W3C home > Mailing lists > Public > public-html@w3.org > September 2008

Re: Acessibility of <audio> and <video>

From: Leif Halvard Silli <lhs@malform.no>
Date: Tue, 02 Sep 2008 20:24:39 +0200
Message-ID: <48BD84E7.7000904@malform.no>
To: public-html@w3.org

Smylers 2008-09-02 16.58:

> Lachlan Hunt writes:
>> Leif Halvard Silli wrote:
>> > Lachlan Hunt 2008-09-01 23.36:

>> > > Unlike video, images have no way embedding accessibility features
>> > > within them, and their meaning is very often depending on the
>> > > context.
>> >
>> > Our recent debate about EXIF proves opposite.
>> Although it can contain descriptions, that's not particularly useful
>> when the alternate text needs to be context sensitive.
> If people start wanting to use videos 

There is difference beween using <video> and video.

> for logos, decoration, mere
> illustration, text replacement, as icons, or whatever then they would

One one side, there is no need to exaggerate. On the other side, 
there is much truth in what you say here.

Take the flash example in LiveDom.validator.nu. How would an 
author classify it? Is it video? How to mark it up using HTML 5? 
That flash example only displays an image with the words "passed".

> need <img>-like alt text -- and we'd have the same thing as with images,
> where a single image could serve different purposes (and as such require
> different alt text) on different pages.

> But there doesn't seem to be a desire for such use of videos 

I just presented one such example.

 > -- they all

> seem to be in the category of being 'important content' on the page --

Important content = 'critical content' = alt text unavailable?

> so, as Lachlan suggests, alternative representations could be embedded
> in the video and still be appropriate.

We know now, that alternative content can be added into graphica 
formats, including videos. However, we need to be able to do it in 
HTML as well.

>> > Link: http://www.dagbladet.no/kultur/2008/09/01/545443.html
>> That's just using the poster frame for its intended purpose: providing
>> a visual, iconic representation of the video to indicate what the
>> video is about.
> If a page has several videos in it, the poster frames for each may be
> chosen such that a sighted user can use them to distinguish them and
> pick which video she wishes to watch.  It may be that no other content
> is needed on the page for her to make such a decision.


> However, somebody reliant on a speaking browser would not have that
> information available.  Obviously such a person wouldn't be able to see
> the videos either, but they may still wish to play them for their audio
> tracks.


> Each video's title, or other information which helps pick between them,
> obviously _could_ be included in the HTML next to the video.  But this
> may be of no benefit to sighted users.  Consider a page with videos of
> speeches, with the poster frames containing head-shots of different
> presidential candidates, each with a visible caption of their name and
> party: putting their this information additionaly on the page with HTML
> would be repeating it visually; that would be unnecessary for sighted
> viewers, and I'm not sure it's reasonable to insist that authors should
> include this duplication for accessibility reasons.

I, for one, did not argue that the content of @title should also 
be repeatad in the mark-up, if that was what you meant.

However, if the poster frame was an <img> with a correctly used 
@alt, then there would be no repetion for sighted users, while 
there would also be a useful description of the poster for those 
with a browser which do not display pictures.

Btw, we should not suggest using the @title as if was some kind of 
@alt. That would only be confusing to authors - and users.

> I'd've thought it better that there's some way in which non-image
> alternative to the poster frame could be made available for speaking
> browsers.

Absolutely. This is what I am arguing.
leif halvard silli
Received on Tuesday, 2 September 2008 18:25:25 UTC

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