Frequently Asked Questions (FAQ)
- What is DO-IT?
- What is the DO-IT Video Collection?
- How is the DO-IT Video Collection funded?
- How does the search feature work?
- Is this approach scalable to larger video collections?
- What video player are you using?
- Are the video players accessible to screen reader users?
- Are your videos available on YouTube?
- Are the videos audio described?
- Can I customize the interface?
- What is your procedure for making your videos accessible?
- Is the DO-IT Video Search source code available?
- What is on your To-Do List?
- Who do I contact with feedback or suggestions?
- Who do I contact for support in using JW FLV PLayer or any of the other products mentioned in this FAQ?
- Are there other examples of video search applications?
- What are some other resources on multimedia accessibility?
What is DO-IT?
The DO-IT (Disabilities, Opportunities, Internetworking, and Technology) Center at the University of Washington has, since 1992, served to increase the success of individuals with disabilities in challenging academic programs and careers. It promotes the use of computer and networking technologies to increase independence, productivity, and participation in education and employment.
What is the DO-IT Video Collection?
Over the years, DO-IT has produced more than 40 videos on a wide range of topics related to people with disabilities accessing curriculum, using technology, and pursuing challenging careers. The DO-IT Video Collection is a website that provides users with a variety of ways to explore all of these DO-IT videos, from 1994 to present. With only a few exceptions, most videos have been encoded for online viewing and can be viewed within our accessible media player. An interactive transcript is also available for most videos, and all videos are additionally available for download in either Quicktime or Windows formats. The DO-IT Video Collection site also includes a search feature that enables users to search the full text of all videos and begin playing videos at specific start times from the search results. This feature is possible because our videos are captioned.
How is the DO-IT Video Collection funded?
DO-IT Video Search was developed with funding from the National Science Foundation (NSF, Cooperative Agreement #HRD-0227995) and continues to be updated and maintained as an activity of the AccessComputing project, also with NSF funding (Grants #CNS-0540615, CNS-0837508, and CNS-1042260). The contents do not necessarily represent the policies of the U.S. federal government, and you should not assume their endorsement.
How does the search feature work?
All of DO-IT's videos are closed captioned. Closed captions come in a variety of formats depending on the type of media being used, but most of these are text or XML files that can easily be parsed by a simple script, and used for searching. For our purposes, we store each individual caption and its associated start and end time as records in a MySQL database. The user interface is written in PHP. When a user searches for a keyword or phrase, a MySQL full-text search query is executed, and results are delivered to the user. Results are grouped by video with the most relevant videos (according to MySQL) listed first. Each item in the results is caption text, including a link that starts playing that video in the embedded media player at the indicated time where that text is being spoken. For the nuts and bolts of the search algorithm, we depend entirely on MySQL full-text search, which we have found to be adequate.
Is this approach scalable to larger video collections?
Admittedly, our database is quite small. We currently have nearly 40 videos, and approximately 5000 captions. We have not tested our approach on a larger collection.
What video player are you using?
The DO-IT Video Collection uses the HTML5 <video> element. HTML5 is the fifth major version (currently in draft) of HyperText Markup Language (HTML), the primary markup language that is used to create web pages. HTML5 includes, for the first time, <video> and <audio> elements, that allow video authors to very easily add multimedia to web pages, and allow users to play these media directly in the browser without installing a plug-in. As a working draft, HTML5 is constantly evolving, but has tremendous potential. With the HTML5 <video> element, it is extremely easy for web authors to add video to their sites, and is already widely supported among browsers.
HTML5 includes markup (the <track> element) that enables video to include closed captions, subtitles, and closed audio description. At this point no browser supports these accessibility features natively, but the interface elements are exposed through a powerful application program interface (API), which allows web developers to develop support for these features. The DO-IT Video Collection currently includes support for closed captions through the HTML5 player. We are exploring strategies for providing closed audio description and sign language as well. Meanwhile, open audio described versions of our videos are always played by default, but this can be changed on the user Preferences page. The latest versions of most browsers support the HTML5 <video> element. One late adopter though is Internet Explorer (IE). IE8 does not support HTML5, but IE9 will have support, including support for <video>.
Since many people are using Internet Explorer, or older versions of other browsers, a fallback method needs to be provided for these users to access videos. The DO-IT Video Collection is using the JW Player as the fallback player. It's a Flash player that supports closed captions and audio descriptions, and has a good API that allows us to control the Flash player using standard HTML buttons. In fact, we use the same set of player control buttons for both the HTML5 and JW Players, so all users get a reasonably consistent interface.
Are the video players accessible to screen reader users?
Yes. Both the HTML5 video player and JW Player are accessible to screen reader users through our custom controls. Each control is assigned a meaningful title attribute, which is announced by screen readers. Access keys are also available so the player can be controlled with a single keystroke from anywhere on the page, without the user having to return focus to the video player. This is a handy feature for all users, but is expecially helpful for screen reader users. Access keys are keyboard keys that are used in combination with one or more other keys, which varies by browser. To see how to use access keys in your browser, see the Wikipedia Access Key article. The following access keys control the DO-IT Video player:
- P - Pause or Play
- R - Rewind
- F - Forward
- A - Toggle Audio Description (HTML5 player only, if closed audio description is available)
- C - Toggle Captions (HTML5 player only)
- M - Mute
- U - Volume up
- D - Volume down
Without our custom controls, screen readers and browsers vary in their support for HTML5 video player controls. Some screen reader/browser combinations read some buttons, while others read none, and this is a moving target. Eventually, we trust that HTML5 media elements will be well-supported and fully accessible. Until then, custom controls are currently the best way to attain a fully accessible and usable interface for screen reader users.
The JW Player version 5.4 is also reasonably screen-reader accessible. All buttons are clearly labeled for screen reader users, but a few non-functional unlabeled graphics create a small amount of screen reader noise. A historical problem with the JW Player is that accessibility has been intermittent. New versions of the player are frequently released, and the new versions have sometimes broken accessibility features. Hopefully that systematic problem has been corrected.
Are your videos available on YouTube?
Yes. Please visit the DO-IT Channel on YouTube, and lend your voice to the comments and discussions there.
Are the videos audio described?
Yes, all of DO-IT's videos include audio description. Audio description is a narrative voiceover that describes content (including key actions or screen text) that is otherwise presented only visually, and is therefore not accessible to someone who is unable to see it. Since the added narration may be distracting to some users, we have produced two versions of all our videos, one with audio description and one without. By default, we show the audio described version of all videos in the DO-IT Video Search application. However, this can be changed on the Preferences page.
One of the reasons we selected JW Player as one of our video players is its support for closed audio description. To our knowledge this is the only web media player that has such support. With this feature, audio description can be delivered in a distinct MP3 audio file, and it can be toggled on and off by a button on the player's control bar, similar to the way closed captions work. We find this to be a nice feature because it allows us to deliver one video that meets the diverse needs of all audience members, rather than having a separate video for users who require audio description. Also, version 5.3 introduced support for ducking, which enables the player to watch the audio description waveform and automatically lower the volume of the program audio whenever audio description is present. This is an exciting feature that ensures adequate contrast between audio sources, and we're currently testing that for possible implementation in the future.
Since support for closed audio description is relatively new, it is only available for DO-IT videos produced in 2008 or later.
To sample audio description, you must have "Closed Audio Description" checked in your Preferences. Also, since only the JW Player provides support for closed audio description, you can only sample it in browsers that do not support HTML5 video. This includes Internet Explore 8 or earlier, plus older versions of all browsers.
Can I customize the interface?
Yes. You can change many of the default settings of the DO-IT Video Search website on the Preferences page. Doing so requires that your browser be set to accept cookies.
What is your procedure for making your videos accessible?
The following is a step-by-step guide through the process by which our videos are produced:
- Write the scripts. All our videos are created from scripts. Often this includes unscripted content (e.g., interviews, footage filmed on location at the University of Washington), but even this content is integrated into the script. Starting with a script results in a more polished presentation and an easier video editing process later. Also, the script content can easily be converted into captions, eliminating the extra time and cost of transcribing the video post-production.
- Plan for accessibility during production. Since all our videos include open captions, we are careful when filming to avoid critical content appearing near the bottom of the frame, where captions will later be displayed. Similarly, since all our videos include audio description, we are careful when scripting to pace the video in ways that ensure that there is enough space for narration to be mixed in.
Produce and encode the videos. Our videos are produced by University of Washington Television (UWTV), and the final deliverable includes media for broadcast television, DVD, and the web. For the latter, videos are encoded into MP4 files (for use in the HTML5 player in Apple Safari, iPhone, iPad, and iTunes), and into Flash Video (FLV) files for use in the JW Player). The FLV files are encoded with keyframes at frequent intervals (approximately one per second), necessary for PHP streaming and linking to particular points within the video. This process also requires that the FLV file be injected with meta data informing Flash of the locations of the keyframes. This is done post-production using Captionate from Manitu Group. UWTV also provides us with Quicktime and Windows Media versions of our videos that users can download and play on their own computers (these versions are open captioned and audio described). Finally, we use ffmpeg2theora to convert our videos to Ogg/Theora files for use in the HTML5 player in Firefox and Opera.
- Prepare for Video Search. Our final step is to save all materials to our web and media servers, then tell the Video Search application where to find these materials by completing a simple behind-the-scenes web form developed for DO-IT staff. This information, including each caption and its start and stop times (extracted from the caption files), is stored to a MySQL database, and is immediately ready for searching.
Is the DO-IT Video Search source code available?
What is on your to-do list?
There are a few known bugs, plus features we'd like to add. All are listed in our To-Do List near the bottom of the About DO-IT Video page.
Who do I contact with feedback or suggestions?
We welcome and encourage your feedback, especially on accessibility and usability of DO-IT Video Search. Please send feedback and suggestions to Terry Thompson, Technology Accessibility Specialist at DO-IT.
Where can I learn more about HTML5?
HTML5 is much-hyped and very well documented. Here are some key links that we've found to be particularly helpful:
- HTML5 Draft Specification
- Everything you need to know about HTML5 video and audio - by Simon Peters on Dev.Opera
- <video>, Accessibility and HTML5 Today - by John Foliot
What are some other resources on video accessibility?
For additional information about captioning, audio description, or other issues related to multimedia, consult the DO-IT Knowledge Base. A good entry point is the article How do I make multimedia accessible?