- From: Nigel Megitt <nigel.megitt@bbc.co.uk>
- Date: Wed, 7 Dec 2016 11:27:20 +0000
- To: "sylvain.kervadec@orange.com" <sylvain.kervadec@orange.com>, "public-tt@w3.org" <public-tt@w3.org>
- Message-ID: <D46DA244.32004%nigel.megitt@bbc.co.uk>
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<mailto:sylvain.kervadec@orange.com>" <sylvain.kervadec@orange.com<mailto:sylvain.kervadec@orange.com>>
Date: Wednesday, 7 December 2016 at 09:41
To: "public-tt@w3.org<mailto:public-tt@w3.org>" <public-tt@w3.org<mailto:public-tt@w3.org>>
Subject: TTML / tts:showBackground='always'
Resent-From: <public-tt@w3.org<mailto: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" xmlns:ttp="http://www.w3.org/2006/10/ttaf1#parameter" xmlns:tts="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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Received on Wednesday, 7 December 2016 11:27:53 UTC