Editor of HTML5 questions need for alt text in movie poster frames
w3.org
w3.org
Ian's often repeated naive-sounding "Why would you do that? What's the use case?" has shot down many feature requests that seemed good in theory, but weren't that useful in practice.
Perhaps description of the video makes description of poster redundant? Maybe one can use ARIA? Maybe media framework can extract description from the video file?
Even if there is a way to describe the poster, will authors actually care to do it? Will they ignore it (naively assuming blind users don't watch videos) or fill it with boilerplate?
The plan seems to be that <track kind="descriptions" src="desc.en.srt"> be used as a child of <video> to provide descriptions in sync with the audio. http://www.whatwg.org/specs/web-apps/current-work/multipage/...
That is NOT questioning an assumption. He seems to imply that blind users have no use for an information that is interesting to other people.
Would you be interested in description of image representing video if you could get description of the actual video?
— I watched a funny video!
— Cool! What was on the poster image?
Poster images for videos are also part of journalistic publications, where the poster also works as a still image and conveys meaning or illustrates a point of the story.
> The image given by the poster attribute, the poster frame, is intended to be a representative frame of the video (typically one of the first non-blank frames) that gives the user an idea of what the video is like. (http://www.whatwg.org/specs/web-apps/current-work/multipage/...)
http://en.wikipedia.org/wiki/Casablanca_%28film%29
I had to check this out. The alt text on the images really are excellent.
Also, time spent on describing poster could be spent on describing the video itself, which might give better indication whether video is worth watching.
It's not like they suddenly want to disallow alt text on movie posters on the web.
Why should a user with impaired vision be denied the same opportunity?
The first-frame preview is an artifact of the visual presentation of the video player and not relevant for non-sighted users, just as the colors used in css is not relevant for non-sighted users. The actual content is the video, and if you want to make that accessible you should follow the recommendations in the spec and "provide alternative media streams and/or to embed accessibility aids (such as caption or subtitle tracks, audio description tracks, or sign-language overlays) into their media streams".
There may be better ways for users with impaired vision to decide whether they want to watch a video.
For sighted users poster is useful, because visual recognition is faster than reading of descriptions.
However, when user has to read some description, then reading of description of one of the frames won't necessarily be faster or more informative than reading title or description of the video itself.
The "poster" image for Casablanca has an alt text: "Black-and-white film screenshot with the title of the film in fancy font. Below it is the text "A Warner Bros. - First National Picture". In the background is a crowded nightclub filled with many people." If you imagine a movie being embedded in a webpage, that might be the alt text for the poster image whereas the title might be "Casablanca".
For example:
Title: Cat jumping on bed
Frame: Image of cat jumping towards bed
Video: Cat jumps toward bed and lands on it.
The vast majority of the time, the poster frame isn't going to be different than the title of the video.
Now, I agree that when it is different, there should be a way to specify an alt text for it. But to require it when it's the same as the title seems silly to me.
Title: Dexter. Description: A likable Miami police forensics expert moonlights as a serial killer of criminals who he believes have escaped justice.
The exact episode also has those attributes:
Title: My Bad. Description: In the aftermath of last season's chilling finale, Rita's death has left Dexter feeling responsible, possibly even...guilty. Unable to deal with the trauma, Dexter makes a drastic decision that will impact everyone around him. Quinn stirs up trouble at the station when he notes that Rita's murder, which is being pinned on the Trinity Killer, doesn't fit his normal murder profile. Things get even more heated when Quinn suggests to LaGuerta that they look at the husband: Dexter Morgan. Meanwhile, Quinn offers Debra much needed support, causing her to see Quinn in a new light.
----
Simply put, titles and descriptions are not the same thing. It seems silly to me that somebody would advocate that they should be treated as the same thing just because there is overlap when the content is a 15 second video of a cat.
The issue is only about describing poster frame of the video (a placeholder picture that is displayed before user hits 'play').
Title: Dexter - My Bad.
Description: Dexter stands in a dank, dirty, dimly lit public bathroom, gripping a fishing anchor, a malevolent look in his eyes.
Isn't the problem there that one doesn't know it is the same. Requiring a description of the poster image, which can be blank as for alt-attributes of non-content images, means that it clearer when the author has simply chosen not to bother attempting to be accessible as opposed to the poster having no useful content beyond the title.
That is pretty bad.
I think they need a group of people with disabilities to review all of the specs. There have to be many more issues like this lurking (that those with disabilities could probably already point me to).
Wow. :( "I'm confused. Why would you (a blind user) want to
know what the poster frame is? How does it affect you?"
Navigating their way there gives them context to what the video will be (in the use case that the video is on a blank page). If the page contains textual content then the user will get context from the text. If the video is completely unrelated to location context or to page-level context then the content will be of little to no interest, so providing an alt description adds no real-world value.
Also note that unless the video has audio captioning then the entire video is of little to no interest. Imagine watching something like Lost in Translation with no visual input and no descriptive captioning.
The 'poster' in this case is specifically a single image preview for a video shown before the video starts playing. According to the spec "typically one of the first non-blank frames".
It can be compared with e.g. a low resolution preview of a high-resolution image, as was used in the early days of the web. It is definitely not obvious that it would make sense to have an alternative text specifically for the lo-res preview as distinct from the alt text for the image itself.
Note that the video element already support an alternative text description - its just the single-frame preview which doesn't support a separate text.
I think Ians questioning of this feature is completely valid.
The HTML5 spec specifically addresses accessibility for video like this:
To make video content accessible to the blind, deaf, and those with other physical or cognitive disabilities, authors are expected to provide alternative media streams and/or to embed accessibility aids (such as caption or subtitle tracks, audio description tracks, or sign-language overlays) into their media streams. (http://www.whatwg.org/specs/web-apps/current-work/multipage/...)
This is much more sensible that providing an alt text for the first frame in the video.
The person who filed the bug is (effectively) saying "if the page author specifies a poster frame, it should be possible to add alt text. If the page author uses the default poster frame, it should be impossible to add alt text."
I believe the question Hixie was getting at was "why would you (a blind user) care about an explicitly-set poster frame but not a default poster frame?" which, I think, is reasonable.
It's likely Hickson's questions, and reluctance to accept a specific proposal without more data, are a matter of seeking understanding, and working through different ideas about what the proper significance and use of a 'poster' image for video might be.
(A better title might be: "Debating fine points of HTML5 accessibility: video 'poster' images and alt taxt".)
You can't understand what a person needs unless you ask them directly. That's what Mr. Hickson is doing here.
And lets not forget the more important matter - videos need transcripts so that the blind and deaf can follow along.
A few days ago I asked for feedback on how I might better explain accessibility to developers over at http://news.ycombinator.com/item?id=1716463 - issues like this are exactly the kind of stuff I was looking for. Feel free to leave comments there if you have them.