saw it at my
local Walmart.)
HDTV isn't simply a better way of showing video. It's as different from regular TV as your new
Willie Nelson CD is from that old cassette tape at the bottom of your dresser drawer.
HDTV is digital. Signals are sent to your set a different way. They can't pick up "ghosts" and they
never waver when a big truck passes by. Colors are pure. Everything is supposed to be sharp.
Whoops. Notice the problem? Everything is supposed to be sharp. But the broadcasters who send you
that glorious video might decide to cut corners electronically. If they do that, what you see at one moment might be much
blurrier than what you see at the next.
Let me explain. HDTV's digital magic isn't actually magic at all. It's all a trick of compression.
You'd do the same thing, too, if you had to send a lot of information in a short period of time.
In other words, if you had to count all the kids sitting in the bleachers at the football game, you
might just count the ones sitting in the front row and multiply that figure by the number of rows. We do this sort of
thing all the time.
Digital TV does it, too, only in a smarter way. Objects in the scene that don't move (such as the
background) are "counted" once and kept in memory. Objects that move a lot are looked at and "recounted" many times a
second.
This works fine in most situations. But the people who control HDTV broadcasts sometimes want to
squeeze more video into the signal than the video was meant to be squeezed, if you know what I mean. So, if these folks
turn up the compression, stuff that moves might not be "counted" fast enough. (I'm using a term we all understand, so
bear with me if it seems a little non-technical.)
You might notice this in an HDTV broadcast of a football game. In the huddle, the quarterback's
face might show a zit here and some drops of sweat there. But while he trots back into formation, his face might look
like a Noxema ad. That would happen when there's too much compression to show the zits and sweat while he's moving.
If this happens a lot, in any kind of HDTV signal, you might think your set has gone bonkers. But
it's not your set. It's NBC. Or CBS. Or some other national channel.
Grin and bear it for now. As equipment improves, this digital smoothing should happen a lot less.
Scott Souva wrote to point out that I was wrong when I wrote that there will be a total switch to
HDTV by Feb. 17, 2009. In fact, the FCC is requiring that broadcasts be done only in digital format. Cable feeds can be
anything cable companies want to send out.
But it's obvious that all serious broadcasters are going to switch to HDTV, and not simply digital
TV. And cable companies that don't offer HDTV feeds will soon be out of business. So, in effect, the FCC rule does guarantee that HDTV will become the norm on that date. - Al Fasoldt
| |