Re: TTML / tts:showBackground='always'

On Wed, Dec 7, 2016 at 11:42 AM, Glenn Adams <glenn@skynav.com> wrote:

> To be clear, I should add that, if no timing appears on region, then
> regions are always temporally active in TTML1; therefore, if showBackground
> is always, then you are correct that a region would be displayed regardless
> of whether content is selected into the region. Note, however, that if a
> region has a transparent background, then there would be no visible marks.
>
> You will need to specify whenVisible on showBackground to avoid this
> situation.
>

s/Visible/Active/


> In TTML2, one could simply specify
>
> <initial tts:showBackground="whenActive"/>
>
> to change the initial value, but you don't have this option in TTML1/IMSC1.
>
>
> On Wed, Dec 7, 2016 at 11:05 AM, Glenn Adams <glenn@skynav.com> wrote:
>
>>
>>
>> On Wed, Dec 7, 2016 at 7:24 AM, <sylvain.kervadec@orange.com> wrote:
>>
>>> Dear Nigel,
>>>
>>>
>>>
>>>             Thanks for your feedback.
>>>
>>> This errata however clarifies the ‘whenActive’ case, but my
>>> misunderstanding concerns the ‘always’ case.
>>>
>>>
>>>
>>> It may come from my wrong interpretation of what is a “Temporally Active
>>> Region”.
>>>
>>> In my example, only the content elements carry timing attributes
>>> (‘begin’ and ‘end’). My understanding is that a region is a temporally
>>> active region when a temporally active content element is associated with
>>> it. Temporally inactive regions are thus not displayed, whatever the value
>>> of tts:showBackground.
>>>
>>
>> Regions are also timed and can take begin/end/dur. See also [1] and [2],
>> particularly:
>>
>> > To the extent that time semantics apply to the content of the layout element,
>> the implied time interval of this element is defined to be coterminous with
>> the *Root Temporal Extent*.
>> [1] https://www.w3.org/TR/ttaf1-dfxp/#layout-vocabulary-region
>> [2] https://www.w3.org/TR/ttaf1-dfxp/#layout-vocabulary-layout
>>
>>
>>
>>> But for example, if a region has to be considered as temporally active
>>> during the entire life of the document, then the tts:showBackground value
>>> has to be evaluated and rendered, even when no content element associated
>>> with this region is temporally active.
>>>
>>>
>>>
>>> IMSC1 prohibits overlapping presented regions. My example would thus be
>>> allowed or prohibited depending on the answer (Actually, it breaks IMSC1
>>> compatibility on other features).
>>>
>>>
>>>
>>> Best regards,
>>>
>>> Sylvain.
>>>
>>>
>>>
>>>
>>>
>>> *De :* Nigel Megitt [mailto:nigel.megitt@bbc.co.uk]
>>> *Envoyé :* mercredi 7 décembre 2016 12:27
>>> *À :* KERVADEC Sylvain IMT/OLPS; public-tt@w3.org
>>> *Objet :* Re: TTML / tts:showBackground='always'
>>>
>>>
>>>
>>> Dear Sylvain,
>>>
>>>
>>>
>>> Please could you read the errata to TTML1 at https://www.w3.org/2013/09/
>>> ttml1-errata.html#errata-8.2.17-1 and see if it answers your question?
>>>
>>>
>>>
>>> For ease of reference, that section is:
>>>
>>>
>>>
>>> [[
>>>
>>> Correction in TTML1 Section 8.2.17 - tts:showBackground attribute
>>> <http://www.w3.org/TR/2013/REC-ttml1-20130924/#style-attribute-showBackground> (published
>>> 2014-07-31)
>>>
>>> *Description*:
>>>
>>> Clarify meaning of whenActive.
>>>
>>> *Resolution*:
>>>
>>> Add the following paragraph immediately prior to the paragraph starting
>>> with "If a computed value of the property ...":
>>>
>>> A region satisfies the whenActive case if (1) it is a *Temporally
>>> Active Region* and (2) content is selected into the region, where that
>>> content is also *Temporally Active*.
>>> ------------------------------
>>>
>>> ]]
>>>
>>>
>>>
>>> Kind regards,
>>>
>>>
>>>
>>> Nigel
>>>
>>>
>>>
>>>
>>>
>>> *From: *"sylvain.kervadec@orange.com" <sylvain.kervadec@orange.com>
>>> *Date: *Wednesday, 7 December 2016 at 09:41
>>> *To: *"public-tt@w3.org" <public-tt@w3.org>
>>> *Subject: *TTML / tts:showBackground='always'
>>> *Resent-From: *<public-tt@w3.org>
>>> *Resent-Date: *Wednesday, 7 December 2016 at 09:43
>>>
>>>
>>>
>>> Dear tt experts,
>>>
>>>
>>>
>>>             I am looking for some clarifications on the expected
>>> behavior of the tts:showBackground parameter defined on a temporally
>>> inactive region.
>>>
>>> To be more specific, I would like to know if the background of a
>>> temporally inactive region with a tts:showBackground equal to ‘always’
>>> shall be displayed or not.
>>>
>>> The topic has already been discussed (https://www.w3.org/AudioVideo
>>> /TT/tracker/issues/314, and 313, 330), but I still don’t know what is
>>> the correct answer.
>>>
>>>
>>>
>>> I am using TTML2 as a reference, as it introduces some missing
>>> definitions on active regions:
>>>
>>> The tts:showBackground definition says that “the background color of a
>>> region is always rendered when performing presentation processing on a
>>> visual medium”, when its value is equal to ‘always’.
>>>
>>> However, the text also says “For the purpose of determining the
>>> semantics of presentation processing, a region that is temporally inactive
>>> must not produce any visible marks when presented on a visual medium.”
>>>
>>> Reading IMSC1, “A presented region is a temporally active region that
>>> satisfies the following conditions:..” seems to indicate that an inactive
>>> region shall not be presented.
>>>
>>>
>>>
>>> My understanding is thus that an inactive region shall not be displayed,
>>> whatever the value of tts:showBackground, but I would appreciate your
>>> guidance on the topic.
>>>
>>>
>>>
>>> Here is an example:
>>>
>>>
>>>
>>> *<?xml version="1.0" encoding="UTF-8"?>*
>>>
>>> *<tt xml:lang="fre" xmlns="http://www.w3.org/2006/10/ttaf1
>>> <http://www.w3.org/2006/10/ttaf1>"
>>> xmlns:ttp="http://www.w3.org/2006/10/ttaf1#parameter
>>> <http://www.w3.org/2006/10/ttaf1#parameter>"
>>> xmlns:tts="http://www.w3.org/2006/10/ttaf1#styling
>>> <http://www.w3.org/2006/10/ttaf1#styling>" ttp:cellResolution="50 30">*
>>>
>>> *   <head>*
>>>
>>> *      <styling>*
>>>
>>> *         <style xml:id="ts0" tts:fontFamily="monospaceSansSerif"
>>> tts:lineHeight="1c" tts:textDecoration="none" tts:fontWeight="normal"
>>> tts:fontStyle="normal" tts:fontSize="1c 1c" tts:color="#FFFFFFFF"
>>> tts:backgroundColor="#00000064" tts:textOutline="#000000FF 0.1c 0c"/>*
>>>
>>> *         <style xml:id="ts1" tts:lineHeight="2c"
>>> tts:textDecoration="none" tts:fontWeight="normal" tts:fontStyle="normal"
>>> tts:fontSize="1c 2c" tts:color="#FFFFFFFF" tts:backgroundColor="#00000064"
>>> tts:textOutline="#000000FF 0.1c 0c"/>*
>>>
>>> *         <style xml:id="ps0" tts:textAlign="center"/>*
>>>
>>> *      </styling>*
>>>
>>> *      <layout>*
>>>
>>> *         <region xml:id="r0" tts:origin="10% 73%" tts:extent="80% 17%"
>>> tts:displayAlign="before"/>*
>>>
>>> *         <region xml:id="r1" tts:origin="10% 66%" tts:extent="80% 24%"
>>> tts:displayAlign="before"/>*
>>>
>>> *      </layout>*
>>>
>>> *   </head>*
>>>
>>> *   <body>*
>>>
>>> *      <div style="ts0">*
>>>
>>> *         <p region="r0" begin="00:00:00.280" end="00:00:01.640"
>>> style="ps0">*
>>>
>>> *            <span style="ts1" xml:space="preserve">extirpé ?</span>*
>>>
>>> *         </p>*
>>>
>>> *         <p region="r0" begin="00:00:02.720" end="00:00:04.840"
>>> style="ps0">*
>>>
>>>             *<span style="ts1" xml:space="preserve">Je dois dire
>>> que...</span>*
>>>
>>>          *</p>*
>>>
>>> *         <p region="r0" begin="00:00:07.880" end="00:00:09.960"
>>> style="ps0">*
>>>
>>>             *<span style="ts1" xml:space="preserve">mes yeux sont
>>> verts, en fait.</span>*
>>>
>>>          *</p>*
>>>
>>> *         <p region="r1" begin="00:00:11.360" end="00:00:11.360"
>>> style="ps0">*
>>>
>>>             *<span style="ts1" xml:space="preserve">Je ne qualifierais
>>> pas</span>*
>>>
>>>          *</p>*
>>>
>>> *         <p region="r1" begin="00:00:11.360" end="00:00:13.280"
>>> style="ps0">*
>>>
>>>             *<span style="ts1" xml:space="preserve">Je ne qualifierais
>>> pas</span>*
>>>
>>>             *<br/>*
>>>
>>> *            <span style="ts1" xml:space="preserve">notre
>>> réticence</span>*
>>>
>>> *         </p>*
>>>
>>> *      </div>*
>>>
>>> *   </body>*
>>>
>>> *</tt>*
>>>
>>>
>>>
>>> The tts:showBackground defaults to ‘always’.
>>>
>>> Two overlapping regions are defined (for single-line and two-lines
>>> subtitles), only one being active at any time.
>>>
>>> If we have to display the background for inactive regions, it does not
>>> look good, as we have two semi-transparent regions on top of each other.
>>>
>>> Adding tts:showBackground=’whenActive’ would solve our problem, but our
>>> contents have been generated without any tts:showBackground value so far.
>>>
>>>
>>>
>>>
>>>
>>> Thanks in advance for your help.
>>>
>>> Best regards,
>>>
>>> Sylvain
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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>>> a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration,
>>> Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci.
>>>
>>> This message and its attachments may contain confidential or privileged information that may be protected by law;
>>> they should not be distributed, used or copied without authorisation.
>>> If you have received this email in error, please notify the sender and delete this message and its attachments.
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>>
>