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Re: text-format discussion from today's call

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Fri, 6 Aug 2010 10:07:16 +1000
Message-ID: <AANLkTikKXocgCzw=AppAp5h332t8dNpGN2S26p4yG4J+@mail.gmail.com>
To: Geoff Freed <geoff_freed@wgbh.org>
Cc: HTML Accessibility Task Force <public-html-a11y@w3.org>, Judy Brewer <jbrewer@w3.org>
Hi Geoff,

This is all very interesting indeed.

I do wonder, however, how much "automatism" can be in there from saying
because "SMPTE is using TTML as their transcoding format for IP delivery of
captions" to saying "TTML also has to be supported by the Web". The problem
about this statement is implementation support in Web browsers. If no Web
browser is implementing support for TTML, TTML will not mean much on the
Web, no matter how many TTML documents exist from repurposed broadcast

But, to be honest, I do not see that as a big problem. Transcoding from one
text format to another is not a big issue where those formats support the
same functionality. I believe that whatever format will be chosen for HTML5,
it will support all the TTML features, so there should be no problem in
transcoding. In fact, even the proposed draft WebSRT by the WHATWG is
already capable of supporting almost all of TTML, so I am not worried about

In fact, if I was a broadcaster, I would probably just create both file
types from my existing broadcast captions and use them as appropriate. It
has been done with video before and is a much bigger problem there since
transcoding in video means data loss. This is not the case for text, so
won't be much of an issue, IMHO.

But, you are right, it is good to know these things and to make sure they
are compatible. Thanks for sharing!


On Fri, Aug 6, 2010 at 2:52 AM, Geoff Freed <geoff_freed@wgbh.org> wrote:

> Greetings, all:
> Regarding the conversation on the call today about timed-text formats, I’d
> like to offer some further thoughts regarding the format eventually
> recommended by the a11y group and/or HTML5 and how it may affect others.  At
> a minimum these comments may further complicate matters.  Sorry...
> Some on the list may be aware that SMPTE (Society of Motion Picture and
> Television Engineers) is coming close to completing a standard for the
> repurposing of broadcast captions for IP delivery.  This standard, called
> SMPTE-TT, is based almost entirely on TTML.  SMPTE-TT will provide
> broadcasters a clearly defined method for converting huge libraries of
> existing captions for Web delivery.
> Many here may also be aware of legislation making its way through the U.S.
> Congress that will, in some form, mandate the inclusion of captions and
> descriptions on some types of video material on the Web, most likely related
> to material that originates in the broadcast sphere and is then transferred
> to the Web.  The U.S. House of Representatives passed its version of the
> bill (HR3101, The 21st-Century Communications and Video Accessibility Act;
> http://www.coataccess.org/node/9733) last week, and the Senate is still
> debating its version but is expected to complete its work soon.
> Among its many provisions, HR3101 contains the following language:
> ============
> (1) CLOSED-CAPTIONING REPORT.—Within 6 months after the date of the first
> meeting of the Advisory Committee, the Advisory Committee shall develop and
> submit to the Commission a report that includes the following:
> (A) An identification of the performance objectives for protocols,
> technical capabilities, and technical procedures needed to
> permit content providers, content distributors, Internet service providers,
> software developers, and device manufacturers to
> reliably encode, transport, receive, and render closed captions of video
> programming delivered using Internet protocol.
> (B) An identification of additional protocols, technical capabilities, and
> technical procedures beyond those available as of the
>  date of enactment of this Act for the delivery of closed captions of video
> programming delivered using Internet protocol that
> are necessary to meet the performance objectives identified under
> subparagraph (A).
> (C) A recommendation for any regulations that may be necessary to ensure
> compatibility between video programming
> delivered using Internet protocol and devices capable of receiving and
> displaying such programming in order to facilitate
> access to closed captions.
> ============
> C is most relevant here:  it’s stating that the committee must recommend a
> format for IP delivery of captions.  The committee specified in (1) will
> probably have significant representation from the broadcast world, and my
> educated guess is that broadcasters are probably going to push for SMPTE-TT
> as the standard to specify in the regulations.  If there is a disconnect
> between this recommendation and what is recommended in HTML5, it could
> create a significant headache for the broadcast industry.  In short,
> harmonization of the text-display formats would be ideal.
> It’s important to keep this specific issue in mind while debating the
> text-format problem, and I raise it just to remind everyone that a good deal
> of video on the Web, especially captioned video, originates elsewhere and
> will continue to do so for some time.  The amount of captioned programming
> repurposed from the broadcast world is significant, and we should be paying
> close attention to what is happening there.  Broadcasters will probably
> favor a single conversion format for captions from terrestrial/cable to Web.
>  In other words, if they’re already having to convert from CEA-608/708 to
> SMPTE-TT (not a done deal), they’re probably not going to want to do another
> conversion, with potentially different results or limitations, to whatever
> format is recommended by HTML5 and its implementers.
> Discuss.
> Thanks.
> Geoff/NCAM
Received on Friday, 6 August 2010 00:08:08 UTC

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