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Techniques for Creating Accessible, Closed Captioned Web-Based Video

Techniques for Creating Accessible, Closed Captioned Web-Based Video. David Klein K. “Fritz” Thompson. California State University - Northridge 21st Annual International Technology and Persons with Disabilities Conference Los Angeles, California March 22, 2007

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Techniques for Creating Accessible, Closed Captioned Web-Based Video

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  1. Techniques for Creating Accessible, Closed Captioned Web-Based Video David Klein K. “Fritz” Thompson California State University - Northridge21st Annual International Technology and Persons with Disabilities Conference Los Angeles, California March 22, 2007 http://disability.law.uiowa.edu/lhpdc/publications/kleinpubs.html

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

  3. Flash Video • Frustrated with “player wars” • Lack of standards compliance • Continual, relentless upgrades • Difficulty in upgrading – pushing users toward paid versions • Hijacking of media types / file extensions

  4. Flash Rationale • Becoming more accessible by version 6 • Full integration with video by version 7 • Greater installed base • Handles video well • Fast • Developer-level flexibility • Can revise interface as needed • Control over accessibility (within Flash capabilities)

  5. 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

  6. Flash Video Player Assembly • The Flash playback engine – videoname.swf • The video – videoname.flv • The caption file – videoname.en_US.qt.txt • Same caption file as used for QT (or SAMI file is possible) • The caption control file – captions.xml • Includes URLs to video and captions files • User can toggle captions in the video player with CC icon (on by default)

  7. 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)

  8. 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>

  9. Flash Video Player Activity • Handout: Flash captions.xml Activity - Assemble Files • Objective: Modify an XML file and assemble the QuickTime captions file with the Flash video player to create a captioned, Flash video.

  10. 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)

  11. Flash Security • Keep files in same folder when possible • Use BASE attribute in HTML • <object><param name="base" value="http://domain.com/"></object • And<embed … base="http://domain.com/" … > • 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

  12. NCAM’s CC For Flash • Display New Captions Can import and display a new caption file at any time • Dynamic Styles Recognizes certain style changes in DFXP files • Language List Provides a list of languages found in DFXP files • Change Caption Language Can change to another caption language while video is playing • Search Can search for a string of text in the caption file and return the time of the next instance where the text occurs in a caption (available for external caption files only)

  13. ccPlayer (Flash video player) • Flash video player for those who don’t want to author their own • Uses the CC for Flash component to display captions • Can be embedded in any HTML page • Plays captions from external DFXP and QTtext files or embedded captions • Minimal programming experience necessary

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