Transcript pps
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, 2006 http://disability.law.uiowa.edu/lhpdc/publications/kleinpubs.html
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
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
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)
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
Flash Video Player Assembly
The Flash playback engine – videoname.swf
The video – videoname.flv
The caption file – videoname_captions.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)
Captions.xml File Characteristics
Use XML standards Tags case sensitive All elements closed
XML Configuration
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.
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)
Flash Security
Keep files in same folder when possible Use BASE attribute in HTML 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