{Minutes} TTWG Teleconference 2025-04-24

Thanks all for attending today’s TTWG call. Minutes can be found in HTML format at https://www.w3.org/2025/04/24-tt-minutes.html


We made 3 Resolutions:


  *   RESOLUTION<https://www.w3.org/2025/04/24-tt-minutes.html#2323>: Republish the PNG-HDR-PQ note to include the most recent edits
  *   RESOLUTION<https://www.w3.org/2025/04/24-tt-minutes.html#3a2f>: Apply streamlined publication to all Note track documents so that merging pull requests will trigger republication automatically
  *   RESOLUTION<https://www.w3.org/2025/04/24-tt-minutes.html#dec1>: Publish DAPT Requirements as a WG Note

The review period under our Decision Policy for each of these three resolutions will end on 2025-05-08. If you have any objections or questions about any of them please raise them as soon as possible.

Those minutes in text format:

   [1]W3C

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


                Timed Text Working Group Teleconference

24 April 2025

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

      [2] https://www.w3.org/2025/03/27-tt-minutes.html

      [3] https://github.com/w3c/ttwg/issues/305

      [4] https://www.w3.org/2025/04/24-tt-irc


Attendees

   Present
          Andreas, Atsushi, Chris_Needham, Cyril, Nigel, Pierre

   Regrets
          Gary

   Chair
          Nigel

   Scribe
          nigel, cpn

Contents

    1. [5]This meeting
    2. [6]Republication of png-hdr-pq WG Note
    3. [7]Apply streamlined publication to all of Note track
       documents
    4. [8]DAPT
         1. [9]Transition DAPT requirements WG draft Note as
            formal Note?
         2. [10]Test suite
    5. [11]IMSC 1.3
         1. [12]Outgoing liaisons regarding IMSC 1.3 and Image
            Profile
         2. [13]Refer ARIB STD-B69 or STD-B62?
    6. [14]AOB
    7. [15]Summary of resolutions

Meeting minutes

  This meeting

   Nigel: [reviews the agenda]
   … Anything to add, or points to cover in those items?

   (nothing)

  Republication of png-hdr-pq WG Note

   Nigel: PR 13 adds a warning note to point to PNG 3rd edition,
   in 2023. We haven't published an updated Note since then.
   … The Note was published in 2017, and the Editor's Draft is
   2023
   … There are some broken references to fix too
   … Proposal is to republish this note to include the most recent
   edits

   Pierre: Sounds good

   Chris: +1

   PROPOSAL: Republish the PNG-HDR-PQ note to include the most
   recent edits

   Nigel: Any objections?

   no objections

   RESOLUTION: Republish the PNG-HDR-PQ note to include the most
   recent edits

   Nigel: Needs an editor, to fix some ReSpec errors

   Pierre: I don't mind doing that

   Pierre: I created [16]w3c/png-hdr-pq#14

     [16] https://github.com/w3c/png-hdr-pq/issues/14


   [17]Comment about this resolution in the issue

     [17] https://github.com/w3c/png-hdr-pq/issues/12#issuecomment-2827988771


   Nigel: Anything else on this topic?

   Pierre: After updating, how do we publish?

  Apply streamlined publication to all of Note track documents

   Nigel: We don't have auto-publication set up for Note track
   documents
   … Atsushi asked if we wanted to do that

   PROPOSAL: Apply streamlined publication to all Note track
   documents so that merging pull requests will trigger
   republication automatically

   Nigel: Any reasons not to do this?

   (none raised)

   RESOLUTION: Apply streamlined publication to all Note track
   documents so that merging pull requests will trigger
   republication automatically

   Nigel: Atsushi, could you set this up for us please, starting
   with the PNG HDR PQ Note?

   Atsushi: Will do

  DAPT

    Transition DAPT requirements WG draft Note as formal Note?

   [18]DAPT Requirements WG Draft Note

     [18] https://www.w3.org/TR/dapt-reqs/


   PROPOSAL: Publish DAPT Requirements as a WG Note

   Nigel: I think this is a useful document, and having a Note
   will be better to reference from the spec
   … Any concerns or questions?

   Chris: Sounds good to me

   RESOLUTION: Publish DAPT Requirements as a WG Note

    Test suite

   Nigel: Lots of the issues have been updated in dapt-tests
   recently

   [19]dapt-tests repo issues

     [19] https://github.com/w3c/dapt-tests/issues


   Nigel: I opened an issue for every feature that's listed in the
   implementation report, assuming we need tests for all of them
   … More recently, I've gone through the spec text and written
   some detail about what test resources we need
   … For example, valid and invalid cases for Profile Root
   … I expect, for all these features there are no presentation
   semantics to test, but there are validity cases
   … We'd expect any validator to confirm validity of valid tests,
   and invalidity of invalid tests
   … There's a question about authoring tools, that aren't
   validators
   … For those, I'd suggest a manual exercise to make the
   authoring tool generate output that stresses each feature
   should have that output be valid in a validator,
   … where the validator also passes the validation test for that
   feature
   … Essentially, if the validator seems to work, and if the
   authoring tool stresses the feature, and the validator
   validates that output, we can say the authoring tool did it's
   job
   … Does that make sense?

   Cyril: Yes. An authoring tool could exercise multiple features,
   so we don't need the same granularity

   Nigel: Yes

   Atsushi: What is WPT doing, for CSS, should be fine for us also

   Nigel: CSS usually has visual output you can test against, but
   in our case we don't have that

   Nigel: I've done 8 of them so far, just the analysis of test
   resources expected. Others welcome to contribute
   … My plan is to keep going through them, there are 9 left

   Cyril: To confirm, we're not going to try to create tests for
   combinations of invalid features?

   Nigel: I think we should keep them as separate as we can

   Cyril: The tests shouldn't be just for passing the exit
   criteria, they should be also more useful for implementers
   … Maybe we can augment the test suite in the future

   Nigel: Yes. Then we might want to discuss partitioning the
   files into CR exit criteria tests vs more general tests, or
   keep them all together

   Cyril: I'd keep them all together, then the CR exit criteria
   tests is a subset

   Nigel: That's fine
   … There's one place in the spec where you can't avoid testing
   related features together: represents and scriptRepresents
   … We should keep the tests to the smallest test resource that
   does the job

   Cyril: I was thinking of using an AI agent to generate tests

   Nigel: As long as we can verify them, OK

   Cyril: Just as a way to learn using the AI agent ;-)

   Nigel: Anything else on tests and implementation reports to
   cover?

   Cyril: Netflix will contribute its implementation, more an
   authoring tool / transformation processor than a validator
   … I don't have a coverage for AD parts. Do you have something
   for those parts?

   Nigel: Yes, could be a third party one rather than BBC
   … I could probably do a validator as well
   … Different approaches there: augmenting the current TTT one,
   written in Java

   Pierre: There's the toy validator created for TTML2, in JS,
   [20]sandflow/ttval
   … It's simple to extend
   … If you're interested in this one, happy work with you on it

     [20] https://github.com/sandflow/ttval


   Cyril: To recap, in terms of passing exit criteria, if we have
   a validator, and a Netflix and BBC/Third party implementation,
   that passes the features, we're good to go?

   Nigel: I think so
   … One of the implementers I spoke to said they may have
   something by IBC in September
   … May need to be quicker than that to include in the
   implementation report

   Cyril: Better to have implementation feedback, in case they
   have suggested changes

   <nigel> +1

   Atsushi: Implementation would be judged feature by feature, we
   have a two implementation requirement

   Nigel: Yes, the exit criteria is feature by feature, rather
   than each implementation having to be complete with respect to
   all the features

   Nigel: Anything else on DAPT tests or implementation reports?

   (nothing)

  IMSC 1.3

    Outgoing liaisons regarding IMSC 1.3 and Image Profile

   Nigel: You'll have seen all the outgoing liaisons I've sent
   … We have some responses, some about updating our liaison
   contact names
   … We've also asked on social media
   … Anything to say about early feedback?

   Pierre: So far, it's been a surprise that nobody seems to have
   been using image profile across an ecosystem. It's used
   internally within some systems, but that's different
   … No suggestion anyone is interested in modifying or
   maintaining it
   … This is the private feedback I've received

   Pierre: I'd be happy to keep Image Profile in IMSC 1.3 if
   someone wants to see changes or maintain it

   Nigel: Just want to record I have the same view, even though I
   proposed removing it.

   Pierre: Part of the challenge is it's hard to maintain if we
   don't know how people want to use it
   … Nothing so far really
   … We should give ourselves a deadline

   Nigel: Some groups have a long response cycle...

   Pierre: June?

   Nigel: That's almost 3 months, a reasonable period, given some
   groups' response cycle

   Pierre: We should aim to publish by end of this year, so go to
   CR soon

   Atsushi: From W3C staff point of view, we might want to get
   more attention from external organisations, e.g., SMPTE
   … so I'd like to write some statement to TAG or W3C management
   to invite points of view, an email about the collaboration
   points

   Nigel: I wrote to SMPTE

   Atsushi: Recently we got a small amount of interaction from W3C
   members. That means we could have smaller amount of interest
   among W3C members
   … We may need to gain more member interaction on the timed text
   work
   … Our output is quite stable, so updating activity should be
   quite low compared to other API development work in W3C

   Nigel: What's the impact on IMSC 1.3?

   Atsushi: There's some pressure that we need to gain impact from
   members of interest in our activity, or say new development is
   important for the public interest
   … This kind of public interest should be questioned for our new
   work in the chartering process. Allow time for development
   within W3C. I hope we could gain more interest from external
   parties to our activities in the near future

   Nigel: I'm not clear what action we might take right now
   … Coming back to the liaisons, I sent them on 3 April. We have
   a call on 5 June, so let's use that to assess responses and
   come to a conclusion regarding image profile

   Atsushi: That should be fine, as I understand

   Nigel: Anything else about the liaisons?

   (nothing)

    Refer ARIB STD-B69 or STD-B62?

   Nigel: Atsushi asked which ARIB document we should reference.
   Is there an easy answer?

   Atsushi: I had a question from ARIB about the charter document.
   IMSC 1.3 defines ARIB STD-B62 but the charter and liaison
   statement mentions ARIB STD-B69, so they're wondering which is
   to be referenced from IMSC 1.3
   … They said originally we referred to B62 for everything, but
   were surprised the liaison statement referred to B69, and also
   that it's in the draft charter

   Nigel: B62 has coding of closed captions

   Atsushi: Both refer to our specification. I haven't checked the
   differences between them
   … They wonder if we want to update it to B69 from B62?

   Nigel: I looked it up and STD-B69 is EXCHANGE FORMAT OF THE
   DIGITAL CLOSED CAPTION FILE FOR DIGITAL TELEVISION BROADCASTING
   SYSTEM

   Nigel: Whereas STD-B62 is MULTIMEDIA CODING SPECIFICATION FOR
   DIGITAL BROADCASTING

   Nigel: I don't mind, we can refer to both, it doesn't have to
   be one or the other
   … The latest B62 looks more recent than B69
   … No strong opinion

   Pierre: Can we file an issue?

   Atsushi: If we do that, I'd like to send an email to them about
   it. It's not a big issue, but we need to confirm

   Nigel: Atsushi, could you please raise an issue in the IMSC
   repo?

   Atsushi: Yes

  AOB

   Nigel: The AC review of the TTWG charter has opened. Please
   encourage your AC rep to vote

   Atsushi: Yes, we want responses from all the participating
   organisations

   Chris: I've responded already

   Atsushi: I've asked the Japanese organisations to vote, but
   some might abstain

   Nigel: Next meeting in 2 weeks on 2025-05-08

   [adjourned]

Summary of resolutions

    1. [21]Republish the PNG-HDR-PQ note to include the most
       recent edits
    2. [22]Apply streamlined publication to all Note track
       documents so that merging pull requests will trigger
       republication automatically
    3. [23]Publish DAPT Requirements as a WG Note


    Minutes manually created (not a transcript), formatted by
    [24]scribe.perl version 244 (Thu Feb 27 01:23:09 2025 UTC).

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