Standards
“Best practices in online captioning” are best achieved through standards, or, to use the term from network television, standards and practices:
- Standards
- Published requirements, guidelines, or specifications
- Practices
- Authors’ implementation of standards combined with other actions
Subject areas
We can view the entire issue of standardization of online captioning as encompassing the following fields:
- Authoring
- When Web sites use multimedia, they are subject to the Web Content Accessibility Guidelines (WCAG, pronounced “wikkag”). WCAG 1.0 is in force now, with WCAG 2.0 in development.
- “Authoring tools” used to create the captions are subject to the Authoring Tool Accessibility Guidelines (ATAG, pronounced “ay-tag”).
- Captions may be stored in standardized formats, such as Synchronized Media Integration Language (SMIL, pronounced “smile”), Synchronized Accessible Media Interchange (SAMI), Timed Text, plain text, (X)HTML, or a host of others.
- The actual form and behaviour of online captions is governed by no published standard. Captions can and do look and behave any way the creator wishes.
- Playback
- Media players and browsers are governed by the User Agent Accessibility Guidelines (UAAG, pronounced “you-ag”).
- Metadata
- No standard exists for accessibility-related metadata. However, Dublin Core may in the future be used for this purpose.
- Some HTML elements, like
link, can be used to specify alternate content.
- Metadata within online video and caption files can permit viewers to select different caption streams (e.g., to match their preferred language), or simply turn captions on and off.
Evaluations
We’ve prepared evaluations of the relationship between online captioning and existing standards: