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Re: Need (or not) for text equivalent of AV files

From: Loretta Guarino Reid <lorettaguarino@google.com>
Date: Wed, 10 Aug 2011 19:51:45 -0700
Message-ID: <CAHu5OWa5F-3GyT69Gt6Ee_=hsWbS4UQVc2HFeZeY3X4u+LY3Vw@mail.gmail.com>
To: maria.moore@utas.edu.au
Cc: public-comments-wcag20@w3.org
On Wed, Jul 20, 2011 at 9:23 PM, <noreply@w3.org> wrote:

> Name: Maria Moore
> Email: maria.moore@utas.edu.au
> Affiliation: University of Tasmania
> Document: W2
> Item Number: Guideline 1.1: Provide text alternatives for any non-text
> content...
> Part of Item:
> Comment Type: general comment
> Summary of Issue: Need (or not) for text equivalent of AV files
> Comment (Including rationale for any proposed change):
> I am a bit unclear about the note on
> http://www.w3.org/TR/UNDERSTANDING-WCAG20/media-equiv-av-only-alt.html,
> that says /Note: /A text equivalent is not required for audio that is
> provided as an equivalent for video with no audio information. For example,
> it is not required to caption video description that is provided as an
> alternative to a silent movie.
> > Surely this does not assist deaf-blind people? I would have thought that
> a text equivalent would be needed.
> Proposed Change:
> Providing an audio description of video only creates another file (the
> audio description), that needs a text equivalent
> ================================
Response from the Working Group
There is never a requirement for an alternative to an alternative.   If an
audio description is required, it is an alternative to visual information
and a visual alternative to the audio alternative for the visual content is
not required.

Note that captions are not required to be "programmatically determined" so a
deaf-blind person cannot necessarily access captions anyway.   Also, audio
descriptions only provide minimal coverage of the visual information unless
extended audio descriptions are used -- which are not required.

A machine readable text description of both audio and visual information
would indeed be helpful to people who are deaf-blind and is one of the ways
of meeting the level A provision.

It is also explicitly required in its own provision at level AAA.

Loretta Guarino Reid, WCAG WG Co-Chair
Gregg Vanderheiden, WCAG WG Co-Chair
Michael Cooper, WCAG WG Staff Contact

On behalf of the WCAG Working Group
Received on Thursday, 11 August 2011 02:52:11 UTC

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