Slide 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


Slide 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


Slide 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


Slide 4

Flash History




Becoming more accessible by version 6
Full integration with video by version 7
Ubiquitous (around 97% share)




Handles video well






YouTube, MySpace
Sorenson Spark codec
ON2VP6 codec

Fast
Developer-level flexibility



Can revise interface as needed
Control over accessibility (within Flash capabilities)


Slide 5

Captioned Flash Video


Flash Video Player (ours)



CC for Flash / ccPlayer (National Center for
Accessible Media – WGBH)



FLVPlayback / FLVPlaybackCaptioning
Components for Flash (Adobe)


Slide 6

Flash Video Player


Allows captioned video without Flash
programming



Open source



Major or minor customization possible



Flash 7.0 and above


Slide 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


Slide 8

FLVPlaybackCaptions


Flash programming required



Minimal Flash knowledge needed



Skins



Closed source, so customization is limited



DFXP caption files



Flash 9.0 (CS3)


Slide 9

Flash Files


Video




Caption file






Integrates video and caption files

Flash player (Shockwave)




We use the QuickTime caption file

XML configuration file




.flv

.swf compiled from Flash code

HTML
Flash code file (.fla)


Optional for further development


Slide 10

Flash Video Player Assembly
Flash program file videoname.swf
Video file videoname.flv
Caption file videoname_captions.txt
(Same file as used for QT)

Caption control file captions.xml
(Video and caption file locations)

Flash code file videoname.fla
(optional)


Slide 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)


Slide 12

XML Configuration



captionfile.txt
video.flv
240
180

1948.03






Slide 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.


Slide 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)


Slide 15

Flash Security


Keep files in same folder when possible



Use BASE attribute in HTML


