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XR Device API Accessibility Review

From: Janina Sajka <janina@rednote.net>
Date: Tue, 3 Sep 2019 15:08:51 -0400
To: public-immersive-web-wg@w3.org
Cc: Ada Rose Cannon <ada@ada.is>, W3C WAI Accessible Platform Architectures <public-apa@w3.org>, public-rqtf@w3.org
Message-ID: <20190903190851.GN2297@rednote.net>

Thank you for requesting our review of your XR Device API from an
accessibility perspective:[1]


Our response today is based on a close reading of this specification by
two APA members[2] and a subsequent discussion of their findings during
a regularly scheduled APA teleconference.[3]

We have found no explicit accessibility problems in this specification,
so we have no objection to it moving forward toward W3C recommendation
status as currently specified.

However, our review has raised a series of questions and concerns, and
we will now look for opportunities to engage with you to establish a
fuller understanding of accessibility opportunities and challenges in XR
technology, as well as greater support for accessibility use cases in
future revisions of your specifications. A significant concern for us is
the question of how semantically rich representations of XR are to be
provided? Semantic constructs are critical to supporting accessibility.

APA wishes to acknowledge our great interest in the emerging XR
technology.  Toward that end an initial  request for a joint meeting
during TPAC was forwarded last week.[4] We hope some of you can join our
discussions. We are also happy to see the announcement of a W3C Workshop
on "Inclusive Design for Immersive Web."[5]

We look forward to working with you more directly as XR matures.

Janina Sajka, Chair
Accessible Platform Architectures (APA)

[1] http://lists.w3.org/Archives/Public/public-apa/2019Jul/0012.html
[2] http://lists.w3.org/Archives/Public/public-apa/2019Jul/0051.html
[3] https://www.w3.org/2019/08/28-apa-minutes.html#item04
[4] http://lists.w3.org/Archives/Public/public-apa/2019Aug/0084.html
[5] http://lists.w3.org/Archives/Public/public-apa/2019Aug/0067.html


Janina Sajka

Linux Foundation Fellow
Executive Chair, Accessibility Workgroup:	http://a11y.org

The World Wide Web Consortium (W3C), Web Accessibility Initiative (WAI)
Chair, Accessible Platform Architectures	http://www.w3.org/wai/apa

   Here is my proposed feedback to the Timed Text Working Group:


    1. While we appreciate that [1]TTML Profiles for Internet Media
       Subtitles and Captions 1.1 is depending on [2]Timed Text Markup
       Language 2 (TTML2), it should still include an introduction that
       guides the reader to a better understanding of its content.  Such
       an introduction could respond to the following questions:

    a. Why are profiles needed for text-only and image-only
    b. What are typical use cases for a image-only captions/subtitles?
    c. What is the purpose of a presentation processor, and a
       transformation processor?

    2. There is a general issue with the way that an author specifies
       layout characteristics of captions and subtitles, such as font
       size, font family, line height, background and positioning.  The
       spec describes the approach of the author specifying a “fixed
       layout” for captions and subtitles that the user cannot change.
       However, it must be possible for the user to overwrite the author’s
       choice of font size, or background color, for example. This is
       necessary for accessibility reasons, in the same way that browsers
       allow the user to change font size and background color.  How can
       we find a good solution for these conflicting interests between
       author and user?  We would like to get into a discussion with you
       on this issue.

    3. Section 2 Documentation Conventions (applies also to [3]Timed Text
       Markup Language 2 (TTML2) section 2.3). For accessibility of the
       spec, information such as whether an element is deprecated or
       obsoleted should not be indicated by color (or background color)
       alone (cf. [4]WCAG 2.0 SC 1.4.1).

    4. Section 5.1 General. The method of associating a text profile
       document instance with an image profile document instance should be
       specified for interoperability reasons, and not be left open to the
       specific implementation.  Also, the association should be in both
       ways, i.e. also from the image profile document instance to the
       text profile document instance.

    5. Section 6 Supported Features and Extensions. All font-related
       features are prohibited for the image profile. This seems to be an
       unnecessary restriction if the image profile contains images in SVG
       format which could be rendered differently based on the author’s
       choice of font characteristics.

    6. Section 7.7.3 itts:forcedDisplay. This seems like a temporary
       solution. Wouldn’t it be better to define semantic layers of
       information that each could be made visible and invisible at
       runtime as appropriate for the user?  For example, the user may
       want to see either speech-only (subtitles), narration speech only
       (parts of subtitles), foreign-language speech-only (parts of
       subtitles) or any combination of them.

    7. Section 7.7.4 itts:altText.  While we see this feature as useful
       for accessibility purposes, it should be mandatory for images
       rather than recommended only. As mentioned in the spec, one could
       take the pertaining text passage from the text profile document
       instance – but (1) an accompanying text profile is not required,
       and (2) the alternative text for the image could be different from
       the textual caption. Therefore, the itts:altText element should
       always be specified, but it should be empty for decorative images
       (not clear if a “decorative image” used as a caption makes sense
       anyway). By requiring an itts:altText for every image, but allowing
       for an empty element in case of a decorative image, we would align
       it with the alt attribute in HTML5 for images.


   Best regards,


   -----Ursprüngliche Nachricht-----
   Von: Accessible Platform Architectures Working Group Issue Tracker
   Gesendet: Mittwoch, 18. Oktober 2017 09:29
   An: public-apa@w3.org
   Betreff: apa-ACTION-2152: Review ttml profiles for internet media
   subtitles and captions 1.1 https://www.w3.org/tr/ttml-imsc1.1/

   apa-ACTION-2152: Review ttml profiles for internet media subtitles and
   captions 1.1 [5]https://www.w3.org/tr/ttml-imsc1.1/


   Assigned to: Gottfried Zimmermann


   1. https://www.w3.org/TR/ttml-imsc1.1/
   2. https://www.w3.org/TR/ttml2/
   3. https://www.w3.org/TR/ttml2/
   4. https://www.w3.org/WAI/WCAG20/quickref/#visual-audio-contrast-without-color
   5. https://www.w3.org/tr/ttml-imsc1.1/
   6. http://www.w3.org/WAI/APA/track/actions/2152


Janina Sajka

Linux Foundation Fellow
Executive Chair, Accessibility Workgroup:	http://a11y.org

The World Wide Web Consortium (W3C), Web Accessibility Initiative (WAI)
Chair, Accessible Platform Architectures	http://www.w3.org/wai/apa
Received on Tuesday, 3 September 2019 19:09:18 UTC

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