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.
Test File Collection
A collection of time-aligned text files for testing is starting to emerge.
- 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):
Specifications: associating external text
- 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
- 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
- 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
- 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
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
- "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
Silvia posted the following blog posts relating to video accessibility:
- “First experiments with itext”
- “The different aspects of video accessibility”
- “ARIA – A Brief Introduction”
- “Updated video accessibility demo”
- “Open Standards for Sign Languages”
- “HTML5 audio element accessibility”
New in Nov09:
- "New proposal for captions and other timed text for HTML5"
- "Dealing with multi-track video (and audio)"
- "The model of a time-linear media resource for HTML5"
- "Manifests for exposing the 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”
- “Media Fragment addressing into a live stream”
- “Demo of deep hyperlinking into HTML5 video”
- “URI fragments vs URI queries for media fragment addressing”
Talks given at:
- "WebJam 2009 talk on video accessibility"
- "Web Directions South 2009 talk on HTML5 video"
- "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/