Accessibility/TimedText
From MozillaWiki
Resources relating to W3C TimedText
- comprehensive requirements
- DFXP satisfied requirements
- 3GPP Timed Text
- Test Cases
- Discussion of open issues on DFXP
Interesting Features
DFXP
- head - body - separated document
- div, p and span elements to structure content; they all have begin, end and duration attributes;
- a "region" element defines the area into which the text is to be rendered; multiple regions can be displayed at the same time and they can spatially overlap
- a "style" element defines a style for a region
- the region is then referred to from an div, p, or span element to define where and how to render the text
- a "layout" element groups metadata and regions
- had dynamic text display through dynamic flow style
- SMIL 2.1 based "set" element to control the animation of some other element
- SMIL 2.1 based "timeContainer" specification to specify local sequential or parallel child elements
- metadata specification possible in Dublin Core style
Example document: http://www.w3.org/TR/2006/CR-ttaf1-dfxp-20061116/#region-mapping-example-1-s
3GPP TimedText
This specification defines the subpart of the DFXP authoring language that is supported on 3GPP and how it maps into the 3GPP file format.
- each timed text track defines a region with width, height, translation
- within the region is defined a text box set into which captions are rendered
- styling is applied to the region and/or the text box(es)
- there is a "layer" value that decides between timed text tracks and video tracks the order of display layers
- i18n is achieved with language spec, writing direction, and character set support
- marquee-scrolling (ticker scrolling) is defined through scroll-in, scroll-out, scroll-delay attributes, scroll speed depends on the duration of this text segment
- dynamic highlighting as in Karaoke or Closed Captions is mentioned
- soft text wrap from line to line is supported to fit text within a text box
- outgoing hyperlinks are supported by attributing them to text boxes
- media mapping is defined for MPEG-4