- From: Nigel Megitt <nigel.megitt@bbc.co.uk>
- Date: Mon, 21 Jul 2014 16:44:31 +0000
- To: Glenn Adams <glenn@skynav.com>
- CC: Pierre-Anthony Lemieux <pal@sandflow.com>, Timed Text Working Group <public-tt@w3.org>
- Message-ID: <CFF3016C.2059B%nigel.megitt@bbc.co.uk>
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 >> >> >>
Received on Monday, 21 July 2014 16:45:03 UTC