Industry Standards at Work: Improving Closed Captioning of Internet Video

The following blog post was written by Ann Marie Rohaly - Director of Accessibility Policy and Standards at Microsoft. She has a Ph.D. in biomedical engineering and has worked in the area of accessibility since 2009.


Eight years ago, five companies saw the future of video. Microsoft, Yahoo, AOL, Google, and WGBH realized television shows and movies increasingly will be delivered on the Internet and understood that industry approaches to closed captions on television were not compatible with the Internet. So, the companies formed the Internet Captioning Forum to work on solutions.

The Internet Captioning Forum’s objective was to ensure that the next generation of video-delivery technologies would be more inclusive for viewers who are deaf, hard of hearing or have other disabilities. After exploring options for closed captioning of video on the Internet, the group concluded an industry standard was needed to promote interoperability and widespread adoption, similar to the way traditional television services - broadcast, cable, and satellite - operate.

The forum submitted a proposal to the Society of Motion Picture and Television Engineers (SMPTE) in 2008. This proposal built on a solid foundation created by the World Wide Web Consortium (W3C) by extending W3C’s Timed Text Markup Language (TTML) standard to meet the needs of the television industry. It published the SMPTE Timed Text (SMPTE-TT) standard two years later.

So, where are we today? The Federal Communications Commission issued closed-captioning regulations in early 2012. Deadlines for adding captions to Internet-delivered programming were phased in by Sept., 30, 2013. And devices had to support closed captioning starting in Jan. 1, 2014.

Today, the industry is working hard on standards that will enable captions to flow from content creator to consumer. The World Wide Web Consortium, for example, is improving its TTML standard. Earlier this year, it published a subset of the standard, known as a profile, tailored to deliver closed captions on the web. The Society of Motion Picture and Television Engineers continues to develop ways to transform common television caption formats into SMPTE Timed Text to deliver existing television content on the Internet. The Digital Entertainment Content Ecosystem defined a profile of SMPTE-TT to deliver captions and subtitles in the UltraViolet™ digital media format. And the Moving Picture Experts Group recently updated its standards to enable timed-text captions in MP4 files.

To learn more about these industry activities visit:



Comments (2)
  1. John Hedges says:

    WebVTT is implemented in web content also. Is this the better format for captions in HTML5 or should TTML be used instead?

  2. Lloyd says:

    It's about time – CC on the internet is useless – the words usually have no relation to what is being said on the video.  I just tune out, unless there is a paragraph below the video explaining what is going on.  I'm positive there are many other deaf and Hard of Hearing persons who share the same experience.  

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