- From: Steve Faulkner <faulkner.steve@gmail.com>
- Date: Sat, 14 May 2011 06:53:26 +0100
- 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>
- Message-ID: <BANLkTinRkyzStBPmQ68hJ9V+n5EGVRMpeg@mail.gmail.com>
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 UTC