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Re: Requirements for external text alternatives for audio/video

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Thu, 25 Mar 2010 15:29:39 +1100
Message-ID: <2c0e02831003242129vf9c82c5s3f066276f4008a58@mail.gmail.com>
To: Geoff Freed <geoff_freed@wgbh.org>
Cc: HTML Accessibility Task Force <public-html-a11y@w3.org>
Hi everyone,

I was hoping for a more lively debate, but it seems Geoff must have
stated all the important issues.

I have now collected Geoff's arguments together with a more broad
legal requirements analysis on our wiki at:

I have tried to capture the general legal requirements for Online from
existing government regulations, which all refer back to WCAG1.0.
Thus, I have tried to analyse WCAG1.0 and WCAG2.0 for their
requirements and have tried making a list of the ones that relate to
media. (I may have made some mistakes, so please correct the wiki if
you come across any.)

It seems to me generally that in contrast to other devices (TV,
Digital TV, etc), Online has thus far had a rather "light" requirement
on the features of captions. It seems that rather than discussing what
features are required, the discussion has thus far focused more on the
requirement that captions (and audio descriptions) be present at all.
This can, however, not be expected for-ever and we will have to be
prepared to introduce higher standards on the quality of captions and
audio descriptions for online.

In my opinion, that actually requires two things:

1) WCAG needs to be extended to include requirements that are similar
to the requirements that other devices face. Maybe this could be added
as a Level AAAA to WCAG2.0 (though, honestly, I would prefer a less
repetitive and convoluted document than WCAG2.0 that deals
specifically with media accessibility requirements).

2) In HTML5 we should provide the extended functionality that other
standards provide for captions, too.

In summary - I would suggest keeping the File Format requirement at
with supporting both, srt and dfxp (or ttml as Sean clarified).


On Tue, Mar 16, 2010 at 6:55 AM, Geoff Freed <geoff_freed@wgbh.org> wrote:
> On 3/14/10 8:08 PM, "Silvia Pfeiffer" <silviapfeiffer1@gmail.com> wrote:
> Hi all,
> (snip)
> We have 15 voices for SRT and 14 for DFXP.
> However, looking at the detailed replies, I can see that we basically
> have two camps: one that says "let's just start simple" and the other
> that says "we need something that is extensible, incorporates styling
> and markup".
> What it tells me is that we never really looked at what our
> requirements for synchronised text alternatives, and in particular for
> caption formats here.
> I'd like us to collect these requirements so we can make a better
> recommendation as a group. We should look at these requirements from
> several view points, some of which may be:
> * a legal POV (what do a11y laws require us to do),
> * a WCAG requirements POV,
> * a a11y user's usability POV,
> * an international user's POV,
> an anything you can think of that I forgot.
> (begin GF)
> One item to note is the US Federal Communications Commission (FCC) DTV
> Decoder Standards, which was adopted in July of 2001.  This document lays
> out the features that DTV CC decoders in the US must support.  The full doc
> itself is at
> http://fjallfoss.fcc.gov/edocs_public/attachmatch/FCC-00-259A1.pdf; I’ve
> attached a plain-text excerpt that summarizes the decoder requirements.
>  These requirements were created after the FCC received numerous comments
> from the deaf and hard-of-hearing community over the importance of having
> both authorial and user access to styling features.  The DTV Decoder
> Standards ensure that CEA-708 captions containing specific styling features
> (e.g., foreground/background color, translucency, font face and size, etc.)
> will appear on digital televisions as the author intended.
> In the US, providers of online media originating on broadcast or cable TV
> are complying with the existing requirements which were based on significant
> public input, and have initiated a technical working group within SMPTE to
> assure that they can “author once, use often” in terms of the captions they
> are paying for. These captions are presently automatically translated to
> CEA-708 caption files with full stylistic mark-up that caption providers
> would like to see preserved when they are transformed to other delivery
> formats, rather than be discarded because the target format doesn’t support
> these features.
> In terms of compatibility with newer standards, note that the Advanced
> Television Systems  Committee (ATSC) Mobile DTV Standard (A/153;
> http://www.atsc.org/standards/a153.php) includes support for the
> transmission of CEA-708 captions, which as you know contains a range of
> styling features.  SMPTE-TT will also contain a wide range of caption-style
> features.
> Another thing to keep in mind is that the deaf/hard-of-hearing community has
> asked specifically for styling features in captions.  Organizations such as
> Telecommunications for the Deaf, Self Help for Hard of Hearing People,
> National Association for the Deaf and the AG Bell Association for the Deaf
> all wrote to the FCC in support of things like foreground/background color,
> text size and location.  The fact that you do not see these features in wide
> use today is not a reason to preclude them from future use.  It would be
> wise to consult with expert users in the deaf and hard-of-hearing community
> before discarding the capacity for a degree of stylistic mark-up. In fact,
> the SMPTE working group has established a liaison relationship with the
> Coalition of Organizations for Accessible Technology, a group of interested
> parties (numbering more than 300 US national and regional organizations
> serving deaf or blind people).  The members of this group would certainly
> have an interest in this discussion.
> All this background information is simply to say... promoting a text-display
> format that does not support minimal styling is, in my view, ignoring the
> stated needs and desires of the people who rely on captioned media.
> Finally, a word about foreign-language subtitles.  Subtitles are frequently
> displayed over a transparent background.  As such, they usually need
> coloring, edging or drop-shadow in order to be made clearly visible.
>  Offering a text-display spec that doesn’t support these features won’t
> really help someone trying to make simple subtitles readable over a busy
> background.
> (end GF)
> (snip)
Received on Thursday, 25 March 2010 04:30:32 UTC

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