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

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

These are good considerations from the current wording however I'm not sure that the intention was to make them different – Pierre, perhaps IMSC should include these factors in the definition of presented region, additionally?

Kind regards,

Nigel


On 21/07/2014 17:39, "Glenn Adams" <glenn@skynav.com<mailto:glenn@skynav.com>> wrote:




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

These are good considerations from the current wording however I'm not sure that the intention was to make them different – Pierre, perhaps IMSC should include these factors in the definition of presented region, additionally?


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<mailto: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<mailto:sysbot%2Btracker@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
>>
>>
>>