Re: ISSUE-313 (Presented Region is informative only): Presented Region section is informative only [TTML IMSC 1.0]

On Mon, Jul 21, 2014 at 4:08 AM, Nigel Megitt <nigel.megitt@bbc.co.uk>
wrote:

> Hi Pierre,
>
> s/A presented region is a region that satisfies all of the following
> conditions are true:/A presented region is a region that satisfies all of
> the following conditions:
>
> Then this is acceptable to me to close Issue-313, as discussed.
>
> However I note that we haven't resolved whether there is any substantive
> difference between 'presented region' in IMSC 1 and 'temporally active
> region' in TTML 1 SE. If they are synonymous and as a result of Issue-314
> we add an erratum to TTML 1 SE to define "temporally active region" then
> we should modify IMSC 1 to use that term in place of "presented region".
>

I think they are not synonymous since a temporally active region may not
produce any renderable pixels (i.e., not be presented) for a number of
reasons, including:

   -
   - extent is zero in some dimension
   - origin is such that region doesn't intersect with root container region
   - display is none

visible is hidden
opacity is 1

> Also, I note from §2.3 in [1] that it is both a requirement to define
> terms and a good practice ("Good Practice 9" also in [1]) to consolidate
> the definitions in a glossary section. I will raise a separate issue that
> IMSC 1 needs to meet the requirements of this document and as far as
> possible also the good practices.
>
> Kind regards,
>
> Nigel
>
> [1] QA Framework: Specification Guidelines
> http://www.w3.org/TR/qaframe-spec/#define-terms-section
>
>
>
> On 20/07/2014 23:03, "Pierre-Anthony Lemieux" <pal@sandflow.com> wrote:
>
> >Hi Nigel,
> >
> >Please indicate whether the text at [1] resolves your comment per your
> >suggestion at [2].
> >
> >[1]
> >
> https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml-ww-profiles/ttml-ww-profiles
> >.html#presented-region
> >[2] http://www.w3.org/AudioVideo/TT/tracker/issues/313
> >
> >Thanks,
> >
> >-- Pierre
> >
> >On Wed, May 21, 2014 at 6:03 AM, Timed Text Working Group Issue
> >Tracker <sysbot+tracker@w3.org> wrote:
> >> ISSUE-313 (Presented Region is informative only): Presented Region
> >>section is informative only [TTML IMSC 1.0]
> >>
> >> http://www.w3.org/AudioVideo/TT/tracker/issues/313
> >>
> >> Raised by: Nigel Megitt
> >> On product: TTML IMSC 1.0
> >>
> >> The definition of Presented Region [1] appears intended to add no
> >>information relative to what is in TTML1SE. I suggest making it
> >>informative rather than normative.
> >>
> >> However it does differ in that in TTML1SE temporally active regions
> >>with opacity=0 will be included in the intermediate synchronic document
> >>construction. Note that TTML1SE does not actually define "temporally
> >>active" directly as used in §9.3.2 Intermediate Synchronic Document
> >>Construction (though it may be implied by reference to SMIL semantics).
> >>Therefore another solution to this issue would therefore be to rephrase
> >>in terms of a localised definition of "temporally active" as applied to
> >>regions.
> >>
> >> For example:
> >>
> >> A region, as defined in [TTML1], is considered temporally active if all
> >>of the following conditions are true:
> >> ...
> >>
> >> Arguably this should be captured in an errata to TTML1SE and not needed
> >>in IMSC 1.0 at all.
> >>
> >> [1] http://www.w3.org/TR/ttml-imsc1/#presented-region
> >> [2] http://www.w3.org/TR/ttml1/#semantics-region-layout-step-1
> >>
> >>
> >>
>
>
>