For example, let's say you had video, text and music that you wanted to run on a Web page. There would be no way to have the music start, then five seconds later have the text appear, then, after the text has appeared, start the video. The html simply cannot handle these complex tasks.
I recently downloaded the Star Wars trailer (http://www.starwars. com). A little more than 2 minutes of medium-quality QuickTime video took up 24meg of disk space and required a good 15 minutes to download on a T1 connection. On anything slower than a 56K modem, forget about it.
In an effort to tackle these problems, the World Wide Web Consortium (W3C) has created a new mark-up language especially for multimedia: the Synchronised Multimedia Integration (SMIL). SMIL is a W3C recommendation that came out earlier this year (http://www.w3.org/AudioVideo).
SMIL is the html for creating multimedia events on the Web. As html does with text and graphics, SMIL uses tags to help define all aspects of how your media files, audio, video, text, and still graphics should be laid out on the screen, and can create hyperlinks between different elements.
While html is great if you want to lay out text and static graphics, it is not very good at presenting multimedia. In order to create robust and complex multimedia you need a new system of mark-up tags designed specifically to deal with the problems of multimedia, including layout, chronology, bandwidth and file format.
SMIL provides Web designers with exacting control over the layout of a multimedia document through Cascading Style Sheets-positioning (http://www. independent.co.uk/net/980421ne/ story4.html). CSS-P is used to define individual elements on the page that can be positioned, re-positioned, shown, moved, removed, or replaced as needed.
The main difference is in how this code is created. Rather than being placed inside of a tag to define different regions on the screen. Other SMIL tags can then be used to manipulate these regions as desired.
However, more than the ability to move the elements around, multimedia requires to be able to synchronise the various elements into a time line.
If you have ever worked with multimedia programs such as Director and Flash, or if you come from a movie or television background, you are probably already familiar with the concept of the time line. Time lines co-ordinate the ways in which the various pieces of a multimedia production work together chronologically.
SMIL includes several tags that allow Web designers to dictate when, where and how the multimedia content is presented. You can set when each of the media clips should start and stop, their duration, and whether they loop; and you can also synchronise them together so that they run simultaneously. This is accomplished with simple attributes in html-like tags.
SMIL is now a recommended standard by the W3C and it is likely to be adapted by all major players in the World Wide Web game.
At first SMIL may seem complicated, especially if you have to wade through the turgid W3C SMIL specification (http://www. w3.org/TR/REC-smil).
I must admit that I was highly sceptical. However, SMIL is boiled down to fairly simple mark-up tags, much like html. If you can understand how html works, SMIL is not much more difficult.
SMIL is worth keeping an eye on in the coming months. Whether it catches on or not will depend on whether it is supported by the major browsers, and, more important, whether or not you use it in your designs.
Jason Cranford Teague (indy_ webdesign@mindspring. com) is the author of `DHTML for the World Wide Web', which is currently available at bookshops, both real and virtual, across the United KingdomReuse content