RE: Comments on Working Draft "Timed Text (TT) Authoring Format 1.0 Use Cases and Requirements"

Dear Guido,

The TTWG has reviewed your comments on [1] and provides the
following responses (inserted inline below).

[1] http://www.w3.org/TR/2003/WD-tt-af-1-0-req-20030915/

We greatly appreciate Nokia's efforts to review and comment, and
understand that this requires valuable resources to accomplish.

Regards,
Glenn Adams, Chair, for TTWG

> From: <guido.grassel@nokia.com> 
> Date: Mon, 8 Dec 2003 14:41:28 +0200
> To: <public-tt@w3.org> 
> Cc: <guido.grassel@nokia.com>, <Art.Barstow@nokia.com> 

> NOK-1: The TT AF should not duplicate functionality that can already
> be found from existing or upcoming W3C Recommendations. Instead it
> should adopt useful functionality from W3C languages such as SMIL,
> XHTML, SVG or CSS. We request adding such a requirement to section
> 4.1. 

We interpret this requirement as stating essentially the following:
"don't invent something new [unless you have a good reason to do so],
and in case you don't invent, then adopt an existing W3C technology".

Although we view this as a very basic requirement under which we have
been operating, we have no objection to documenting it as such;
therfore, we will add a new general requirement to this effect.

> NOK-2: Use of the TT AF in combination with SVG and SMIL are very
> important and should be mentioned as a requirement. For instance, it
> should be possible to use the TT AF as a 'textstream' media object in
> a SMIL presentation.

The current work (and requirements) document focuses solely on the
specification and use of an authoring content format, and not a
distribution format. 

Since SMIL is effectively designed to work with distribution formats
for use by its media objects, we believe it is best to not explicitly
define such usage in the TT Authoring Format Requirements.
Nevertheless, we recognize the need for such a usage, and intend to
address that as possible future work of the TTWG. In this regard, we
would solicit Nokia's participation in helping define such a
distribution format.

Note that the current requirements document does not exclude the
use of the authoring format as a distribution format; so, it would be
possible, though perhaps not desirable, to use the authoring format
directly as content referenced by a text media object in SMIL. Keep
in mind, however, that it is unlikely that the current authoring
format will be expressed in a format that is suitable for streaming,
particularly not suited for arbitrary stream entry points.

> NOK-3: Use of the TT AF as a distribution format is insufficiently
> represented in use cases and in requirements. It appears that the TT
> AF is primarily intended as an authoring format that serves as input
> to a transcding process into a proprietary distribution format. Use
> of the TT AF as distribution format should be at least equally
> important as serving as an authoring format.

Your observation is correct. And we do view a distribution format as
important as an authoring format. However, we do not agree that use of
the authoring format directly as a distribution format is desirable.
Further, we have determined that the group should take up the formal
definition of a distribution format only after we have completed an
authoring format.

One of the primary requirements driving an authoring format is the
existence of many distribution formats, with none of these being
sufficient as an authoring format interchange standard. As a
consequence, our current focus is on satisfying this need rather than
adding one more item to the already large set of distribution formats.

As a side-bar, we have already noted that SVG would be a reasonable
distribution format.

> NOK-4: A "Basic" language profile of the TT AF should also be defined
> that is suitable for distribution to constraint embedded devices such
> as mobile terminals. We request adding such a requirement to section
> 4.1. 

We have discussed the issue of defining profiles for the authoring
format and have determined that the axis for determination should be
around authorial usage scenarios, e.g., subtitling versus captioning,
visual presentation versus aural presentation (via text to speech),
and so on.

When the TTWG does take up the definition of a distribution format,
then it is expected that device capabilities will be a determiner in
profiling the distribution format.

> NOK-5 It must be possible to author TT documents in a device
> independent way. We request adding such a requirement to section 4.1. 

Because we have focused on an authoring format rather than a
distribution format, the current approach is effectively device
independent, since we are expressing authorial intention and not
expressing device behavior. However, if you should have specific
ideas about some features being device dependent, then please
let us know.

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