Making Web Multimedia Accessible Needn’t Be Boring

claude80By Claude Almansi
Guest Author
7 November 2008

Some people see the legal obligation to follow Web content accessibility guidelines – whether of the W3C or, in the US, of section 508 – as leading to boring text-only pages. Actually, these guidelines do not exclude the use of multimedia on the web. They say that multimedia should be made accessible by “Providing equivalent alternatives to auditory and visual content” and in particular: “For any time-based multimedia presentation (e.g., a movie or animation), synchronize equivalent alternatives (e.g., captions or auditory descriptions of the visual track) with the presentation.”[1]

This is not as bad a chore as it seems, and it can be shared between several people, even if they are not particularly tech-savvy or endowed with sophisticated tools.

Captioning with

Phishing Scams in Plain English, by Lee LeFever[2], was uploaded to, and several volunteers did the captions in the different languages. The result can be embedded in a blog, a wiki or a web page. The captions also appear as copyable text under dotsub“Video Transcription,” which is handy if people discussing the video want to quote from it. Besides, a text transcription of a video also tends to raise its ranking in search engines, which still mainly scan text.

The only problem is that the subtitles cover a substantial part of the video.

Captioning with SMIL

This problem can be avoided by captioning with SMIL, which stands for Synchronized Multimedia Interaction Language. A SMIL file, written in XML, works as a “cogwheel” between the original video and other files (including captioning files) it links to and synchronizes.[3]

The advantage, compared to DotSUB, is that captions stay put in a separate field under the video and don’t interfere.

This is why, after having tried DotSUB, I chose the SMIL solution for: “Missing in Pakistan – Sottotitolazione Multilingue.[4]

So far, the simple text timecoded files for SMIL captioning still have to be made off-line, though Alessio Cartocci – who conceived the player in the example above – has already made a beta version of an online SMIL captioning tool.

Captioning with SMIL Made Easy on

The Missing in Pakistan example is on, the site where the WebMultimediale project team experiments with the creative potential of applying accessibility guidelines to online multimedia – for instance, in collaboration with theatrical companies.

web_multiHowever, the project also has a public video sharing and captioning platform,, where everyone can upload a video and its captioning file to produce a captioned video for free. The site is fairly bilingual, Italian-English. By default, you can only upload one captioning file, but you can contact Roberto Ellero, the founder of the project, through if you wish to add more captions. also has a video tutorial in Italian on how to produce a time-coded captioning file using MAGpie, which is only accessible when you are signed in, but as it is in Italian, English-speaking users might prefer to use the MAGpie Documentation[5,6] directly.

Other Creative Potentialities of SMIL

As can be seen in the MAGpie Documentation and in the W3C Synchronized Multimedia page[3], SMIL also enables the synchronization of an audio description file and even of a second video file, usually meant for sign language translation. While these features are primarily meant to facilitate access to deaf and blind people, they can also be used creatively to enhance all users’ experience of a video.

5 Responses

  1. There is yet another great tool for subtitling online videos: No need to download or purchase anything. it’s free and it’s on the web!

  2. Thank you so much: from the demo video, the interface of Overstream is very much like the one of (desktop) MAGpie. And authors can download their captions as an .srt file too. See point 6 in

    Let’s hope:

    – they add some more video hosting providers ( and Internet Archive for instance) to the ones they presently support

    – they don’t go the way of Mojiti (which allowed the same things as overstream, though maybe less accurately in the timecoding) whose CIO sold the tech of to Hulu, only usable in US.

    One advantage of SMIL captioning is that you can have switchable captions in several languages (and other things like audiocaptioning and 2nd video in sign language). But as videos are only streamed through overstream, you could caption them several times for several languages without having to re-upload them.

    Another advantage of SMIL is that it is an open tool, whereas Overstream technology is “patent-pending”, according to . And that means that outside developers cannot build on from it.

    But it is indeed a great tool.

  3. Claude, please consider expanding this into an article for I-Blog. The thrust could be a review of Overstream with an eye to comparison with other similar online services. Fascinating stuff. Thanks! -Jim

  4. Jim, apologies for answering so late. Thank you for the offer to review Overstream – it’s the “comparison with similar online services” that is presently holding me back. There is a great SMIL-based one I had the privilege to beta-test in April 2007 I’d wish to cover. The problem is that t it is still in non-public beta…

  5. Re my former comment about Overstream: they have now added to the platforms from which videos can be captioned on theirs. See .

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