- From: Nigel Megitt <nigel.megitt@bbc.co.uk>
- Date: Thu, 9 Mar 2017 17:28:35 +0000
- To: "public-tt@w3.org" <public-tt@w3.org>
- Message-ID: <D4E73D59.3A188%nigel.megitt@bbc.co.uk>
Thanks all for attending today's extended TTWG meeting. Minutes can be found in HTML format at https://www.w3.org/2017/03/09-tt-minutes.html
In text format:
[1]W3C
[1] http://www.w3.org/
Timed Text Working Group Teleconference
09 Mar 2017
See also: [2]IRC log
[2] http://www.w3.org/2017/03/09-tt-irc
Attendees
Present
Andreas, Dae, Glenn, Nigel, Pierre, Thierry
Regrets
Mike
Chair
Nigel
Scribe
nigel
Contents
* [3]Topics
1. [4]This meeting
2. [5]IMSC
3. [6]TTML
4. [7]AOB
* [8]Summary of Action Items
* [9]Summary of Resolutions
__________________________________________________________
<scribe> scribe: nigel
This meeting
Nigel: We have one main issue to discuss for IMSC, though Mike
sent his regrets.
Andreas: I won't be able to join next week.
Nigel: Okay lets get the views from here then and discuss it
briefly without fully concluding
... until Mike has been able to contribute.
... That's all on IMSC. On TTML2 we have a number of issues to
cover.
... I don't think there are any other main agenda topics, I can
give an update under AOB
... on my trip to CSUN last week.
... There's been some progress on moving WebVTT to the next
working draft but I don't
... think that's an agenda item for us today. You'll have seen
David's encouragement by email
... to review and look at the dispositions.
... Any other business, or specific points to raise?
Dae: For IMSC 1.next we are introducing fillLineGap? Will this
carry forward to TTML2?
Nigel: Yes we need the semantic in TTML2, and I believe that
Glenn has begun some work
... on it in TTML2.
Dae: There's no support for it in CSS yet though?
Nigel: No, I did raise an issue on CSS.
Pierre: I started a wiki listing CSS features that are needed
for subtitles. I encourage us to
... lobby for this.
Nigel: +1
Andreas: A question for Nigel as BBC representative: It's clear
that BBC guidelines have a
... clear requirement documented for this feature. Could this
be brought to the awareness
... of the CSS WG? I think it is nowhere more obvious than in
the BBC guidelines. It is just
... an example but you made a strong point for it too.
Nigel: Yes absolutely, very happy to do that.
[10]https://github.com/w3c/imsc/wiki/TTML2-features-for-inclusi
on-in-IMSC2
[10] https://github.com/w3c/imsc/wiki/TTML2-features-for-inclusion-in-IMSC2
Pierre: That's the list of TTML2 features for inclusion in
IMSC2.
Nigel: There's no pointer to which features are or are not
doable in CSS?
Pierre: No, I started doing that with textEmphasis but I
haven't with anything else.
... I can help with the mapping but ultimately Glenn is the
expert there in terms of TTML2,
... so it requires his participation.
Glenn: If you're talking about CSS mapping I have no interest
in doing that.
Dae: I don't mind volunteering to take a first go at this
because most of the features have
... a straightforward mapping or fallback. I wonder how robust
the fallback has to be?
Glenn: My solution to mapping to HTML is to map to SVG in HTML.
Nigel: To an extent that does not fully resolve the problem
since CSS affects the presentation
... of text in SVG in any case and may be used to make it more
accessible.
Glenn: I don't recognise that, metadata can be added to SVG to
make it accessible.
Nigel: Since IMSC2 is a subset of TTML2 then any features that
we want to be in IMSC2 need
... to be in TTML2. If we need IMSC2 to be mapped to CSS then
we need to make sure the
... fallbacks and limitations are clear.
Glenn: We decided some time ago to make HTML/CSS mapping
orthogonal to TTML2
... development.
Dae: I will aim to do a first draft of the CSS mapping before
next week's meeting.
Glenn: I don't disagree that it is useful to know where the
challenges are. If there are tweaks
... that can be made to make things a little easier I don't
generally object to doing that.
Nigel: We need to pragmatic here - if we are forced to wait for
a normative reference to
... a CSS spec for everything then we will be waiting for a
long time.
Dae: I think this is about a fallback in some cases.
Pierre: For example what is the CSS equivalent of fontShear?
Glenn: There is none.
Pierre: We should note it then.
Glenn: We have not done that in the past. For example in TTML1
XSL-FO does not support
... all the semantics, and there's a note that declares that
such unmappable semantics exist.
... We did not let that gate us for TTML1.
Pierre: In the scope of IMSC1 features there is in fact a clear
mapping via XSL-FO to CSS.
... XSL says what the differences are between it and CSS.
That's the case for TTML1 now and
... it made the mapping clear and easy to do.
Glenn: It's under ยง9.3.3 under synchronic flow processing, a
note about there being no
... XSL counterpart.
... We've had to go beyond XSL-FO and CSS in TTML2 due to new
requirements that
... still are not satisfied in CSS land.
Andreas: What we need to acknowledge is that since TTML1
started as a standard the
... importance of CSS mapping has increased in general in the
domain and for members and
... for W3C. For IMSC1 and IMSC2 there may be the situation
where the industry will not
... support a feature without a clear CSS mapping, so I can
support that for everything we
... want to include especially in IMSC we should do everything
we should do to make it
... work with web technology.
Pierre: Are you opposing doing the mapping work Glenn?
Glenn: I am not opposing it, I just don't think it is a
necessary part of TTML2 and can be
... done elsewhere.
Pierre: So you will not object to that or to PRs on TTML2?
Glenn: Sure, I will consider PRs on TTML2.
... The other question that is deeper is that during that
mapping process there may be a
... suggestion to make changes in TTML2, and that's reasonable,
but we have to ask ourselves
... the practical question if waiting for that to be completed
could become a blocking or gating factor for wide review.
... If during the WR process progress is made on this then we
can look at that and decide
... if we want to make any changes as we come to CR to
accommodate that.
Nigel: [draws this discussion to a close]
IMSC
[11]https://github.com/w3c/imsc/issues/213
[11] https://github.com/w3c/imsc/issues/213
Nigel: I am not sure what the outstanding points are with this
that need to be discussed.
Andreas: I think the last edit from Pierre would be fine. Nigel
you brought in an extra
... issue which is how far you give a recommendation or
requirement for how far foreign
... namespace content should be defined. My view is this is not
in scope of IMSC or TTML
... so would not be necessary, but it is just a recommendation
so I wouldn't object to it.
Nigel: It's even weaker than that - it's an informative note
only to say that it is a good idea
... to define a content specification but I agree that we
cannot force people to make good
... implementations!
... It's in a pull request:
[12]https://github.com/w3c/imsc/issues/217
[12] https://github.com/w3c/imsc/issues/217
Pierre: Now Mike has told me he wants to be specific about
exactly which elements
... support foreign namespace elements and which do not, but I
do not want to rewrite
... TTML1!
Nigel: There are 3 new things since last time:
... 1. If we should remove the exception for the tt element?
... 2. Clarify that foreign namespace attributes are permitted
on all TTML1 elements.
... 3. Add an informative note about good practice for content
specification.
Pierre: I think there's a dispute that has not been resolved
where Mike wants to introduce
... consideration of XML Schema validation.
Nigel: I think that's further than we should go.
Andreas: First I thought we do not need to be as specific as in
TTML1 but now when I look
... at it maybe it would be good to document it wherever it is,
because for example
... <style> does not allow <tt:metadata> as a child element,
which differs from what the
... EBU group does, and has done for years, so there are people
making mistakes on this.
Pierre: So you're supporting Mike's idea of explicitly listing
the elements where metadata
... is permitted?
Andreas: I can understand not wanting to put too much in the
IMSC spec but somewhere
... it should be documented.
Pierre: My reluctance is simply that it requires interpretation
of TTML1, which I typically
... recommend we don't do, but if we feel it is useful and Mike
thinks so then maybe it
... is enough.
Nigel: I really like the way it is done now by referring to
Table 3 in TTML1.
Pierre: It is wrong though because for example <head> permits
metadata. Maybe we should
... for simplicity just list the elements directly.
Nigel: OK, I'm fine with listing in an informative note the
elements. That's probably a service
... to the world.
Pierre: In that case I'm happy to do it.
Nigel: The second point is to be clear that foreign namespace
attributes are permitted on
... all TTML1 elements.
... I think if we are going to summarise what TTML1 permits we
should do it accurately.
... I went to the trouble of checking TTML1 and in fact every
element defined in that spec
... permits foreign namespace attributes.
Pierre: The risk is that people should go and read TTML1.
Glenn: I agree that we should not paraphrase TTML1, it's okay
to have a generic note saying
... to see TTML1.
Nigel: Summarising, there's a concern that we should not list
things that are defined in TTML1.
... For me, I think we should either summarise correctly or not
at all.
Pierre: I think you and Mike are agreed on that.
... I will list all the elements that permit foreign namespace
metadata and change the lsit
... of elements in TTML1 that permit foreign namespace
attributes.
Nigel: Moving on to the note about content specifications, the
note I have added is:
... "For validation purposes it is good practice to define and
use a content specification for all foreign namespace elements
and attributes used within a Document Instance. "
... The reason I think we should do this is from going back to
the text in TTML1 about
... validation, you may end up with non-pruned foreign
namespace elements that should
... be validated against a content specification, and this
provides a small hint to plug that gap.
Andreas: I will not object, but I would prefer not to do this.
It could be good practice also
... to ignore unexpected content.
Pierre: I will add that paragraph, update the PR. If Mike is
happy then we go ahead. If not then maybe the solution is to
remove that paragraph.
... if that also satisfies Mike.
Nigel: Ok I wouldn't object to that if it gets us to consensus.
... OK that's all for IMSC, let's take 2 minutes and come back
for the next hour on TTML.
TTML
Dae: I'd like to clarify if we are addressing horizontal review
comments before CR?
Glenn: When I made that comment I did not plan to have to
resolve all HR comments prior
... to going to WR. I did not mean I would not address them if
possible. I think it is still an
... open issue about if we need to resolve them prior to going
to WR.
Nigel: We will need to make a call when we want to resolve to
publish the WR for WD.
Pierre: I recommend assigning issues.
Glenn: I don't object to assigning issues to get more people
working on them however I
... will need to do the merge so that will depend on the effort
I have to do the editorial tasks.
... I have no objection to others preparing PRs. I might
delegate the merge task to others if
... time is limited. I need to have oversight on the final
text.
Nigel: I don't think we should have a blanket policy on pushing
all HR issues out to after WR.
... We need to be able to take it on a case by case basis.
Pierre: For issue 233 on HDR that's a blocking issue for
Movielabs.
... I'm happy to prepare a PR for it.
Glenn: Sure.
[13]https://github.com/w3c/ttml2/issues/233
[13] https://github.com/w3c/ttml2/issues/233
Pierre: I will prepare a PR for that.
Nigel: I expect a BBC proposal also, for the non-absolute
luminance case.
... I've assigned that issue to you and me, Pierre.
Dae: If anyone else feels there is a specific issue that we
must resolve as soon as possible
... then it would be good to make that known.
Pierre: Assigning issues is an approach that works well, where
the assignee needs to propose
... a disposition.
Nigel: By the way I have one, the audio description one:
[14]https://github.com/w3c/ttml2/issues/195
[14] https://github.com/w3c/ttml2/issues/195
Pierre: We need to document any deferred issues and agree them
in the group based on the rationale.
Nigel: On the AD issue I have done the pre-editing work to
define the semantics and Glenn
... is in progress on the editing.
Pierre: For the TTML1 issues that flow into TTML2 also then in
my view they all must be
... resolved. They're bugs.
Glenn: I have probably different criteria for bugs.
Pierre: There are a bunch of "discussed and agreed" issues.
Glenn: They're well up on my priority list and I'm trying to
get through them whether they
... are labelled as bugs or not.
... I'm working on the 58 issues marked TTML2WR but I have no
objection to anyone
... else assigning themselves to an issue.
Pierre: An efficient solution is not to ignore issues and
respond to them sooner otherwise
... things will get worse in the future and people might get
angry.
Glenn: I'm not trying to make any decisions for the group by
the way, I'm just labelling
... what I am working on.
Pierre: I have to leave now.
Nigel: By the way Andreas left before the TTML agenda item too.
Dae: I would like to raise the bopomofo issue
[15]https://github.com/w3c/ttml2/issues/253
[15] https://github.com/w3c/ttml2/issues/253
Glenn: This refers to a particular script which is used in
Taiwan to annotate Chinese
... in pedagogical works. I would not expect it to be seen in
subtitling except possibly in
... educational programmes for children. It is only really used
when teaching children in
... Taiwan how to read Chinese.
Nigel: I think we should put this on hold until Richard's
request to @bobbytung gets a
... response, and act on that response when it comes. It may be
that we decide this is not
... high enough on our priority list and we choose to go ahead
without Bopomofo support.
... I did want also to discuss the em units issue:
[16]https://github.com/w3c/ttml2/issues/216
[16] https://github.com/w3c/ttml2/issues/216
Glenn: On that particular issue there is an editorial point on
the text which I would like to
... be opened as a new issue.
... That one wasn't an early merge.
Nigel: That's strange, I commented that it was an early merge
and marked as one, but the
... history doesn't show that. I'm a bit confused about that.
... It turns out that Pierre and I had similar editorial
comments, so I guess we can raise those
... as new issues.
... There may be some consensus on the 3D and images issue:
[17]https://github.com/w3c/ttml2/issues/239
[17] https://github.com/w3c/ttml2/issues/239
Nigel: The last points by Mike, Pierre and I are that we do not
need to have left/right images.
Glenn: On the point about using condition I would like to add
named parameters there.
Nigel: I don't think that's necessary but I would not object to
it.
Glenn: I can do that very quickly and post a PR that does that
and see what comments there are.
Nigel: The only reason against doing that is if it generates
additional test cases that we do
... not actually need. Otherwise I don't have a problem with
that.
Glenn: I'll add a comment to the effect that this is what I
will do.
nigel: The next issue I listed was the TTML1 pull request:
[18]https://github.com/w3c/ttml1/pull/233
[18] https://github.com/w3c/ttml1/pull/233
Nigel: This is one of Andreas's.
Glenn: We had the whole issue of whether padding should be on
the inside or the outside of regions.
... I see this is a note. I need to do more than just add this,
I would need to add an errata
... info and change info, but I see you made a suggestion.
... So, mutatis mutandis, we can mark this as discussed and
agreed?
Nigel: I think so.
Glenn: That means "the necessary changes having been made"
Nigel: I've logged that on the issue.
... What about the open pull request?
[19]https://github.com/w3c/ttml2/pull/273
[19] https://github.com/w3c/ttml2/pull/273
Dae: Richard raised issues 274 and 275 based on that.
Nigel: Oh right I did not realise the relationship was there,
there's no tracing in the issues or the pull request.
Dae: I think there's another one aside from 274, it might not
be 275.
AOB
Nigel: Last week I went to the CSUN annual conference on
assistive technology and presented
... on AD in TTML2 (current status anyway, and desired end
goal) and also on live subtitles
... in TTML via the EBU-TT Live work.
... There was a really good and engaged audience for the AD in
TTML2 talk, and in fact
... there were a number of AD talks over the conference. There
turns out to be a use case
... for pan, and also for SSML for text to speech, for example
to disambiguate different ways
... of processing a number like 1876 that could be a year or a
number.
Glenn: I do not want to embed the whole of another language
into TTML2!
... Also it would be difficult where they have created new
elements and put attributes on those.
... What I have done is to create new attributes only to keep
it consistent with how TTML does things.
... We have very strongly avoided elaborating our element
vocabulary.
Nigel: Understood. Anyhow I thought it is worth mentioning this
may be a good time to take advantage of the groundswell of good
feeling.
... Thanks everyone. [adjourns meeting]
Summary of Action Items
Summary of Resolutions
[End of minutes]
__________________________________________________________
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Received on Thursday, 9 March 2017 17:29:05 UTC