W3C home > Mailing lists > Public > public-html-a11y@w3.org > May 2011

Re: [media] alt technologies for paused video (and using ARIA)

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Thu, 12 May 2011 13:08:55 +1000
Message-ID: <BANLkTinf1BPB5uBcL0kp7J0ZA2QMv4gdeg@mail.gmail.com>
To: "E.J. Zufelt" <everett@zufelt.ca>
Cc: John Foliot <jfoliot@stanford.edu>, David Singer <singer@apple.com>, HTML Accessibility Task Force <public-html-a11y@w3.org>, James Craig <jcraig@apple.com>, Michael Cooper <cooper@w3.org>
On Thu, May 12, 2011 at 12:17 PM, E.J. Zufelt <everett@zufelt.ca> wrote:
> On 2011-05-11, at 10:05 PM, Silvia Pfeiffer wrote:
>> On Thu, May 12, 2011 at 12:03 PM, E.J. Zufelt <everett@zufelt.ca> wrote:
>>> On 2011-05-11, at 8:26 PM, Silvia Pfeiffer wrote:
>>> Is that really the case? IIUC, neither aria-label nor alt are
>>> conforming attributes on media elements and screen readers ignore
>>> them. A test with ChromeVox confirms this, though I cannot test any
>>> other screenreader on my mac.
>>> I did a simple test of this:
>>> <video controls aria-label="My video player">
>>> </video>
>>> Using VoiceOver on SL and Safari 5 the label wasn't read.
>>> Using NVDA 2010.1 on FF 3.6 the label was read when tabbing to the player
>>> controls
>>> Using JAWS 11 in Firefox 3.6 the label was read instead of the player
>>> controls, as AFAIK JAWS 11 doesn't support rendering the controls in the
>>> virtual buffer.
>> Hi Everett,
>> Thanks heaps for this test! Can you do me a favor and run another test
>> with the @alt attribute instead of @aria-label?
> None of the tree AT broswer pairs appears to support alt on the video control.

Ah, very interesting. Thanks so much for this experiment!

It seems we have the following situation:

* there is a need for a short text alternative for poster content in
the video element

* there is no need for a short text alternative for the video content
in the video element (users will want that, but that is an equal need
for sighted and non-sighted users)

* right now, some screenreaders read out @aria-label as a text
alternative on a paused video, since it is a label on an interactive
element when @controls is present

* no screenreader reads out @alt as a text alternative on a paused video

What do we conclude from this?

Is @aria-label good enough for containing a very short description of
the poster content?

In its definition,
http://www.w3.org/TR/wai-aria/states_and_properties#aria-label , it
"provides the user with a recognizable name of the object", with the
most appropriate mapping being to the "accessible name of the user
interface element"
http://www.w3.org/TR/wai-aria/terms#def_accessible_name . Thus, this
would really mean the text "a video" for every single instance of
<video aria-label>, which isn't very useful.

However, all the examples that I found of aria-label use provide a
short sentence to explain to users what it is that they are seeing
rather than to explain what user interface element a user is on: e.g.
Since the WAI specification also compares aria-label to title, this
use seems to make sense.

So, I think it is possible that @aria-label is sufficient for the
short text alternative for the image that we are talking about. And we
already have that in the spec and also implemented in some

Received on Thursday, 12 May 2011 03:15:47 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 19:55:56 UTC