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

From: Steve Faulkner <faulkner.steve@gmail.com>
Date: Sat, 14 May 2011 06:53:26 +0100
Message-ID: <BANLkTinRkyzStBPmQ68hJ9V+n5EGVRMpeg@mail.gmail.com>
To: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Cc: Jared Smith <jared@webaim.org>, John Foliot <jfoliot@stanford.edu>, Everett Zufelt <everett@zufelt.ca>, HTML Accessibility Task Force <public-html-a11y@w3.org>
hi Silvia,

>Are you saying that the title attribute is not a useful
>attribute at all because it doesn't work on all devices?

no not at all, I am saying it is not useful for providing a visible label as
some users cannot see the label as it cannot be accessed using the keyboard
or on  mobile browsers/touch screens.

you may be interested in this article:
Using the HTML title attribute
http://www.paciellogroup.com/blog/2010/11/using-the-html-title-attribute/

regards
stevef

On 14 May 2011 05:00, Silvia Pfeiffer <silviapfeiffer1@gmail.com> wrote:

> Hi Steve,
>
> I'm curious: Are you saying that the title attribute is not a useful
> attribute at all because it doesn't work on all devices?
>
> Cheers,
> Silvia.
>
>
> On Sat, May 14, 2011 at 2:29 AM, Steve Faulkner
> <faulkner.steve@gmail.com> wrote:
> > Hi all,
> >
> > Use of the title attribute is not appropriate for all users as it's not
> input device independent content.
> >
> > The video element is the player it is not the video itself.
> >
> > Labeling the video element does not equate to providing a text
> alternative for the content whether it's the static poster or the video
> being played.
> >
> > Regards
> > Stevef
> >
> > Sent from my iPhone
> >
> > On 13 May 2011, at 01:16, Silvia Pfeiffer <silviapfeiffer1@gmail.com>
> wrote:
> >
> >> On Fri, May 13, 2011 at 3:31 AM, Jared Smith <jared@webaim.org> wrote:
> >>> On Thu, May 12, 2011 at 12:35 AM, Silvia Pfeiffer
> >>> <silviapfeiffer1@gmail.com> wrote:
> >>>
> >>>> Because if you have a black image sitting there the text alternative
> >>>> surely shouldn't say that it's an Apollo launch. That would be the
> >>>> wrong description of that image.
> >>>
> >>> Exactly. We're not concerned about letting the user know that there's
> >>> a black image there. We're concerned about letting them know that it's
> >>> a video about the Apollo launch... which is what sighted users can
> >>> easily surmise from the visual presentation and context of that video.
> >>
> >> I don't follow. Let's assume a Web page that has only a video element
> >> on it. Nothing else. That video element is black because nobody has
> >> bothered to put a different image on it. Thus, the sighted user
> >> doesn't know what's behind it. Why should the blind user be told what
> >> the video will play? That's not a "text alternative" to the visual
> >> presentation. That is additional information. For a black frame, the
> >> text equivalent should be "black frame", otherwise a sighted user
> >> looking at that video and a blind user looking at that video receive a
> >> different impression and are not able to talk to each other about it.
> >>
> >> Once the video is playing, the sighted user can indeed surmise the
> >> content from the visual presentation, and the blind user from the
> >> audio description or transcription. To give the text equivalent to the
> >> content of the timed visual presentation as text when the placeholder
> >> frame is shown would not be providing equivalence to the visuals.
> >>
> >>
> >>
> >>>>>> Certainly a short alternative presenting the
> >>>>>> content of what the video is would be useful for accessibility for
> >>>>>> screen reader users (sighted users can, after all, use the entire
> >>>>>> visual context to more likely determine the video's content).
> >>>>
> >>>> What is the entire visual context? If there is text given underneath,
> >>>> it is also accessible to the blind user, in particular if it is
> >>>> referenced through aria-describedby.
> >>>> We cannot assume anything about
> >>>> the rest of the page when we describe the paused video.
> >>>
> >>> Here's the ambiguity again. Are we describing "the paused video" (the
> >>> thing that the user might play) or are we describing the poster frame
> >>> (the static image that might, but often doesn't provide additional
> >>> information about the thing the user might play)? Or both? In this
> >>> case (a black frame), there is no poster frame content to describe,
> >>> but the paused video is still there and I believe it needs a short
> >>> description.
> >>
> >> I've tried be clear: it is the placeholder frame that we are
> >> describing, independent of whether it comes from the video or from a
> >> different resource.
> >>
> >>
> >>> In one sentence you indicate that we should consider the context, but
> >>> the next sentence suggests we should ignore it.
> >>
> >> Sorry if I was unclear: but they are two different use cases. The
> >> first one where I am suggesting to consider the context is where the
> >> context is available and can be pointed to through aria-describedby.
> >> If no such context is available, we still need a text replacement for
> >> the visual presentation which in case of a paused video can be
> >> aria-label and in case of a playing video would be audio descriptions
> >> and captions.
> >>
> >>> I believe context is
> >>> vital in determining the alternative for any non-text element. In this
> >>> case, if the visual context clearly presents to sighted users that the
> >>> video is about the Apollo launch, I would think it important to also
> >>> present this to a screen reader user.
> >>
> >> Yes, agreed. For this case, aria-describedby should be sufficient, no?
> >>
> >>
> >>>> What if only
> >>>> the black frame is sitting there and nothing else? Would you still
> >>>> describe that as "Apollo launch"?
> >>>
> >>> Yes, if it is presented visually in the surrounding context that the
> >>> video is about the Apollo launch.
> >>
> >> Let's assume no surrounding context (since that can be linked with
> >> aria-describedby). Would it be right to tell the blind user he/she is
> >> expecting an Apollo launch video without having to look into the
> >> video, while a sighted user has to click play and find out? Let's
> >> assume this is related to some game where you are shown three black
> >> frame videos and have to pick one to find, e.g. the Apollo launch
> >> while the other two are about cats and dogs (or something else) and
> >> you win when you pick the right one. Exposing the content of the video
> >> on the placeholder frame would be wrong, because it excludes people
> >> with screenreaders from the game (since they would have an unfair
> >> advantage). Not describing the black frames would be wrong, too,
> >> because the blind user cannot discover that there are three videos
> >> with black frames on the page.
> >>
> >> I think that if we want to provide a short summary of the video's
> >> content during the time that the video is paused and no other text is
> >> on the page, we'd have to find a solution both for sighted and blind
> >> users (and probably for low-bandwidth users, too). For this situation,
> >> @title would probably be the right approach?
> >>
> >>
> >>> This becomes even more significant for users that are navigating by
> >>> interactive elements. They would likely skip all descriptive text
> >>> content and jump directly to the video - which you would have present
> >>> no descriptive content until it is played. If there were multiple
> >>> videos, a screen reader might read "video, video, video". This would
> >>> be somewhat akin to "click here" which makes sense in its visual
> >>> context but requires screen reader users to explore the context to
> >>> determine what it is. And as noted before, this would bypass the WCAG
> >>> SC 1.1.1 requirements for descriptive identification of time-based
> >>> media. A short alternative to the video removes all these issues.
> >>
> >> IIUC that's exactly what @aria-label was created for.
> >>
> >> Let me try to come up with a mental model that describes the way I
> >> look at the video element better.
> >>
> >> The video element is an interactive element. Therefore, when you jump
> >> to the video, you need to be informed of your options. In essence,
> >> that's "hit space to play/pause toggle". But a sighted person doesn't
> >> just see the play/pause button - they also see the placeholder frame.
> >> Basically, you can look at it as a very big button that includes the
> >> placeholder frame. It's the image content of that frame plus the play
> >> sign that makes the sighted user hit "play". Similar to how an
> >> @aria-label describes what a button or form entry field exposes to the
> >> sighted users, @aria-label should here also expose to the blind user
> >> that this play button comes with an image. Given this view, I suggest
> >> it makes sense to include the placeholder frame's description in
> >> @aria-label.
> >>
> >>
> >>>>>> Now consider that the poster frame (whether author defined, random,
> or
> >>>>>> first frame) is an image of the moon, though the video is primarily
> >>>>>> about the Apollo 11 launch. A short alternative of "The moon" (or
> >>>>>> similar) would be an appropriate alternative for the poster frame,
> but
> >>>>>> would provide little utility (and, in this case, false information)
> >>>>>> about what the content of the video actually is.
> >>>>
> >>>> No, it wouldn't. The sighted user doesn't get more information either.
> >>>
> >>> Sure they do. They can see the entire context of the video to
> >>> determine what the video is about. Now a screen reader user could read
> >>> before or after (which one is a crap shoot), but with much more
> >>> effort. Would we ever omit @alt on an image on a page about the Apollo
> >>> mission based on the assumption that the screen reader user can figure
> >>> out what it is based on its context? Of course not! Then why would we
> >>> omit it for a video in the same place?
> >>
> >> We would use @aria-describedby to point to the text on the screen, IIUC.
> >>
> >>
> >>>> You have to always assume there is nothing else on the page when you
> >>>> define text alternatives for an element.
> >>>
> >>> I strongly disagree (http://webaim.org/techniques/alttext/#context).
> >>> The same non-text element may have very different alternatives
> >>> depending on its context. This is likely the crux of this issue.
> >>>
> >>> There's more to a video than what is presented visually when it's not
> >>> playing - just like there's often more to alternative text than what
> >>> the image looks like.
> >>
> >> I don't dispute this. I agree that the exact text of what you are
> >> putting into a text alternative is indeed very much defined by what
> >> its purpose is. I'm not trying to argue about what the text should be,
> >> rather about which visual representation the text should describe.
> >> Should it describe something that is actually visible at the time that
> >> the page is rendered or should it provide a summary of something that
> >> cannot be seen yet?
> >>
> >>
> >>>>>> This then seems to call for up to 5 (yikes!) types of alternative:
> >>>>>> 1. Short alternative for the <video>
> >>>>
> >>>> That's not necessary, because we have @transcription, track and other
> >>>> page text for this (always assuming you mean the playing video here).
> >>>
> >>> @transcription and track are certainly alternatives to the playing
> >>> video. But these wouldn't be available until the video is activated.
> >>> Again, if page context describes what the video is going to play to
> >>> sighted users, this information should also be presented to screen
> >>> reader users in a short alternative.
> >>
> >> When there is text available, @aria-describedby would be used. Is that
> >> not sufficient?
> >>
> >>
> >>>>>> 2. Long alternative for the <video> (if necessary)
> >>>>
> >>>> That's what @transcription (off-page) and @aria-describedby (on-page)
> provide.
> >>>
> >>> Yep.
> >>>
> >>> Of note is that aria-describedby does not currently (and probably
> >>> won't ever) support structured content or interactive elements. As
> >>> Steve kindly informed me, it's mapped to the accdescription property
> >>> which is a text string. This introduces some limitations for when long
> >>> description needs to provide structured content, which lends itself to
> >>> @transcription or @longdesc or... something.
> >>
> >> Would @aria-describedby support language markup, I wonder?
> >>
> >>
> >>>>>> 3. Short alternative for the poster image (if necessary, when not
> >>>>>> identical to #1)
> >>>>
> >>>> Yes, that's what my use case number one is and what I suggested
> @aria-label for.
> >>>
> >>> Except that it's currently ambiguous as to what should be described -
> >>> the video or the poster frame.
> >>
> >> Sorry if that seemed confused. It didn't seem confused to me - I
> >> always thought of it just describing the placeholder image. Maybe the
> >> model of the placeholder image being part of the play button makes
> >> that approach clearer.
> >>
> >> For description of the video, I'd suggest @title, which is then both
> >> usable by sighted and non-sighted users.
> >>
> >>
> >>>>>> 4. Long alternative for the poster image (if necessary, though I
> think
> >>>>>> this would be somewhat rare)
> >>>>
> >>>> That could easily be part of the long alternative for the <video>.
> >>>
> >>> But you said previously that we only need short or long alternatives
> >>> for the poster frame, not for the <video>. See why I'm confused? :-)
> >>
> >> OK, fair enough. :-)
> >>
> >> I follow all your 4 use cases/needs and I agree with them. I am trying
> >> to figure out if we need any new attributes to satisfy them and am
> >> also trying to figure out whether the existing attributes are
> >> sufficient and also mean the right thing. While I am fully aware that
> >> there is some relationship to the <img> case, not everything will be
> >> identical. For example, we have the opportunity of @aria-label,
> >> because video is an interactive element, which img isn't. I am very
> >> keen to get this right without making it complicated on authors. And I
> >> am also keen to get to a stage where we can give clear instructions to
> >> authors on how to mark up things, which is rather hidden in the
> >> existing spec.
> >>
> >>
> >>> This really is a great discussion. I agree that the issue is primarily
> >>> about terminology and explaining what should be described and how.
> >>>
> >>> Jared Smith
> >>> WebAIM.org
> >>>
> >>
> >> Thanks for your patience to continue this discussion!
> >>
> >> Cheers,
> >> Silvia.
> >>
> >
>



-- 
with regards

Steve Faulkner
Technical Director - TPG

www.paciellogroup.com | www.HTML5accessibility.com |
www.twitter.com/stevefaulkner
HTML5: Techniques for providing useful text alternatives -
dev.w3.org/html5/alt-techniques/
Web Accessibility Toolbar - www.paciellogroup.com/resources/wat-ie-about.html
Received on Saturday, 14 May 2011 05:54:18 GMT

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