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Re: Implicit duration of anonymous spans + error at MediaSeqTiming002.xml?

From: Glenn Adams <glenn@skynav.com>
Date: Sat, 23 Dec 2017 12:30:49 -0700
Message-ID: <CACQ=j+fYq48KoN5Wu-3riJtiT_bJpiRQiDxTbS4xpwAcETjFeg@mail.gmail.com>
To: Pierre-Anthony Lemieux <pal@sandflow.com>
Cc: TTWG <public-tt@w3.org>
On Sat, Dec 23, 2017 at 12:26 AM, Pierre-Anthony Lemieux <pal@sandflow.com>
wrote:

> Hi all,
>
> The discussion at [1] on the implicit duration of singleton spans has
> prompted me to review the TTML1 and IMSC1 tests.
>
> [1] https://github.com/w3c/ttml1/issues/193
>
> I am wondering if MediaSeqTiming002.xml might have incorrect guidance.
> As described at [2], it implies that "default duration for elements in
> [a seq container] is 0" and that the following should not be rendered:
>
> <div timeContainer="seq" dur="20s">
> ...
> <p begin="00:00:05:00">This text must not appear.</p>
> ...
> </div>
>
> Is that correct? Isn't the implicit duration of the <p> indefinite
> since its anonymous span has an indefinite duration per TTML1?
>

The relevant spec text is in 10.4:

The implicit duration of an anonymous span is defined as follows: if the
> anonymous span's parent time container is a parallel time container, then
> the implicit duration is equivalent to the indefinite duration value as
> defined by [SMIL 2.1] <https://w3c.github.io/ttml1/index.html#smil21>; if
> the anonymous span's parent time container is a sequential time container,
> then the implicit duration is equivalent to zero.


which handles the cases of the parent being a par or a seq distinctly.


> Best,
>
> -- Pierre
>
> [2] https://github.com/w3c/ttml1/issues/303
>
>
Received on Saturday, 23 December 2017 19:31:42 UTC

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