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RE: [media] progress on video transcript discussion

From: David MacDonald <david100@sympatico.ca>
Date: Wed, 6 Jun 2012 16:32:53 -0400
Message-ID: <BLU0-SMTP187B8F4F5AE7F1D7D5DDBCFE0D0@phx.gbl>
To: "'Silvia Pfeiffer'" <silviapfeiffer1@gmail.com>, "'HTML Accessibility Task Force'" <public-html-a11y@w3.org>
Good discussion....

Sylvia's suggested code snip for the use case of embedded video:

<video src="video.mpg" aria-label="video with transcript below"

I think this would confuse a blind user... double message..."transcript
below", and transcript linked from video element... but there is no
transcript below... just the linked transcript from within the video element
... maybe the linked version should drop the aria label, or change to say
"video available" or something...

David MacDonald

CanAdapt Solutions Inc.
  "Enabling the Web"

-----Original Message-----
From: Silvia Pfeiffer [mailto:silviapfeiffer1@gmail.com] 
Sent: June-05-12 10:27 PM
To: HTML Accessibility Task Force
Subject: [media] progress on video transcript discussion

Hi all,

I wanted to share what I took out of today's transcript phone conference.
This includes both conclusions that we have come to in the course of the
discussion as well as a proposal of how to progress.
Some of this is my personal interpretation, so chip in if you disagree
anywhere, or have any other suggestions.

Points that we discussed:

1. Interactive Transcript

This was the simplest part of our discussion, so I want to get this out of
the way up front.

We discussed the need for interactive transcripts in HTML5. Everyone agreed
that it is a very important feature and there are many use cases. Examples
of current solutions include:

The main problem, however, is the timeline that we are given to finalize
HTML5. We do not want to start with a new feature that requires many cycles
to become perfect (e.g. the video element has taken 5 years to be sorted
with all its attributes and elements). So, we want to move this feature to
HTML.next and encourage Web developers to use JavaScript solutions for
creating more interactive transcript examples so we can learn more about the
needs for features and attributes. We'd in particular like to encourage Web
developers to make use of TextTrack and TextTrackCue objects as their source
for interactive transcripts since it is likely a good way to provide the
information required to render an interactive transcript in the browser.
We'd also like to start the design of a solution in HTML.next and continue
the already fruitful discussions.

For HTML5, however, we're shelving this issue.

2. Programmatic linkage of video and transcript

The bigger issue - and one which we haven't resolved yet, but have made good
progress on, was the question about the need of programmatic linkage between
the video and its transcript.

Our discussion started around options of having the transcript tightly
coupled with the video element, i.e. how to make it part of the video

We achieved general agreement that an actual rendering of the transcript
inside the boundaries of the video element (e.g. as an overlay or an
alternative to the video) doesn't make much sense. The transcript itself
needs to be rendered outside the video element, e.g.
in a different region on the page or on a different page.

The second use case for tightly coupling the transcript to the video element
was about the possibility of "activating" the transcript from the video
element's controls. The idea here is that we would have a button on the
video controls that when clicked might take us to another Web page with the
transcript on it, or when clicked might unveil a section on the Web page
near the video that shows the transcript, or when clicked might scroll us
down to a page offset where the transcript is displayed. This is a nice
theory, but is this actually being used this way?

I personally have been unable to see transcripts used in this way in any
kind of video player on the Web. Where transcripts are displayed, I have
only seen links or text below the video. The only player that was different
is the video player of the Rachel Maddow show, see
http://www.msnbc.msn.com/id/26315908/vp/47654476#47654476 . This player uses
the transcript button to reveal/hide an interactive transcript. Interactive
transcripts are already tightly linked with the video through their
synchronized timeline, so having a button to turn an interactive transcript
on/off makes some sense. However, we have already said that we are moving
interactive transcripts to HTML.next, so this is not something we need to
solve now.

So, I actually believe that neither do we need a solution that renders the
transcript inside the video element, nor do we need a solution that creates
a transcript button of some sort on the video element.

So, what do we actually need a programmatic linkage between the video and
the transcript for?

In my mind, we have been mingling up two actual use cases: the first one
where the transcript or a transcript activation button is visible on the
page further down, and the second one where no transcript is visible on the
page with the video and the transcript is actually on a different page
(possibly because the video was embedded).

The situation where the transcript is on the page but completely invisible
(including there is no button to make it un-hide) is not one that I want to
entertain here, since it can be satisfied by having a separate Web page
off-page and thus falls into the second use case.
(Also, I think it is pretty bad practice and should be discouraged.) Note
that having a button on the page that can hide/unhide the transcript text
makes this fall into the first use case and is not a different use case.

2.1. First use case: Linkage of video and transcript where the transcript is
visible on the page

Sighted users need no programmatic linkage in this case, since they can
clearly see the transcript (or transcript link) further down on the page.

However, blind users may find it difficult to discover that a transcript is
available when they directly go to the video element.
So, we need to make sure the availability of the transcript is announced
when reaching the video element, and possibly provide a means to directly
jump to the transcript (to avoid dealing with other DOM clutter).

(Note: at one stage I thought @aria-describedby will solve this problem, but
when it refers to an <a> element, it just renders flattened text, and when
it reads a full text transcript, it can't be navigated since it's all just a
single AccDescription of the element.
So, I'm dropping this suggestion. So here are some new thoughts.)

The announcement can likely be made using @aria-label.

The linkage could be made by introducing a new @role attribute value of
"transcript" so it is possible to gain it as a navigation landmark.
This role would then go onto the element that contains the transcript, which
could be an <a>, <div>, <p>, <iframe> or anything else really (including
<button> or <textarea>).

There are many knowledgeable people on this list about aria, so maybe you
can chip in here.

2.2 Linkage of video and transcript where the transcript is not visible on
the page

At first sight this is a non-usecase: if we can't see the transcript, why
would we need to link to it from the video, in particular since we don't
want to put buttons into the video?

It took me a while to understand this myself: when you publish a video on
your page, you have control and you can put the transcript (or transcript
link) below the video and announce it in the screen reader etc. But once
this video is embedded somewhere else, you need a link to discover the
transcript's availability and jump back to the original page. (This is
actually the same for full-screen video, but it's easy to exit fullscreen to
get back to the transcript.)

One solution that needs no new markup is: the Web developer creates a
snippet of embed text (in an iframe) that includes a visible link back to
the original page and gives it a @role=transcript so it's discoverable by
blind users. That reduces this use case back to the previous use case
(transcript is visible). However, the problem with this is that the page
that embeds the video may not want to show such a link and may only want the
video, thus removing the extra link.

This is a problem both for sighted and non-sighted users. They may find
themselves on a page that has a video and there is a transcript available
for this video, but they have no means of discovering the availability of
the transcript or navigating to it. Sighted users may never find out that a
transcript actually exists. For non-sighted users it's even worse - they
could be misled into believing there is a "transcript available below" when
the @aria-label attribute has been copied, but then search for it in vain.

So, my suggestion here would be to introduce a @transcript attribute on the
video that requires a full URL (we should discourage the use of relative
URLs since they don't work when embedding which is the main use case here).
Browsers would display this URL in the context menu of the video element, so
sighted users can discover them. Web developers can be clever, create their
own video controls and include the link there if they like. And blind users
will be told that there is a "transcript available" and have some means of
activating the linkage.

This would be the markup:

<video src="video.mpg" aria-label="video with transcript below"
<div id="transcript" role="transcript">
<h4>This is a transcript</h4>
<p>blah blah blah</p>

And the embed would have:

<video src="video.mpg" aria-label="video with transcript below"

Here is another example markup with an off-page link:

<video src="video.mpg" aria-label="video with transcript below"
<a id="transcript" role="transcript" href="transcript.html">Transcript</a>

Now, it is possible that publishers may want to shorten this to

<video src="video.mpg" aria-label="video with transcript below"
<a id="transcript" role="transcript" href="transcript.html">Transcript</a>

and this would essentially mean duplicating the link. I don't see that as a
problem, however, since they satisfy two different use cases.

I'm fully aware that this is somewhat related to the @longdesc discussion.
This use case could, therefore, also be solved by using @aria-describedAt
containing a link to the transcript (as in fact I have suggested before).
>From what I've learnt in previous discussions, we want the extra semantics
of it being a transcript and not just a random long description, so
introducing a new attribute for this seems right. If we can make it always
have a full URL! ;-)

Hope this all helps to make progress.

Received on Wednesday, 6 June 2012 20:33:27 UTC

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