Video on demand

Will broadband make broadcast TV redundant? I doubt it. Personal video recorders like SKY+ are already changing how many of us watch TV, and their future looks much more promising.

With cheap disc drives now down to below a dollar a gigabyte, the next couple of years should see the first terabyte SKY+ boxes. The cheap disc drives of 25 years ago held 5 megabytes, and if you plot their capacities you see them reaching the terabyte mark around now. That's about 500 hours of cinema, more than many of us watch in a year. If they maintain the same growth rate discs might manage another thousand-fold increase in the next 10 to 15 years. A petabyte disc can store 500,000 hours of video, which is more than all the professional film mankind created in the first 100 years of cinema.

So when the first petabyte Sky+ boxes hit the streets, they'll have to come preloaded with all the film created up to the time of manufacture, and use their remaining capacity to capture every new film as it is produced. At the moment, that's about 5,000 hours a year, or a mere 10 terabytes. With multi-channel decoders, these future generation SKY+ boxes will spend all their time storing new films, as it is broadcast 24 hours a day on high speed channels designed for recording devices. Most of this material will, of course, be encrypted, so you'll still be paying to view it - but you'll be paying to decrypt it off your own recorder.

Watching "real" time TV will then be the exception, rather than the rule, with news bulletins, weather reports and sports events being the only programmes transmitted for instant viewing. As far as professionally produced films are concerned, the Internet need only be used to carry decryption keys and credit card details. That will free up the available bandwidth for amateur narrowcasting and video telephony.