For people with sensory disabilities, however, the use of this social media to convey important information is frustrating. Videos are rarely captioned, few provide audio description of visual content, and even the players themselves are often inaccessible to screen readers and other assistive technology. In the last few months, however, Google has helped bring the need for accessible video to mainstream consciousness. Their launch of easy-to-use captioning tools—even auto-captioning—is helping set a new standard for what a video should include.
Because of YouTube’s innovation, MassMATCH set out to learn more about the new captioning tools for the benefit of our program and community. We wanted to know how to use them. We also wanted to know how to go beyond them to provide access to more people with disabilities. Below are tips, tricks, and tools for accessible video that we have gleaned from the web and from experts in the field. The article includes advice on captioning, audio description, and accessible video players. It is intended to provide general awareness as well as deeper insight for novice video producers and anyone embedding video content on a website.
Thanks to Geoff Freed of the Carl and Ruth Shapiro Family National Center for Accessible Media (NCAM), Marsha Schwanke of the Burton Blatt Institute (BBI) at Syracuse University, and Jayme Johnson of the High Tech Center Training Unit at the California Community Colleges for contributing insight and resources used for this article.
CaptioningCaptions improve access to people who are deaf or hard of hearing, to anyone who is a visual learner, and—thanks to Google’s new Translate Captions feature for YouTube—to people who use languages other than English.
So how do you get started?
Learn some captioning do’s and don’ts
Captions are not just subtitles. In addition to dialogue they must convey any audible information needed to understand a video (i.e. a door slams).
o For a quick review, see Captioning FAQs from WGBH Media Access Group.
o To become a captioning nerd, visit the Captioning Key from Described and Captioned Media Program.
Sample the YouTube auto-captioning feature
Yes, YouTube will now automatically caption (subtitle) your English-language videos using speech recognition technology. However, the results are mostly quite poor (even hilarious) as the speech recognition algorithm is still “learning.” Still it’s worth using because YouTube allows you to download the auto-generated captions and correct them. This will save a lot of time over other options if the auto-generated captions are recognizable, and if you don’t have a lot of non-speech information to caption as well.
To request your video be captioned1. Sign into your YouTube account.
2. On the Captions and Subtitles pane, click the “Request Processing” button (you will only see this button if the video hasn't been processed yet).
3. You'll see Machine Transcription (processing) in the list of available caption tracks, which means it is working. Keep in mind that it can take a few days for the speech recognition track to become available for viewing and download.
To download your captions once they are ready:
1. Sign into your YouTube account.
2. On the Captions and Subtitles pane, look for the track called "English: Machine Transcription." Click the Download button next to that track.
3. A “captions.sbv” file will be saved to your desktop (it’s a text file with timecode information that you can use with caption software or open with a regular text editor like Notepad.)
Caption with the YouTube auto-timing feature
If the YouTube auto-captioning results are too rough to edit, YouTube also offers an auto-timing feature for captioning. Unlike auto-captioning, auto-timing requires you make a transcript of your video (which gives you more control, but does take time). Auto-timing means, however, that you don’t have to provide timing information for when your captions should be displayed on the screen – instead, the YouTube speech recognition algorithm figures this out for you.
To use the auto-timing feature:
1. Make a simple text transcript (.txt file) of your video (and it must be your video) using Notepad or WordPad (Windows) or TextEdit (Mac).
2. Upload to your YouTube account,
3. YouTube synchronizes your text with your video’s audio content (you can also provide a caption file in specific formats if you have one).
For more information, INDATA provides an easy step-by-step guide to YouTube’s auto-timing at this blog page. INDATA doesn’t mention it, but you can also download and correct any glaring timing errors.
Consider using captioning software
You may also skip the YouTube auto-timing and auto-captioning features and create an honest-to-goodness caption file (i.e. files with these file extensions: .smil, .sami., .sub, .srt, .dfxp, .rt). This gives you maximum control over the timing of your captions (since you time them yourself). Many caption-file formats work with YouTube, but may also be used with standalone players (those installed on your computer, like Windows Media Player, QuickTime or iTunes). The downside is that caption files take a lot longer to make—rule of thumb is 5-10 times the length of the video you are captioning. (This means a 5 minute video may take 25 -50 minutes to caption.)
Here are some captioning resources:
o MAGPie is free captioning software created by WGBH’s NCAM (the Carl and Ruth Shapiro Family National Center for Accessible Media). It has recently been updated (March 2010) to make installation smoother (version 2.5). It will caption most video file formats (but not file extensions .wmv, .rm, or .ra). It will also create caption files in many formats for use with many players (.sami, .rt, .txt, dfxp and ttxt). YouTube is compatible with .sub, .srt, .txt, .rt and dfxp).
o Additional captioning software options include CapScribe, Macaw, World Caption Tool (for Mac), and QuickTime Pro.
o Automatic Sync Technologies Service is a company that provides captioning and transcription services.
Descriptive VideoTo help make a video comprehensible for people who are blind or have low vision, videos are sometimes also produced with audio description of visual content. This is known as descriptive video. Audio description works with a separate audio track that is synched with the video. The track uses the natural pauses in a video to describe key visual elements. YouTube, however, does not support the inclusion of additional audio tracks.
Here’s what you need to know:
Narrate your videos to be descriptive from the start to avoid the need for separate audio-description files
The best way to make sure people who are blind or who have low vision can comprehend your video’s content is to remember these audiences before you shoot your video clip. In the body of your narration, cue the listener in to what is happening on the screen, but only as much as is necessary. Too much information is confusing. See this Job Accommodation Network outreach video on AT for Employment for its simple method of orienting the listener. If you use this technique, you can still use YouTube effectively for video sharing. If not…
- Review standard techniques in audio description by Joe Clark.
Consider do it yourself audio-description file tools
o QuickTime Pro
o Adobe Premiere / Audition
o Apple iMovie / GarageBand
Consider hiring a professional audio-description service
Truthfully, if your video needs to be audio described (particularly if it is longer than a few minutes), this is best left to professionals because audio description is an art form. Read more about audio description at this AccessIT page and WGBH’s Media Access Group Descriptive Video Service page. Also, sample an audio-described and captioned video from Inclusive Technologies (“The Assistive Technology Boogie”).
Find a player that supports audio descriptionOnce your video is audio described and captioned, there are website-embeddable video players that will support all your files (see VideoLAN-VLC below).
Accessible Video Players
Video players are software that play your video files, and hopefully your caption and audio-description files too. They are the little TVs that pop up on your website when, for example, you embed using that html snippet that YouTube provides. Unfortunately, YouTube’s standard embeddable player is not accessible for screen readers. Google knows it and likely this will change. But for now, here are some options:
The Web Accessibility Center (WAC) at Ohio State University (OSU) provides code (html snippets) and instructions for creating accessibility controls for the YouTube player. It requires some developer knowledge, but it looks like a fairly straightforward way to continue to have YouTube host your videos (if they do not require audio-description files). The Center is currently working to update this page to reflect YouTube’s new auto-captioning feature. However the video player instructions should work with any captioned YouTube. It will not support audio-description files, however.
JW Player 5.1
JW Player 5.1 is Flash-only (.FLV video files), free (open source) and plays both caption and audio-description files (it also advertises that it is the only player that can play both closed captions and closed audio descriptions, which means they can be hidden or revealed). It will also play YouTube. The player provides keyboard controls (using the TAB and SPACE controls), screen-reader-labeled buttons, and a full-screen button. Plus, above the player are visually hidden controls that allow screen-reader users to control play, mute, and stop. Review the captions plug-in for the JW Player and the audio description plug-in for the JW Player. Note: the player requires captions be in in DFXP or TTML format. Several caption software tools can help create or convert your file to DFXP/TTML (including MAGpie). Stanford University offers a free online .srt-to-.DFXP converter.
VideoLAN-VLC media player
VideoLAN-VLC is accessible, free (open source), and plays files of most formats (not just Flash), supporting both captions and audio description. Installation requires some developer know-how, and hosting your videos on your own server (not on YouTube).
The National Center for Accessible Media (NCAM) created ccPlayer, a free Flash player that utilizes DFXP/TTML files to display captions. It will play DFXP/TTML caption files created by MAGpie or by other software. The ccPlayer Web site provides embedding instructions which presume some developer know-how, but you do not need to be a Flash author to use ccPlayer. The player is accessible by both keyboard and screen-reader users, and plays only Flash video files (.FLV). It does not support audio-description files. NCAM hopes to enhance the player to allow it to reference videos directly from a user’s YouTube channel, caption files included (and that would be a neat trick!). For now, using ccPlayer requires hosting your videos on your own server (rather than on YouTube).
Specifically for Flash developers who want total control over the appearance of the video player and captions, NCAM also created CCforFlash, a free captioning component that can be added to a Flash project. The CCforFlash component is completely customizable, and allows authors to control the width and height of the caption region, the caption and background colors, the opacity of the background, and the font family and size of the captions themselves. Many other features are described at the CCforFlash Web site.
You can also provide a link to your video (hosted on your own server) and bypass embedding a video player altogether. The link will open a standalone player installed on the user’s computer (assuming they have the player for the file type you link to). The advantage of most standalone players (i.e. Windows Media Player, QuickTime Player, RealPlayer, iTunes) is that they tend to be more accessible. They work with keyboard and screen readers and support captions and often audio-description files (Windows Media Player does not support audio description). Read about accessing captions and audio description on different standalone media players at this AccessIT page.
- Marsha Schwanke of the Burton Blatt Institute (BBI) at Syracuse University will be conducting a free webinar on September 8, 2010 at 2 pm EST on “Creating Accessible Videos for Your Website.” The webinar is part of a series and coordinated by the DBTAC: Great Lakes ADA Center and the DBTAC: Pacific ADA Center on behalf of the National Network of ADA Centers. Register at this Accessible Technology Webinar page.
- The Carl and Ruth Shapiro Family National Center for Accessible Media (NCAM) at the WGBH Educational Foundation is a resource for caption and audio-description tools and guidelines as well as information about research-and-development projects aimed at making media more accessible at home, in the classroom, in public spaces and on handheld devices. For more information, contact Donna Danielewski.
- Creating Accessible iTunes U Content (opens in iTunes). iTunes U is Apple’s distribution system for getting educational material (lectures, film, audiobooks, tours) to students through iTunes. Here NCAM provides guidelines for how to add captions and audio descriptions to media posted to iTunes U, playable on Apple devices such as the iPod, iPhone, iPad, iTunes and the QuickTime Player. Video and audio examples are included, as is information on creating accessible PDF documentation. If you do not have access to iTunes, you can view and download the guidelines directly from NCAM’s Web site.