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Re: 48-Hour Call for Consensus (CfC): Proposed TTML Comments

From: Janina Sajka (janina@rednote.net) <(janina@rednote.net)>
Date: Tue, 25 Feb 2020 17:07:14 -0500
To: public-apa-admin@w3.org
Message-ID: <20200225220714.GA2403@rednote.net>

Janina Sajka writes:
> Colleagues:
> This is a Call for Consensus (CfC) to the Accessible Platform
> Architectures (APA) Working Group proposing the following review
> response on:
> ttml profiles for internet media subtitles and = captions 1.2  
> https://www.w3.org/tr/ttml-imsc1.2/
> This draft response was first posted to APA on 22 January last at:
> https://lists.w3.org/Archives/Public/public-apa/2020Jan/0022.html
> It's language has been tweaked by yours truly.
> <begin draft comment>
> 1.)    Reference to WCAG 2.1:  
> We appreciate the addition of section
> <https://www.w3.org/TR/2019/WD-ttml-imsc1.2-20191128/#wcag-applications> D.1
> WCAG Considerations and its content.  This is very helpful.  We would, though,
> like to change the phrasing "WCAG 2.1 recommends" to "WCAG 2.1 requires",
> because the WCAG success criteria are normative requirements rather than
> recommendations. 
> 2.)    Requested Additional WCAG 2.1 References:  
> In addition to the guidelines and success criteria you already reference, we
> would like to see references to the following WCAG 2.1 success criteria that are
> also applicable to the TTML profiles specification:
> 	a.        <https://www.w3.org/TR/2018/REC-WCAG21-20180605/#contrast-minimum> Success Criterion 1.4.3 Contrast (Minimum) (applying to the text-only profile)
> 	b.        <https://www.w3.org/TR/2018/REC-WCAG21-20180605/#non-text-contrast> Success Criterion 1.4.11 Non-text Contrast (applying to the image-only profile)
> 	c.        <https://www.w3.org/TR/2018/REC-WCAG21-20180605/#language-of-page> Success Criterion 3.1.1 Language of Page (using the xml:lang attribute)
> 	d.        <https://www.w3.org/TR/2018/REC-WCAG21-20180605/#language-of-parts> Success Criterion 3.1.2 Language of Parts (using the xml:lang attribute)
> 3.)    Reference to MAUR:  We also appreciate the addition of section D.2 MAUR
> Considerations
> <https://www.w3.org/TR/2019/WD-ttml-imsc1.2-20191128/#maur-applications>.
> Thank you. We trust the MAUR will continue helpful to the wider community.
> 4.)     With respect to the
> <https://www.w3.org/TR/2019/WD-ttml-imsc1.2-20191128/#altText> 7.12.2 altText
> named metadata item, this is directly related to the accessibility requirement
> of having an alternate text version for images (<https://www.w3.org/TR/2018/REC-WCAG21-20180605/#non-text-content> Success Criterion 1.1.1
> Non-text Content). Could you add a note here saying something like: "Note:
> Authors are encouraged to provide text alternatives for every non-decorative
> image and/or compound image set by using the altText named metadata item. This is
> necessary for making the image in the document accessible to persons with (visual)
> disabilities, thus complying with
> <https://www.w3.org/TR/2018/REC-WCAG21-20180605/#non-text-content> W CAG
> 2.1 success criterion 1.1.1 (Non-text content)."
> 5.)    Suggested Introduction Section for First-Time Readers: The document
> would be easier to read and understand for first-time readers if it had an
> introduction that guided the reader to a better understanding of its content.
> Such an introduction could serve to introduce the reader to items such as the
> following:
> 	a.       Why are profiles needed for text-only and image-only captions/subtitles?
> 	b.       What are typical use cases for image-only captions/subtitles?
> 6.)    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.  It should be made clear that authors
> can and should define the viewport and text characteristics, but these
> definitions may be overridden by the user by setting up their user agent to
> better meet their particular needs as users (cf. MAUR, 3.7 Requirements on the
> use of the viewport
> <https://www.w3.org/TR/2015/NOTE-media-accessibility-reqs-20151203/#requirements-on-the-use-of-the-viewport>).
> For example, a user with vision impairment who also requires caption support
> may want to have all captions displayed in the lower third of the screen with
> a large font, disregarding the definition of various viewports and font types
> defined by the author.  We recommend adding a note to the spec to advise
> authors that  the final rendition of their document may not follow their
> specified styling and positioning, but follow user-defined styling and
> positioning instead.
> 7.)     <https://www.w3.org/TR/2019/WD-ttml-imsc1.2-20191128/#forced-content>
> Section C. Forced content: This seems like a temporary solution to us.
> Mightn't it be better to define semantic layers of information so that each
> layer could be made visible and invisible at runtime as appropriate for the
> user?  For example, the user might want to see either speech-only (subtitles),
> narration speech only (parts of subtitles), foreign-language speech-only
> (parts of subtitles) or some combination of these.
> </draft-comment>
> ***Action to Take***
> This CfC is now open for objection, comment, as well as statements of
> support via email. Silence will be interpreted as support, though
> messages of support are certainly welcome.
> If you object to this proposed action, or have comments concerning this
> proposal, please respond by replying on list to this message no later
> than 23:59 (Midnight) Boston Time, Tuesday 25 February.
> NOTE: This Call for Consensus is being conducted in accordance with the
> APA Decision Policy published at:
> http://www.w3.org/WAI/APA/decision-policy
> Our thanks to Dr. Gottfried Zimmerman for reviewing the TTML
> specification and providing us with his recommended response above as
> logged in.  Action-2224<https://www.w3.org/WAI/APA/track/actions/2224>.
> -- 
> 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


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, 25 February 2020 22:07:28 UTC

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