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trackbot, start meeting
<trackbot> Meeting: Timed Text Working Group Teleconference
<trackbot> Date: 01 December 2016
<scribe> scribe: nigel
nigel: For today, I'd like to
cover the TTML Profiles registry, maybe the Unicode ticket, and
the Security & Privacy section for TTML2.
... AOB?
mike: I'd like a minute on the
IANA registry and the page that supports that, and also
... the post from Pierre about imscjs.
nigel: Sure, we did actually discuss imscjs a little last week though it's not well minuted.
nigel: This is about the issues and PRs etc, and if we should update it now.
mike: Is the IANA registration complete?
nigel: Yes it was updated on 2016-09-30
-> http://www.iana.org/assignments/media-types/application/ttml+xml
nigel: It refers to the profile
registry document.
... Now looking at the open issues/PRs:
-> https://github.com/w3c/tt-profile-registry/pulls
nigel: This is the moment to say that the open issues/pull requests are all the work to be done.
mike: I think the passage of time is sufficient here.
nigel: I concur.
group: [no objection]
mike: OK I'll go ahead and push this up towards the top of my list.
nigel: Thank you!
action-478?
<trackbot> action-478 -- Nigel Megitt to Draft a liaison to hbbtv requesting further information and proposing an option e.g. to extend imsc 1 to allow signalling of background height on span, and request timelines etc. -- due 2016-09-26 -- PENDINGREVIEW
<trackbot> http://www.w3.org/AudioVideo/TT/tracker/actions/478
nigel: This is now sent and I updated the action with the archive link to the liaison that was sent.
close action-478
<trackbot> Closed action-478.
action-487?
<trackbot> action-487 -- Nigel Megitt to Send generic liaison to atsc, arib, mpeg, dece, cta, dash-if, dtg, hbbtv, smpte. -- due 2016-11-24 -- PENDINGREVIEW
<trackbot> http://www.w3.org/AudioVideo/TT/tracker/actions/487
nigel: Same applies here - the
liaisons were sent, thanks to Pierre and all for helping
edit
... the text. Links to the liaisons as archived are in the
action.
close action-487
<trackbot> Closed action-487.
nigel: Apologies to Mike for the confusion about the SMPTE one, which was my mistake.
action-488?
<trackbot> action-488 -- Nigel Megitt to Send liaison to dvb replacing first sentence from generic response with acknowledgement sentence. -- due 2016-11-24 -- PENDINGREVIEW
<trackbot> http://www.w3.org/AudioVideo/TT/tracker/actions/488
nigel: I did this, and logged the message archive link in the action.
close action-488
<trackbot> Closed action-488.
nigel: One thing to note is I bumped the response date from 1 Jan to 8 Jan to accommodate my lateness in sending those messages. Apologies if that causes any difficulties!
action-485?
<trackbot> action-485 -- Thierry Michel to Ask richard ishida for assistance in unblocking the unicode ticket 8915. -- due 2016-11-10 -- PENDINGREVIEW
<trackbot> http://www.w3.org/AudioVideo/TT/tracker/actions/485
nigel: There has been an update on the Unicode ticket
-> http://unicode.org/cldr/trac/ticket/8915#comment:8
pierre: I think we have the
scripts to produce one of the things they are asking for, the
delta.
... Maybe we should go through the questions now?
nigel: I think that would be useful, quickly.
pierre: Question 1...
nigel: Does anyone here know the difference between supplemental and exemplar sets in Unicode?
pierre: I'm not sure, we maybe need to dig deeper or ask for clarification. This may not be a question for us to answer.
nigel: Agreed.
... It's good they're considering _how_ to do it rather than
_if_.
pierre: Exactly, that is
encouraging.
... Question 2: I think the answer is "yes" to both
questions.
... I think the Unicode tables try to be statements of fact
rather than mandatory. And that's all we need, a description of
the characters that are used for captions in a particular
language.
glenn: [speculates that
supplemental sets are additional characters but examplar sets
are lists of existing characters for a particular
context]
... So I think the answer for question 2 is yes to a and yes to
b.
nigel: +1
pierre: Question 3: We definitely have created that delta set and can point to it.
<scribe> ACTION: pal Update the Unicode ticket 8915 with a link to the deltas between what we recommend and what is already in main and aux sets. [recorded in http://www.w3.org/2016/12/01-tt-minutes.html#action01]
<trackbot> Created ACTION-489 - Update the unicode ticket 8915 with a link to the deltas between what we recommend and what is already in main and aux sets. [on Pierre-Anthony Lemieux - due 2016-12-08].
pierre: Maybe they are saying
that if characters are in use for captioning in a language
then
... it should be added to aux for that language. That would be
fine by me.
nigel: Q 3a may be that they have found a mistake?
pierre: There are two parts to
3a. We can provide the background behind the selection,
which
... is indeed an empirical examination of real data. The other
part, about Hebrew and other
... latin scripts, I will follow up with someone who knows
about this.
glenn: I agree with the question, it does look extremely odd. Also it may cause trouble having characters with different directions.
pierre: The basic latin set is
included all the time even with Hebrew, so the question is
why
... is a special case made for U+0178 : LATIN CAPITAL LETTER Y
WITH DIAERESIS?
nigel: Looking at the list,
Hebrew includes Latin Extended-A which has other
characters
... as well as U+0178.
pierre: It sounds like either
there is a mistake - I will check - but also explain that all
the
... Latin Extended A characters are included (plus other Latin
characters) in all the locales.
glenn: I don't believe it includes all Latin characters defined in Unicode.
pierre: I should have said the "base set" (whatever it's correct name is).
glenn: Yes, Vietnamese latin characters are not included for example.
pierre: Should I pass draft text to the group before updating the ticket?
nigel: I think you can go ahead and update the ticket directly.
pierre: Thanks for keeping tabs on the ticket by the way.
nigel: No worries. Thanks to Richard for prompting them - that really helped.
action-485?
<trackbot> action-485 -- Thierry Michel to Ask richard ishida for assistance in unblocking the unicode ticket 8915. -- due 2016-11-10 -- PENDINGREVIEW
<trackbot> http://www.w3.org/AudioVideo/TT/tracker/actions/485
nigel: Since this is unblocked, I'll close this.
action-485: [Meeting 2016-12-01] This seems to be unblocked - thank you Richard! Closing.
<trackbot> Notes added to action-485 Ask richard ishida for assistance in unblocking the unicode ticket 8915..
close action-485
<trackbot> Closed action-485.
nigel: Do you want a minute on imscjs?
glenn: I would like to hear more about it.
pierre: This is a javascript
library intended for rendering IMSC 1 documents into
HTML5
... as faithfully as possible to the spec.
-> https://github.com/sandflow/imscjs
pierre: There are three main
parts, parsing, turning into ISDs and then mapping the ISDs
into HTML5.
... That last part could be replaced by other renderings.
... There are also links to test sample renderings from TTML1
and IRT tests.
... This work is sponsored by MovieLabs.
... This is an initial beta release, intended to be
substantially complete in API and in
... functionality, and the goal is to walk towards a 1.0
release in the next couple of months.
andreas: I also tested it and
found it helpful. I did not find any error yet, and everyone
I
... told about it said it is really helping for TTML
implementation. Another thing that could
... be relevant is that very easily you can produce images for
all of the TTML samples that
... are in the test suite, so therefore it could be helpful for
this group, and you could think
... about providing images together with the test suite.
pierre: It works only in Chrome
and Firefox because of security issues, but from Firefox
... you can actually export the sequence of images associated
with each ISD.
andreas: It is also helpful for TTML to HTML mapping, so we also benefit from that.
glenn: I agree with Andreas, it's
very nice to have this available.
... Did you create any new test content or did you use the
former TTML test suite?
... Also have you had a chance to document any rough spots in
terms of trouble mapping
... to HTML or CSS that required giving up formatting semantics
or other things like that?
pierre: I've been using for test
the TTML1 test vectors that are compatible with IMSC1,
... especially for timing semantics that has been extremely
helpful. Also the IRT test vectors
... because they come with nice expected renders, so that's
been nice for finding bugs.
... Ultimately I would like to come up with really good IMSC 1
specific test vectors. I have a
... question for W3C about copyright etc and how they would
feel about turning TTML1 tests
... into IMSC 1 tests.
... On the second question so far I think in the case of IMSC1
there's nothing that cannot
... be mapped to HTML, but time will tell! I've seen some
interesting things with unicode bidi
... and embed, and need to see if there's a spec or a browser
issue - that will take more time.
... One of the IRT test vectors has a discrepancy.
... Another one is xml:space="preserve" which is also something
where we might find surprises.
... Overall, the two features that required the most work were
linePadding and multiRowAlign
... because both of those features require determining line
breaks when there are no specific
... line breaks.
nigel: What about box-decoration-break: clone for linePadding?
pierre: The issue here is
multiple nested spans with different background colours. The
clone
... works great if there is only a single background colour for
the entire background of the
... p or the span.
glenn: On multiRowAlign did you end up using display: inline-block ?
pierre: Yes I think so, after finding line breaks and inserting br elements where needed.
glenn: I'll have to take a look at it with some examples - these are tricky areas for sure.
pierre: The strategy is to do a
first pass putting every character in its own span, then
check
... the vertical position of each, and when it changes then
insert a hard break.
mike: Comment: I had the
opportunity to throw some DECE film content at it that
was
... coded to DECE specs, and it looked like it was doing the
right thing, without looking
... in extreme detail. That was encouraging, with 300-400kb of
XML.
... Question: There's a partial implementation of
IMSC-1/EBU-TT-D in dash.js and I wondered
... if you had some thoughts about integrating into that?
pierre: Yes, in fact I have been
touch with one of the main developers of dash.js TTML
code,
... and his comments were 1. How are images supported? and 2.
Why are IE and Edge not supported?
... In fact images are supported, using an image
resolver.
... I have not had time to test with IE and Edge, and I was
pleasantly surprised how
... far IE11 has come, and there's a pull request to make 2
changes that will make the
... library compatible with both. The goal was always to make
it compatible with Edge.
... I expect to merge that very soon, and then update the
README. It should be compatible
... with the latest version of Edge, Safari. Chrome, Firefox
and IE11.
... It turns out there is only one CSS feature not supported by
Edge and it was really
... easy to get around it.
nigel: I just want to mention
Security and Privacy. We currently don't have a section on
this,
... and I've discussed with David Singer and Glenn and this has
led to issue 224 being raised.
-> https://github.com/w3c/ttml2/issues/224
nigel: We have three examples now, but any others would be welcome - please contribute to the issue.
glenn: I thought of another, the use of xlink to cause browsing away to other content.
nigel: I've added that to the
issue.
... We're out of time for today (slightly over) and we've
covered the main agenda topics. Thanks everyone! [adjourns
meeting]