Captions
Adobe® Flash® software is frequently used to deliver audio and video content. Any audio that contains substantive content should include a synchronized text equivalent in the form of captions.
Standards support
Adobe Flash Professional CS6 software provides a component that allows developers to easily add captions to either FLV or H.264 video in Flash. The FLVPlaybackCaptioning component enables captioning for the FLVPlayback component. The FLVPlaybackCaptioning component uses a World Wide Web Consortium (W3C) Timed Text XML file (TTML - formerly known as DFXP) and adds those captions to the FLVPlayback component with which the FLVPlaybackCaptioning component is paired.
Adobe has worked with many caption tool vendors and service providers to encourage the support of TTML. Several options are available for developers who are interested in providing captions, including do-it-yourself tools and vendors that can provide TTML caption data files for those that want to outsource this important and detailed work. A list of tools and vendors that support TTML is available to help developers choose the method best suited to each situation.
"We have been delighted to work with Adobe to achieve an amazing feat: turning the once challenging task of captioning video in Flash into an easy and standards-based process for developers and content producers alike. The tools and components created by Adobe, the Media Access Group at WGBH, and others make video in Flash a welcome and accessible technology for people who are deaf or hard of hearing."
director, Media Access Group at WGBH and The Carl and Ruth Shapiro
Family National Center for Accessible Media (NCAM)
Captioning component
You use the FLVPlaybackCaptioning component with one or more FLVPlayback components. In the simplest scenario, a FLVPlayback component is dragged onto the stage, an FLVPlaybackCaptioning component is dragged onto the same stage, the caption data file URL is identified, and showCaptions is set to true so that the captions are on by default.
Figure 1. View of the Flash FLVPlaybackCaptioning component and settings
In Figure 1, the caption file is set in the source parameter. Additional parameters to customize your FLVPlayback captioning can be set, but in this example simply saving and publishing the SWF file results in captions as shown in Figure 2.
Figure 2. Captions appearing over the video window
Content providers may want to deliver captions in a different location onscreen. The FLVPlaybackCaptioning component allows developers to identify a separate text field to display the captions. In the screenshot below, a new dynamic text field not only displays the captions in a new location, but also takes advantage of the ability of Flash to embed font information so that even users who do not own a font can view captions in the font selected by the developer.
Figure 3. Captions appearing in a separate text area
The FLVPlaybackCaptioning supports caption display in full-screen video mode also, so users can enjoy large video with enlarged captions for easier reading.
Support for embedded cue points
The FLVPlaybackCaptioning component also displays caption data contained in embedded cue points. One advantage of using FLV cue points is that caption data exists within the FLV file, reducing the number of files to track. Captionate is a captioning tool that allows authors to add cue points to FLV files.
International support
The FLVPlaybackCaptioning component supports Unicode character display. This allows caption display for non-Western languages and for special characters such as the musical note that are familiar to viewers of captioning.
Accessible interface
The captioning support in Flash is complemented by support for keyboard and screen reader interaction with the video playback controls, making Flash the most accessible way to deliver video on the web. For more information about accessible video controls in Flash, read the video design guidelines document.
