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{minutes} TTWG Meeting 1/5/2014

From: Nigel Megitt <nigel.megitt@bbc.co.uk>
Date: Thu, 1 May 2014 15:08:58 +0000
To: Timed Text Working Group <public-tt@w3.org>
Message-ID: <CF882121.1D0AE%nigel.megitt@bbc.co.uk>
Available at http://www.w3.org/2014/05/01-tt-minutes.html


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

                               - DRAFT -

                Timed Text Working Group Teleconference

01 May 2014

   See also: [2]IRC log

      [2] http://www.w3.org/2014/05/01-tt-irc


          Mike, pal, nigel, glenn, Plh, jdsmith





     * [3]Topics
         1. [4]IMSC FPWD
         2. [5]Issue discussed over the past week
         3. [6]Action Item overdue and due next week
         4. [7]F2F in September
         5. [8]MPEG liaison re MIME Codecs parameter
     * [9]Summary of Action Items

   <trackbot> Date: 01 May 2014

   <scribe> scribeNick: nigel


   nigel: We published the FPWD today

   pal: the Latest version link doesn't work yet

   plh: that's because it hasn't been officially published yet -
   the dated version does work, the latest will work later in the


     [10] http://www.w3.org/2014/03/timed-text-charter.html

   pal: Next step for IMSC is to collect comments and set a goal
   for LC based on level of comment received.
   ... In parallel let's work on IMSC2 based on the progress in
   ... The faster we move through IMSC1 the sooner we'll be able
   to put emphasis on IMSC2.
   ... Is it reasonable to set a target for LC for end of May?

   mike: I'll make SMPTE and DECE aware of this.

   nigel: I'll make EBU aware.
   ... Suggest we review the level of comments received in 2 weeks
   and assess the feasibility of an end of May LC then (on the
   15th May)

Issue discussed over the past week


   <trackbot> Issue-299 -- dur must be greater than zero --
   pending review


     [11] http://www.w3.org/AudioVideo/TT/tracker/issues/299

   nigel: Would Glenn be able to contact Dick Bulterman re the
   reasoning behind 0 dur prohibition in SMIL?

   glenn: yes, I will do that.
   ... On the other point re "willfully violated" I think we
   should stay with the same language as in HTML which has been
   extensively used in quite a few
   ... specifications, so it would be consistent to stay with it.
   ... we refer to SMIL normatively for the semantics but not the
   syntax so we could argue that we may define 0 to be permitted
   for dur in TTML syntax.
   ... However this could create some confusion on the part of
   readers if there is a discrepancy between them. We were silent
   on this in TTML 1 and did not discuss it previously.

   plh: Re "willful" I would agree with nigel that it has negative

   nigel: That's my argument too - my suggestion is "deliberately"
   in place of "willfully"

   glenn: I notice that in TTML1 we use this phrase "without
   taking into account any semantics defined by this
   specification". I could try to reword it to make
   ... clear that we are overriding the semantics.

   RESOLUTION: We will avoid the term "willful violation" in our


   <trackbot> issue-304 -- Non-standard unqualified attributes not
   permitted -- open


     [12] http://www.w3.org/AudioVideo/TT/tracker/issues/304


   <trackbot> action-285 -- Glenn Adams to Implement proposed
   errata in issue-304 -- due 2014-05-01 -- OPEN


     [13] http://www.w3.org/AudioVideo/TT/tracker/actions/285

Action Item overdue and due next week

   glenn: I do plan to use the same namespace in TTML2 as we used
   in TTML1. We did specifically specify the namespace in TTML1 to
   be mutable.

   pal: I don't recall where that action idea came from but the
   discussion raises in my mind re actual implementation. Do we
   know what existing implementations
   ... will do if they find an attribute that they don't recognise
   in a namespace that they do recognise? Do we have any practical
   data points on this?

   glenn: I don't know of any research to give an answer to this.

   pal: Not having to define a new namespace is a really good idea
   but the assumption around disruption of existing
   implementations is of potential concern.
   ... I'm not sure there's much action to do other than to ask
   the question. If no objections we should go with the current
   plan. It's possible that introducing a new namespace will be
   more disruptive.

   glenn: Agree with the point about introducing a new namespace.
   ... The processing rules would expose new names in the
   namespace to the processor. In the DFXP Viewer programme we
   coded it to effectively test for errors in the attributes that
   were used
   ... but I don't believe we did anything to reject the document.
   It was an informational warning. It's possible that if I fire
   that up with a TTML2 document with new attributes in the
   ... namespaces it may raise a warning. I haven't checked all
   the other implementations.
   ... TTML2 §4 also provides some wording on this.
   ... We may want to elaborate on that wording in TTML2 and add
   an errata to TTML1 to deal with this, but perhaps that's a
   different action item.

   action-275: Closing as per discussion today, on the basis that
   we will extend the existing namespace and follow up with
   enhanced wording to §4 in a separate action.

   <trackbot> Notes added to action-275 Review issues in cp12 and
   if one is needed for handling new attributes in ttml2 in same
   namespace as ttml1 then raise it, and link to issue-286..

   close action-275

   <trackbot> Closed action-275.

   <scribe> ACTION: glenn to elaborate on wording in §4 on
   namespace extension in TTML2 and as an errata to TTML1
   [recorded in

   <trackbot> Created ACTION-287 - Elaborate on wording in §4 on
   namespace extension in ttml2 and as an errata to ttml1 [on
   Glenn Adams - due 2014-05-08].

F2F in September


   <trackbot> action-281 -- Nigel Megitt to Talk to frans about
   hosting a meeting -- due 2014-04-24 -- PENDINGREVIEW


     [15] http://www.w3.org/AudioVideo/TT/tracker/actions/281

   nigel: A room of up to 60 people has been reserved at EBU in
   Geneva on 16th and 17th September for us to use for this face
   to face meeting.

   close action-281

   <trackbot> Closed action-281.

   nigel: The goal of this F2F is to work on our charter
   deliverable of a WebVTT <--> TTML mapping

MPEG liaison re MIME Codecs parameter


   <trackbot> action-283 -- Nigel Megitt to And dsinger to respond
   to mpeg liaison -- due 2014-05-01 -- PENDINGREVIEW


     [16] http://www.w3.org/AudioVideo/TT/tracker/actions/283

   close action-283

   <trackbot> Closed action-283.

   mike: In MPEG a couple of weeks ago the DASH group asked for
   some help with the codecs parameter. We decided that W3C should
   manage this with respect to TTML and WebVTT in particular.
   ... MPEG meets every 3-4 months and not much happens in between
   meetings. This means that the response will not be until 2nd or
   3rd week July.
   ... However the intent is that W3C takes ownership of this
   issue so we can act on this more quickly.
   ... Technically, there's a missing requirement. We need to
   indicate the presence of other namespaces since most profiles
   support foreign namespaces.
   ... I don't think it's a fundamental problem but we need to
   reconsider the labels to identify namespaces not profiles.
   ... On the second point the 4C code needs to be defined too
   [minutes incomplete]

   glenn: I don't agree with Mike's point about namespaces. So we
   need to discuss this more.

   mike: The MPEG group's intention was to signal namespaces.
   ... We can also do what we do in TTML2 with the document
   content profile but the codec string folk in the File Format
   group of MPEG felt that string would be too cumbersome and
   ... I agree with you that we should consider that mechanism.

   glenn: Is the purpose of this to define what is required by the
   decoder or is it to define what the content adheres to?

   mike: the latter, what the content adheres to.
   ... The way this works in DASH is that the manifest describes
   the content that is available and the decoder selects the best
   resources for its capabilities.

   glenn: That describes a processor profile not a related content

   mike: I can see that point of view. The important thing is to
   provide an unambiguous identifier which is not too long a

   glenn: If we assume that we can discuss and get folks to agree
   on profile designations, possibly a list of them, then it's
   simply a matter of creating short names to link to those
   ... profile designation URIs.

   mike: I like it. We should talk about mapping it through to the
   mechanism we've already designed.

   nigel: when the page has been created I will add a section on
   meaning and endorsement.

   glenn: I've already got some prior work I can reuse for that.

   mike: Additional to the short name and URI should we also
   encourage a resolvable link to the definition?

   glenn: Yes we should encourage that and a reference to the

   mike: short name, profile URI, profile document URL,
   specification URL, schema/electronic representation URL would
   be a good set of columns.
   ... Everything after the short name and profile URI is
   encouraged but optional.

   <scribe> ACTION: nigel to create issue for codecs parameter
   [recorded in

   <trackbot> Created ACTION-288 - Create issue for codecs
   parameter [on Nigel Megitt - due 2014-05-08].

Summary of Action Items

   [NEW] ACTION: glenn to elaborate on wording in §4 on namespace
   extension in TTML2 and as an errata to TTML1 [recorded in
   [NEW] ACTION: nigel to create issue for codecs parameter
   [recorded in

   [End of minutes]

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Received on Thursday, 1 May 2014 15:08:51 UTC

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