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Re: Video Poster image (was RE: DRAFT analysis of fallback mechanisms for embedded content ACTION-66)

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Sat, 11 Dec 2010 15:43:54 +1100
Message-ID: <AANLkTim6TRkYqcOm=KpGtO409rjqiaz-kapUHB+BvXFJ@mail.gmail.com>
To: David Singer <singer@apple.com>
Cc: HTML Accessibility Task Force <public-html-a11y@w3.org>, Maciej Stachowiak <mjs@apple.com>, Ian Hickson <ian@hixie.ch>
On Thu, Dec 9, 2010 at 2:27 AM, David Singer <singer@apple.com> wrote:
> I agree, a poster IS the video.  we should not encourage bad practices by pretending/allowing otherwise.
>
> I have three questions about annotating audio/video resources:
>     can I
>        (a) provide a short "alt" text? for video
>        (b) provide a long description?
>        (c) link to a transcript?
>
> These seem to be more important, to me, than worrying about whether the poster is semantically different from the video.

I couldn't agree more.

In my view we should have the following:

>        (a) provide a short "alt" text? for video

@aria-label would provide for this (alternative suggestions I have
seen were: @alt or @title but they may be too confusing); essentially
in typical video pages the "video title" and the @poster image
normally provide a quick impression, so these need to be described in
the short alternative text.

>        (b) provide a long description?

@aria-described-by would provide for such IMO; alternatively, a
@summary could be provided on the element, too, but it would be just
as useful to sighted as to vision-impaired users, such that I would
leave this to the Web page - often enough videos have a description
underneath/aside them.

>        (c) link to a transcript?

A "transcript" is a interesting different type of text alternative,
actually. A transcript can be time-synchronized, in which case it
becomes something akin to captions. However, transcripts typically
appear as full text on the side of the video such that sighted people
can use them, too. Better still they appear as interactive
transcripts, see for example TED videos or YouTube videos e.g.
http://www.youtube.com/watch?v=EDNZMw4_mJY and
http://www.ted.com/talks/sheryl_wudunn_our_century_s_greatest_injustice.html
(you have to open the interactive transcripts).

I've experimented with interactive transcripts a bit for use in
accessibility, see http://www.annodex.net/~silvia/a11y_bcp/ (I am
hoping to put a few more best practices up there, but this is
currently only a draft). You will notice that I distinguish between
transcripts in a linked resource (which is in fact what a long
description should be) and interactive transcripts. You will need to
click around on the transcript and on the video a bit to understand
what it does. I believe these are the two core use cases and they can
already be satisfied with existing markup. But I would be happy for us
to improve these ideas.

Cheers,
Silvia.
Received on Saturday, 11 December 2010 04:52:00 GMT

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