Goodbye video tape editing, hello digital disk. Niall McKay looks at th e pros and cons of both
Twenty years ago the television industry underwent a revolution when it moved from film to video tape. Now a second revolution is taking place that may herald the end of the video tape and the introduction of the floppy disk as the new medium for moving images. This transformation is being driven by the recent introduction of computer-based video editing as television and film industries alike grasp this new technology.

Already many films, commercials and television programmes have been edited on a computer. This year alone, Mary Shelley's Frankenstein, the new Levis commercials and the top television series The Bill have all employed this desktop video editing method to reduce costs, increase flexibility and decrease the amount of time in post-production.

Film editing, the process whereby the many hours of footage shot are cut and glued together into a programme fit for viewing, has been the stronghold of the traditionalists. In the past the film industry has dismissed editing on videotape as a downmarkettechnology; proper editors, the industry liked to believe, sliced out chunks of film with a blade and stuck them together with sticky tape.

In contrast, the video and television industries have gone in the opposite direction. Year in, year out, the process is becoming more expensive and more complicated as production houses strive to offer the latest in graphics, special effects and increased video-tape quality.

But by using new technologies from Avid, a US-based company, and Britain's Lightworks, post-production companies, television studios and video production companies can now edit material on what amounts to little more than a modified Apple Macintosh computer, costing between £20,000 and £60,000.

Paul Hutchings, owner of P3, a corporate video production company in London's West End, warns that the potholes and pitfalls of desktop video editing are like those of its predecessor, desktop publishing. "It has the same dangers as publishing. Just because you can buy and even operate the equipment doesn't mean that you can make programmes. There is a whole visual language that you need to understand to produce something the viewer won't laugh at, or fall asleep during," he says.

It is the technological advances in computer storage techniques that have made it possible for editors to transfer video or film on to a computer's hard disk and cut and paste those clips in a similar manner to cutting and pasting on a word processor. Editors also have the advantage of being able to edit a video clip as many times as they wish without losing quality.

More important, they can make changes to the tape without having to relay the whole section of video after the change in a process known as non-linear editing. This is akin to being able to make incremental changes to a document on a computer instead of having to retype the whole document again, as you would have to do on a typewriter. Such a technology would have been of great use to Oliver Stone, who had to make more than 250 changes to Natural Born Killers after screening it for the American film censors.

The technology is moving so fast that companies are having difficulty keeping up to date. Only a year ago desktop video editing was not capable of producing a finished product fit for broadcast. At that time it gave technicians a crude but useful guide to follow. While this is still true for feature films and commercials, the output of an Avid Media Composer is now as near as makes no difference to the standard broadcast television video format, BetaSp.

The BBC is using an Avid Media Composer to edit its daily news programme Here and Now. Once editing is complete, the machine can be hooked up to a transmitter and the programme pumped out on-air from the hard disk - thus dispensing with the need for assistants to circumnavigate the corridors of Television Centre studios with a video tape.

Dave East, a picture editor for the BBC, says: "Two years ago people were telling me that it would be seven years before we could do what we can do now. I expect the industry to undergo many changes in the next few years, not unlike 20 years ago, when wemoved from film to video tape."

Mr East sees the sophistication of the software, not the hardware, as the limiting factor on adoption of the technology. "This is going to have a revolutionary impact on the industry, because within five years we will no longer need to use tape. Instead we will use floppy disks," he argues.

And if there is no need for any tape, the images can be digitised and stored on an electronic filing cabinet or database, in exactly the same way as data is stored today, allowing users to log on and download the video to their desktop computer. The BBC is planning to do just this over the next few years.

By installing a central database that can handle video as well as sound and text, journalists and producers will be able to pull down news footage, arrange it in the order they wish and write a script. An editor can then put a professional gloss to the piece while a news editor checks it for errors and schedules the time it will be broadcast. Yet the technology to carry the signal from the database to the desktop may not be quite ready yet.

If every silver lining has a cloud, desktop video editing is no exception. The West End's post-production houses are worried. Most have recently made massive investments to upgrade their facilities from analogue to digital tape format.

Mr Hutchings says: "With the Japanese video manufacturers, you never know where you stand. You could invest a lot of money in one technology, only to find a year later that they have halved the price, brought out a new technology, or both, which means that you will never recoup your investment."

Robin Shenfield, manager of The Mill, one of the largest independent post-production houses in Europe, says: "I think these technologies just mean that the entry cost is coming down year by year. Eight years ago I spent £250,000 on a Bosch 3D animation unit. Now l can get better effects from a Silicon Graphics machine, which costs around £50,000. But we can't afford not to be on the cutting edge, or we will lose business."