Don’t call me DOM

I gave a couple of talks over the past month, where I chose not to use the W3C-traditional HTML-based slides (using Slidy), but instead to use a more graphical approach, using two different tools:

• Prezi, a Flash-based commercial tool that I used for a presentation I gave on Web 2.0 and beyond
• JessyInk, an open-source extension to the open-source SVG editor InkScape, with which I built the presentation I gave on W3C and the Social Web.

I’m summarizing below my experiences with both these tools.

Prezi

Prezi is a Flash-based tool, that allows both to build and show 2D-presentations.

As I was trying to validate a large number of XHTML MP 1.2 files (the ones in one of the OMA’s XHTML MP test suite – whose welcome page itself ironically is not well-formed), I realized that the tool I was using, based on the WDG HTML validator as packaged by Debian, was making network access requests when used on these XHTML MP 1.2 files. I then moved to use xmllint with the --valid option, but it had the same behavior.

As one of the W3C Systems team member, I’m acutely aware how bad is the practice of fetching DTDs over the network over and over again.

So, while exploring the world of Web video, after having successfully transcribed a one hour long video of one my presentations, and turned that transcription into an HTML 5 video with subtitles, I started to look in more details as to what HTML 5 brought to the table that made this synchronization possible.

The rather obvious change that HTML 5 brings to the table is the HTMLMediaElement DOM Interface, and in particular the currentTime property, which at any time reflects the part of the media content that is played.