Concepts

1
Concepts Techniques for Accessible, Closed
Captioned Web-Based Video
David Klein K. Fritz Thompson

• 10th Annual Accessing Higher GroundAccessible
  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
• xxx (open and close tags)
• (no explicit close tag use the slash)

12
XML Configuration

• captionfile.txtn
• video.flv
• 240
• 180
• 1948.03

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
• om/"
• Or
• 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/fp
  layer_security.html