{minutes} TTWG Meeting 2017-04-13

Thanks all for attending today's TTWG meeting. Minutes can be found in HTML format at http://www.w3.org/2017/04/13-tt-minutes.html


In text format:


   [1]W3C

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


                Timed Text Working Group Teleconference

13 Apr 2017

   See also: [2]IRC log

      [2] http://www.w3.org/2017/04/13-tt-irc


Attendees

   Present
          Pierre, Philippe, Nigel, Andreas, Mike

   Regrets
          Glenn

   Chair
          Nigel

   Scribe
          nigel

Contents

     * [3]Topics
         1. [4]This meeting
         2. [5]TPAC 2017 Advanced planning
         3. [6]IMSC
         4. [7]TTML
     * [8]Summary of Action Items
     * [9]Summary of Resolutions
     __________________________________________________________

   <scribe> scribe: nigel

This meeting

   Nigel: I added to the agenda the TPAC 2017 advanced planning,
   and we have TTML and
   ... IMSC topics. Any other things to cover?

   Pierre: I'd like to discuss moving forward with the test
   vectors for IMSC 1.

   Nigel: Great let's do that.

TPAC 2017 Advanced planning

   Nigel: I believe we already agreed to meet at TPAC for at least
   2 (and possibly 4) days.
   ... I will need to complete a survey saying how many days we
   want to meet for and if
   ... we wish to meet any other groups.
   ... TPAC this year is in Burlingame, 6-10 November.

   [10]https://www.w3.org/2017/11/TPAC/Overview.html


     [10] https://www.w3.org/2017/11/TPAC/Overview.html


   Nigel: I will also need to state the days preferences, our
   flexibility, and any overlaps with other groups to avoid.
   ... There is another big event in San Francisco at the same
   time so flights and
   ... accommodation will be limited - advice is to book early.
   ... Does anyone already know of any date preferences for our
   meetings?

   Andreas: I will need to check - if we meet for 4 days then I
   will probably not join TTWG on all those days.

   Nigel: OK I will come back to this next week - I have until
   mid-May to complete the
   ... questionnaire on behalf of the Group.

IMSC

   Nigel: Two things here: firstly liaisons, secondly test suite.
   ... For practical reasons I was unable to send the final
   liaison until yesterday but have
   ... now done so, with apologies to the last group to receive
   the message, which gives them
   ... a bit less time to deal with it.
   ... The next thing is the test suite.

   Pierre: There's been a source of recurring complaint that there
   is no complete test suite
   ... for IMSC so what I've done over the past couple of weeks is
   to combine tests from the TTML
   ... test suite and the IRT test suite, and licences on both
   allow that. I have modified those
   ... files to be conformant IMSC 1 and to make them more
   appropriate for generating test
   ... vectors. Then I ran IMSC.js on them and generated a
   sequence of PNGs, one for each ISD
   ... based on them. I would like to submit those back to W3C and
   make them the official
   ... IMSC test vectors. One obvious objective is to help folk
   develop and test software, another
   ... is if results differ then we can review that in an issue,
   in case it is an issue with the test,
   ... IMSC.js or the spec. In practice I would create a pull
   request against the IMSC repo
   ... replacing the test subfolder with the test vectors.

   Nigel: One question is whether we base the IMSC 1.0.1 CR exit
   criteria on these tests or
   ... part of them or if it is completely separate?

   Pierre: This submission is not intended for the exit criteria
   of IMSC 1.0.1 - it could be but that is not my primary goal.

   Nigel: Does it include tests for the new features?

   Pierre: Not yet, but I would hope to add them in time.

   Mike: One of the new features has no presentation output, so
   the test would be that it does
   ... not break.

   Nigel: Quite right, though a console output might log
   recognition of the activeArea.
   ... So the request is for W3C to host a test suite for
   implementors beyond CR. Philippe, is that commonly done?

   Philippe: Yes, we could do that, but I would say that you
   should not put W3C staff in the
   ... critical path.
   ... I would recommend setting up a github repository for it and
   serving it, then we can
   ... create a link to serve it from W3C with a redirect.

   Nigel: So that repo could be the imsc repository, right?

   Philippe: It could be but I would not recommend it. The test
   suite licence would be different
   ... so we do not need to track the IPR in the same way.
   ... I can create another repo in W3C - it is not complicated.
   If you really want one repository,
   ... then be aware that any contributions from outside the group
   will be tracked for IPR and
   ... you will not be able to accept them.
   ... We have licences for tests, so having two licences for one
   repository would be a bit more

   <plh>
   [11]https://github.com/w3c/web-platform-tests/blob/master/LICEN

   SE.md

     [11] https://github.com/w3c/web-platform-tests/blob/master/LICENSE.md


   <plh>
   [12]https://github.com/w3c/web-platform-tests/blob/master/CONTR

   IBUTING.md

     [12] https://github.com/w3c/web-platform-tests/blob/master/CONTRIBUTING.md


   Philippe: complicated. For example the web platform tests have
   a separate repository.
   ... The examples above don't look at all like what is in the
   IMSC repository.
   ... The more I think about it they should be in a separate repo
   with a clearly different licence
   ... and contribution guideline from the spec.

   Pierre: Then I would propose to remove the tests from the spec
   repository.

   Nigel: Will it be okay to set CR exit criteria based on tests
   outside the spec repo?

   Philippe: Of course, the tests are not part of the spec.
   ... I recommend that we create a separate repo for this, and
   then tell me where to link from
   ... in the W3C website and I will do it.

   Pierre: I will take an action item to point you exactly to
   where they are.

   Philippe: Thank you, I am happy to fork an existing repo.

   Pierre: I will try to make it simple for you.

   Philippe: It would be easier for me to create the repo, and set
   the access rights the same as
   ... the group's spec repos.

   Pierre: OK.

   <plh> [13]https://github.com/w3c/imsc-tests


     [13] https://github.com/w3c/imsc-tests


   Philippe: That is a link to the repository.

   Pierre: I will push the tests there.

   Nigel: Great. Thank you!
   ... The existing CR implementation report is based on the tests
   in the spec repo, so it
   ... wouldn't be great to remove them.

   Pierre: Actually the IMSC 1 implementation report links to the
   Mercurial repo so nothing we
   ... do here will affect the formal IMSC 1 implementation
   report.

   Nigel: Ok then I guess you're free to clean up the IMSC repo as
   you like!

   Pierre: Thanks, I'll suggest something.

   Nigel: Now we need to begin thinking about the Exit Criteria
   for IMSC 1.0.1 CR.
   ... My starting point would be for two independent
   implementations passing each of some
   ... new tests for the new features, which would be:

   <plh> w3c/imsc-tests should be all set

   Nigel: 1. Not failing when processing a document with
   ittp:activeArea present
   ... 2. (perhaps) indicating on some console output the found
   value of ittp:activeArea.
   ... 3. Successful presentation of the lineGap style as per the
   example in the spec, in other
   ... words turning that example into a test vector.
   ... I think we should set the shortest period that we are able
   to according to the Process,
   ... which I think is a month?

   Philippe: For CR it is 4 weeks.

   Nigel: Thanks.
   ... That would be my proposal. Does anyone think we need
   anything more?

   group: Nothing more needed.

   Pierre: If you file an issue to remind me then I will add
   those.

   [14]https://github.com/w3c/imsc/issues/226


     [14] https://github.com/w3c/imsc/issues/226


   Nigel: Done, in above issue #226.

TTML

   Nigel: Even in Glenn's absence I would like to discuss our
   working process. He has sent me
   ... some written notes since he is unable to be present.
   ... Glenn's view as he's expressed it to me is that the ED is
   the Editor's prerogative to
   ... work with, and that it does not necessarily represent the
   Group's consensus.
   ... I would rather not work against each other here but work in
   harmony. However we do

   <plh> [15]https://www.w3.org/AudioVideo/TT/IMSC/tests/


     [15] https://www.w3.org/AudioVideo/TT/IMSC/tests/


   Nigel: seem to want a group consensus so one option is to
   create a new branch to serve
   ... as the group's consensus and publish WDs based on that.

   Pierre: This is also an issue because the ED is linked from the
   version on /TR.
   ... Another issue is that if someone creates a PR based on an
   issue, especially if they have
   ... been asked to, then the discussion on the PR should happen
   on that PR, so that everyone
   ... can track what is changing. It is unreasonable to create a
   separate pull request and have
   ... the discussion somewhere else, or no discussion in the case
   of an early merge, because
   ... it makes it hard to compare with the original submission.

   Andreas: Also, to reflect the earlier discussions, this relates
   to the position of the Editor in
   ... the TTML1 and TTML2 activity, where the Editor has an
   extremely strong role. In my
   ... experience this is even a bit stronger than usual, and
   maybe is not helpful for the group
   ... dynamic, so we need to agree how the different roles work
   some time.

   Nigel: In my role as Chair, I think I need to identify when
   there is or is not consensus. Right
   ... now it is clear that there are changes being merged into
   the ED for which there is not
   ... consensus in the Group.
   ... Glenn's view on how to proceed is to raise issues on the
   merged spec. I think we
   ... should recognise that from a perspective of the end result
   document that could result
   ... in an okay end result, even if it is not a happy process.

   Mike: Looking at this from afar, it seems like we are not all
   agreed on the process we follow.

   Nigel: Exactly, I would like to come up with some kind of
   action plan to resolve this.
   ... Philippe, have you seen any other examples from other
   groups that we could take
   ... inspiration from?

   Philippe: If this doesn't work for you guys in the Group then
   it needs to change, that's the
   ... bottom line. If the group wants to review stuff done in the
   Editor's own branch then that's
   ... okay.

   Nigel: Before I make any proposal are there any other thoughts
   for how to resolve this?

   Mike: Step one is to talk to the Editor, and if that does not
   work then step two is for the
   ... Chair to take control of merges to the draft.

   Philippe: Yes.
   ... There is an easy way - we can change permission settings to
   restrict who can merge
   ... into the repository.

   Nigel: Okay, that's fine. And regarding the point about the
   ownership of the ED, is there
   ... anything in W3C or the Process about that?

   Philippe: To be clear in lots of other groups the ED does not
   represent the consensus of
   ... the group, even if the ED is linked from the /TR page.
   ... Formal consensus is only represented in the WD.

   Pierre: So do the CSS editors try to capture group consensus in
   the ED?

   Philippe: No they don't.

   Pierre: And are the changes to the ED made with pull requests
   or done unilaterally by the Editor.

   Philippe: I would have to check. It used to be that they would
   be done unilaterally by the Editor.
   ... In some cases the Group would ask for changes on moving to
   WD.

   Pierre: The great thing about pull requests is you don't have
   to do that.

   Philippe: I agree, but if you do not have that working method
   then it does not apply.

   Mike: The goal is for the ED to reflect the current consensus.
   Forcing the members to try to
   ... correct something that was not originally proposed is a lot
   of work that perhaps is not
   ... necessary. It is odd at best to have the editor to do
   something different to what is in WD.
   ... I believe it would be a better process to use pull requests
   and merge on consensus
   ... into the ED.

   Philippe: Nigel, you're right, the Process does not make any
   requirements on the ED.
   ... If the editor cannot produce a draft that the group is
   willing to agree on then you may
   ... need a different Editor.

   Nigel: Okay we've discussed this enough today. In Glenn's
   absence I will not impose the
   ... option to stop early merge as indicated in the agenda,
   however I will take an action to
   ... talk to Glenn about this situation. Something will change
   one way or the other.
   ... In Glenn's absence are there any TTML issues that anyone
   wants to raise?

   Andreas: I have to drop off the call now.

   Nigel: The only one from my list on the agenda that I think we
   can easily cover is:

   [16]There's no apparent use case for the "any" term in
   ttp:contentProfiles

     [16] https://github.com/w3c/ttml2/issues/139


   Nigel: I agree with Pierre (who raised the issue) that there's
   no meaning for "any" here and
   ... we should simply remove it.

   Pierre: That was like 2 years ago.

   Nigel: I've added a comment on the issue.
   ... I've also labelled it as "Discussed and agreed".

   Pierre: I'd like to look at 244

   -> [17]https://github.com/w3c/ttml2/issues/244 Signaling HDR
   pixels in PNG for use with <image>

     [17] https://github.com/w3c/ttml2/issues/244


   Pierre: I'm sympathetic to the point that TTML2 does not define
   any image formats.
   ... However the proposal raised here is something the industry
   will do regardless, i.e. to put
   ... PQ pixels in PNGs. Noting this in TTML2 seems reasonable
   because it is most likely to
   ... happen in subtitles, and because W3C is the home of PNG. I
   had suggested adding it
   ... as an informative annex in TTML2. An alternative perhaps is
   to create a WG Note, but I
   ... think it is important to write it down somewhere otherwise
   people will do crazy stuff
   ... all differently. The advantage of a WG Note is that if
   someone outside this Group wants
   ... to make it more formal then it is easier to pull out. The
   drawback is it is further away
   ... from TTML2 though there could be an informative pointer to
   the WG Note.
   ... I think it is important to point to something but I'm not
   all set on it being in the TTML2
   ... spec.

   Nigel: From my perspective, it is easier to get consensus on a
   WG note and it does not need
   ... to hold up TTML2, so I think if you want to draft something
   then go ahead.
   ... Is a problem here that it is a misuse of PNG in some way?

   Pierre: That's a really big question, on review I think not.
   PNG allows for arbitrary
   ... gamma exponents but it only supports power law EOTFs and
   also arbitrary ICC color profiles,
   ... so it is not clearly an abuse of PNG, just not using one of
   the built in EOTF gamma curves
   ... defined today, instead using an ICC which is permitted. I
   think this is classed as a
   ... permitted extension. It may be better if PNG were to
   support EOTFs other than just gamma,
   ... but that's something that others in W3C may want to work
   on.

   Mike: Would changes to PNG be made in ISO or W3C?

   Philippe: It would be W3C. It certainly has been developed
   jointly in the past with ISO. I can
   ... even give you the right contact in W3C.

   Pierre: Maybe the sequence of events is to draft the WG Note
   and then see if there is further
   ... interest.

   Philippe: Chris Lilley created the Color CG with Mark Watson -
   Chris is the guy to talk to

   <plh> [18]https://github.com/w3c/strategy/issues/58

     [18] https://github.com/w3c/strategy/issues/58


   Philippe: in any case and he is also the one tracking our PNG
   stuff such as the above issue.

   Nigel: WG Notes can be turned into Recs later, right?

   Philippe: Yes they can or they can be parked.

   Pierre: My position is we should publish the WG Note and then
   make it available to the Color CG,
   ... and even bring Chris Lilley into that work. That makes it
   really concrete.

   Nigel: I'm happy with that.

   Mike: I don't have a particular plan in mind I just wanted to
   raise the question and see if
   ... there is another group we should collaborate on it. This
   plan to publish a WG Note and
   ... then work with others is a good plan.

   Pierre: Ideally PNG would be updated to take into account these
   new use cases, but that
   ... would take some work to get sufficient critical mass.

   Nigel: I've added a comment to the issue on this.

   Pierre: Could we create a repo for this?

   Philippe: Sure, what name do you want?

   Group: [some discussion] png-hdr-pq

   Nigel: That allows for other HDR extensions to PNG, if needed,
   to be placed in other WG Notes
   ... whose repositories would be called e.g. png-hdr-??? where
   ??? would be replaced.

   Philippe: I'll get onto that.

   Nigel: Thank you!

   <plh> [19]https://github.com/w3c/png-hdr-pq


     [19] https://github.com/w3c/png-hdr-pq


   Nigel: I've added a link to that and closed the issue - any
   request to create a reference to
   ... the WG Note should be done in a separate new issue.

   Pierre: I'll use Respec for this.

   Philippe: I'll set it up for the WG Note.
   ... I will also set up the master branch to be the one that
   github.io serves.

   Pierre: That's great.

   Philippe: I did the same thing for the imsc-tests repo as well.
   ... And it is replicated on the W3C website.

   <scribe> ACTION: tmichel Update the TTWG homepage and
   publications pages for the new repos [recorded in
   [20]http://www.w3.org/2017/04/13-tt-minutes.html#action01]

     [20] http://www.w3.org/2017/04/13-tt-minutes.html#action01


   <trackbot> Created ACTION-495 - Update the ttwg homepage and
   publications pages for the new repos [on Thierry Michel - due
   2017-04-20].

   Nigel: I think we've run out of steam for today. Thanks all. We
   have 2 hours again next week. [adjourns meeting]

Summary of Action Items

   [NEW] ACTION: tmichel Update the TTWG homepage and publications
   pages for the new repos [recorded in
   [21]http://www.w3.org/2017/04/13-tt-minutes.html#action01]

     [21] http://www.w3.org/2017/04/13-tt-minutes.html#action01


Summary of Resolutions

   [End of minutes]
     __________________________________________________________


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Received on Thursday, 13 April 2017 16:23:43 UTC