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Re: Speed on Animated Gifs

From: James Little <james.little@onetel.co.uk>
Date: Wed, 14 May 2003 10:34:05 +0100
Message-ID: <3EC20D8D.702E617C@onetel.co.uk>
To: Charles McCathieNevile <charles@sidar.org>
CC: w3c-wai-ig@w3.org
Thanks for the reply Charles - I'd never heard of SVG, had a quick look and
it's seems very interesting - will be sure to check it out in some more

Are there any 'rules' with Flash as to how fast you can make it?  Do you
have to be able to "pause" the flash (that doesn't seem to be a default
setting - I don't do the flash on the site I work for, however I can't see a
"pause" setting when I rigth click on the live Flash files) ?

As an example, there is some Flash on a site that I go to that displays some
text that says something like :

"Check out this new range" and 2 seconds later it will say "of dvds, cds and
videos" - that seems like a long time, however at the bottom corner of this
flash there is an icon constantly flashing (It's a box, with a label on the
front, the box changes to the same box, but with a different color label,
there are 4 of these).

Would the constant flashing at the bottom mean the site is inaccessible?  Or
is this OK if the user is able to stop the flash?



Charles McCathieNevile wrote:

> There are two issues with animation. The most serious is photo-sensitive
> epilepsy, which means that things which blink in a range between a
> couple of times a second and 50-odd times per second can cause people to
> suffer a seizure - effectively a serious health risk, as well as being a
> very poor customer experience.
> The other issue (which is the one that effects me, for example) is
> distracting people - some people simply cannot read content around a
> flashing image. Fortunately we can now get browsers that will just turn
> the animation off, but if there is something important in it we need to
> see it through first - the text alternative is not typically displayed
> alongside the image in a graphic view. (I know some people like "access
> Bob" use lynx all the time to deal with the problem - I use a mix of
> browsers depending on where i am and what I am doing - most airports
> have IE available but it is harder to find a lynx terminal).
> So my advice is to make it have at most 2 frames per second, and if
> possible go slower. You might also like to consider an animated vector
> format such as flash or SVG (I would only use SVG for lots of reasons,
> but flash can be made to do the job and you can provide
> "(nearly)-equivalent" alternatives for either case). They will give you
> smooth animation, and you can work especially with SVG using lots of
> neat XML tools to do things like auto-generate XHTML equivalents...
> cheers
> Chaals
>  (See Web Content Accessibility Guidelines, guideline 7 -
> http://www.w3.org/TR/WCAG10/wai-pageauth.html#gl-movement - for some
> more info)
> James Little wrote:
> >Guys/Girls,
> >
> >Does anyone know if there is an acceptable "time" between frames on
> >Animated Gifs?  I have one that needs to go on a site that I develop,
> >but I don't want to break 3.7.1 and 3.7.2 ("Flickering, flashing and
> >blinking should be avoided or at least
> >limited.").
> >
> >I heard somewhere that there was an acceptable amount of time, but I
> >can't remember exactly what it is.
> >
> >Thanks
> >
> >James
> >
> >
> >

Received on Wednesday, 14 May 2003 05:35:44 UTC

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