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RE: Are developers responsible for video full screen mode (Success Criteria 2.3.1)

From: Brian Stevens <bstevens@ilsworld.com>
Date: Fri, 12 May 2017 15:08:10 +0000
To: Gregg C Vanderheiden <greggvan@umd.edu>
CC: IG - WAI Interest Group List list <w3c-wai-ig@w3.org>
Message-ID: <0859D7085D4B4B4DA0CE16F0E65771A76F47428A@mbx024-e1-nj-2.exch024.domain.local>
Hi Gregg,

Thanks! This is helpful, I hadn’t thought of putting a text warning about full screen mode, that would be an easy fix. Could I also disable the full-screen button to address this?

1. Yes, the site does fail for some of the videos when they are at full screen.

2. We have about 200 animated videos and most are 15-60 seconds long, about 2hrs total, so it’s not a single video that fails at full screen. So far I’ve only tested 6 minutes of these videos, but I got 6 errors from PEAT. I was surprised too that they failed, since most problems happened on seemingly benign panning shots. The videos were made 9 years ago using Maya 3D software.
The example in this link got the worst results. Hopefully you can view it:

The first 3 seconds where the camera pans over the fake money is where the Luminance flash warning in PEAT was maxed out.
I would guess that the culprit is the 3D animation over a high contrast pattern with no motion blur and funny frame-rate skipping.

We may be able to test all videos in full screen mode and correct them on a case-by-case basis (for example, use After Effects to add directional blur to the problematic segment of the linked example), but it might be more cost-effective for us to just remove the full-screen button or add the text warning you suggested. Are there any easy fixes to the video you know of?

Originally I was kind of wondering if there’s a difference in where the responsibility falls when it comes to enlargement controls on the user’s operating system, vs. enlargement controls that we offer on the web-site. Because Success Criteria 2.3.2 says it guards against “an unknown amount of magnification or high contrast”, and I’d guess full screen mode is a known amount of magnification, but I’m not 100% clear if the description differentiates the two. So if I could be sure about this distinction, I’d know technically whether we’d be failing Level A, or failing Level AAA, if full screen mode fails for us.

Either way, we will try to do what we think is best for the user, but I was just after clarification.

Thanks again so much for your help!!

Brian Stevens

From: Gregg C Vanderheiden [mailto:greggvan@umd.edu]
Sent: Thursday, May 11, 2017 10:31 PM
To: Brian Stevens <bstevens@ilsworld.com>
Cc: IG - WAI Interest Group List list <w3c-wai-ig@w3.org>
Subject: Re: Are developers responsible for video full screen mode (Success Criteria 2.3.1)

Question 1:  Does your site fail if the image is at Full Screen?     If not — then of course you are ok.

If it DOES fail at full screen — and full screen viewing is an option on your page — then the safe thing to do is to place a warning above the video that says    "CAUTION: When viewed full screen this video may trigger seizures in people who are photosensitive”

[To not put up such a warning is a bit like leaving an open manhole cover without warning barriers -  for people who have photosensitive seizure disorders. ]

There was the famous incident in Japan where a cartoon sent about ~300 children to the hospital.   They then showed the video on the evening news and sent another ~300 to the hospital.

And then there was the London Olympics Promotion video...

Question 2:  If it does fail at full screen - what is it that fails?   The Trace R&D Center Photosensitive Epilepsy Analysis Tool will show you exactly where it fails.    There are a number of things that can be done to a video that fails - so that it will not fail.

But it usually is hard to fail the test - and there are ways to change a video very subtly to fix them.


Gregg C Vanderheiden

On May 11, 2017, at 9:54 PM, Brian Stevens <bstevens@ilsworld.com<mailto:bstevens@ilsworld.com>> wrote:


Some of my company's animated videos fail Success Criteria 2.3.1, but only in the optional full screen mode (as provided automatically with HTML5 video). At the default size, as they are presented, the videos pass.

We're using the Trace Center Photosensitive Epilepsy Analysis Tool ( PEAT ) (Version 1.6). The PEAT User Guide says to "Test out multimedia at the size that it will appear on your web site. E.g., if a video will be presented in a small window rather than a full screen mode, then test it at the smaller size."

I just wanted to be sure, would this mean developers are not responsible for full screen mode for 2.3.1?

The only related documentation in the WCAG I could find that mentions viewing modes is in Technique G176, where it says "Users with lower resolution displays or that enlarge or view their screens closely would have a higher risk depending on the viewing distance. To address the needs of this group, G19: Ensuring that no component of the content flashes more than three times in any 1-second period<https://www.w3.org/TR/2016/NOTE-WCAG20-TECHS-20161007/G19.html> should be used since it is independent of screen resolution or viewing distance."
This is basically almost saying that accommodating unpredictable resizing is covered by Success Criteria 2.3.2 instead, which is Level AAA. Does that include a full screen mode offered by the site itself?

Sorry if I am answering my own questions, I just wanted to know definitively. Thanks!!

Brian Stevens

Received on Friday, 12 May 2017 15:08:47 UTC

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