Video Breakthroughs

Adobe Media Server 5 features support for closed captioning. But why is it important, and what are the options?

Summary :

- Why closed captioning?

- Why 608/708?

- What does Adobe Media Server 5 do?

- How to render closed captions?

Captioning is coming to internet video. Legislation goes into effect in the US during 2012 and 2013 that mandates closed captioning on certain categories of online content – see our earlier post for details on the legislation. But even apart from this legislation, closed captioning is a good thing for accessibility and usability, and is yet another milestone as internet video marches towards maturity.

Unfortunately, closed captioning is not a single technology or “feature” of video that can be “turned on”. There are a number of formats, standards, and approaches, ranging from good to bad to ugly. Closed captioning is kind of a mess, just like the rest of digital video, and is especially challenging for multiscreen publishers.

So if you want to publish video today for web, mobile, and connected TV delivery, what do you have to know about closed captioning? This post will outline the basics: how closed captions work, formats you may need to know about, and how to enable closed captions for every screen.

For DASH implementation, read this document : http://t.co/89n8sZdY

At first glance, video captioning might not seem like a huge deal. Maybe it might appeal to you if you need to meet accessibility requirements in your workplace, or you're just doing it to be nice to people with hearing difficulties.

You're pretty far from the mark though. Yes, accessibility is an important driver for video captioning on the web. But it's about much more than ‘deaf people’ (and you should be providing quality captioning for them anyway!)

In addition to important accessibility benefits, captioning your video can allow automatically generated transcripts, text search-ability within videos (imagine what will be possible once Google supports crawling WebVTT!), chapter markers and powerful metadata capability, and much more! You could provide a track of time-specific comments on the video (the same way SoundCloud allows commenting on specific parts of audio) or even a live twitter feed on your video (similar in style to the ABC'S Q&A program.)

“Alright!”, you say. “I'm convinced. How does HTML5 allow me to caption my video?”

For a while, there wasn't an easy way to do it. Guys like Bruce Lawson were coming up with creative ways (if a little hacky) to implement support, in lieu of a proper standard.

Now, however, there's a really nice way to provide support - the HTML5 <track> element and its associated JavaScript API. There's a slight catch though. No currently shipping browser supports either of these features/standards. They will soon - Webkit has support in development, and Firefox can now parse the <track> element (but can't do anything with it yet.)

But you want to caption your HTML5 video now. And for that, you need Captionator.js.