Re: [IMSC] Thoughts re: issue-312 -- itts:forcedDisplay

I've been contemplating the forced display logic a bit more, and I'm
wondering why we need it at all. If any content is present in a TTML input
document to a compliant TTML presentation processor, then it must format
all of the content in accordance with the TTML presentation semantics.

That is, if there is some content in a TTML document that someone would
like to annotate as 'forcedDisplay', then it is already being displayed
(modulo time activation, tts:display, and tts:visible). In other words,
there is nothing other than these three criteria that would cause it to not
be displayed. So there is no need for forcing anything.





On Mon, Jun 23, 2014 at 9:10 AM, Glenn Adams <glenn@skynav.com> wrote:

>
> On Mon, Jun 23, 2014 at 1:43 AM, John Birch <John.Birch@screensystems.tv>
> wrote:
>
>>  As an aside, what would be the impact on conditional region use? Where
>> would content end up if the original target region was removed by a
>> condition? I can see how it might end up in a parent region, but in the
>> absence of a higher level parent region it would move to a default region?
>>
>
> We would have to address this in spec text either way. It would also be
> possible to define a ttp parameter that let the author choose the behavior:
> no region or default region.
>
>
>>
>> Best regards,
>> John
>>
>>
>>  *From*: Glenn Adams [mailto:glenn@skynav.com]
>> *Sent*: Monday, June 23, 2014 08:15 AM
>>
>> *To*: John Birch
>> *Cc*: pal@sandflow.com <pal@sandflow.com>; public-tt@w3.org <
>> public-tt@w3.org>
>> *Subject*: Re: [IMSC] Thoughts re: issue-312 -- itts:forcedDisplay
>>
>>  In that case, my original proposal to use @condition on content
>> elements should suffice, since it would have the same effect as tts:display
>> in the sense of including/excluding a content element in the layout/flow
>> process.
>>
>>  Nevertheless, I can fathom uses for such a conditional to be applied to
>> not only content elements, but also region, as well as styling. For the
>> purpose of conditionalizing styling, applying it to <set/> seems the best
>> option.
>>
>>
>> On Sun, Jun 22, 2014 at 11:46 PM, John Birch <John.Birch@screensystems.tv
>> > wrote:
>>
>>> Agreed re content selection. I am unaware of an example where preserving
>>> layout is relevant... Or would be absolutely necessary.
>>>
>>> So yes... I believe that the use case can be supported using display.
>>>
>>> best regards,
>>> John
>>>
>>>
>>>
>>>  *From*: Glenn Adams [mailto:glenn@skynav.com]
>>> *Sent*: Monday, June 23, 2014 06:28 AM
>>> *To*: John Birch
>>> *Cc*: pal@sandflow.com <pal@sandflow.com>; public-tt@w3.org <
>>> public-tt@w3.org>
>>> *Subject*: Re: [IMSC] Thoughts re: issue-312 -- itts:forcedDisplay
>>>
>>>
>>> On Sun, Jun 22, 2014 at 11:14 PM, John Birch <
>>> John.Birch@screensystems.tv> wrote:
>>>
>>>> Whilst it may be less problematic for IMSC to diverge from TTML1 I do
>>>> have more problems with it not being a subset of TTML2. My preference would
>>>> be for a solution that is compatible.
>>>>
>>>> On the forcedDisplay point I do believe that this represents a content
>>>> classification rather than a stylistic attribution... Albeit poorly named.
>>>> I.e. Forced subtitles are content that is different to 'normal'
>>>> subtitles... As Pierre has illustrated, they are often used for
>>>> translations of on-screen texts, or for translations of invented languages
>>>> (e.g. Klingon or Navi). They are a sub classification of subtitle. I am
>>>> however struggling to think of a better term than 'forced subtitles' as
>>>> other alternatives are narrower in scope.
>>>>
>>>> Consequently I suggest that these are handled as a content
>>>> categorisation that invokes a specific style. Possibly a new style
>>>> attribute value is needed: visibility = 'forced'.
>>>>
>>>
>>>  From the examples I've seen so far, this is a content selection (as in
>>> active or not active) issue rather than a style (visibility) issue. That
>>> is, I haven't seen any examples where it should map to tts:visible as
>>> opposed to tts:display.
>>>
>>>  I think we should not disconnect this issue from that of how to treat
>>> content tagged with different languages. Furthermore, we could use the
>>> @condition approach to dynamically select different region extent/origin
>>> based on media device features.
>>>
>>>
>>>>
>>>> Best regards,
>>>> John
>>>>
>>>>
>>>> John Birch | Strategic Partnerships Manager | Screen
>>>> Main Line : +44 1473 831700 | Ext : 2208 | Direct Dial : +44 1473
>>>> 834532
>>>> Mobile : +44 7919 558380 | Fax : +44 1473 830078
>>>> John.Birch@screensystems.tv | www.screensystems.tv |
>>>> https://twitter.com/screensystems
>>>>
>>>> Visit us at
>>>> Broadcast Asia, Marina Bay Sands, Singapore 17-20 June, Stand 5E4-01
>>>>
>>>>
>>>> *John Birch | Strategic Partnerships Manager | Screen *Main Line : +44
>>>> 1473 831700 | Ext : 2208 | Direct Dial : +44 1473 834532
>>>> Mobile : +44 7919 558380 | Fax : +44 1473 830078
>>>> John.Birch@screensystems.tv | www.screensystems.tv |
>>>> https://twitter.com/screensystems
>>>>
>>>>
>>>> *Visit us at Broadcast Asia, Marina Bay Sands, Singapore 17-20 June,
>>>> Stand 5E4-01*
>>>>
>>>> *P** Before printing, think about the environment*
>>>>
>>>>
>>>> *John Birch | Strategic Partnerships Manager | Screen *Main Line : +44
>>>> 1473 831700 | Ext : 2208 | Direct Dial : +44 1473 834532
>>>> Mobile : +44 7919 558380 | Fax : +44 1473 830078
>>>> John.Birch@screensystems.tv | www.screensystems.tv |
>>>> https://twitter.com/screensystems
>>>>
>>>>
>>>> *Visit us at Broadcast Asia, Marina Bay Sands, Singapore 17-20 June,
>>>> Stand 5E4-01*
>>>>
>>>> *P** Before printing, think about the environment*
>>>>
>>>>
>>>> P Before printing, think about the environment----- Original Message
>>>> -----
>>>> From: Pierre-Anthony Lemieux [mailto:pal@sandflow.com]
>>>> Sent: Monday, June 23, 2014 04:55 AM
>>>> To: Glenn Adams <glenn@skynav.com>
>>>> Cc: public-tt@w3.org <public-tt@w3.org>
>>>> Subject: Re: [IMSC] Thoughts re: issue-312 -- itts:forcedDisplay
>>>>
>>>> > If you want to define it in IMSC1 as a style attribute that will map
>>>> to a future conditional
>>>> > style construct in TTML2, then that is fine, but there is no
>>>> guarantee we will directly support
>>>> > that attribute in TTML2 (as opposed to requiring that the more
>>>> general mechanism be used). As it is,
>>>> > IMSC1 is likely not going to be a strict subset of either TTML1 or
>>>> TTML2.
>>>>
>>>> Sounds like a reasonable approach.
>>>>
>>>> Best,
>>>>
>>>> -- Pierre
>>>>
>>>> On Sun, Jun 22, 2014 at 8:45 PM, Glenn Adams <glenn@skynav.com> wrote:
>>>> > Do you have a real world example of where conditional content couldn't
>>>> > handle it? In any case, I think we can define a conditional styling
>>>> > mechanism as well as conditional content, and then author can choose
>>>> the one
>>>> > that makes sense.
>>>> >
>>>> > If you want to define it in IMSC1 as a style attribute that will map
>>>> to a
>>>> > future conditional style construct in TTML2, then that is fine, but
>>>> there is
>>>> > no guarantee we will directly support that attribute in TTML2 (as
>>>> opposed to
>>>> > requiring that the more general mechanism be used). As it is, IMSC1 is
>>>> > likely not going to be a strict subset of either TTML1 or TTML2.
>>>> >
>>>> >
>>>> > On Sun, Jun 22, 2014 at 9:42 PM, Pierre-Anthony Lemieux <
>>>> pal@sandflow.com>
>>>> > wrote:
>>>> >>
>>>> >> > In this example, the conditional content would suffice, since there
>>>> >> > is no layout interaction between the two regions.
>>>> >>
>>>> >> Perhaps, but this cannot be guaranteed to be always the case.
>>>> >>
>>>> >> -- Pierre
>>>> >>
>>>> >> On Sun, Jun 22, 2014 at 8:40 PM, Glenn Adams <glenn@skynav.com>
>>>> wrote:
>>>> >> > In this example, the conditional content would suffice, since
>>>> there is
>>>> >> > no
>>>> >> > layout interaction between the two regions.
>>>> >> >
>>>> >> >
>>>> >> > On Sun, Jun 22, 2014 at 9:31 PM, Pierre-Anthony Lemieux
>>>> >> > <pal@sandflow.com>
>>>> >> > wrote:
>>>> >> >>
>>>> >> >> Hi Glenn,
>>>> >> >>
>>>> >> >> Attached is an example inspired from an opening shot from The
>>>> Muppets
>>>> >> >> (2011) Blu-Ray.
>>>> >> >>
>>>> >> >> The forced subtitle is the translation of the "High School" sign.
>>>> It
>>>> >> >> appears when French is selected as the language, even if the user
>>>> has
>>>> >> >> not explicitly selected French subtitles, i.e. when 'forced mode'
>>>> is
>>>> >> >> true.
>>>> >> >>
>>>> >> >> The translation of the voiceover is not labeled 'forced', and thus
>>>> >> >> shows up only when French subtitles are selected, i.e. 'forced
>>>> mode'
>>>> >> >> is false.
>>>> >> >>
>>>> >> >> Best,
>>>> >> >>
>>>> >> >> -- Pierre
>>>> >> >>
>>>> >> >> P.S.: in UVVU, 'forced mode'=='true' is called "Alternate
>>>> Subtitling
>>>> >> >> Presentation Mode" and 'forced mode'=='false' is called "Primary
>>>> >> >> Subtitling Presentation Mode".
>>>> >> >>
>>>> >> >> On Sat, Jun 21, 2014 at 7:17 PM, Glenn Adams <glenn@skynav.com>
>>>> wrote:
>>>> >> >> > Could you point at or construct a real world example, i.e.,
>>>> images of
>>>> >> >> > what a
>>>> >> >> > mixture of forced and non-forced content looks like depending on
>>>> >> >> > whether
>>>> >> >> > a
>>>> >> >> > forced display parameter is true or false?
>>>> >> >> >
>>>> >> >> >
>>>> >> >> > On Sat, Jun 21, 2014 at 6:56 PM, Pierre-Anthony Lemieux
>>>> >> >> > <pal@sandflow.com>
>>>> >> >> > wrote:
>>>> >> >> >>
>>>> >> >> >> Hi Glenn,
>>>> >> >> >>
>>>> >> >> >> > why would one want it to occupy layout space if not selected?
>>>> >> >> >> > that doesn't make any sense;
>>>> >> >> >>
>>>> >> >> >> The forced content would have been positioned with the
>>>> non-forced
>>>> >> >> >> content present. Simply removing the non-forced content from
>>>> flow
>>>> >> >> >> would potentially change the rendered position of the forced
>>>> >> >> >> content.
>>>> >> >> >>
>>>> >> >> >> I will confirm this.
>>>> >> >> >>
>>>> >> >> >> Best,
>>>> >> >> >>
>>>> >> >> >> -- Pierre
>>>> >> >> >>
>>>> >> >> >> On Sat, Jun 21, 2014 at 5:50 PM, Glenn Adams <glenn@skynav.com
>>>> >
>>>> >> >> >> wrote:
>>>> >> >> >> >
>>>> >> >> >> > On Sat, Jun 21, 2014 at 6:43 PM, Pierre-Anthony Lemieux
>>>> >> >> >> > <pal@sandflow.com>
>>>> >> >> >> > wrote:
>>>> >> >> >> >>
>>>> >> >> >> >> Hi Glenn,
>>>> >> >> >> >>
>>>> >> >> >> >> Thanks for these initial thoughts.
>>>> >> >> >> >>
>>>> >> >> >> >> > 3. evaluating this sub-tree in a postorder traversal,
>>>> prune
>>>> >> >> >> >> > elements
>>>> >> >> >> >> > if they are not a content element, if they have a
>>>> condition
>>>> >> >> >> >> > attribute
>>>> >> >> >> >> > that evaluates to false,
>>>> >> >> >> >>
>>>> >> >> >> >> "Forced" does not remove the content element from layout and
>>>> >> >> >> >> flow,
>>>> >> >> >> >> but
>>>> >> >> >> >> instead
>>>> >> >> >> >> effectively sets the visibility to zero, like
>>>> >> >> >> >> tts:visibility="hidden".
>>>> >> >> >> >
>>>> >> >> >> >
>>>> >> >> >> > it should; why would one want it to occupy layout space if
>>>> not
>>>> >> >> >> > selected?
>>>> >> >> >> > that doesn't make any sense;
>>>> >> >> >> >
>>>> >> >> >> > i don't see how to handle conditional content and conditional
>>>> >> >> >> > visibility; i
>>>> >> >> >> > think the best you will get is the former
>>>> >> >> >> >
>>>> >> >> >> >>
>>>> >> >> >> >>
>>>> >> >> >> >> Best,
>>>> >> >> >> >>
>>>> >> >> >> >> -- Pierre
>>>> >> >> >> >>
>>>> >> >> >> >> On Sat, Jun 21, 2014 at 5:38 PM, Glenn Adams <
>>>> glenn@skynav.com>
>>>> >> >> >> >> wrote:
>>>> >> >> >> >> >
>>>> >> >> >> >> >
>>>> >> >> >> >> > On Sat, Jun 21, 2014 at 6:07 PM, Pierre-Anthony Lemieux
>>>> >> >> >> >> > <pal@sandflow.com>
>>>> >> >> >> >> > wrote:
>>>> >> >> >> >> >>
>>>> >> >> >> >> >> > What do you mean by "application" in this context?
>>>> >> >> >> >> >>
>>>> >> >> >> >> >> The entity that is instructing the presentation
>>>> processor to
>>>> >> >> >> >> >> render
>>>> >> >> >> >> >> the IMSC document.
>>>> >> >> >> >> >>
>>>> >> >> >> >> >> > I also don't know what parameter means in this context,
>>>> >> >> >> >> >> > e.g., what does it mean vis-a-vis a TTML parameter,
>>>> i.e.,
>>>> >> >> >> >> >> > an attribute expressing a TTML parameter.
>>>> >> >> >> >> >>
>>>> >> >> >> >> >> It is not a TTML parameter, as in a ttp:*, but instead a
>>>> state
>>>> >> >> >> >> >> variable passed to the presentation processor
>>>> instructing it
>>>> >> >> >> >> >> to
>>>> >> >> >> >> >> render
>>>> >> >> >> >> >> or not non-forced content, like a function argument in a
>>>> >> >> >> >> >> procedural
>>>> >> >> >> >> >> language.
>>>> >> >> >> >> >>
>>>> >> >> >> >> >> > I am opposed to a one-off solution to a special case
>>>> of the
>>>> >> >> >> >> >> > conditional
>>>> >> >> >> >> >> >  content problem. And the forcedDisplay feature is
>>>> exactly
>>>> >> >> >> >> >> > such
>>>> >> >> >> >> >> > a
>>>> >> >> >> >> >> > special case.
>>>> >> >> >> >> >>
>>>> >> >> >> >> >> Can you think of a generic solution that would reduce to
>>>> a
>>>> >> >> >> >> >> single
>>>> >> >> >> >> >> attribute controlling the rendering of forced content?
>>>> If so,
>>>> >> >> >> >> >> we
>>>> >> >> >> >> >> could
>>>> >> >> >> >> >> consider using it in IMSC.
>>>> >> >> >> >> >
>>>> >> >> >> >> >
>>>> >> >> >> >> > I haven't given it much thought, but if we were to
>>>> introduce as
>>>> >> >> >> >> > the
>>>> >> >> >> >> > general
>>>> >> >> >> >> > mechanism a new element type:
>>>> >> >> >> >> >
>>>> >> >> >> >> > <tt:switch condition="expression">
>>>> >> >> >> >> > ... content elements ...
>>>> >> >> >> >> > </tt:switch>
>>>> >> >> >> >> >
>>>> >> >> >> >> > then we could also, or as an alternative, introduce an
>>>> >> >> >> >> > attribute
>>>> >> >> >> >> > @condition
>>>> >> >> >> >> > on content element vocabulary, e.g.,
>>>> >> >> >> >> >
>>>> >> >> >> >> > <div condition="expression"/>
>>>> >> >> >> >> >
>>>> >> >> >> >> > where expression uses a simple expression language such as
>>>> >> >> >> >> > media
>>>> >> >> >> >> > queries
>>>> >> >> >> >> > level 4 [1] or a derivative.
>>>> >> >> >> >> >
>>>> >> >> >> >> > [1] http://dev.w3.org/csswg/mediaqueries4/
>>>> >> >> >> >> >
>>>> >> >> >> >> > For example,
>>>> >> >> >> >> >
>>>> >> >> >> >> > <p condition="(forced)"/>
>>>> >> >> >> >> >
>>>> >> >> >> >> > <p condition="not (forced)"/>
>>>> >> >> >> >> >
>>>> >> >> >> >> > <p condition="(locale: en)"/>
>>>> >> >> >> >> >
>>>> >> >> >> >> > <p condition="not (locale: en)"/>
>>>> >> >> >> >> >
>>>> >> >> >> >> > <p condition="(forced) or not (locale: en)"/>
>>>> >> >> >> >> >
>>>> >> >> >> >> > ...
>>>> >> >> >> >> >
>>>> >> >> >> >> > Where the semantics of @condition is essentially changing
>>>> step
>>>> >> >> >> >> > 3
>>>> >> >> >> >> > of
>>>> >> >> >> >> > 9.3.3
>>>> >> >> >> >> > [construct intermediate document] to read essentially as
>>>> >> >> >> >> > follows:
>>>> >> >> >> >> >
>>>> >> >> >> >> > 3. evaluating this sub-tree in a postorder traversal,
>>>> prune
>>>> >> >> >> >> > elements
>>>> >> >> >> >> > if
>>>> >> >> >> >> > they
>>>> >> >> >> >> > are not a content element, if they have a condition
>>>> attribute
>>>> >> >> >> >> > that
>>>> >> >> >> >> > evaluates
>>>> >> >> >> >> > to false, if they are temporally inactive, if they are
>>>> empty,
>>>> >> >> >> >> > or
>>>> >> >> >> >> > if
>>>> >> >> >> >> > they
>>>> >> >> >> >> > aren't associated with region R according to the
>>>> [associate
>>>> >> >> >> >> > region]
>>>> >> >> >> >> > procedure;
>>>> >> >> >> >> >
>>>> >> >> >> >> >>
>>>> >> >> >> >> >>
>>>> >> >> >> >> >> Thanks,
>>>> >> >> >> >> >>
>>>> >> >> >> >> >> -- Pierre
>>>> >> >> >> >> >>
>>>> >> >> >> >> >> On Fri, Jun 20, 2014 at 10:56 PM, Glenn Adams
>>>> >> >> >> >> >> <glenn@skynav.com>
>>>> >> >> >> >> >> wrote:
>>>> >> >> >> >> >> >
>>>> >> >> >> >> >> > On Fri, Jun 20, 2014 at 10:33 PM, Pierre-Anthony
>>>> Lemieux
>>>> >> >> >> >> >> > <pal@sandflow.com>
>>>> >> >> >> >> >> > wrote:
>>>> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> Hi Glenn,
>>>> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> Thanks for the feedback.
>>>> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> > no, [forcedDisplayModeParameter] should not be a
>>>> >> >> >> >> >> >> > parameter,
>>>> >> >> >> >> >> >> > in
>>>> >> >> >> >> >> >> > which
>>>> >> >> >> >> >> >> > it would go into some
>>>> >> >> >> >> >> >> > parameter namespace, but should be a metadata
>>>> attribute,
>>>> >> >> >> >> >> >> > ittm:forcedDisplay
>>>> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> forcedDisplayModeParameter != itts:forcedDisplay.
>>>> >> >> >> >> >> >> forcedDisplayModeParameter would be a parameter
>>>> passed by
>>>> >> >> >> >> >> >> the
>>>> >> >> >> >> >> >> application to the processor, not a parameter within
>>>> the
>>>> >> >> >> >> >> >> document.
>>>> >> >> >> >> >> >
>>>> >> >> >> >> >> >
>>>> >> >> >> >> >> > What do you mean by "application" in this context? I
>>>> also
>>>> >> >> >> >> >> > don't
>>>> >> >> >> >> >> > know
>>>> >> >> >> >> >> > what
>>>> >> >> >> >> >> > parameter means in this context, e.g., what does it
>>>> mean
>>>> >> >> >> >> >> > vis-a-vis
>>>> >> >> >> >> >> > a
>>>> >> >> >> >> >> > TTML
>>>> >> >> >> >> >> > parameter, i.e., an attribute expressing a TTML
>>>> parameter.
>>>> >> >> >> >> >> >
>>>> >> >> >> >> >> >>
>>>> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> > in other words, TTML will remain silent on any
>>>> >> >> >> >> >> >> > presentation
>>>> >> >> >> >> >> >> > semantics
>>>> >> >> >> >> >> >> > of
>>>> >> >> >> >> >> >> > such an attribute;
>>>> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> How would interoperability be achieved?
>>>> >> >> >> >> >> >
>>>> >> >> >> >> >> >
>>>> >> >> >> >> >> > By defining a standard mechanism for expressing
>>>> conditional
>>>> >> >> >> >> >> > content
>>>> >> >> >> >> >> > contingent on external processor state, e.g., selected
>>>> >> >> >> >> >> > language,
>>>> >> >> >> >> >> > whether
>>>> >> >> >> >> >> > display of some content is forced or not, etc.
>>>> >> >> >> >> >> >
>>>> >> >> >> >> >> > I am opposed to a one-off solution to a special case
>>>> of the
>>>> >> >> >> >> >> > conditional
>>>> >> >> >> >> >> > content problem. And the forcedDisplay feature is
>>>> exactly
>>>> >> >> >> >> >> > such
>>>> >> >> >> >> >> > a
>>>> >> >> >> >> >> > special
>>>> >> >> >> >> >> > case.
>>>> >> >> >> >> >> >
>>>> >> >> >> >> >> >>
>>>> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> Thanks,
>>>> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> -- Pierre
>>>> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> On Fri, Jun 20, 2014 at 8:58 PM, Glenn Adams
>>>> >> >> >> >> >> >> <glenn@skynav.com>
>>>> >> >> >> >> >> >> wrote:
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> > On Fri, Jun 20, 2014 at 7:05 PM, Pierre-Anthony
>>>> Lemieux
>>>> >> >> >> >> >> >> > <pal@sandflow.com>
>>>> >> >> >> >> >> >> > wrote:
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >> Hi all,
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >> During our last call, I noted two concerns with the
>>>> >> >> >> >> >> >> >> itts:forcedDisplay
>>>> >> >> >> >> >> >> >> feature as currently drafted.
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >> (a) the semantics of the itts:forcedDisplay
>>>> feature are
>>>> >> >> >> >> >> >> >> not
>>>> >> >> >> >> >> >> >> sufficiently specified
>>>> >> >> >> >> >> >> >> (b) the representation of itts:forcedDisplay as an
>>>> >> >> >> >> >> >> >> attribute
>>>> >> >> >> >> >> >> >> is
>>>> >> >> >> >> >> >> >> not
>>>> >> >> >> >> >> >> >> desirable
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> > that should read as a style attribute
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >> To address (a), below is proposed prose:
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >> """
>>>> >> >> >> >> >> >> >> The presentation processor SHALL accept an optional
>>>> >> >> >> >> >> >> >> boolean
>>>> >> >> >> >> >> >> >> parameter
>>>> >> >> >> >> >> >> >> called forcedDisplayModeParameter, whose value may
>>>> be
>>>> >> >> >> >> >> >> >> set
>>>> >> >> >> >> >> >> >> by
>>>> >> >> >> >> >> >> >> the
>>>> >> >> >> >> >> >> >> application. If not set, the value of
>>>> >> >> >> >> >> >> >> forcedDisplayModeParameter
>>>> >> >> >> >> >> >> >> shall
>>>> >> >> >> >> >> >> >> be assumed to be equal to "false".
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> > no, it should not be a parameter, in which it would
>>>> go
>>>> >> >> >> >> >> >> > into
>>>> >> >> >> >> >> >> > some
>>>> >> >> >> >> >> >> > parameter
>>>> >> >> >> >> >> >> > namespace, but should be a metadata attribute,
>>>> >> >> >> >> >> >> > ittm:forcedDisplay
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> > i'm not sure why you wish to lengthen the name
>>>> >> >> >> >> >> >> > unnecessarily
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >> If the value of forcedDisplayModeParameter is
>>>> "true", a
>>>> >> >> >> >> >> >> >> content
>>>> >> >> >> >> >> >> >> element with a itts:forcedDisplay computed value of
>>>> >> >> >> >> >> >> >> "false"
>>>> >> >> >> >> >> >> >> shall
>>>> >> >> >> >> >> >> >> be
>>>> >> >> >> >> >> >> >> assumed to have a tts:visibility computed value
>>>> equal to
>>>> >> >> >> >> >> >> >> "hidden",
>>>> >> >> >> >> >> >> >> even if tts:visibility is otherwise set to "true".
>>>> >> >> >> >> >> >> >> """
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> > now, this is again placing style/presentation
>>>> semantics
>>>> >> >> >> >> >> >> > on
>>>> >> >> >> >> >> >> > this
>>>> >> >> >> >> >> >> > metadata
>>>> >> >> >> >> >> >> > attribute, which is inapropriate
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >> The idea is to essentially ignore the
>>>> itts:forcedDisplay
>>>> >> >> >> >> >> >> >> attribute
>>>> >> >> >> >> >> >> >> unless otherwise specifically requested by the
>>>> >> >> >> >> >> >> >> application.
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> > i'm not sure what "requested by the application"
>>>> means
>>>> >> >> >> >> >> >> > here
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >> This also
>>>> >> >> >> >> >> >> >> clarifies that itts:forcedDisplay has "no effect on
>>>> >> >> >> >> >> >> >> content
>>>> >> >> >> >> >> >> >> layout
>>>> >> >> >> >> >> >> >> or
>>>> >> >> >> >> >> >> >> composition, but merely determines whether composed
>>>> >> >> >> >> >> >> >> content
>>>> >> >> >> >> >> >> >> is
>>>> >> >> >> >> >> >> >> visible
>>>> >> >> >> >> >> >> >> or not."
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> > if that is the purpose, then the tts:visibility
>>>> property
>>>> >> >> >> >> >> >> > should
>>>> >> >> >> >> >> >> > be
>>>> >> >> >> >> >> >> > used
>>>> >> >> >> >> >> >> > and
>>>> >> >> >> >> >> >> > therefore there is no need for a new forcedDisplay
>>>> >> >> >> >> >> >> > attribute
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >> As next step, I plan to create examples.
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >> Re: (b), I am not comfortable rejecting a solution
>>>> that
>>>> >> >> >> >> >> >> >> users
>>>> >> >> >> >> >> >> >> have
>>>> >> >> >> >> >> >> >> devised and implemented based on actual use cases
>>>> and in
>>>> >> >> >> >> >> >> >> the
>>>> >> >> >> >> >> >> >> absence
>>>> >> >> >> >> >> >> >> of specific guidance and/or prohibition in TTML
>>>> 1.0.
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> > if those users expect that the TTWG would simply
>>>> adopt a
>>>> >> >> >> >> >> >> > solution
>>>> >> >> >> >> >> >> > as
>>>> >> >> >> >> >> >> > a
>>>> >> >> >> >> >> >> > fait
>>>> >> >> >> >> >> >> > accompli, then they are naive; an appropriate
>>>> process
>>>> >> >> >> >> >> >> > would
>>>> >> >> >> >> >> >> > have
>>>> >> >> >> >> >> >> > been
>>>> >> >> >> >> >> >> > to
>>>> >> >> >> >> >> >> > bring use cases and requirements to the TTWG first,
>>>> not
>>>> >> >> >> >> >> >> > bring a
>>>> >> >> >> >> >> >> > solution
>>>> >> >> >> >> >> >> > as
>>>> >> >> >> >> >> >> > a given
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> > at this point, I think the best that can be hoped
>>>> for
>>>> >> >> >> >> >> >> > IMSC
>>>> >> >> >> >> >> >> > is
>>>> >> >> >> >> >> >> > to
>>>> >> >> >> >> >> >> > define
>>>> >> >> >> >> >> >> > a
>>>> >> >> >> >> >> >> > metadata attribute ittm:forcedDisplay which is
>>>> described
>>>> >> >> >> >> >> >> > as
>>>> >> >> >> >> >> >> > a
>>>> >> >> >> >> >> >> > hint
>>>> >> >> >> >> >> >> > that
>>>> >> >> >> >> >> >> > the
>>>> >> >> >> >> >> >> > associated content is intended to be selected as a
>>>> >> >> >> >> >> >> > candidate
>>>> >> >> >> >> >> >> > for
>>>> >> >> >> >> >> >> > display
>>>> >> >> >> >> >> >> > by
>>>> >> >> >> >> >> >> > a higher level protocol (outside the scope of
>>>> formally
>>>> >> >> >> >> >> >> > defined
>>>> >> >> >> >> >> >> > TTML
>>>> >> >> >> >> >> >> > processing); in other words, TTML will remain
>>>> silent on
>>>> >> >> >> >> >> >> > any
>>>> >> >> >> >> >> >> > presentation
>>>> >> >> >> >> >> >> > semantics of such an attribute;
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> > on the other hand, we may choose in TTML2 to define
>>>> a
>>>> >> >> >> >> >> >> > conditional
>>>> >> >> >> >> >> >> > content
>>>> >> >> >> >> >> >> > mechanism similar to the SMIL or SVG switch
>>>> element, that
>>>> >> >> >> >> >> >> > could
>>>> >> >> >> >> >> >> > address
>>>> >> >> >> >> >> >> > this
>>>> >> >> >> >> >> >> > use case
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >> Best,
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >> -- Pierre
>>>> >> >> >> >> >> >> >>
>>>> >> >> >> >> >> >> >
>>>> >> >> >> >> >> >
>>>> >> >> >> >> >> >
>>>> >> >> >> >> >
>>>> >> >> >> >> >
>>>> >> >> >> >
>>>> >> >> >> >
>>>> >> >> >
>>>> >> >> >
>>>> >> >
>>>> >> >
>>>> >
>>>> >
>>>>
>>>>
>>>>  This message may contain confidential and/or privileged information.
>>>> If you are not the intended recipient you must not use, copy, disclose or
>>>> take any action based on this message or any information herein. If you
>>>> have received this message in error, please advise the sender immediately
>>>> by reply e-mail and delete this message. Thank you for your cooperation.
>>>> Screen Subtitling Systems Ltd. Registered in England No. 2596832.
>>>> Registered Office: The Old Rectory, Claydon Church Lane, Claydon, Ipswich,
>>>> Suffolk, IP6 0EQ
>>>>
>>>
>>>
>>>  This message may contain confidential and/or privileged information.
>>> If you are not the intended recipient you must not use, copy, disclose or
>>> take any action based on this message or any information herein. If you
>>> have received this message in error, please advise the sender immediately
>>> by reply e-mail and delete this message. Thank you for your cooperation.
>>> Screen Subtitling Systems Ltd. Registered in England No. 2596832.
>>> Registered Office: The Old Rectory, Claydon Church Lane, Claydon, Ipswich,
>>> Suffolk, IP6 0EQ
>>>     ­­
>>>
>>
>>
>>  This message may contain confidential and/or privileged information. If
>> you are not the intended recipient you must not use, copy, disclose or take
>> any action based on this message or any information herein. If you have
>> received this message in error, please advise the sender immediately by
>> reply e-mail and delete this message. Thank you for your cooperation.
>> Screen Subtitling Systems Ltd. Registered in England No. 2596832.
>> Registered Office: The Old Rectory, Claydon Church Lane, Claydon, Ipswich,
>> Suffolk, IP6 0EQ
>>     ­­
>>
>
>