RE: does anyone currently fail colour contrast for text in timed media from Jonathan Avila on 2017-02-08 (w3c-wai-gl@w3.org from January to March 2017)

From: Jonathan Avila <jon.avila@ssbbartgroup.com>
Date: Wed, 8 Feb 2017 19:22:14 +0000
To: GLWAI Guidelines WG org <w3c-wai-gl@w3.org>
Message-ID: <DM5PR03MB27806FBF26C46A018905DD039B420@DM5PR03MB2780.namprd03.prod.outlook.com>
After the CVAA was passed in the US many user agents and media players added the ability to control caption fonts colors, and other display properties to conform with requirements for hardware and content owners.

https://www.law.cornell.edu/cfr/text/47/79.103


Jonathan

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From: John Foliot [mailto:john.foliot@deque.com]
Sent: Wednesday, February 08, 2017 2:15 PM
To: Gregg C Vanderheiden
Cc: Detlev Fischer; GLWAI Guidelines WG org; Jonathan Avila
Subject: Re: does anyone currently fail colour contrast for text in timed media

TL; DR:

The WebVTT specification allows for both CSS styling and positioning of Closed Captions and their bounding box, and can be manipulated by the author (in theory - unsure of practice)

*****

Gregg wrote:

> But most captions are closed captions — which means that they are generated by the player - outside of the control of the author  (e.g. the presentation is a function of the user agent) - and users can choose to have captions be large or small, with background or without.

Uhm... sorta.

One of the goals behind the creation of WebVTT (as opposed to TTML) was that, because it was more HTML-syntax-like than TTML (which uses an XML-based syntax), that it could be "styled" using CSS - at least that is the intent. See: https://w3c.github.io/webvtt/#styling


(Note: while this is part of the current WebVTT spec, I am unaware of any browser support, and more importantly, I've never seen an example of this, although I've been keeping my eye open for one. If anyone has ever seen this, can you ping me off-list please? Thanks)


When we worked on the MAUR (Media Accessibility User Requirements<https://www.w3.org/TR/media-accessibility-reqs/>) we captured this under a number of different requirements:

  *   [CC-9] Permit a range of font faces and sizes.
  *   [CC-10] Render a background in a range of colors, supporting a full range of opacity levels.
  *   [CC-11] Render text in a range of colors. The user should have final control over rendering styles like color and fonts; e.g., through user preferences.

...so there *ARE* some author requirements there, although, again it is early days and I've never seen an example of this.

Gregg also commented on the positioning of the captions bounding box (and it concealing part of the scene) - again, we've articulated the NEED for this to be adjustable even if we do not have current examples to illustrate this, although, again, WebVTT allows for positioning (https://w3c.github.io/webvtt/#regions).

  *   [CC-5] Support positioning in all parts of the screen - either inside the media viewport but also possibly in a determined space next to the media viewport. This is particularly important when multiple captions are on screen at the same time and relate to different speakers, or when in-picture text is avoided.
  *   (Related) [CC-14] Allow the use of mixed display styles— e.g., mixing paint-on captions with pop-on captions— within a single caption cue or in the caption stream as a whole. Pop-on captions are usually one or two lines of captions that appear on screen and remain visible for one to several seconds before they disappear. Paint-on captions are individual characters that are "painted on" from left to right, not popped onto the screen all at once, and usually are verbatim. Another often-used caption style in live captioning is roll-up - here, cue text follows double chevrons ("greater than" symbols), and is used to identify different speakers. Each sentence "rolls up" to about three lines. The top line of the three disappears as a new bottom line is added, allowing the continuous rolling up of new lines of captions. When displaying captions using the paint-on style, it is important to ensure that the final words that are displayed are visible for enough time for them to be read.
  *   (Related) [CC-15] Support positioning such that the edge of the captions is a sufficient distance from the nearest screen edge to permit readability (e.g., at least 1/12 of the total screen height above the bottom of the screen, when rendered as text in a right-to-left or left-to-right language).

HTH

JF


On Wed, Feb 8, 2017 at 12:11 PM, Gregg C Vanderheiden <greggvan@umd.edu<mailto:greggvan@umd.edu>> wrote:
Just some thoughts.


  *   if they are open captions — then mandating contrast mandates that captions be of the kind that have a block of solid color behind the text, hiding the scene - since there is no way to really control the background otherwise.    This is not the preferred captioning for most people because it blocks the scene.
  *   But most captions are closed captions — which means that they are generated by the player - outside of the control of the author  (e.g. the presentation is a function of the user agent) - and users can choose to have captions be large or small, with background or without.
  *   What is not clear to me is what control the page author has of the viewer that will be used.

     *   how much control does the author have over which viewer is used — and the features of the viewer?

        *   types of caption features  (background/transparent, size, color, position, etc)

     *   what about the content viewed on different platforms with different viewers?
     *   how much can we require authors to use particular viewers with particular capabilities



Gregg C Vanderheiden
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On Feb 8, 2017, at 3:51 AM, Detlev Fischer <detlev.fischer@testkreis.de<mailto:detlev.fischer@testkreis.de>> wrote:

I can't see why poor contrast of captions should not fail SC 1.4.3. Why just advisory? Captions are clearly a form of text, and screenshots can provide clear evidence of failure.
In audits I frequently see white caption text on transparent grey background which means contrast is FAR below 4.5:1 whenever the video background happens to be bright.
Detlev

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Jonathan Avila schrieb am 07.02.2017 18:14:



David, I have not failed videos with insufficient contrast.  However, that situation and open captions with poor contrast are something I would point out as advisory or best practice.



Jonathan



From: David MacDonald [mailto:david100@sympatico.ca]
Sent: Tuesday, February 07, 2017 6:50 AM
To: Glenda Sims; Gregg C Vanderheiden; Jonathan Avila
Cc: Aparna Pasi; WCAG
Subject: Re: does anyone currently fail colour contrast for text in timed media




Thanks Glenda





Hey Gregg, I'll loop you in.





Yes, I agree audio description (or transcript) should reflect important visual information including text, but I'm thinking about 1.4.3 Colour contrast of text in movies ... In this case it's yellow text on the whiteboard in an animated movie.





Here's my take.





1.4.3 applies to "images of text" which have been "rendered in a non-text form *in order to achieve a particular effect* ..."





So the glossary is assigning an intention to the creation of the text. The author put it in an image because she wanted it in a special font, or a special position in relation to a background which might have been hard to do with CSS etc... This is not the case for a movie. Authors rarely make movies with the intention of achieving a particular text effect.





I haven't been watching movies looking for colour contrast failures of significant text. I was wondering if any others (Glenda, Jon, John, Gregg, etc.) would agree.


Cheers,
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On Mon, Feb 6, 2017 at 11:50 PM, Glenda Sims <glenda.sims@deque.com<mailto:glenda.sims@deque.com> <mailto:glenda.sims@deque.com> > wrote:


Hey David,





Looking at the glossary term for "image of text" leads me to believe that I'd need to watch the video to know for sure.  If the text on the blackboard is significant and there is not audio reference to it....then, I think I would fail it under 1.2.5 Audio Description (Prerecorded)



image of text


text that has been rendered in a non-text form (e.g., an image) in order to achieve a particular visual effect


Note: This does not include text <http://www.w3.org/TR/2008/REC-WCAG20-20081211/#textdef>  that is part of a picture that contains significant other visual content.


Example: A person's name on a nametag in a photograph.

Cheers,


G


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On Mon, Feb 6, 2017 at 10:24 PM, Aparna Pasi <aparna.pasi@deque.com<mailto:aparna.pasi@deque.com> <mailto:aparna.pasi@deque.com> > wrote:


Hey David,


To be honest, I haven't failed video animation or captions as I haven't seen such a scenario.


I believe we should fail them as they are conveying information however, success criteria doesn't include anything about timed media.


Thanks,


Aparna





On Tue, Feb 7, 2017 at 4:30 AM, David MacDonald <david100@sympatico.ca<mailto:david100@sympatico.ca> <mailto:david100@sympatico.ca> > wrote:


For instance a video an animation of someone in front of a blackboard with text on it.





The definition appears to limit the SC to static images...





Thoughts?


Cheers,
David MacDonald



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Received on Wednesday, 8 February 2017 19:22:51 UTC