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Decision on CfC: Proposed TTML Comments

From: Janina Sajka (janina@rednote.net) <(janina@rednote.net)>
Date: Wed, 26 Feb 2020 08:28:33 -0500
To: public-apa-admin@w3.org
Cc: W3C WAI Accessible Platform Architectures <public-apa@w3.org>
Message-ID: <20200226132833.GD2389@rednote.net>

This consensus call has received only messages of support, and one email
with two grammatical corrections. I have edited the below included draft
APA comment with the suggested corrections.

Having received only wide support from APA, this CfC is agreed to as a
consensus APA Decision and will now be appropriately forwarded.

The head of thread for this CfC can be found at:



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

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 the Media Accessibility User Requirements (MAUR)
W3C Note:  We also appreciate the addition of section D.2 MAUR
Thank you. We trust the MAUR will continue to be 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
 	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
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),
(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 Wednesday, 26 February 2020 13:28:49 UTC

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