Digital vs. interactive vs. internet vs. broadcast

There's a lot I don't know about the brave new world of electronic media, but a few things are starting to stick in my brain:

• Video is the 500lb gorilla. Everything else we currently do takes much less space and bandwidth.
• Unless you have fiber or something similar, video is pushing the limits of your bandwidth (*)
• Even if you do have fiber, you can use up large chunks of it with bigger and shinier video, or more channels, or better-than-real-time downloads.
• TV in the US is set to go digital in the next couple of years. This frees up large chunks of bandwidth for other uses (**).

That last chunk of bandwidth is primo stuff. It was originally allocated to TV exactly because it's suited to transmitting video images into buildings and across wide swathes of rural land.

Now let's look at video in the internet world, as opposed to old-fashioned TV with rabbit ears (Dad, what are "rabbit ears"? Well, in the olden days TVs had antennas sticking up on top of them ...):

• It's digital. That means, subject to various legal and technical restrictions, you can make exact copies of it, save it, view it and edit it with a plain old home computer.
• It's available on demand (or at least, upon polite request with money attached). You don't have to wait for your show to be on.
• It can be interactive. You can do video conferencing, for example.

The interesting thing is that none of these requires the internet. It's been possible for years to record video digitally with a camcorder, make your own DVDs, and so forth. You can (again subject to legal and technical restrictions) digitally record TV programs received via cable, satellite or over the air. Video on demand is a standard feature of cable service. Video conferencing can be done (and in some cases is done) via closed circuit.

This is not to say that the internet can't add value, for example by making video conferencing available to everyone instead of just to parties who happen to have the infrastructure for it. The point is that much of the goodness of new media is not strongly tied to the net, nor is it, as is sometimes implied, a direct consequence of the net being involved.

The internet is inherently point-to-point. Your basic internet packet has a single destination address. You can also specify broadcast and multicast addresses, but those require extra thought and machinery to handle efficiently. The internet is also symmetrical in structure. Anyone can send to anyone. The other party might not listen, but that's a different story.

Broadcast TV, on the other hand, has a very different structure. One party broadcasts to many. It does so very efficiently and scalably. Someone puts up a tower. As many people as want to buy receivers. This can be and is being done for digital video as it was for analog. Traditional cable TV -- everything but the on-demand part -- is somewhat less easily scalable, but it still has the advantage of having only one fixed route: from the broadcast center out to the viewers.

Why should we persist in using old distribution machinery when we've got the infinite flexibility of the net? For one thing, people remain interested in live TV coverage. If I want to watch the NCAAs and a million other people do as well, then why bother the internet backbone about it when the network can just beam the games up to a satellite or broadcast them over the cable network.

The one-way broadcast model still works just fine in cases where you might well want digital content, but don't care about interactivity. In fact, it should generally work better, and using it offloads traffic that would otherwise have to go through the backbone.

Which leaves me to ponder what really ought to end up happening to all that prime broadcast bandwidth.

(* A standard DVD plays back about 4 hours of video from about 8GB of data, or about half a megabyte per second. This is curiously close to the bandwidth of my cable internet connection, and in fact video full-screen comes across more or less OK, but not dazzlingly well. It's interesting to note that the same cable can also keep at least 3 tuners happy showing and/or recording TV shows with good fidelity. It's almost as though cable companies are in the TV business, but I digress ...)

(** Most of it was bought up by Verizon, with Google only putting in a minimum bid. More could be said ...)