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Subject: Re: [office] Table Refresh Delay



"Warren Turkal" <turkal@google.com> wrote on 07/18/2008 04:29:01 PM:
>
> Does the MPEG4 spec have a similar restriction? It seems to me that
> allowing quick changes in a video could also cause an epileptic fit.
>

I don't know.  Unfortunately even JTC1/SC34 members are not given free access to other ISO standards.  So short of shelling out $70 to buy a copy, I cannot check.  Ironically, if we did want to make a statement on the safety implications of flickering, we are required to do so according to ISO/IEC Guide 51 "Safety aspects -- Guidelines for their inclusion in standards", but that is not available to us free.  That would cost $63.

But one assumes that there is a risk with  MPEG4 as well.  At the very least you could have a video of an ODF editor doing a table refresh really fast.

In any case, there is some good background here on the general problem:

http://en.wikipedia.org/wiki/Blink_element

http://en.wikipedia.org/wiki/Photosensitive_epilepsy

Sounds like the risky range is 2 Hz - 55 Hz, which should be avoided according to Section 508 of the Rehabilitation Act:

http://www.section508.gov/index.cfm?FuseAction=Content&ID=12#Web

What I'm not sure is whether "flicker" is the same as update, or is "flicker" just a symptom of poor graphics layer, e.g., cannot update text without first blanking it out.  With double-buffering, XOR'ing images, etc., we should have be able to have flicker-free updates if we wanted.  Your mouse doesn't flicker when you move it around your screen, does it?  That is more than 2Hz.

-Rob

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