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:

• “Jumping to time offsets in HTML5 video”

http://blog.gingertech.net/2009/08/19/jumping-to-time-offsets-in-videos/

• “Media Fragment addressing into a live stream”

http://blog.gingertech.net/2009/08/26/media-fragment-addressing-into-a-live-stream/

• “Demo of deep hyperlinking into HTML5 video”

http://blog.gingertech.net/2009/09/02/demo-of-deep-hyperlinking-into-html5-video/

• “URI fragments vs URI queries for media fragment addressing”

http://blog.gingertech.net/2009/09/08/uri-fragments-vs-uri-queries-for-media-fragment-addressing/

Talks given at:

• "WebJam 2009 talk on video accessibility"

http://blog.gingertech.net/2009/10/09/webjam-2009-talk-on-video-accessibility/

• "Web Directions South 2009 talk on HTML5 video"

http://blog.gingertech.net/2009/10/09/web-directions-south-2009-talk-on-html5-video/

• "HTML5 Video element discussions at TPAC meetings"

http://blog.gingertech.net/2009/11/16/html5-video-element-discussions-at-tpac-meetings/

• "Tutorial on HTML5 open video at LCA 2010" http://blog.gingertech.net/2010/01/26/tutorial-on-html5-open-video-at-lca-2010/