{Minutes} TTWG Meeting 2020-03-19

Thanks all for attending today's TTWG meeting. Minutes can be found in HTML format at https://www.w3.org/2020/03/19-tt-minutes.html

In text format:


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

                Timed Text Working Group Teleconference

19 March 2020

   [2]Previous meeting. [3]Agenda. [4]IRC log.

      [2] https://www.w3.org/2020/03/12-tt-minutes.html

      [3] https://github.com/w3c/ttwg/issues/101

      [4] https://www.w3.org/2020/03/19-tt-irc


          Andreas, Atsushi, Cyril, Glenn, Nigel, Pierre





    1. [5]This meeting
    2. [6]AOB - RFC8759
    3. [7]TTML2 Implementation Report
    4. [8]IMSC 1.2 - PING comments
    5. [9]IMSC 1.2 CR Transition
    6. [10]IMSC 1.2 Reference to TTML2
    7. [11]IMSC 1.2 PING comments regarding privacy
    8. [12]CSS font-matching algorithm may introduce
       fingerprinting issues imsc#530
    9. [13]Meeting close

Meeting minutes

   Log: [14]https://www.w3.org/2020/03/19-tt-irc

     [14] https://www.w3.org/2020/03/19-tt-irc

  This meeting

   Nigel: Today we have some comments on IMSC, a check-point on
   … and one AOB so far. Pierre will be with us but half an hour
   later than the beginning so
   … we should rejig the order
   … Is there any other business?

   group: [no other business]

  AOB - RFC8759

   Nigel: I thought the group would be interested to know about

   [15]RFC8759 RTP Payload for Timed Text Markup Language (TTML)

     [15] https://tools.ietf.org/html/rfc8759

   Nigel: It provides a generic mechanism in the context of RTP
   for people to send
   … streams of TTML documents.
   … There are some constraints, like media time only, and the
   times are related to the
   … RTP timestamps.
   … This is formalisation of work previously discussed with, and
   reviewed by, this group.

   Andreas: Congratulations for it. I think BBC put most work into

   Nigel: Yes, the author works at BBC R&D.
   … There was other supporting input as well from other parties.

   Andreas: I wanted to ask how this relates to the IMSC live
   proposal, if this could be a
   … good connecting point to push this?

   Nigel: There's a key difference between what can be done with
   TTML over RTP and
   … what can be done with the proposed TTML Live extensions.
   … That difference is that TTML Live extensions can allow
   retrospective modification of
   … the content on the TTML timeline.
   … This cannot be done with TTML over RTP because RTP is a "now
   do this..." type of system.
   … Conversely that RTP way is simpler for the same reason.

   Andreas: For EBU-TT live there is the concept of a carriage
   … Is there the same concept for TTML Live?

   Nigel: Yes there is

   Andreas: Then you would say TTML over RTP would not be such a
   carriage specification?
   … Or could it be one that uses a subset of the TTML Live

   Nigel: Really good question. I did write the mapping down at
   one stage.
   … I wrote something about this a while back:

   [16]TT-Live to TTML in RTP and back

     [16] https://github.com/w3c/tt-module-live/blob/master/tt-live-1/design/live-to-rtp.md

   Nigel: I should adjust that document now the RFC has been
   … This document describes the conversion in each direction. It
   can be done.

   Andreas: Thanks Nigel

  TTML2 Implementation Report

   Nigel: I think the main work now is tests.
   … I saw Glenn's comment on one of the tests yesterday which I
   reviewed and agreed with.

   Glenn: Yes, slow start getting going on those tests, but expect
   to see some PRs this week
   … on that. I want to get them out there so we can get some
   implementations wrapped up
   … and get moving on the proposed recommendation process.

   Nigel: Also worth noting there has been some activity on the
   privacy review of IMSC and TTML2
   … this week.

   Glenn: Yes, I saw that. I think it won't take much effort. We
   can pull some small amounts
   … of text into the appendix to address those points.

   Nigel: I agree

   Glenn: Those will be editorial changes for the proposed Rec.

   Nigel: Yes

   Glenn: Expect some pull requests for that process too.

   Nigel: On the classification of change, they will be changes
   that have no effect on conformance.

   Glenn: That's correct.
   … That appendix is non-normative anyway.

   Nigel: That will be useful or important for IMSC 1.2 also.
   … I think we expect to update the ref from IMSC 1.2 to TTML2 to
   point to TTML2 2nd Ed
   … and that's an agenda point for today.
   … It could be that the resolution to the privacy issues
   consists of changes both to TTML2
   … and to IMSC 1.2.

   Nigel: One of the comments is that TTML doesn't mention
   anything about secure transport.
   … But I think it makes no comment about transport at all.

   Glenn: That's correct. We abstract out the transport by
   referring to the document
   … processing context.
   … It makes it easy for us to deal with this I think, by
   throwing it in the black box.
   … We can make handwaving gestures to refer to this to say, if
   you're interested, pay
   … attention to [blah blah].

   Nigel: That's right. One of the suggestions is that we should
   change any URLs in examples
   … to make sure the protocols are secure ones.

   Glenn: Yes I will check that, it may be worth doing.

  IMSC 1.2 - PING comments

   Nigel: We received comments from PING via Nick Doty, which he
   has kindly
   … raised as a GitHub issue.
   … Let's cover those after the other two agenda points.

  IMSC 1.2 CR Transition

   Nigel: Where are we up to with transition?

   Atsushi: Immediate approval was not gained. It will be
   discussed in tomorrow's slot, including
   … recent updates.

   Nigel: Does the team need me or Pierre to be part of that

   Atsushi: I need to update following the comments from HR
   … Also comments on these reviews are welcome.
   … Comments on the transition request issue are welcome from

   Pierre: What's really important for us to understand is if the
   delay is due to lack of agenda
   … time or because of concerns regarding comments?

   Atsushi: It is the first of those. I needed to raise a comment
   by last Friday's slot.

   Pierre: Now it is ready so it can be considered tomorrow?

   Atsushi: Yes

   Pierre: So there will be no update to the transition request?

   Atsushi: We can add new information at any time.

   Pierre: If the meeting is tomorrow then we have no more time to
   make modifications
   … unless we do it now.
   … I want to avoid a response tomorrow to say the request is not
   complete, let's wait another week.

   Atsushi: I think the current transition request is complete and
   also refers to recent updates.

   Nigel: Thank you.
   … Then there will be a small modification to the document to
   reflect the new publication
   … date.

   Atsushi: I believe so.

  IMSC 1.2 Reference to TTML2

   Nigel: I wanted to check in with the group here.
   … My assumption has been that we will update the TTML2 ref from
   IMSC 1.2 to point
   … to TTML2 2nd Edition before going to Rec. Are there any

   Pierre: I don't have a different assumption, please file an

   Nigel: Happy to do that.
   … Does anyone think we should not do it?

   group: [silence]

   Nigel: OK I think that is consensus to update the ref to TTML2
   2nd Ed. Thanks.

   [17]IMSC #531 Update TTML2 ref to point to TTML2 2nd Ed

     [17] https://github.com/w3c/imsc/issues/531

  IMSC 1.2 PING comments regarding privacy

   Nigel: The reason it's useful to reference TTML2 2nd Ed is
   because some of the
   … privacy comments may be addressed in part by reference.

   Pierre: I think we need all the issues to be logged on IMSC
   … It is not practical to trace comments on other repos.
   … We should not process anything that is not on the IMSC repo.
   … I propose we let the W3C team know this.

   Nigel: I'm not aware of any expectation to do so.
   … Just for completion, Nick Doty raised one issue on IMSC 1.2
   and one on TTML2.
   … I think this these are all the issues we are expecting
   following the email review.
   … I also think they made the right call about which repos to
   file them against.
   … The generic resource fetching issue is filed against TTML2
   where the features are defined,
   … and the more specific domain related feature about
   fingerprinting regarding font
   … matching is filed against IMSC 1.2.

  CSS font-matching algorithm may introduce fingerprinting issues

   github: [18]https://github.com/w3c/imsc/issues/530

     [18] https://github.com/w3c/imsc/issues/530

   Nigel: Did we actually introduce CSS font matching algorithm?
   … I see at [19]https://w3c.github.io/imsc/imsc1/spec/

   … that we introduced:
   … "A Processor MAY use the [css-fonts-3] §5 font matching
   algorithm for associating a font with a run of text."
   … My question is, if this is an option, not a requirement, why
   wouldn't the CSS handling
   … of the privacy issue be implied by reference.

     [19] https://w3c.github.io/imsc/imsc1/spec/ttml-ww-profiles.html#text-font-source

   Pierre: Just to point out that in §10.5 we mention the CSS font
   matching algorithm
   … is also referenced via a defined term Font Matching
   … Editorially we should improve that.

   Nigel: Right, and that's in the HRM section.
   … The HRM considerations are in my view concerned with document
   validation, and there's
   … no requirement for the presentation processor to follow any
   steps in the HRM to
   … render content.
   … I would not expect a user-oriented player to execute the
   steps of the HRM.

   Andreas: +1

   Nigel: And therefore there's no privacy issue associated with
   … That takes us back to 8.5.3.

   Pierre: To your earlier point Nigel, I don't see what action we
   can reasonably take.
   … There are a lot of "mays" and "under discussion" and no
   proposed resolution.

   [20]Email that prompted this issue

     [20] https://lists.w3.org/Archives/Public/public-tt/2020Mar/0013.html

   Nigel: There are additional questions in the email that are not
   in the GitHub issue.

   Pierre: We have generic text in TTML2 about loading of
   resources, I believe.

   Glenn: There are some handwavy statements

   Pierre: About resource fetching?
   … In the absence of specific concerns we can only offer generic

   Glenn: Exactly.
   … I don't know what we can practically say.

   Pierre: We can ask about specific issues with the TTML2 text.

   Glenn: Ask for spec-ready text we can drop in.

   Pierre: Exactly, that's what we should do.
   … We can't tell CSS and HTML how to do fingerprinting

   <atsushi> +1

   SUMMARY: TTWG thanks @npdoty for raising this. In the context
   of continuing discussions and without understanding any
   specific improvements we can currently make, we will proceed
   with no changes for the time being.

   SUMMARY: Discussion of additional questions raised in the
   linked email to continue offline.

  Meeting close

   Nigel: Thanks everyone. [adjourns meeting]

    Minutes manually created (not a transcript), formatted by
    [21]scribe.perl version 113 (Sat Mar 7 01:13:06 2020 UTC).

     [21] https://w3c.github.io/scribe2/scribedoc.html

Received on Thursday, 19 March 2020 17:24:11 UTC