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{minutes} TTWG Meeting 2017-07-06

From: Nigel Megitt <nigel.megitt@bbc.co.uk>
Date: Thu, 6 Jul 2017 15:25:09 +0000
To: "public-tt@w3.org" <public-tt@w3.org>
Message-ID: <D58414B2.43C21%nigel.megitt@bbc.co.uk>
Thanks all for attending today's TTWG meeting. Minutes can be found in HTML format at https://www.w3.org/2017/07/06-tt-minutes.html

In text format:


      [1] http://www.w3.org/

                Timed Text Working Group Teleconference

06 Jul 2017

   See also: [2]IRC log

      [2] http://www.w3.org/2017/07/06-tt-irc


          Nigel, Dae, Glenn, Thierry, Mike, Pierre





     * [3]Topics
         1. [4]This Meeting
         2. [5]TTML
         3. [6]TTML2 WR Outgoing communications
         4. [7]TTML next steps.
         5. [8]TTML issues
         6. [9]IMSC
         7. [10]HDR in PNG
         8. [11]WebVTT review feedback
         9. [12]TPAC 2017
     * [13]Summary of Action Items
     * [14]Summary of Resolutions

   <scribe> scribe: nigel

This Meeting

   Nigel: We have TPAC, IMSC, TTML, I don't know if we will cover
   WebVTT and HDR in PNG.

   Glenn: I can only stay for 1 hour today, so TTML first would be
   better. Same will be true
   ... throughout July and early August.

   Nigel: I'm not going to be present on 17th and 24th August.
   ... Any other business or specific points anyone wants to make
   sure we cover?

   group: [silence]

   Pierre: I only have about 1 hour today.


   Nigel: We have to think about next steps for TTML - we have
   comms for the wide review,
   ... TTML1 3rd Ed. perhaps and continuing on the open issues on

TTML2 WR Outgoing communications

   Glenn: It was good to see Thierry's draft call for wide review.
   I'm going to read that and
   ... maybe suggest a summary of changes since TTML1.

   Thierry: +1

   Nigel: +1. I think I've already done it and we've discussed it
   Glenn. but I haven't found it yet.
   ... I'll take the action to find that and add it to the text.

   Glenn: My focus on TTML now is to resolve the outstanding
   issues including the previous
   ... issues reported by Richard. The ones that predated
   Richard's comments I'm probably
   ... going to prioritise a little higher since they have been
   lingering for a while. The TTML1
   ... - some of the issues on TTML2 require resolving TTML1
   issues so they will naturally get
   ... addressed in that process too, mostly. A few months back I
   had already tweaked the TTML1

   <tmichel> In addition to the features introduced in IMSC1 and
   generally refining TTML1 features, it adds support for East
   Asian languages, enables stereoscopic 3D, and details the
   mapping to HTML and CSS. Glenn Adams (Skynav) is the editor of

   <tmichel> [15]https://www.w3.org/2016/01/emmyawardttml.html.en

     [15] https://www.w3.org/2016/01/emmyawardttml.html.en

   Glenn: ED in GitHub to make use of the new format, and I had
   put some effort into preparing that.
   ... The current ED of TTML1 says 3rd Ed. and is mainly in the
   new format, maybe needs
   ... some more tweaking.

   Nigel: As far as I recall we agreed the approach to all the
   TTML1 issues, so it should be
   ... straightforward to process them.

   Glenn: Yes the only one I need to look at is the one raised by
   Pierre about region resolution.

   <inserted> [16]Ambiguous definition for determination of
   descendant region identifier. #194

     [16] https://github.com/w3c/ttml1/issues/194

   Glenn: I need to convince myself that it won't break anything.

   Pierre: This is what happens if you associate say a div with
   region1 and a child p with region2.

   Nigel: Thank you!
   ... OK that sounds like it needs some more thought before we
   can discuss it.
   ... Going back to the comms on TTML2.
   ... Thierry, you just posted some text above - was there more?


     [17] https://www.w3.org/AudioVideo/TT/docs/TTML-Profiles.html

   Thierry: We drafted this for the Emmy press release, and
   there's something in the page linked above.

   Nigel: I'm pretty sure Glenn and I worked on some wording, I
   need to go and find it.

   Thierry: I recall that, but it looks like it didn't go into the
   spec, that paragraph.

   Nigel: Okay I'll do some archaeology.

   Glenn: We added the subsection that enumerates the high level
   syntactic changes.

   Thierry: If I recall, it was after TPAC 2016.

   Nigel: If everyone could read Thierry's draft and feed back on
   the reflector that would be helpful.
   ... Are there any groups to whom we need to customise our
   ... For example SMPTE. If a general message works that would be

   Glenn: I think we should use a general message.

   Mike: I can't off the top of my head think of any specific
   messages for particular organisations.

   Nigel: Thierry, when we've agreed this text please could you
   send those out based on the
   ... liaison addressees we used for IMSC 1.0.1 which were all
   BCCed to member-tt and CCed
   ... to team-liaisons?

   Thierry: Yes, will do.

   Nigel: Thank you

   Thierry: I'll wait for the go-ahead on the final text.

   Nigel: By the way, for the minutes I want to note that we
   published the WD for WR on June 30.
   ... Thanks Glenn for making the last changes to get that out by
   our deadline.

TTML next steps.

   Nigel: Glenn, are you going to work on TTML1 3rd Ed first as a
   precursor to TTML2?

   Glenn: That wasn't my plan specifically, it's mainly to knock
   off the TTML2 issues, some of
   ... which involves resolving TTML1 issues in 1 3rd Ed. I'll be
   driven by TTML2 issues rather
   ... than TTML1 issues.
   ... In the next 2-3 months I intend to make good progress on
   both fronts.

   Nigel: And the next thing we'll need thinking ahead to CR is
   some exit criteria and test
   ... suites.

   Glenn: The issue of creating a formal test suite for TTML2 is
   something we haven't really
   ... taken up yet.

   Nigel: True, I just want to flag up that we will need it.
   ... We also will need to think about implementations - our work
   implementing the audio
   ... features is going well so we may be able to generate some
   test material for that too.

TTML issues

   Nigel: I just want to raise that we noticed a couple of things
   that need fixing in the HDR appendix
   ... so I just opened an issue and a pull request.

   [18]Remove HLG HDR step 8 superscript 5b #398

     [18] https://github.com/w3c/ttml2/pull/398

   [19]Error in HLG HDR appendix step 8 #397

     [19] https://github.com/w3c/ttml2/issues/397

   Nigel: I also made some formatting changes to put mathematical
   expressions in code blocks
   ... rather than just body text.
   ... I've assigned Pierre as a reviewer there, though obviously
   anyone might want to look.
   ... I think I've taken an action from someone outside the group
   to feed in a point about
   ... quantisation in the PQ section, which needs to use narrow
   range signal not full range.

   Pierre: I've not heard that feedback before.

   Nigel: Ok I'll raise the issue then.


   Nigel: Thierry please could you explain about the transition to

   Thierry: I have sent the transition request to the Director CC
   plh last Friday and I was
   ... expecting a response on Friday or Monday but on Monday I
   got the response that they
   ... had not had the time to process the transition request - to
   do with 4th July and the EME
   ... work, so Philippe said he would give us a response
   tomorrow. Depending on the time
   ... I get the response it will be published on Tuesday or
   Thursday, because I need to send
   ... it to the Webmaster 2 days in advance. That's very
   unfortunate because it seemed like an
   ... easy decision, with very few comments, but I can't do much
   about it.
   ... Everything was ready, the spec is already in TR.

   Nigel: Do we have to edit the spec due to the publication date

   Thierry: Yes I will have to move it to the final destination
   and then change the end date
   ... of the CR, from Aug 6 to whatever it is, 11th or 13th, as
   well as the publication date on
   ... the top of the document.
   ... It's pending an email from plh now, and I'll let you know
   as soon as there is a response.

   Pierre: Thierry, if you can let me know the exact changes made
   to /TR so I can reflect them
   ... in the Editor's draft please?

   Thierry: 3 things: the URI, the pub date and the end of review

   Pierre: I understand, just let me know the new values and I'll
   reflect it.
   ... I try to keep GitHub matching exactly what is published.

   Thierry: I will, I'm sorry about that.

   Nigel: The other thing I wanted to raise on IMSC 2 is that we
   need to start thinking about
   ... the scope and requirements of IMSC 2 so we know what it
   will look like, and maybe
   ... publish something with a time-limited review period so that
   we can make sure all the
   ... inputs are gathered and we have something like a
   requirements document to refer to.

   Pierre: I've begun working on this and there's the wiki page

   Nigel: Great, thank you.


   Nigel: I think there's been some progress here.

   Pierre: I've not had time to process Chris's feedback.

   Nigel: Understood. It looks mostly positive, so it may allow us
   to release the block on
   ... publishing the note.

WebVTT review feedback

   Nigel: David's obviously not on the call, but just to reiterate
   that there is a request for the WG
   ... to review and hopefully approve the CG's dispositions.

   [20]WebVTT Wide review wiki page

     [20] https://www.w3.org/wiki/WebVTT_Wide_Review

TPAC 2017


   <trackbot> action-497 -- Nigel Megitt to Invite csswg to joint
   meeting at tpac 2017, with list of topics. -- due 2017-06-15 --


     [21] http://www.w3.org/AudioVideo/TT/tracker/actions/497

   Nigel: I began to look at this and yet again, with apologies
   Dae, I failed to find the list of
   ... CSS issues we want to discuss, that you put together Dae.

   Dae: Is it the IMSC 2 wiki page?

   [22]TTML2 features for inclusion in IMSC2

     [22] https://github.com/w3c/imsc/wiki/TTML2-features-for-inclusion-in-IMSC2

   Dae: I edited it to add my transform proposals, in #218

   [23]First Pass at IMSC2 to CSS Fallback #218

     [23] https://github.com/w3c/imsc/issues/218

   Nigel: Ah ok thank you.
   ... One of my motivations for raising this aside from the issue
   is that the TAG offered
   ... to assist with facilitating the meeting with CSSWG and they
   are coming to London in a
   ... few weeks, so I plan to meet them then and hope to discuss
   this general issue, of CSS
   ... support for styling needed for subtitles and captions.
   ... I'll collate this information ahead of that meeting and
   send it through.
   ... Dae, your helpful comment on imsc#218 is dependent on
   ttml2#254 and ttml2#240.
   ... Now that ttml2#240 is closed do you want to have a look at
   the impact on textEmphasis?

   Dae: Sure.

   Nigel: Since we did that back in March we have added
   fillLineGap so that obviously needs
   ... to be added.

   Pierre: Also linePadding and multiRowAlign, neither of which is
   supported by CSS.

   Nigel: Thank you!

   Pierre: Also I'm going to post a link to a question posed by
   Tab Atkins to the CSS mailing list back in 2015:


     [24] https://lists.w3.org/Archives/Public/www-style/2015Sep/0077.html

   Pierre: I've never seen it answered and I think it's relevant
   because it deals with the inner workings
   ... of XSL-FO and CSS.
   ... There's some interesting behaviour, where UAs seem to
   behave differently from the spec.
   ... It's been a real issue to deal with this.
   ... It's related to whitespace collapse and deletions before
   line breaks. UAs treate line breaks
   ... very differently depending on if they occur because of a
   <br> or a linefeed character.
   ... I ran into it but it looks like Tab Atkins ran into it
   earlier. It deals with the basic processing
   ... in CSS and also impacts TTML.
   ... In a nutshell, if you put a space before a <br>
   specifically in a span that is a sibling of a br,
   ... then that space does not get removed.
   ... Chrome does not delete that space for instance.

   Glenn: The only way you know if it is there is if there's some
   border or background?

   Pierre: Exactly.

   Glenn: I'm pretty sure XSL-FO would need that space to be
   deleted at the end of the line
   ... for the purpose of backgrounds etc... Hmm maybe!

   Pierre: Here's the codepen:

   <pal> [25]https://codepen.io/palemieux/pen/PjeKyq

     [25] https://codepen.io/palemieux/pen/PjeKyq

   Pierre: The space being visible or not can affect line height
   and have other weird effects.
   ... The reason it is a bug is pretty obvious - if the space is
   outside the span, as a node between
   ... the sibling span and the br then it is deleted. So the
   whitespace removal algorithm might
   ... be dumb and operate before the entire line is built.

   Glenn: I remember seeing this before and other people have
   recognised there's some
   ... subtlety here. Firefox does not put the space in.

   Pierre: And Edge does.

   Glenn: Firefox tried to do what IE did so I guess IE did it the
   way Firefox does it now.

   Pierre: From the CSS spec I see no reason why the space should
   be retained. From an XSL
   ... and a CSS perspective it should make no difference if the
   space is in or out of a span.

   Glenn: I agree, unless it were a non breaking space or an em
   space or something. Regular
   ... white space should not appear.

   Pierre: To complicate this, Andreas has been running test
   suites based on XSL processors
   ... and at least in the processor he has used that space does
   show up.

   Glenn: I can see why this might be a problem when you are
   trying to get HTML/CSS to render
   ... linePadding for example.

   Pierre: Or anything with a background.

   Nigel: I'll gather the existing stuff together and figure out
   where to put it then share it
   ... for review before sending it to TAG and CSSWG.
   ... Thierry please could you create a TPAC wiki page like we
   have had in previous years?

   Thierry: Yes, add an action please.

   <scribe> ACTION: Thierry Create a TTWG wiki page like in
   previous years [recorded in

     [26] http://www.w3.org/2017/07/06-tt-minutes.html#action01

   <trackbot> Created ACTION-499 - Create a ttwg wiki page like in
   previous years [on Thierry Michel - due 2017-07-13].

   Nigel: Okay, we've covered all our agenda points, so let's
   adjourn. Thanks everyone! [adjourns meeting]

Summary of Action Items

   [NEW] ACTION: Thierry Create a TTWG wiki page like in previous
   years [recorded in

     [27] http://www.w3.org/2017/07/06-tt-minutes.html#action01

Summary of Resolutions

   [End of minutes]

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