Are You Ready to Support Closed Captioning?
Closed-captions are an important element for members of your online video audience who are hearing impaired. So it’s important that content providers review the Twenty-first Century Communications and Video Accessibility Act of 2009, which is working its way through the legislative process right now. The act, which amends the Communications Act of 1934, requires that some video content providers offer the capability to display closed captions and make encoded video description and emergency information audible.
More benefits from transcript data
Besides complying with the pending law (if and when it becomes law) and providing a great experience to your hearing-impaired audience members, enabling closed captioning can also serve the following purposes:
- The transcript can be used for narration for visually-impaired individuals.
- With the right player-side technology, the time-coded aspect of the video transcript enables your audience to find and go directly to specific scenes or moments in the video.
- There is greater opportunity to increase your video’s global reach with translated caption content.
- The transcript can be indexed by search engines for greater discoverability.
- It helps non-native speakers and other learners (such as children) with word identification, enriching their experience with your video.
- It gives audiences a way to experience and understand your video content if they can’t listen to audio during their viewing session for any other reason.
How does it work?
Closed captioning, which relies on temporal metadata (associated with a specific timeframe), isn’t very complicated when you have the right systems in place. To provide captions as an option with your videos, you need three things:
1. A complete transcript of each video, converted into a time-coded text file (either SAMI or DFXP):
- Distribution format exchange profile (DFXP) is an XML-based language for marking timed-based text, such as closed captions and subtitles.
- SAMI (Synchronized Accessible Media Interchange) is a markup language for simplifying caption creation for media playback on a PC.
2. A player that supports captions, like thePlatform’s Player Dev Kit
3. A video management system that can deliver the requisite SAMI/DFXP file, like thePlatform’s mpx Beta.
You can incorporate SAMI-format caption files into your media objects, and your users can choose to view captions when they play Flash video.
Players built with the Player Dev Kit support closed captioning in two different ways:
- Using separate caption files that conform to either the SAMI 1.0 or DFXP 1.0 specifications
- Reading data embedded into an MPEG4 media stream
SAMI and DFXP files
thePlatform’s mpx Beta video management system relies on a custom field named “Subtitles” when constructing release metafiles that reference separate caption files. You create this custom field before assigning any caption media files to your media.
When a Player Dev Kit player sees a SAMI or DFXP file reference included in the metafile for a clip, it enables closed captioning for the user by displaying a closed-caption button. The user can click it to display captions, and they then get a menu of the available caption languages, based on choices that you provide. When they click the language that they want to view, the player begins displaying captions.
Until they make another choice, the player remembers their language preference and displays captions whenever that language is available. This makes the user experience much better for your closed-captioning users who make repeated visits to your site.
MPEG-4 files.
You don’t need to set up a “Subtitles” field if your MPEG-4 files contain transcript data. The Player Dev Kit automatically processes caption data that is embedded within the MPEG4 stream, and the language for the captions is added to the closed caption button in the player.
thePlatform has integrated partners like PLYmedia and RAMP that can help you prepare and render your captions in a Player Dev Kit player. Contact your Account Manager to learn more.
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