{Minutes} TTWG Meeting 2020-05-28

Thanks all for attending today's TTWG meeting. Minutes can be found in HTML format at https://www.w3.org/2020/05/28-tt-minutes.html


Please note that we made one Resolution:

Resolution<https://www.w3.org/2020/05/28-tt-minutes.html#r01>: The window for new requirements for future versions of IMSC after 1.2 is now open.

Given the nature of this resolution I don't consider this to be something that is likely to generate much adverse comment, however should there be any objection to this, the review period under our decision policy will end on 11th June 2020.

New requirements for IMSC can be raised at https://github.com/w3c/imsc-vnext-reqs/issues


Those minutes in plain text:

   [1]W3C

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


                Timed Text Working Group Teleconference

28 May 2020

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

      [2] https://www.w3.org/2020/05/21-tt-minutes.html

      [3] https://github.com/w3c/ttwg/issues/117

      [4] https://www.w3.org/2020/05/28-tt-irc


Attendees

   Present
          Andreas, Atsushi, Cyril, Gary, Nigel, Pierre, Vladimir

   Regrets
          -

   Chair
          Gary, Nigel

   Scribe
          nigel

Contents

    1. [5]This meeting
    2. [6]IMSC 1.2 CfC to request transition to PR
   3. [7]IMSC vNext requirements window
    4. [8][WR/ARIB] Mixture of text and image w3c/imsc#543
    5. [9]Meeting close
    6. [10]Summary of resolutions

Meeting minutes

  This meeting

   Nigel: Today we have some IMSC topics: PR transition, vNext
   requirements window,
   … and ARIB issues. We also have a placeholder for TTML2 IR but
   I don't think there's
   … much to discuss there.
   … AOB or points to remind the Chair to make sure get covered?

   Pierre: Admin: can we talk about the pull requests that are
   updating links on the published Rec.?
   … They say the PR is not for release. Can we take 5 minutes on
   this.

   Nigel: Right, on IMSC?

   Pierre: Yes, old IMSC, 1.0.1, 1.1

  IMSC 1.2 CfC to request transition to PR

   Nigel: Reminder that the CfC is open until 5th June.

   [11]CfC to request transition of IMSC 1.2 to PR

     [11] https://lists.w3.org/Archives/Public/public-tt/2020May/0033.html


   [12]Draft transition request

     [12] https://github.com/w3c/transitions/issues/245


   Nigel: Anything to raise on this topic?

  IMSC vNext requirements window

   Nigel: 2 current drivers for this (so far):
   … 1. Netflix requirements provided by Cyril a few weeks back
   … 2. ARIB liaison
   … Of course there may be other requirements.
   … Historically we have opened a window for people to register
   new requirements,
   … and I propose doing the same thing again. The question is the
   time window for
   … doing this.
   … Any proposals?

   Pierre: It would help if we as a community try to guess what
   the scope would be.
   … It's hard before calling for requirements, but it would help
   on the timing.
   … We have contributions from Disney and Netflix that are very
   specific.
   … We have ARIB which are very specific too and potentially the
   changes will be more significant.
   … Do we foresee anything else?

   Nigel: I don't think I'm aware of any right now.
   … Something else that's relevant is that CSS is working on Ruby
   stuff at the moment
   … so we potentially have a sync point with their work.

   <atsushi> (sorry for delay of my email on these, Nigel)

   Nigel: It feels that there may be a need to get agreement with
   multiple parties who might
   … take a while to respond.

   Pierre: That's my feeling too.
   … We could adopt a new more flexible process where we could
   issue regular snapshots
   … and address issues as they come up, and decide to go to Rec
   or not Rec based on
   … how much we have.
   … If we do the traditional process for Rec like we did with
   IMSC 1.2 then it will be many months.
   … Question for Netflix is how urgent the fontShear work is for
   Rec publication.

   Cyril: Good question, I would say the sooner the better because
   I want to avoid divergence
   … between actual implementation and content deployed.
   … But alignment with CSS is important, at the same time.

   Pierre: Thinking out loud, a more iterative process is not
   incompatible with the idea of
   … a requirements window for establishing the scope of what we
   are doing.
   … We could freeze them now!

   Nigel: Not sure that's wise!

   Pierre: I'm saying a short period, give people 2 months rather
   than 6.

   Atsushi: Comment on font shear. In i18n JLREQ task force we
   discussed font shear in
   … Japanese. But our knowledge was that font shear is not used
   in Japanese typography
   … so the TF decided not to state any requirement for font shear
   in JLREQ.
   … There is a common way to share font in Japanese typography
   used for publishing,
   … but we haven't had mutual agreement to state something to CSS
   WG yet. Just for information.

   Cyril: That's interesting because it is exactly the opposite of
   the conversation I had with
   … the CSS WG member from Google who is from Japan. Koji Ishi
   maybe. The way we want
   … to do shearing in general is exactly the way it is done in
   Japanese typography so we
   … probably need to resolve that.

   Atsushi: I think he mentioned the common way that font shear is
   done in recent Japanese
   … books. For input to CSS WG we may need to state something
   from some sort of
   … Japanese group. We failed to get to agreement in the JLREQ
   TF. To have some statement
   … we have to get input from a digital publishing group in
   Japan. I think I need to go back
   … to W3C Keio with this to complete the coordination.

   Nigel: Another question about a requirements gathering phase is
   how we make it known
   … to the world. For example liaisons, as we have done
   previously, or a W3 blog post etc
   … It seems that some folk have come to us without any need for
   this.
   … Can we say now that the requirements window is open, and
   think about the closing date
   … and comms for it in the next few days?

   PROPOSAL: The window for new requirements for future versions
   of IMSC after 1.2 is now open.

   Nigel: Any objections?

   <atsushi> +1

   Cyril: no

   Pierre: Sounds good to me

   Resolution: The window for new requirements for future versions
   of IMSC after 1.2 is now open.

   <atsushi> (+1 means go ahead w/ no objection)

   Nigel: Thank you.

  [WR/ARIB] Mixture of text and image w3c/imsc#543

   github: [13]https://github.com/w3c/imsc/issues/543


     [13] https://github.com/w3c/imsc/issues/543


   Vladimir: Just for clarification, can we clarify exactly what
   they mean by inline graphics?
   … I'm not sure what they really mean.

   Nigel: I understand it to be the kind of requirement where a
   company logo is inserted as
   … a graphic inline with text.

   Vladimir: If someone wants to use a PUA code point in a user
   defined font for this, then
   … there is nothing we can do to stop them. I would say that
   would be a pretty unobjectionable
   … use of PUA codes because that's exactly what they're for.
   It's not going to hinder text

   <cyril> this IMSC requirement has an example [14]https://
   github.com/w3c/tt-reqs/issues/15

     [14] https://github.com/w3c/tt-reqs/issues/15


   Vladimir: processing or editing or search. I think that is not
   really a concern.
   … My concern was about GSUB substitution when you need to
   select the right form.
   … Anything that would be used to avoid doing standard
   processing for truly text content.
   … If they want to simplify things by missing some functionality
   I would say that's a bad idea.
   … They say that if GSUB is used before IVS is used then, it
   sounds like they want to simplify
   … by avoiding the need to do it. I think they just want to use
   PUA to see something they
   … want to be displayed. I would say that is a bad idea. It
   might work in a closed system
   … where the Timed Text is authored in the same environment but
   as soon as you attempt
   … to make it something more interoperable then you can't expect
   everyone to do it the same way.

   Nigel: I wanted to note that PUA use can impact text
   processing, for example if a company
   … name is being substituted for its logo, then you might
   reasonably want to do things like
   … Text to Speech of the text,
   … Searching by text name,
   … all before any substitution. If PUA is used that really will
   break those use cases.
   … I think that is why we got to the point of using GSUB as a
   good idea before.

   Vladimir: I absolutely agree with this. I don't think that PUA
   should be used in place of
   … a company name, because the implementation will break.

   Cyril: I agree with what Vlad said. I talked to my Netflix
   experts and they are of the same
   … opinion that we should avoid PUA as much as possible for all
   the reasons that were
   … explained. I am wondering how ARIB got the notion that we
   require GSUB, because I
   … don't think it is mentioned in the spec. Secondly maybe we
   should add something
   … to limit the complexity of the implementation. I don't know
   if we can, for example limit
   … the font functionality required for IMSC. Are there profiles
   for this? I don't know.

   Vladimir: Any attempt to do something to simplify
   implementation to let them off the hook
   … of a specific standardised feature, I think is not a good
   idea, because that feature may
   … manifest itself elsewhere that we cannot predict.
   … If normal text comes in and implementations drop a
   standardised case then
   … preprocessing would be needed. The short answer: I don't
   think it's a good idea to
   … simplify implementations if it goes against the standardised
   feature set.

   Pierre: I think what we should do is get actual samples. It
   just occurred to me that there
   … are no examples of what they are trying to do. We should try
   to see how this works
   … in practice. We had a long thread on what we wanted to do
   with GSUB and we should
   … try it and assess how well supported and how easy it is.
   … We're at the point where we need to try it before we come up
   with a solution.
   … I would actually go back to ARIB and request a sample.

   Nigel: That's a really good idea

   Cyril: Are there tools that allow us to easily create fonts
   with a GSUB substitution?

   Vladimir: Any font tool - most of them allow substitutions. You
   write your own rules as
   … a code entry, to substitute a sequence of glyphs. You don't
   know what those glyphs
   … represent. You just set a rule. Any sequence of input can be
   substituted. For example
   … a company name substituted by a logo is perfectly possible.
   … For example the Zapfino font, on most Macs I think, has a
   substitution entry that
   … substitutes the name of the font for the ligature. They do it
   just to showcase it.
   … You can substitute a ligature or anything else.

   Nigel: That's an input sequence of code points?

   Vladimir: The input is a sequence of unicode text points.
   … Then map those to glyph ids.
   … Then most of the time the substitution rules apply to those
   glyph ids
   … Then you have character codes, and depending on location and
   many other rules, the
   … base glyph can be substituted by something else.
   … For example in Arabic, a positional variant; for Japanese, a
   variation sequence definition.
  … If you have a ligature for example for a sequence of glyphs,
   that is applied to the glyph
   … id sequence mapped from the character codes.
   … You end up as part of this process as one code point entry
   mapped to a glyph that is
   … one of a number of possibilities.

   Andreas: A question re GSUB and PUA. Regarding the concerns
   that Nigel mentioned
   … for example using text for a screen reader, where is the
   difference between GSUB and
   … the use of PUAs? Both are not very accessible.

   Vladimir: It's exactly opposite. Your accessibility is defined
   by the code point sequence.
   … Then your Unicode sequence does not change and is used by the
   screen reader.
   … The font level modifications will only affect visible
   display, not the content itself.
   … That is why this is probably the only accessible way of doing
   things.
   … If you move visualisation decisions upstream and simply use a
   PUA code point to map
   … to a particular glyph, then you break accessibility, because
   now your screen reader has
   … no idea what that is.

   Andreas: And there is no requirement that the mapping of the
   glyphs that people will read
   … will go with what is specified by the code points.

   Vladimir: Exactly, which is why PUA should be avoided unless
   there is something that has
   … no meaning for somebody who cannot see the text.

   <cyril> Zapfino example:
   data:text/html,<div%20style="font:%2048px%20Zapfino">Zapfino<br
   >Zapfin%20o

   Vladimir: If you have "company name, logo" where logo is a PUA
   then that's fine if the screen reader
   … ignores the PUA but if the company name is omitted then it
   will not be accessible.

   Nigel: This reminds me of presentation-scheme based fallback
   options, and I think we
   … should avoid those if we possibly can.

   Vladimir: Yes exactly, and that is the basis of the Unicode
   choice to let font engines
   … do substitutions where needed so that they only affect visual
   presentation.

   Cyril: I asked my font expert if there is a limit to the length
   of the substitution, and he
   … told me it can be very long, like 30 glyphs. Is there a
   limit?

   Vladimir: I don't think so, only practical limitations.
   … Substitution tables can define a chain of substitutions and
   it is only limited by
   … complexity and how far a font designer wants to go.

   Cyril: Vladimir you were asking for an example. Earlier on IRC
   I posted a link to one of the
   … requirements that we have. Nigel showed an example of the
   Twitter logo inline with the
   … text.

   Nigel: Thanks for digging that out!

   Cyril: It's w3c/tt-reqs#15

   Pierre: That's the issue that led to the current situation in
   IMSC and TTML.
   … It would be good to get input from ARIB with sample text and
   corresponding render.

   Vladimir: Yes, for example if someone wants to define the logo
   as a PUA code in addition
   … to the name Twitter, then that would be fine.
   … But if you drop the name and only use the PUA for the logo,
   it breaks accessibility.
   … Better to do it as a font substitution, for visual
   presentation.
   … As far as content sequences are concerned the name Twitter is
   still there.

   Cyril: Also graceful degradation, in case the font engine
   doesn't support substitution.

   Vladimir: I agree. Any time substitution fails you see the
   original unsubstituted text.
   … For company names that's fine. For Devanagari almost
   everything is a substitution, so
   … the presentation would fail.

   Cyril: I'm trying to get back to the ARIB issue and understand
   what exactly they wanted.
   … They end by saying to consider that PUA is a simple
   implementation and a clear indication
   … on the use of GSUB would be helpful.
   … On the first point I think we disagree with them. We don't
   want to recommend it.

   Pierre: I can't even conclude that without seeing what they
   want to do and making sure
   … that we can do it.

   Cyril: I agree that would be useful. I wonder if we should say
   that PUA is not recommended.

   Pierre: Imagine they come back with a PUA example where we
   can't give a better alternative.

   Cyril: You would want to say at this stage we cannot ...

   Pierre: I would like to get a solid example.

   Cyril: Yes, okay that's good.

   Pierre: If they cannot produce an example that also informs us
   a lot.

   Vladimir: 2 final comments. One on what was just discussed. I
   don't think we can do anything
   … to stop them using PUA codes. If someone decides to use it we
   cannot prevent it.
   … On the substitution side, trying to define something in the
   TTML spec, all we can say
   … is we expect font engines to be conformant with the OFF
   standard.
   … If they support the standard then that's not a concern.

   Cyril: I don't think we want to explain how substitution works
   in general, but maybe
   … an example of how to use substitution to explain how it can
   be used to produce
   … inline graphics could be useful in TTML.

   Vladimir: That would be fine [assuming that the spec is stuck
   to]

   Cyril: I agree.

   SUMMARY: TTWG to request ARIB for examples, and consider adding
   a substitution example to IMSC or TTML.

   Nigel: I think I heard no proposals for substantive language
   about support for particular
   … features.

   Cyril: I think Pierre [who left a moment ago] was saying we
   should wait for examples first.

   <Vladimir> just an illustration to my previously used example:
   [15]https://www.myfonts.com/fonts/linotype/zapfino-extra/


     [15] https://www.myfonts.com/fonts/linotype/zapfino-extra/


   Cyril: The action is to request this from ARIB as part of a
   general response?

   <Vladimir> the whole name is substituted with the glyph that
   represents the font name

   Nigel: I would prefer to wait until we have covered the other
   ARIB issues but if it is going to
   … be many weeks then I would prefer to do it sooner.

   Cyril: Yes that makes sense.

   <cyril>
   data:text/html,<div%20style="font:%2048px%20Zapfino">Zapfino<br
   >Zapfin%20o

  Meeting close

   Nigel: Thanks everyone. We're out of time so I'll adjourn now.
   … We didn't manage to get to Pierre's AOB point, so hopefully
   we can cover that off-line.
   … [adjourns meeting]

Summary of resolutions

    1. [16]The window for new requirements for future versions of
       IMSC after 1.2 is now open.


    Minutes manually created (not a transcript), formatted by
    [17]scribe.perl version 117 (Tue Apr 28 12:46:31 2020 UTC).

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






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