ISSUE-309: Image profile needs to permit text equivalent

Image profile fails WCAG 1.2

Image profile needs to permit text equivalent

State:
CLOSED
Product:
TTML IMSC 1.0
Raised by:
Nigel Megitt
Opened on:
2014-05-21
Description:
IMSC1 Image profile [1] defined in §6 does not permit a text equivalent. If this profile is used to provide captions as an alternative to audio then it will fail the WCAG2 guideline 1.2 [2]. From a practical perspective this would mean that users who can neither see nor hear well can not use tools to translate the content into e.g. Braille.

[1] http://www.w3.org/TR/ttml-imsc1/#image-profile-constraints
[2] http://www.w3.org/TR/2008/REC-WCAG20-20081211/#media-equiv

Some potential ways to solve this:
1. Permit text to be included within the image profile that describes the images.
2. Require or recommend that when image profile captions are provided there should be a text profile caption track available simultaneously.

Related Actions Items:
No related actions
Related emails:
  1. {minutes} TTWG Meeting 24/7/2014 (from nigel.megitt@bbc.co.uk on 2014-07-24)
  2. {agenda} TTWG Meeting 24/7/2014 (from nigel.megitt@bbc.co.uk on 2014-07-23)
  3. Re: Revised ED of IMSC (from pal@sandflow.com on 2014-07-22)
  4. RE: Revised ED of IMSC (from John.Birch@screensystems.tv on 2014-07-22)
  5. Revised ED of IMSC (from pal@sandflow.com on 2014-07-17)
  6. {minutes} TTWG Meeting 17/7/2014 (from nigel.megitt@bbc.co.uk on 2014-07-17)
  7. Revised Editor's Draft of IMSC (from pal@sandflow.com on 2014-07-16)
  8. {agenda} TTWG Meeting 17/7/2014 (from nigel.megitt@bbc.co.uk on 2014-07-16)
  9. Issue-309 "Image profile fails WCAG 1.2" (from nigel.megitt@bbc.co.uk on 2014-07-15)
  10. {minutes} TTWG Meeting 10/7/2014 (from nigel.megitt@bbc.co.uk on 2014-07-10)
  11. {agenda} TTWG Meeting 10/7/2014 (from nigel.megitt@bbc.co.uk on 2014-07-09)
  12. RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from John.Birch@screensystems.tv on 2014-07-07)
  13. RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from John.Birch@screensystems.tv on 2014-06-25)
  14. Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from pal@sandflow.com on 2014-06-24)
  15. Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from John.Birch@screensystems.tv on 2014-06-24)
  16. Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from pal@sandflow.com on 2014-06-23)
  17. Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from John.Birch@screensystems.tv on 2014-06-23)
  18. Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from John.Birch@screensystems.tv on 2014-06-23)
  19. Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from pal@sandflow.com on 2014-06-22)
  20. Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from pal@sandflow.com on 2014-06-20)
  21. RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from John.Birch@screensystems.tv on 2014-06-20)
  22. {minutes} TTWG Meeting 19/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-19)
  23. RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from mdolan@newtbt.com on 2014-06-19)
  24. RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from John.Birch@screensystems.tv on 2014-06-19)
  25. Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-06-19)
  26. RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from John.Birch@screensystems.tv on 2014-06-19)
  27. Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from pal@sandflow.com on 2014-06-18)
  28. RE: {agenda} TTWG Meeting 19/6/2014 (from mdolan@newtbt.com on 2014-06-18)
  29. {agenda} TTWG Meeting 19/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-18)
  30. RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from John.Birch@screensystems.tv on 2014-06-18)
  31. Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from pal@sandflow.com on 2014-06-17)
  32. RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from John.Birch@screensystems.tv on 2014-06-17)
  33. Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from pal@sandflow.com on 2014-06-17)
  34. RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from John.Birch@screensystems.tv on 2014-06-17)
  35. Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from pal@sandflow.com on 2014-06-17)
  36. RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from John.Birch@screensystems.tv on 2014-06-16)
  37. {minutes} TTWG Meeting 12/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-12)
  38. RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from mdolan@newtbt.com on 2014-06-12)
  39. Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-06-12)
  40. RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from mdolan@newtbt.com on 2014-06-12)
  41. Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-06-12)
  42. RE: {agenda} TTWG Meeting 12/6/2014 (from mdolan@newtbt.com on 2014-06-12)
  43. Re: {agenda} TTWG Meeting 12/6/2014 (from pal@sandflow.com on 2014-06-11)
  44. Re: {agenda} TTWG Meeting 12/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-11)
  45. Re: {agenda} TTWG Meeting 12/6/2014 (from pal@sandflow.com on 2014-06-11)
  46. Re: {agenda} TTWG Meeting 12/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-11)
  47. {agenda} TTWG Meeting 12/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-11)
  48. {agenda} TTWG Meeting 29/5/2014 (from nigel.megitt@bbc.co.uk on 2014-05-28)
  49. {minutes} TTWG Meeting 22/5/2014 (from nigel.megitt@bbc.co.uk on 2014-05-22)
  50. RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from John.Birch@screensystems.tv on 2014-05-22)
  51. Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-05-22)
  52. RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from John.Birch@screensystems.tv on 2014-05-22)
  53. RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from mdolan@newtbt.com on 2014-05-21)
  54. {agenda} TTWG Meeting 22/5/2014 (from nigel.megitt@bbc.co.uk on 2014-05-21)
  55. RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from John.Birch@screensystems.tv on 2014-05-21)
  56. Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from glenn@skynav.com on 2014-05-21)
  57. ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0] (from sysbot+tracker@w3.org on 2014-05-21)

Related notes:

Added guidance in https://dvcs.w3.org/hg/ttml/diff/2720fa1fae9c/ttml-ww-profiles/ttml-ww-profiles.source.html

Pierre-Anthony Lemieux, 6 Jun 2014, 23:27:52

The proposed resolution to this is not consistent with the approach taken for forcedDisplay (see also Issue-312). In the latter case it is stated that the two types of content must be provided in the same document. In this case it is stated that the content provider may optionally provide multiple documents.

A simple resolution to this would be to permit text to be included in the image profile.

Nigel Megitt, 12 Jun 2014, 11:05:29

> The proposed resolution to this is not consistent with
> the approach taken for forcedDisplay (see also Issue-312).

Distribution of image- and text-based subtitles/captions is completely unrelated to forcedDisplay.

Industry practice (as captured in the member submission) indicates that keeping image and text subtitles/captions in separate documents is preferable.

Please see [1] for the latest proposal that allows optional alt text to be associated with images.

[1] http://www.w3.org/mid/0981DC6F684DE44FBE8E2602C456E8AB016C0AF63C%2540SS-IP-EXMB-01.screensystems.tv

Pierre-Anthony Lemieux, 12 Jul 2014, 04:37:17

This was discussed at the HTML accessibility media sub-group on 14 July, minutes at [1], with Nigel and Pierre present.

[1] http://www.w3.org/2014/07/14-html-a11y-media-minutes.html

The conclusion was that though alt text may be provided, it is not essential, and it is not a requirement to permit some form of alternate text to images in the specification, as long as there is a known mechanism for providing alternate text based media with appropriate metadata. An analogy was made to different language translations of the same content.

Follow-up actions:
* add a note to describe this scenario (where an accessible text version of image profile content is provided) and how it should be handled, advising content providers what they should do;
* describe what mechanism external to IMSC documents should be present to facilitate this.

Nigel Megitt, 15 Jul 2014, 16:25:37

The schema at [1] was mentioned for metadata to describe the accessibility of the content, and to identify resources related for adaptation of the same content.

[1] http://www.a11ymetadata.org/the-specification/

Nigel Megitt, 16 Jul 2014, 10:39:40

Addressed in https://dvcs.w3.org/hg/ttml/diff/c6af2ff635f9/ttml-ww-profiles/ttml-ww-profiles.source.html

Pierre-Anthony Lemieux, 17 Jul 2014, 04:20:21

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David Singer <singer@apple.com>, Nigel Megitt <nigel.megitt@bbc.co.uk>, Chairs, Thierry Michel <tmichel@w3.org>, Philippe Le Hégaret <plh@w3.org>, Atsushi Shimono <atsushi@w3.org>, Staff Contacts
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