W3C home > Mailing lists > Public > public-tt@w3.org > May 2014

{minutes} TTWG Meeting 15/5/2014

From: Nigel Megitt <nigel.megitt@bbc.co.uk>
Date: Thu, 15 May 2014 14:58:50 +0000
To: TTWG <public-tt@w3.org>
Message-ID: <CF9A949C.1DB67%nigel.megitt@bbc.co.uk>
Minutes available at: http://www.w3.org/2014/05/15-tt-minutes.html


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

                               - DRAFT -

                Timed Text Working Group Teleconference

15 May 2014

   See also: [2]IRC log

      [2] http://www.w3.org/2014/05/15-tt-irc


          nigel._pal, Mike, jdsmith

          Frans_de_Jong, Glenn_Adams




     * [3]Topics
         1. [4]MPEG liaison re MIME Codecs parameter
         2. [5]F2F planning
         3. [6]Issues discussed and raised over the past week
         4. [7]Change Proposals
     * [8]Summary of Action Items

   <trackbot> Date: 15 May 2014

MPEG liaison re MIME Codecs parameter

   <scribe> scribeNick: nigel

   nigel: Can't cover this topic fully today as we need Glenn and
   David to contribute to the conversation, but we can summarise
   the state of the debate to date.

   mike: I'm concerned that we haven't addressed my email that
   described the points of disagreement.
   ... the thread seems to have evolved towards document
   conformance profiles, i.e. documents conform to all of the
   profiles that are signalled. Then a decoder only needs to know
   that it can support one of the listed profiles
   ... in order to proceed. This is useful but not sufficient. The
   proposal requires registration of the profile, which is fine,
   but it doesn't allow 3rd party namespaces to be added and
   signalled like the current
   ... 14496 does. That forces the industry to register all
   separate combinations of namespaces. That's not the end of the
   world but the discussion hasn't solved that.

   nigel: It's a point of dispute in the reflector whether
   namespace signalling is needed at all - they're features of
   specifications already.

   mike: It would be a problem for Ultraviolet if all the features
   needed for processing a document can't be defined, e.g. TTML
   subset plus image processing subset.

   pal: Why can't we delegate that combinatorial logic to the

   mike: Yes that will work for the profiles defines by
   Ultraviolet. But it does not solve the problem when the
   document contains 608 and 708 data. There's no way to signal
   that. Someone would have to register
   ... the Ultraviolet profile that includes 608 or the one that
   includes 708 or the one that includes both.

   pal: When you say 608 is that a separate specification?

   mike: yes.

   pal: So another row in the specification table could contain
   m608 and reference that other specification.

   mike: Yes. It forces anyone using a combination of namespaces
   to register with W3C the combination. There's no concept in the
   current proposal to say 'processor needs both X and Y'.
   ... The proposal is necessary but not sufficient - it would say
   'doc conforms to X, Y and Z so if you support any of those you
   can decode the document'. This doesn't cover other namespaces
   ... which would have to be combined and the combination
   registered with W3C.

   pal: So you'd like a way to signal 'document conforms to A+B or
   C or D' to create on the fly new combinations of conformance by

   mike; Right. The argument on the thread was that this allows
   custom profiles to be created on the fly. Today that's already
   possible in the ISO specs. We were only really dealing with the
   unwieldiness of the long strings.

   scribe: It's not the end of the world as long as the
   registration process is lightweight.

   nigel: It would be really helpful Mike if you could point the
   discussion to where the requirement for combinations of
   profiles comes from in the ISO specs.

   mike: It would also be helpful to talk about the registration
   process. If the bar is really low then it's much more
   compelling to force people to register the combinatorial
   profiles they want.

   nigel: Describes lightweight process.

   mike: Maybe we could codify reasons why a registration may be
   rejected, e.g. Not TTML, Already Registered etc.

F2F planning

   nigel: It's for me and David to work on the agenda. The goal is
   to work on our deliverable of the TTML <--> WebVTT mapping.

Issues discussed and raised over the past week


   <trackbot> issue-307 -- Conformance language and processor
   profile rather than content profile. -- open


      [9] http://www.w3.org/AudioVideo/TT/tracker/issues/307


   <trackbot> issue-308 -- It is unclear how a document is
   associated with a related video object -- open


     [10] http://www.w3.org/AudioVideo/TT/tracker/issues/308

   pal: We're awaiting glenn's input on issue-307.
   ... I think nigel wanted to think more about 308.
   ... my action item now is to fix the typo re Related Media
   ... I believe the current document does not mandate that a
   document be attached to a single frame rate.

   nigel: okay I'll review more.

   pal: I propose to make the change to Related Video Object
   either by defining it or changing it. Then I'll close the issue
   and if there's an issue related to frame rate we can open a new

   mike: Historically we made it 'media object' to be more generic
   than video and the link is external to TTML.

   pal: my plan is to define Related Video Object as the video
   component of the Related Media Object.

   nigel: We need to clarify that frameRate in an IMSC document
   does not need to be identical to the frame rate of the related
   media object.

   pal: Would a note be sufficient?

   nigel: yes, possibly.

Change Proposals


     [11] https://www.w3.org/wiki/TTML/changeProposal002

   nigel: I've got a feeling we may need Glenn to review this
   before we can close it.
   ... In fact Glenn has put a note at the bottom showing he's
   implemented it so it's for jdsmith to verify that the
   implementation meets the expectation.


     [12] https://dvcs.w3.org/hg/ttml/rev/c9fd49837446

   nigel: that's the change set on TTML2
   ... The editor's draft for TTML2 is at


     [13] https://dvcs.w3.org/hg/ttml/raw-file/default/ttml2/spec/ttml2.html

   jdsmith: I have a question about change proposal 5. It's not
   really a change, but a representative way to map to HTML.
   ... We've reviewed that here, and it's pretty much what we do.
   What's the destination for the change?

   nigel: It can be an appendix to TTML2, or striped all the way
   through TTML2 per feature, or a separate note altogether.
   ... If the whole world is moving away from XSL-FO towards CSS
   then it would make sense to add it throughout TTML2 on a
   feature by feature basis.

   jdsmith: I could map the rendering to the sections in TTML2.

   plh: I think this would be extremely useful.

   pal: If it applies equally both to TTML1 and TTML2 it should
   not be an appendix to TTML2.
   ... In that case a separate document would be useful.

   plh: I can see it either way. You can use it for TTML1
   additionally to TTML2.

   nigel: I would prefer it to be striped through TTML2 to
   encourage new implementers to start there not at TTML1.

   jdsmith: I'll start working on the mapping to sections.

   plh: We don't want to overload the editor.
   ... You could potentially become another editor for this
   ... By the way some features may not be mappable if CSS doesn't
   have the features, and it's important to highlight them. That
   will probably give rise to a sub-profile of TTML2 that avoids
   non-CSS features.

   jdsmith: Let me look at the work of striping it through, see
   what Glenn thinks and hopefully confirm next week.

   <scribe> ACTION: nigel to create a wiki page for the September
   F2F with a draft agenda and an 'intention to attend' section.
   [recorded in

   <trackbot> Created ACTION-289 - Create a wiki page for the
   september f2f with a draft agenda and an 'intention to attend'
   section. [on Nigel Megitt - due 2014-05-22].

   plh: We're also looking at setting up an Extensible Web Summit
   in Berlin in September just beforehand. This would give people
   a good reason to be in Europe around that time.
   ... The dates aren't final yet - our German office is looking
   for a host. The location will be Berlin because on the 13/14th
   Sep there's a Javascript conference. Once it's settled I'll
   report that back here.
   ... It may help people to attend.
   ... On the testing front, there are lots of good movements
   there. We have a test suite for WebVTT - I'll add the links to
   it to our wiki dashboard. At some point we need to look at what
   we can do for TTML.
   ... The old tests are still valid but we may need to refactor
   them so they can be run automatically.

   nigel: Change Proposal 26 is our home for this

     [15] https://www.w3.org/wiki/TTML/changeProposal026

   plh: Waiting until September before diving into the tests will
   be really helpful. Any progress with scripting languages and
   declarative languages that help automatic testing is good for

   Re Codecs we're tentatively scheduled for the 29th.

   plh: regrets for the next 2 weeks.

Summary of Action Items

   [NEW] ACTION: nigel to create a wiki page for the September F2F
   with a draft agenda and an 'intention to attend' section.
   [recorded in

   [End of minutes]

    Minutes formatted by David Booth's [17]scribe.perl version
    1.138 ([18]CVS log)
    $Date: 2014-05-15 14:57:27 $

     [17] http://dev.w3.org/cvsweb/~checkout~/2002/scribe/scribedoc.htm

     [18] http://dev.w3.org/cvsweb/2002/scribe/



This e-mail (and any attachments) is confidential and may contain personal views which are not the views of the BBC unless specifically stated.
If you have received it in error, please delete it from your system.
Do not use, copy or disclose the information in any way nor act in reliance on it and notify the sender immediately.
Please note that the BBC monitors e-mails sent or received.
Further communication will signify your consent to this.

Received on Thursday, 15 May 2014 14:59:21 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 17:43:35 UTC