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Desktop Video AGOCG Report

Video Editing

For years people have had to rely on traditional production houses to create high quality video, dismissing desk top equipment as incapable of producing the same effect. Today, however, users of desktop equipment can produce the kinds of effects which would have been impossible only a few years ago. Several factors have contributed to this, including improved links to high end video formats, enabling a professional standard end result. Programs for image editing and morphing, for example, have now made impressive effects commonplace.

Computers have been used in the video editing process for many years. Their rôle has primarily been to store Edit Decision Lists (EDLs) and to facilitate subsequent changes to the list, recalculating start and stop times of individual clips of video automatically. The source material itself is still held on video tape and the output, whether it be rough-cut or final programme, has also to be recorded on tape. The addition or extension of a video clip to the middle of an existing compilation would require all material that follows the new clip to be re-recorded as well. To avoid this costly re-editing process it has previously been necessary therefore to plan carefully the hundreds of independent shots that go in to an average programme and assemble them in sequence. This is called linear editing.

Desktop video editing can free the programme maker from this constraint. Non-linear editing is achieved by digitising all of the source video material to high capacity high speed disk drives then compiling the various segments of the programme from this new digital source. Clips can then be assembled in any order, re-ordered, shortened lengthened or deleted. Professional transitions, special effects and titles can be added easily in the digital domain. The completed programme can then be written back out to video tape for duplication and distribution in the conventional way.

The Mac has stolen the march on PC's in this field. The plethora of video composing programs for the Mac e.g. Adobe Premiere, Videofusion and CoSA's After Effects, has put impressive effects within the reach of any Mac User.

The desktop video revolution has been for many somewhat of a disappointment. The problem is that no one vendor has yet produced an architecture that allows a range of software and hardware products from different suppliers to work together seamlessly to create a fully functional professional video production system.

The launch of Apple's QuickTime in 1991 was hailed by many as finally providing just such a unifying architecture for video on the Mac. However, in practice, QuickTime has only addressed a part of the problem. While it has made it possible for software and hardware products such as video capture cards to work together, it fails to provide ways to integrate video devices, such as camcorders and videodecks, into a fully functional video production system. As a result very few of the products on the market today have the same plug-in-and-play ease of configuration that has been a common feature of the Mac environment. This has not stopped manufacturers from bringing products into the market. Many of these use QuickTime and third party device control systems, such as VideoMedia's widely supported V/LAN system, to provide desktop video systems based on the Mac.

There is a definite demarcation of high and low end video production. The low cost end of the market is where users want to record PC produced animations and presentations to video, so that there is no need for broadcast quality images, where S-VHS will do. Sony Umatic is the standard in low to medium budget productions and gives excellent results. Many people now believe that Hi-8 will replace Umatic in the medium term, as many news crews are moving to this format. At the top end is the broadcast videographics, where there is a wealth of software for graphics creation, colour imaging and animation. Here the Mac is competing head-to-head with suppliers such as Aston, Quantel and Silicon Graphics.

A video digitiser card like SuperMac's VideoSpigot or the Radius VideoVision is the basic component for QuickTime movie making. These cards vary hugely in price and offer different levels of image manipulation. To add sounds, one needs either a card with built in sound capabilities (e.g., RasterOps MediaTime) or a separate audio card (e.g., Audio Media NuBus)

There are a number of advantages of the Mac platform over the Silicon Graphics machines, not least of which is the flexibility of the systems afforded by the relatively high availability of software and add ons. To equip the SG machines with comparable software can sometimes be as much as a factor of ten times the cost.

Several hardware and software products have been released which effectively move desktop video production in the same direction as that taken by desktop publishing (DTP), that is, moving it from a professionals-only operation into the hands of a much wider audience. Hopefully some of the lessons learned during the proliferation of DTP will transfer to the video editing sphere.

A useful review of several video editing products can be found in the MacUser issue of 1 October 1993, pages 55 63.

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