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Concepts & Techniques for Accessible, Closed Captioned Web-Based Video

Concepts & Techniques for Accessible, Closed Captioned Web-Based Video. David Klein K. “Fritz” Thompson. 10th Annual Accessing Higher Ground: Accessible Media, Web and Technology Conference Boulder, Colorado November 7, 2007 http://disability.law.uiowa.edu/lhpdc/publications/kleinpubs.html.

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Concepts & Techniques for Accessible, Closed Captioned Web-Based Video

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  1. Concepts & Techniques for Accessible, Closed Captioned Web-Based Video David Klein K. “Fritz” Thompson 10th Annual Accessing Higher Ground:Accessible Media, Web and Technology Conference Boulder, Colorado November 7, 2007 http://disability.law.uiowa.edu/lhpdc/publications/kleinpubs.html

  2. Flash • Video is played back by Flash Player • Version 7 or above of the Flash Player required for the end user • Interface (controls, layout) located in .swf file

  3. Flash Video • De facto Web standard because of “player wars” • Lack of standards compliance • Continual, relentless upgrades • Difficulty in upgrading – pushing users toward paid versions • Hijacking of media types / file extensions • People just want video to work

  4. Flash History • Becoming more accessible by version 6 • Full integration with video by version 7 • Ubiquitous (around 97% share) • YouTube, MySpace • Handles video well • Sorenson Spark codec • ON2VP6 codec • Fast • Developer-level flexibility • Can revise interface as needed • Control over accessibility (within Flash capabilities)

  5. Captioned Flash Video • Flash Video Player (ours) • CC for Flash / ccPlayer (National Center for Accessible Media – WGBH) • FLVPlayback / FLVPlaybackCaptioning Components for Flash (Adobe)

  6. Flash Video Player • Allows captioned video without Flash programming • Open source • Major or minor customization possible • Flash 7.0 and above

  7. CC for Flash / ccPlayer • ccPlayer allows captioned video without Flash programming • Flash components • Skins • Little Flash knowledge needed • Closed source, so customization is limited • DFXP caption files • Flash 8.0

  8. FLVPlaybackCaptions • Flash programming required • Minimal Flash knowledge needed • Skins • Closed source, so customization is limited • DFXP caption files • Flash 9.0 (CS3)

  9. Flash Files • Video • .flv • Caption file • We use the QuickTime caption file • XML configuration file • Integrates video and caption files • Flash player (Shockwave) • .swf compiled from Flash code • HTML • Flash code file (.fla) • Optional for further development

  10. Flash Video Player Assembly

  11. Captions.xml File Characteristics • Use XML standards • Tags case sensitive • All elements closed • <tag>xxx</tag> (open and close tags) • <tag /> (no explicit close tag; use the slash)

  12. XML Configuration <?xml version="1.0" encoding="ISO-8859-1"?> <flashcaptioning> <ccconfig> <CaptionLocation>captionfile.txt</CaptionLocation> <VideoLocation>video.flv</VideoLocation> <VideoSizeWidth>240</VideoSizeWidth> <VideoSizeHeight>180</VideoSizeHeight> <!--Time in seconds --> <VideoTotalTime>1948.03</VideoTotalTime> <!-- The following is a placeholder --> <XMLFileUsed></XMLFileUsed> </ccconfig> </flashcaptioning>

  13. Flash Video Player Activity • Handout: Activity 3: Flash Video Player • Objective: • Modify an XML file and assemble the QuickTime captions file with the Flash video player to create a web-enabled, captioned, Flash video.

  14. Flash Video Player Files • Place all files together in a folder • Video (.flv) • Caption file (video_caption.txt) • XML file (caption.xml) • Flash video player file (.swf)

  15. Flash Security • Keep files in same folder when possible • Use BASE attribute in HTML • <object><param name="base" value="http://domain.com/"></object • Or<param name="base" value= “."> • Test thoroughly, especially among browsers and browser versions • More: • http://www.macromedia.com/devnet/flash/whitepapers/security.pdf • http://www.macromedia.com/devnet/flash/articles/fplayer_security.html

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