Using Closed Captions for Online Video

Web video accessibility is a broad term that refers to making videos usable for all types of viewers. Traditionally, it refers to those with impairments, but more recently the definition has broadened. At LongTail Video, we feel strongly about creating the means of equal access to online video content. By building products that support features such as multi-language video captions, we aim to increase viewer accessibility. Though there are many pieces to making a video fully accessible, in this post we focus the discussion on closed captions.

Understanding Video Captions

Video captions are very similar to subtitles. The major difference is that captions describe all of the relevant audio detected in the video, whereas subtitles focus solely on the words spoken in the film. For example, if a phone is ringing in the background a caption will display something like, “the phone is ringing”, and a subtitle will display nothing. Captions are “closed” when a user can toggle the captions on/off during video playback. Captions are “open” when they are burned directly into the video, which means they are displayed 100% of the time. Making sure your captions are closed is important – it allows you to support all types of users with the same piece of media, increasing both accessibility & inclusiveness.

The Current State of Video Captions

Captions have conventionally existed for television, but only more recently have been introduced into online video. Although The World Wide Web consortium (W3C) has established a set of guidelines known as Web Content Accessibility Guidelines that provide a standardized and definitive set of rules for how to develop accessible online content, online video accessibility federal regulations are still in their infancy.

Since 2010, American accessibility advocates have urged Congress to modify an existing bill that would mandate captions for any online video that has also appeared on TV. Just last month, the Federal Communications Commission (FCC) released their final rules on closed captioning for IP-delivered video programming. Though only a small step towards a more universal regulation, it applies to all full-length video television programming in the United States, previously distributed with closed captions.

As closed-captioning of online video programming emerges, speed of adoption is key. is an early adopter who uses the JW Player with our Captions Plugin to display their cataloged live broadcasting footage.

Hulu’s CTO, Eric Feng quotes that “users send us feedback about closed captions more often than almost any other feature, so what started as a small side project has turned into a very important part of our user experience…”.

Video Captioning Tools

In our own product development at LongTail Video, we see similar requests, and have recently pushed two product updates for online video captioning:

  • Bits on the Run Video Captioning – we now allow users to upload captions in the SRT and DFXP formats to the Bits on the Run Dashboard. Users can then publish their videos with closed captions for accessibility and Section 508 compliance. In addition, videos can now be published with multiple subtitle tracks, for viewers language selection.
  • JW Player Captions Plugin for HTML5 – we recently updated our Captions Plugin to support both Flash and HTML5 mode. This means closed captions will now appear in both the Flash and HTML5 rendering mode for videos embedded with the Captions Plugin.

Aligning with the trends in industry, the tools in which closed captions are created have improved as well. Services such as Subtitle Workshop and Jubler are offline tools used to edit text-based subtitles, or in our case, closed captions. Online services that we recommend are Universal Subtitle and our partner, dotSUB.

Added Benefits of Video Captioning

What video publishers may not yet realize is that there is more to captioning videos than simply increasing accessibility among the hearing-impaired. In fact, there are quite a few side benefits such as:

  • Mobile video – when users watch mobile video, sound is not always available, or loud enough.
  • Language barriers – for non-native-language viewers, closed captions make it easier to follow the video.
  • Search engine indexingas quoted by Google: “When you start adding text to all of your videos, search is aided tremendously.” Textual descriptions of your video footage increase the accuracy of the content indexing.
  • In-video search – with your text indexed, it becomes easy to implement an in-video search which allows a user to jump directly to a particular section within the video. Check out Hulu’s implementation of their captions search feature.

As video captioning enters the HTML5 market, and standards are developed around the element, captions will become even easier to publish.

With big names in video like Hulu and YouTube (where captions are included on all English-language videos uploaded after April 2010), putting emphasis on closed captions, we can be certain that the future will indeed be captioned. We encourage you, as a video publisher, to start experimenting with video captioning and create a workflow where closed captioning is a regular part of your video publishing process.


  1. Tony Perez August 4, 2012 - 03:55 EDT

    Great article. What about support for Live streams what are the constraints around that and does anyone knwo of someone using JW player with live stream captions?

  2. JamesMH October 24, 2012 - 05:51 EDT

    Is there any update on when the
    element will be supported for iOS by BitsonTheRun?


  3. Meagan July 12, 2012 - 05:08 EDT

    @Dana, thanks for you input, we definitely agree. We also recommend dotSub to our users as a captioning service. We partner with them as a custom captioning service (plugin) for the JW Player, our video player. Best of luck and keep captioning!

  4. JeroenW October 25, 2012 - 08:34 EDT

    Well, first iOS has to support it. It didn’t make it into iOS6, though developers indicated they simply ran out of time. That’d suggest it will be part of the next major iOS update?

  5. JeroenW August 6, 2012 - 05:07 EDT

    Live streaming is difficult at this point, since the captions need to be built and ingested in real time. There are some tools / encoders out there that support it, but I don’t know exactly which.

    Our Captions plugin supports TX3G text tracks in live streams sent by the Wowza or Flash media servers. So if you can setup a workflow that renders this output, you’re fine!

  6. Dana Tan July 12, 2012 - 01:13 EDT

    Great article, thanks especially for the Google quote. I have recently embarked on a project to add captions to over 90 videos produced by my company At first, management was puzzled, saying things like “I don’t think this applies to our customers” and best of all “YouTube already adds captions.” Well, maybe YouTube is trying to add captions, but have you actually ever read them? Have you ever tried to watch a video that is using YouTube-generated captions? It’s a joke. They are horrible. Just try one. You’ll immediately understand what I mean. If you are going to rely on being indexed on YouTube generated captions, you are going to get indexed for a bunch of stuff that has absolutely nothing to do with the content of your video. Writing good, timed, accurate, well-edited captions will go a long way to getting your video content properly indexed, for the proper terms. P.S. I am using to help me do the captions, it’s a great tool and a great video engine.

  7. @matdwright March 27, 2012 - 12:57 EDT

    Great article! It’s just a shame that online content providers aren’t (in the UK) forced to make online video more accessible to those who are hearing or sight impaired (including search and social engines!).

  8. Roger February 14, 2012 - 12:35 EDT

    JW Player Captions Plugin for HTML5 – we recently updated our Captions Plugin to support both Flash and HTML5 mode. This means closed captions will now appear on all devices (iOS, Android, desktop browsers) for videos embedded with the Captions Plugin.” (My emphasis in bold.)

    Hooray … great news if it’s true, I’ll try it as soon as I can.

    If it is just as simple as this statement suggests, does the page at the link you gave ( for the Captions Plugin need updating ?

    As I write this, that text has some apparent contradictions. For example …

    1. Under the heading Introduction, you say “The plugin works in both Flash and HTML5, but not on iOS due to technical limitations”, but this new article suggests this is not so.
    2. Under the heading SRT (SubRip), you say “The SRT format … is supported in both Flash and HTML5 mode on all desktop browsers. On Android, SRT is only supported in Flash mode. SRT is not supported on the iPad/iPhone, since it is not possible to render custom graphics during (fullscreen) video playback”, which again, seems to be contradicted by what you have just posted.
    3. Under the heading MP4 (3GPP Text Tracks), it says It is not supported in HTML5. Ditto previous query.
    4. Under the heading DFXP (W3C TimedText), it says “The Captions plugin also supports it in Flash mode (desktop + Android), but not in HTML5.” Ditto again.

    I’m also interested in this from the BOTR point of view – are the iOS restrictions gone there too ?

    If there are any provisios, please clarify.



  9. JeroenW February 14, 2012 - 03:15 EDT

    Ah, yuk. Unfortunately, that statement in this article is not true. I’ll get it fixed. The various types of captions only work on some devices now, and nothing works on all:

    *) SRT works on desktop browsers in Flash + HTML5 and on Android only in Flash. Never on iOS.
    *) DFXP works on desktop browsers only in Flash and on Android only in Flash. Never on iOS.
    *) MP4 works on desktop browsers only in Flash, on Android only in Flash and on iOS always.

    The lack of DFXP support on desktop HTML5 browsers is due to our implementation, not due to technical constraints. Expect us to start supporting DFXP on desktop HTML5 within a few months too (matter of building it).

    With BOTR, we support SRT and DFXP captions, not MP4 ones. This means we currently do not support captions on iOS with BOTR. Since we still prefer Flash over HTML5 on Android with BOTR, captions will show up on Android too.

    We believe the HTML5
    element will get widely supported in 2012, on desktop browsers and (more important) Android/iOS alike. When that happens, we’ll support SRT and DFXP on every browser and device. At the same time, we’ll de-emphasize MP4 captions. They’re currently a short-term solution to getting captions on iOS.

  10. Meagan February 14, 2012 - 03:50 EDT

    @Roger, post is updated – thanks for the catch. We apologize for the confusion.

  11. Roger February 14, 2012 - 03:15 EDT

    Jeroen, thanks for straightening things out. Shame really, but I am glad to see that you are pushing this because it is important. As you say, the TRACK tag is clearly very important. And with the moves away from Flash, more power to anybody who can present a comprehensive solution.

    Please press on with your plans on both platforms – we look forward to early delivery ;-)


  12. Timoto April 3, 2012 - 10:06 EDT

    It seems that captions/subtitles are not supported by google video sitemaps native and mrss.

    But people have been ranting about video seo and captions/subtitles for ages now, so does that not mean it IS working somehow ?

    How about this plugin

    that claims to sit ontop of jwplay to help provide better seo ?

    Are they just selling on buzz words ?

    How about the mRSS can that not be used with an srt file like this ?:

    And perhaps that might get picked up at least by RSS syndication which in turn might get searched by google ?

  13. JeroenW April 4, 2012 - 09:17 EDT

    As far as we know, Google does not yet scan captions, but is investigating this. So today, SEO should not get improved. I think it’s likely that this will happen in the near future.

    You can indeed load SRT subs using “media:subTitle”. I don’t know which readers would pick them up though, and again I think Google would not be one of them yet.

  14. JeroenW March 28, 2012 - 01:18 EDT

    Thanks for the feedback! To be honest, practical impact on search is still minimal, since e.g. Google does not support captions in its videositemaps. Movement is needed on multiple fronts still…

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