RE: apa-ACTION-2224: Review ttml profiles for internet media subtitles and captions 1.2 https://www.w3.org/tr/ttml-imsc1.2/

I have had a look at TTML Profiles for Internet Media Subtitles and Captions 1.2 - W3C First Public Working Draft 28 November 2019 <https://www.w3.org/TR/2019/WD-ttml-imsc1.2-20191128/> , based in my previous review from 2017-11-14 <https://lists.w3.org/Archives/Public/public-apa/2017Nov/0008.html> , and on the summary of substantive changes <https://www.w3.org/TR/2019/WD-ttml-imsc1.2-20191128/#substantive-changes-summary> .

 

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

 

<draft-feedback>

 

(1)    Reference to WCAG 2.1.  We appreciate the addition of section D.1 WCAG Considerations <https://www.w3.org/TR/2019/WD-ttml-imsc1.2-20191128/#wcag-applications>  and its content.  Here, we would like to see references to other WCAG 2.1 success criteria that are applicable to the TTML profiles specification, such as:

a.       Success Criterion 1.4.3 Contrast (Minimum) <https://www.w3.org/TR/2018/REC-WCAG21-20180605/#contrast-minimum> 

b.       Success Criterion 1.4.4 Resize text <https://www.w3.org/TR/2018/REC-WCAG21-20180605/#resize-text> 

c.       Success Criterion 1.4.11 Non-text Contrast <https://www.w3.org/TR/2018/REC-WCAG21-20180605/#non-text-contrast> 

d.       Success Criterion 3.1.1 Language of Page <https://www.w3.org/TR/2018/REC-WCAG21-20180605/#language-of-page> 

e.       Success Criterion 3.1.2 Language of Parts <https://www.w3.org/TR/2018/REC-WCAG21-20180605/#language-of-parts> 

 

(2)    7.12.2 altText named metadata item <https://www.w3.org/TR/2019/WD-ttml-imsc1.2-20191128/#altText> . This is directly related to the accessibility requirement of having an alternate text version for images (Success Criterion 1.1.1 Non-text Content <https://www.w3.org/TR/2018/REC-WCAG21-20180605/#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 altText named metadata item. This is necessary for making the document accessible to persons with (visual) disabilities, thus complying with WCAG 2.1 success criterion 1.1.1 (Non-text content) <https://www.w3.org/TR/2018/REC-WCAG21-20180605/#non-text-content> .”

 

(3)    Introduction for first-time readers. The document would be easier to read for first-time readers if it had 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 captions/subtitles?

b.       What are typical use cases for image-only captions/subtitles?

 

(4)    We are still not happy with the relation between author-specified formatting and user-specified formatting (if possible at all). 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.  We would like to get into a discussion with you on this issue. 

 

(5)    Section C. Forced content <https://www.w3.org/TR/2019/WD-ttml-imsc1.2-20191128/#forced-content> . 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. 

 

</draft-feedback>

 

Best regards,

Gottfried 

 

 

-----Ursprüngliche Nachricht-----
Von: Accessible Platform Architectures Working Group Issue Tracker [mailto:sysbot+tracker@w3.org] 
Gesendet: Mittwoch, 4. Dezember 2019 18:45
An: public-apa@w3.org
Betreff: apa-ACTION-2224: Review ttml profiles for internet media subtitles and captions 1.2 https://www.w3.org/tr/ttml-imsc1.2/

 

apa-ACTION-2224: Review ttml profiles for internet media subtitles and captions 1.2  <https://www.w3.org/tr/ttml-imsc1.2/> https://www.w3.org/tr/ttml-imsc1.2/

 

 <https://www.w3.org/WAI/APA/track/actions/2224> https://www.w3.org/WAI/APA/track/actions/2224

 

Assigned to: Gottfried Zimmermann