Re: 48-Hour Call for Consensus (CfC): Comments on WebVTT--Quick Responses Needed

Thanks, Gottfried.

Screen readers can catch a lot of spelling errors--and I had caught
another. But this one slipped by!

Janina

Gottfried Zimmermann writes:
> +1
> 
> I found just one typo: At the end of item #2: "APA would be please to
> assist..." is missing a final 'd' on 'please'.
> 
> Best regards,
> Gottfried 
> 
> -----Ursprüngliche Nachricht-----
> Von: Janina Sajka [mailto:janina@rednote.net] 
> Gesendet: Donnerstag, 25. Januar 2018 22:17
> An: Accessible Platform Architectures Administration
> <public-apa-admin@w3.org>
> Betreff: 48-Hour Call for Consensus (CfC): Comments on WebVTT--Quick
> Responses Needed
> 
> Colleagues:
> 
> This is a Call for Consensus (CfC) to the Accessible Platform Architectures
> (APA) Working Group on our review of the WebVTT specification as requested
> at:
> 
> https://lists.w3.org/Archives/Member/w3c-archive/2017Dec/0107.html
> 
> Please note these are comments following on work in response to PF-WB
> comments from 2015.
> 
> Please note also that the draft comments below cover some similar issues
> present in our current CfC on TTML Profiles:
> 
> http://lists.w3.org/Archives/Public/public-apa-admin/2018Jan/0000.html
>  
> 
> <Begin draft comments>
> 
> *Item #1 Users of Magnification:*
> 
> The bug-tracker indicates the following response(s):
> 
>   * Snap to flag (assumption: snap-to-lines flag)
> 
>      -> Concern: the concern is likely that if text is explicitly positioned
> on certain lines, there is potential that enlarging the text may lead to
> text growing outside the rendering area (e.g. text positioned in the
> top-most line), or successive lines may grow into each other.
> 
>      -> Reply: First we have to understand that when content is enlarged,
> the video is typically enlarged together with the text. Therefore, the
> occurrance of this problem is rare. Secondly, there is a conflict between
> authoring requirements and rendering limitations. The browser rendering
> algorithm will [adjust?] as well as it can, but once text breaks out of the
> video rendering boundaries, there is not much it can do.
> 
>      -> APA Response: APA recognizes the technical constraints noted here
> with regard to rendering limitations. Authoring Guidance recommendations
> should nonetheless indicate the potential of this problem, and urge content
> authors to strive to have captions (etc.) be no greater than 50% of the
> default width of the viewport (which would allow for a text increase of
> roughly 200% without clipping). APA notes that for low-vision users, even at
> full-screen, those users may still need to enlarge the caption text to meet
> their reading needs.
> 
> 
>   * Sizing of the captions rendering area
> 
>      -> Concern: the concern is likely that the display area of captions is
> limited to the background area of the video element it is rendered onto and
> that with magnification the captions may go outside this rendering area.
> 
>      -> Reply: The area outside the video element is no usable to render
> captions onto (think about full-screen mode, or if the video is on a Web
> page there is other content around the video element). Therefore, after
> having done all it can to try and retain visibility of all caption text, the
> browser will hit the limit of what it can do.
> 
>      -> APA Response: APA again recognizes the technical constraints noted
> here with regard to rendering limitations. We once again recommend good
> authoring guidance to ensure that content authors are aware of the potential
> issue raised, so that authoring decisions regarding line-lengths and amount
> of caption text rendered on screen at any single instance can be made with
> this knowledge.
> 
> 
>   * Visibility of captions when text is zoomed
> 
>      -> Concern: the concern is likely about what happens when the text is
> zoomed, but the video isn't.
> 
>      -> Reply: If there are tools that do this, then you will hit the issues
> of overlapping text and disappearing text when hitting the boundaries of the
> rendering area faster than normal. However, it is unlikely that a tool would
> exist that zooms just the text and not the video element on screen.
> Normally, all content on a Web page is zoomed when magnification or zooming
> tools are in use.
> 
>      -> APA Response: It was APA's understanding that one of the benefits of
> WebVTT was that it could be further styled by the content author using CSS.
> User stylesheets today provide the ability for users to modify and enlarge
> onscreen text, and tools and browser extensions exist today to accomplish
> this task.
> 
> The presumption that video content would be zoomed to the same level of
> caption text is, from APA's perspective, unfounded and incorrect, and the
> emergent WCAG 2.1 specifically will have a new Success Criteria (Success
> Criterion 1.4.12 Text spacing -
> http://rawgit.com/w3c/wcag21/master/guidelines/index.html#text-spacing)
> which currently notes that caption files (when supplied as stand-alone
> time-stamped documents) are covered by this SC. Please also see:
> https://rawgit.com/w3c/wcag21/text-spacing/understanding/21/text-spacing.htm
> l
> 
> > Normally, all content on a Web page is zoomed when magnification or
> zooming tools are in use.
> 
> Respectfully, this is factually incorrect. Browser-based zoom traditionally
> operates like this, however other Assistive Technology tools may only zoom a
> part of the whole web page, or may only apply zoom to text (and/but not
> imagery). Some user-agents and platforms also allow for end-user font
> magnification (for example, on the Android platform, individual users can
> choose from different default font sizes, that are applied to all on-screen
> content.
> 
> APA again recognizes the technical limitations noted here with regard to
> rendering limitations, and strongly recommends that appropriate authoring
> guidance to address all 3 related issues noted here be included (directly)
> in the Recommendation.
> 
> ----------
> 
> *Item #2: The spec should include feature explanations in plain language*
> 
>      -> Reply: no change, we rely on external documents to provide an
> authoring guide.
> 
>      -> APA Response: There are actually 2 responses here.
> 
> The first is related to an on-going request from APA that W3C Technical
> Recommendations also include, when and where necessary, prose summaries in
> "plain english" that explain features and functions of the various parts of
> any given spec. The intent here is to explain what is happening with the
> technology in lay terms, rather than explain how to create content using the
> technology. (i.e.: don't just show an API [sic], explain it.) This remains
> an important request from APA, but is not a blocking issue.
> 
> The second response is related to Authoring Guidance documents (referenced
> in your reply). Following up on the Bug Tracker, it shows a link to an
> authoring guidance document (
> https://docs.webplatform.org/wiki/concepts/VTT_Captioning), yet that URL
> returns a 404 today.
> 
>    - Has this document been relocated elsewhere? If yes, can we please have
>    the reference URL. If no, does the WG plan on updating/recreating this
>    document? (This also ties-back to Item #1)
> 
>    - The current WebVTT Working Draft (https://www.w3.org/TR/webvtt1)
>    currently has 'editorial guidance' as part of the normative specification
>    addressing privacy and security, and APA's request is that editorial
>    guidance for accessibility considerations also be provided in the same
>    fashion (i.e. directly in the Rec, as opposed to linking out.)
> 
> 
> APA would be please to assist in the review of any authoring guidance that
> emerges from the WebVTT WG.
> 
> ----------
> 
> *Item #3: Captions on the audio element*
> 
>      -> Reply: fixed, explanations added.
> 
>      -> APA Response: Thank you.
> 
> 
> 
> APA trusts this meets your request, and we are happy to further elaborate on
> any of these issues as required.
> 
> <End Draft Comments>
> 
> *       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, Monday 29 January.
> 
> APA Tracking Notes
> 
> These comments reiterate requirements published in the W3C Note: Media
> Accessibility User Requirements (MAUR):
> http://www.w3.org/TR/media-accessibility-reqs/#captioning
> 
> Inasmuch as similar comments to TTML have been Under an APA CfC, that TTML
> CfC will now be extended to expire with this CfC:
> http://lists.w3.org/Archives/Public/public-apa-admin/2018Jan/0000.html
> 
> The WebVTT comments in this CfC were drafted for APA by John Foliot and are
> in sync with our TTML comments referenced above:
> http://www.w3.org/WAI/APA/track/actions/2162
> 
> Further APA discussion is logged at:
> http://www.w3.org/2018/01/24-apa-minutes.html#item05
> 
> Janina
> 
> 
> ----------------------------------------------------------------------------
> --
> 
> 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 Friday, 26 January 2018 13:02:15 UTC