Accessibility/Video a11y Aug09

Video Accessibility Status Aug 2009 & Nov 2009 & Feb 2010 update

by Silvia Pfeiffer

This is a status report on the progress of video accessibility. I thought I'd publish this snapshot since it is a nice collection of resources around where video accessibility stands right now.

Update Feb 10: The new W3C HTML5 Accessibility Task Force has been founded in Dec 09 and activities for specification improvements and trial implementations are now happening there.

Test File Collection

A collection of time-aligned text files for testing is starting to emerge.

Text files for video/audio in different formats are available from: http://svn.annodex.net/itext/elephants_dream/ and http://svn.annodex.net/itext/chocolate_rain/

These include:

34 srt files for captions/subtitles in 34 different languages for “Elephants Dream” Blender Foundation movie – these are good for tests of srt support and different charactersets (i18n)
1 srt file and audio recording of audio description in English for “Elephants Dream” – these are good to test audio descriptions for the blind in two different formats
1 srt file for chapter markers for “Elephants Dream” – this tests sectioning and direct access to chapters
1 lrc and 1 qttext file for lyrics for “Chocolate Rain” video and music file CC-licensed by Tay Zonday – this tests different file formats for text annotations and support of accessibility for audio

Further accessibility-related files have been added (Nov 09):

all 34 srt files have been converted to utf-8 for use with Kate
a script has been added to create Ogg Kate files and merge them with Ogg Video files - the binary files are not in the repository
1 audio description file which can also be added to a Ogg video file using oggz-merge
added 1 subtitle file in SAMI Microsoft Synchronized Accessible Media Interchange format subtitle file and one in Substation2 format, thanks to Guillaume Olivrin
added 1 sign language file in South African Sign Language provided by Nare Mmonwa

Further accessibility-related files have been added (Feb '10):

1 DFXP W3C Timed Text format subtitle file

Specifications: associating external text

Specifications for how to associate out-of-band time-aligned text with a HTML5 video (and audio) tag as well as how to parse multitrack media files and expose the same attributes, DOM API and JavaScript API are in the making.

an initial specification for out-of-band time-aligned text files for HTML5 video is available from https://wiki.mozilla.org/Accessibility/HTML5_captions
initial discussions have been had on the mailing lists of the following communities: W3C HTML WG, WHATWG, W3C WAI-XTECH, Free ARIA community, Xiph accessibility
Feedback and discussions are collected at https://wiki.mozilla.org/Accessibility/Experiment1_feedback

Update Nov09:

an second specification for out-of-band time-aligned text files for HTML5 video is available from https://wiki.mozilla.org/Accessibility/HTML5_captions_v2, with a main change being the introduction of a structuring element itextlist
Feedback and discussions are collected at https://wiki.mozilla.org/Accessibility/Experiment2_feedback

Update Feb10:

a specification that was created from a discussion in the W3C Accessibility Task Force is available from: http://www.w3.org/WAI/PF/HTML/wiki/Media_TextAssociations
discussions about standard formats tend towards: SRT and DFXP

Specifications: JavaScript API for multitrack media

Update Feb10:

a specification that was created from a discussion in the W3C Accessibility Task Force is available from: http://www.w3.org/WAI/PF/HTML/wiki/Media_MultitrackAPI

Demo implementations using javascript

A collection of JavaScript implementations for associating time-aligned text with audio/video is starting to emerge.

There are demos at http://www.annodex.net/~silvia/itext/ - their open source code is available from http://svn.annodex.net/itext/.

The demos consist of the following:

"Elephants Dream" with subtitles and captions, chapter markers, and textual audio annotations for screen readers
"Elephants Dream" with a different video player skin to test video player controls accessibility
"Chocolate Rain" as video with subtitles and as audio with lyrics
"Elephants Dream" with a demonstration of how to directly jump to time offsets in videos through URL changes

Update Nov09:

"Elephants Dream" following the second itext specification is available at http://www.annodex.net/~silvia/itext/elephant_no_skin_v2.html

Related open bugs in Mozilla

The following bugs relate to video and audio accessibility at Mozilla:

"Support for Kate overlay streams in video tag" https://bugzilla.mozilla.org/show_bug.cgi?id=481529
"Implement UI for subtitles on html5 video/audio" https://bugzilla.mozilla.org/show_bug.cgi?id=515898
"Ogg Theora video with two audio tracks fails to play" https://bugzilla.mozilla.org/show_bug.cgi?id=516323

Related open bugs in W3C HTML WG

http://www.w3.org/Bugs/Public/show_bug.cgi?id=8659

http://www.w3.org/Bugs/Public/show_bug.cgi?id=5758

Publications

Silvia posted the following blog posts relating to video accessibility:

“First experiments with itext”

http://blog.gingertech.net/2009/07/29/first-experiments-with-itext/

“The different aspects of video accessibility”

http://blog.gingertech.net/2009/08/03/aspects-of-video-accessibility/

“ARIA – A Brief Introduction”

http://blog.gingertech.net/2009/08/21/aria-a-brief-introduction/

“Updated video accessibility demo”

http://blog.gingertech.net/2009/09/14/updated-video-accessibility-demo/

“Open Standards for Sign Languages”

http://blog.gingertech.net/2009/09/16/open-standards-sign-language/

“HTML5 audio element accessibility”

http://blog.gingertech.net/2009/09/16/html5-audio-element-accessibility/

New in Nov09:

"New proposal for captions and other timed text for HTML5"

http://blog.gingertech.net/2009/10/06/new-proposal-for-captions-and-other-timed-text-for-html5/

"Dealing with multi-track video (and audio)"

http://blog.gingertech.net/2009/10/17/dealing-with-multi-track-video-and-audio/

"The model of a time-linear media resource for HTML5"

http://blog.gingertech.net/2009/11/23/model-of-a-time-linear-media-resource/

"Manifests for exposing the structure of a Composite Media Resource"

http://blog.gingertech.net/2009/11/25/manifests-exposing-structure-of-a-composite-media-resource/

Also the following relate to media fragment addressing, which will enable a deeper interaction with audio and video and thus improve accessibility as well: