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Adapting Video for VI Learners

Design issues and approaches

Preparing to get the best from DVD

Digital Versatile Disc is a set of standards both for a high-density next generation CD-ROM, and for the way in which video and other information is encoded on it.

DVD technology

DVD can be thought of as a 'semi-random' format. Designers can put many sections of material on the disk, and then define chains of these to make up programmmes. Entries to these predefined programme chains are chosen through menus. Each material section can contain

  • video (anywhere between 2 to 8 hours, depending on the kind of disc),
  • up to 8 audio tracks containing high-quality surround sound, or lower quality 'commentary',
  • still pictures each with audio,
  • up to 32 miniwindows containing chunks of text for titling, or limited palette graphics and animation.

With these and the interactive features offered through remote controllers, programme producers can create films (including those which skip sections for parental control, and branching films for an 'adventure game' feel); games and quizzes; searchable 'edutainment' programmes; sports with viewer selected camera angles; or extended audio (up to 55 hours of high quality stereo on the lowest density of DVD disk). You will see from the more detailed summary how much scope there is for more accessible educational programmes.


Total home production of DVD materials is likely to be outside the scope of small organisations for a long while. It is much more likely that you will present a specialist studio with a set of 'assets' (video, text, audio, graphics) and a design outline specifying the ways in which these assets are to be assembled, leaving them to use their high capacity computer systems to form the links and menus for your proposed structure, compress the material to MPEG-2 standards for DVD, and create a master copy (just as a few years ago, only specialist houses created CD-ROMs, and a few years prior to that, video was never created locally).

There are several payoffs for taking all this trouble. VHS is cheap, but you can't add supplementary, nonlinear support for disabled students in anything like so effective a way. Multimedia offers interactivity and nonlinearity, but not everyone has a properly specified PC of the right type: DVD players are set to be as universal as CD players, and cheap. You can be pretty sure that your programme can be played at home on the student's domestic DVD player.


Entertainment studios are talking about using DVD features for recording multiple views on a scene (or a sports pitch); parental control, and even user choice of plot - an idea inherited from computer adventure games.

From our point of view though, DVD's biggest attraction is that it makes many more resources available for adding supplementary support without compromising mainstream viewing. Multiple language non-linear optional audio is available: so is closed multilanguage subtitling. Educational designers can therefore add audio subtitling which can automatically break from and return to the main video flow if there is not enough time available to get an idea across, and closed text subtitles can similarly be extended, pauseing the screen action if need be. Still frame, slow motion and walk-rounds are easy to add, and can be used to give enlarged or adapted views (perhaps with simplified diagrams, or with critical objects shown away from cluttered backgrounds) .

What you can do right now:

Lets assume you are filming for a conventional educational pack. You can use your knowledge of what DVD will offer to plan for later upgrades.

To do this, consider what you would like to add in the future by way of supplementary support, either interleaved or through extra reference materials. Before filming, set out a plan identifying these extra assets and a structure which would support them as though you were working toward a DVD disc. The video you are actually producing will appear as just one path through this web of material.

When you come to filming, collect material for both the simplified path and the DVD assets. These will include multiple camera angles taken for clarity, high quality stills, unconstrained audio subtitles designed for a non-linear environment, text descriptions and subtitles. (You will be able to use many of these in external supplementary materials or alternative versions of the VHS programme, so the extra effort has two benefits).

You now have the wherewithall to create a next-generation product. Although we have been discussing collecting these assets in the context of DVD production, you will find that you can also consider using them in multimedia products. Which you choose will depend on budgets, your existing use of multimedia or DVD, the length of the video component needed versus the degree of interactivity you would like.