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Re: TTML / tts:showBackground='always'

From: Glenn Adams <glenn@skynav.com>
Date: Wed, 7 Dec 2016 11:05:18 -0700
Message-ID: <CACQ=j+c=uXYPFOFHVZihvWyChjpyQHUB7qTGRxOtVDTAwgqUfw@mail.gmail.com>
To: sylvain.kervadec@orange.com
Cc: Nigel Megitt <nigel.megitt@bbc.co.uk>, "public-tt@w3.org" <public-tt@w3.org>
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.
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Received on Wednesday, 7 December 2016 18:06:15 UTC

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