W3C home > Mailing lists > Public > public-tt@w3.org > September 2016

Re: Minutes from today's TTWG meeting

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Tue, 20 Sep 2016 06:30:25 +1000
Message-ID: <CAHp8n2kTMknEb_e-HO5idbwchb79bjDb7fnQweCNZ22TF3ju6g@mail.gmail.com>
To: Nigel Megitt <nigel.megitt@bbc.co.uk>
Cc: Public TTWG List <public-tt@w3.org>
There's nothing stopping the group to decide to move WebVTT to CR right
now. Why not just get it done?

Best Regards,
Silvia.

On 20 Sep 2016 3:33 AM, "Nigel Megitt" <nigel.megitt@bbc.co.uk> wrote:

> Thanks all for a very productive first day of our Lisbon TPAC face to face
> meeting. Minutes can be found in html format at
> https://www.w3.org/2016/09/19-tt-minutes.html
>
> We made 1 resolution:
>
> *RESOLUTION: If we do not move WebVTT to CR in this Charter period then we
> will not include it in any new Charter.*
>
> The review period for this resolution under our Decision Process ends on
> Monday 3rd October.
>
> Minutes in text format:
>
>    [1]W3C
>
>       [1] http://www.w3.org/
>
>                 Timed Text Working Group Teleconference
>
> 19 Sep 2016
>
>    See also: [2]IRC log
>
>       [2] http://www.w3.org/2016/09/19-tt-irc
>
> Attendees
>
>    Present
>           Rohit, Nigel, Glenn, Thierry, Dae, Andreas, David,
>           Pierre
>
>    Regrets
>    Chair
>           Nigel
>
>    Scribe
>           nigel
>
> Contents
>
>      * [3]Topics
>          1. [4]Agenda bash
>          2. [5]Plan for Joint Meeting with Web & TV IG
>          3. [6]WebVTT stuff
>          4. [7]Tagging
>          5. [8]TTML1 Errata
>          6. [9]TTML2 Pull Requests
>          7. [10]IMSC 2
>          8. [11]Agenda bash
>          9. [12]TTML2 implementation work
>      * [13]Summary of Action Items
>      * [14]Summary of Resolutions
>      __________________________________________________________
>
>    <scribe> scribe: nigel
>
> Agenda bash
>
>    group: [discusses topics on meeting page
>    [15]https://www.w3.org/wiki/TimedText/tpac2016#Schedule
>
>      [15] https://www.w3.org/wiki/TimedText/tpac2016#Schedule
>
>    <glenn> +Present Glenn
>
>    nigel: Seems like the topics list is pretty close to the order
>    we want to cover stuff in.
>
> Plan for Joint Meeting with Web & TV IG
>
>    nigel: We are meeting the Web & TV IG at 11, so need to provide
>    an update etc.
>    ... Discusses proposal for Web & TV IG consisting of update on
>    our work in TTML,
>    ... audio description requirements, issue of relationship
>    between encoded video, media player
>    ... and timed text presentation; live contribution and BBC
>    subtitle guidelines. (last two points from Nigel with a
>    different hat on!)
>
>    andreas: I have some slides to discuss on TextTrackCue
>    interface support for different formats in HTML5.
>    ... I would also point to the unconference session on this on
>    Wednesday. They may also
>    ... want to log this as work that needs doing by a Web & TV IG
>    task force.
>
>    nigel: Good idea, let's do that ahead of my stuff on AD, live
>    contribution etc.
>
>    andreas: [Previews slides] including missing MIME type on track
>    element in HTML5
>
>    nigel: Thanks, let's do that after the TTWG update and if
>    there's time to hand back to me for the other parts then let's
>    do that.
>
> WebVTT stuff
>
>    david: Number one priority is to find a new Chair to cover this
>    topic - I've indicated already to
>    ... plh etc that I don't have the time to devote to this.
>
>    glenn: What's the status of implementation work?
>
>    david: At Apple it's bug fixing, keeping up with customers.
>
>    glenn: On the Chrome and webkit list I don't see much activity.
>    I am not following mozilla or Edge.
>    ... What's the status in other groups e.g. MPEG referencing
>    WebVTT?
>
>    david: The Chair does need to make progress on moving it to Rec
>    so it can be normatively referenced.
>    ... There is implementation work excluding region support in
>    many implementations.
>
>    andreas: I think there have been updates to the specification
>    that have not been reflected in
>    ... implementations so this is a problem.
>
>    nigel: I've noticed that too - Simon made some really good
>    changes around 10-11 months ago,
>    ... which i suspect have not been implemented. I'm not sure
>    about the status of editing to
>    ... address the readability review feedback.
>
>    david: Apple's implementations predate those changes.
>
>    andreas: It's hard to know if those changes will ever make it
>    into implementations.
>
>    nigel: From a BBC perspective there are features that are
>    essential for accessibility that look
>    ... like they would have to be put at risk for CR due to lack
>    of implementation, so that would
>    ... be a "red flag" for me.
>    ... For example the BBC's editorial guidelines at
>    [16]http://bbc.github.io/subtitle-guidelines/
>    ... cannot I believe be met by most implementations of WebVTT
>    right now.
>
>      [16] http://bbc.github.io/subtitle-guidelines/
>
>    action-475?
>
>    <trackbot> action-475 -- Nigel Megitt to Contact the chair of
>    the web & tv ig to ask about schedule and joint meeting time.
>    -- due 2016-07-28 -- OPEN
>
>    <trackbot>
>    [17]http://www.w3.org/AudioVideo/TT/tracker/actions/475
>
>      [17] http://www.w3.org/AudioVideo/TT/tracker/actions/475
>
>    nigel: oops I meant:
>
>    action-473?
>
>    <trackbot> action-473 -- Thierry Michel to Contact co-chairs
>    and essential parties on how to move forward on vtt; need an
>    action plan -- due 2016-06-30 -- OPEN
>
>    <trackbot>
>    [18]http://www.w3.org/AudioVideo/TT/tracker/actions/473
>
>      [18] http://www.w3.org/AudioVideo/TT/tracker/actions/473
>
>    nigel: Thierry did this, but I don't believe we have an action
>    plan.
>
>    david: We need a suitable volunteer to go through the review
>    comments and respond.
>
>    thierry: The Community Group has looked into the review
>    feedback - about 30 comments
>    ... have been discussed: that's the current status. Now those
>    comments need to be approved
>    ... by the TTWG (and discussed) and then we should send those
>    responses to the commenters.
>    ... At some point we need to coordinate between the CG and the
>    WG to progress those.
>    ... This has not changed for more than a year, probably because
>    some people involved have
>    ... left and Simon does not participate actively in the WG. We
>    are experiencing joint work with
>    ... a CG and a WG and we need to invent a process to deal with
>    this.
>
>    nigel: This works both ways - the WG also has not scheduled any
>    effort to work on this.
>
>    andreas: I'm not really convinced that the CG exists as a
>    traditionally defined group.
>
>    nigel: Shall we close the action? The "contact the chairs" part
>    is done, we're missing an action plan.
>
>    david: Leave it open.
>
>    action-473: Discussed in TTWG F2F 2016-09-19 - need a volunteer
>    to progress this, possibly a new Chair.
>
>    <trackbot> Notes added to action-473 Contact co-chairs and
>    essential parties on how to move forward on vtt; need an action
>    plan.
>
>    action-396?
>
>    <trackbot> action-396 -- David Singer to Produce evidence of
>    request for wide review for webvtt, for the archive -- due
>    2015-04-17 -- OPEN
>
>    <trackbot>
>    [19]http://www.w3.org/AudioVideo/TT/tracker/actions/396
>
>      [19] http://www.w3.org/AudioVideo/TT/tracker/actions/396
>
>    david: I have not yet done this.
>
>    action-396: TTWG F2F meeting 2016-09-19: David has not been
>    able to do this yet.
>
>    <trackbot> Notes added to action-396 Produce evidence of
>    request for wide review for webvtt, for the archive.
>
>    nigel: TO be controversial/challenging, WebVTT has been on our
>    Charter since 2013 and we
>    ... have made very little progress. Should we drop it?
>
>    david: If we don't complete it in this Charter period [end
>    March 2018] then we should not
>    ... recharter it - I propose that as a resolution.
>
>    PROPOSAL: If we do not make progress on moving WebVTT to
>    Recommendation in this Charter period we do not intend to
>    include it on any rechartering.
>
>    thierry: That's a final step - I think we should be aiming to
>    move to CR well before that.
>
>    david: I agree.
>
>    glenn: We could publish it as a WG Note, to make it easier for
>    external people to reference.
>
>    nigel: This is a lot easier.
>
>    thierry: That would probably be a final step to that work.
>
>    nigel: In fact publishing a Note is a process requirement if we
>    stop working on it.
>
>    thierry: We would do that if we removed it from the Charter.
>
>    glenn: It would be helpful to have a document that does not
>    have the word "Draft" in it.
>
>    thierry: I'm happy to help with the wide review; that's one
>    thing. The second thing is the CR.
>    ... We could stay in CR for a couple of years and monitor
>    implementation work, or we could
>    ... remove non-implemented features. Right now there are a lot
>    of features that are not
>    ... implemented. That's something we could do in parallel.
>    Maybe it is not useful to have
>    ... comments on features that we are likely to drop.
>
>    nigel: I want to signal that if we have to drop features that
>    are essential for accessibility then
>    ... I will have to object to it progressing.
>
>    thierry: There's also a lack of specification text on
>    integrating CSS. We could maybe save time
>    ... by not addressing issues that we know are unlikely to be
>    implemented in the next two years.
>
>    group: discussion about who is interested in contributing to
>    implementation work etc and therefore progressing responses to
>    comments.
>
>    RESOLUTION: If we do not move WebVTT to CR in this Charter
>    period then we will not include it in any new Charter.
>
>    andreas: We could mention the TTML to WebVTT mapping document
>    in the Web & TV IG meeting.
>    ... We published it last year and are awaiting implementation
>    comments. We are waiting for a
>    ... stable reference for WebVTT in order to proceed.
>
>    thierry: You would expect to see at least a CR document?
>
>    andreas: CR would clearly indicate a stable set of features you
>    can map against.
>
> Tagging
>
>    david: DASH and the MP4 file format have a way to tag the kind
>    of role of a track, using a URI
>    ... to identify the vocabulary used, and then a term from that
>    vocabulary. I need a URI to
>    ... refer to the @kind vocabulary in the HTML5 specification,
>    and there isn't one.
>
>    pierre: There is one but it is not complete, specified in DASH.
>
>    david: It is not specified in the HTML document itself.
>
>    pierre: That's correct. As long as we can reference the one in
>    DASH that can be used.
>
>    david: Agreed there is a DASH vocabulary.
>
>    pierre: So the request to add one to HTML is not required for
>    MPEG CMAF because the DASH one can be used.
>
>    david: I got agreement from WHATWG and the Web Platform WG for
>    about:html-kind as the URI
>    ... that refers to the @kind vocabulary in the HTML
>    specification.
>    ... And I have registered that with IANA.
>    ... I'm waiting for that URI to appear in a revision of the Web
>    Platform docs. When it is then
>    ... I will update the IANA form.
>
>    nigel: It's good to have that but I would note that in my view
>    the kind vocabulary is terrible.
>
>    glenn: There are some semantics associated, such as prevention
>    of display of metadata tracks by the UA.
>
>    david: I would agree that the HTML vocabulary is both under-
>    and over-specified simultaneously! (in different ways)
>
>    nigel: In my view it is insufficiently rich to describe the
>    purpose and intent of the track data.
>
>    pierre: It would be great if as making the HTML vocabulary more
>    official we could also fix it.
>
>    david: I support that.
>    ... CMAF does prefer DASH at the moment - it says to use the
>    DASH term if it supports what you want to do.
>
>    nigel: I also note that we have not addressed how to extract
>    something equivalent to kind
>    ... within a timed text document so that it can be extracted
>    and used to embed into a host HTML page.
>    ... We did address language recently, but not kind.
>
>    david: Some people want to manage external manifest files, but
>    I'm in favour of self describing documents.
>    ... I'm also aware of ongoing discussions about tags for easy
>    to read captions (mandated by FCC) and karaoke.
>
>    pierre: There is a very specific definition of those two terms
>    in karaoke.
>
>    glenn: In TTML2 we have a named metadata item for easy reader.
>    There's nothing on karaoke per se.
>    ... nothing that uses that term in TTML2.
>
>    nigel: [adjourns for a break] - let's meet in Auditorium IV at
>    1100 for our update to Web & TV IG.
>
>    <nigel_> nigel: Joint meeting - see #webtv
>
> TTML1 Errata
>
>    nigel: Are there any other errata other than for backgrounds on
>    spans and lines?
>
>    pierre: The only thing I'd mention is that the computed style
>    resolution for % is very well defined
>    ... but the computed style for em is not so clear when you say
>    e.g. tts:fontSize="2em" but
>    ... that is with respect to the current font size but that is
>    not well defined in TTML1. I assume
>    ... it is relative to the parent element's font size but it
>    does not say that clearly.
>
>    glenn: I would consult TTML1 and then go back and reference
>    XSL-FO which would take me
>    ... to CSS2. Without having done a recent review of that I
>    don't know off the top of my head
>    ... but I'm pretty sure you're right - it would have to make
>    use of the computed font size of
>    ... the parent element.
>
>    pierre: Notice that we already have issue #206 on the ttml1
>    repo which is a bug about
>    ... specifying em units for fontSize on region.
>
>    nigel: That sounds very similar.
>
>    glenn: Right now there are 23 open issues on TTML1 so I would
>    expect that there are some
>    ... errata to be written for those and they probably also need
>    to be fixed in TTML 2 also.
>
>    pierre: I can go ahead and create an issue for this.
>
>    glenn: Go ahead - also refer to #206 - it may be related but
>    more general.
>    ... I think I propose that it should be in relation to 1c.
>
>    pierre: That was my first thought, but looking at XSL-FO I
>    think it is probably more like %.
>
>    nigel: Okay, so the one on the agenda is:
>    [20]https://github.com/w3c/ttml1/issues/209
>
>      [20] https://github.com/w3c/ttml1/issues/209
>
>    andreas: I think there has not been much progress since we last
>    discussed it. We said we need
>    ... more investigation to find a good solution. I want to point
>    to something related.
>    ... This problem about gaps between lines has been addressed by
>    the HbbTV 2.0.1 spec
>    ... which a lot of televisions will implement. At the moment
>    that is not really interoperable
>    ... and compatible with IMSC 1 so we should pay attention to
>    it.
>    ... References spec text from HbbTV 2.0.1 that, specific to
>    EBU-TT-D 1.0 defines that
>    ... where the lineHeight is "normal" or <125% the background of
>    each generated inline area
>    ... shall be rendered such that there are no gaps between the
>    rendered backgrounds of
>    ... adjacent lines.
>
>    glenn: We have a quasi default of doing what CSS does, which is
>    different from what this suggests.
>    ... This mandates behaviour that is at variance with the XSL-FO
>    and CSS behaviour.
>
>    andreas: Yes.
>
>    glenn: By the way issue #209 on the TTML spec has a length
>    discussion on this.
>    ... The bottom line in my reading is that the height of an
>    inline area in CSS is implementation defined.
>    ... Different implementations have fine tuned themselves to be
>    consistent with each other, outside of any spec.
>
>    nigel: You can see an editorial requirement example of this at
>    [21]http://bbc.github.io/subtitle-guidelines/#Background-size
>
>      [21] http://bbc.github.io/subtitle-guidelines/#Background-size
>
>    glenn: I agree that we need to nail this down - also see issue
>    #212 in TTML1.
>
>    nigel: [22]https://github.com/w3c/ttml1/issues/212
>    ... [23]https://github.com/w3c/ttml1/issues/209
>
>      [22] https://github.com/w3c/ttml1/issues/212
>      [23] https://github.com/w3c/ttml1/issues/209
>
>    pierre: A browser based CSS implementation would display a gap?
>
>    glenn: Correct
>
>    andreas: There are scripting techniques for getting around
>    this.
>
>    pierre: If we feel this is a common requirement for
>    accessibility then it needs to be addressed in the CSS WG
>
>    glenn: I've had a detailed offline discussion with Bert Bos
>    about this and he pointed out that
>    ... one of the advanced level 4 modules might at some point be
>    able to deal with this.
>    ... There are a whole bunch of assumptions in CSS on inline
>    non-replaceable areas, for example
>    ... you cannot specify the content height manually. The height
>    property explicitly does not
>    ... apply. That was the first problem we ran into, because we
>    wanted the height of the content
>    ... box to extend to the line area. Somewhere I proposed a mode
>    for the style engine to use
>    ... different semantics for the height of content areas. The
>    question is can you have a profile
>    ... that defaults the parameter to a particular value.
>
>    nigel: The pressing need here is to issue some statement on
>    this for TTML1.
>
>    piere: I recall that some people use a style where they do
>    actually want the gap.
>
>    andreas: yes, for example if you have the lineheight at 200%
>    you don't want such a big background area.
>
>    pierre: In CSS can you always add padding to every line?
>
>    glenn: You can but the problem is you cannot determine at
>    authoring time what value to add.
>    ... At first order we should document more carefully what the
>    current situation is in TTML1.
>    ... That may allow people to come up with no-gap semantics. We
>    could define the default
>    ... semantics to be the no-gap scenario but if we do that we
>    need to allow the author to define
>    ... the other behaviour. If we change the default now what
>    would that break?
>
>    nigel: I understand that the content rectangle is not well
>    defined?
>
>    glenn: It is not, but all the browser implementations do it
>    roughly the same way.
>
>    nigel: Could we add an informative note via an erratum to say
>    that the content rectangle is
>    ... not well defined but is commonly implemented so that it
>    does not go to the line height?
>
>    pierre: That's not what I'm hearing. I think CSS needs to
>    address this.
>
>    glenn: I'm worried that we cannot easily go back and
>    retroactively define the content height
>    ... to never show a gap.
>
>    pierre: It would be easier to do that if it were not that some
>    folk like the gap.
>
>    glenn: In TTML2 we can add a new mode that drives that, but in
>    TTML1 what can we do?
>
>    andreas: This requirement for no gaps came from accessibility
>    guidelines to get proper presentation.
>    ... The minimum we could say is that some specifications could
>    define this.
>
>    pierre: If someone is overriding that rendering it needs to be
>    flagged.
>
>    andreas: That will not change, I think this is more of an
>    interoperability problem.
>    ... There is an initial step e.g. for an IMSC 1.1, and then a
>    long term TTML2 solution.
>    ... For now we should say something about this in TTML1.
>
>    pierre: +1
>
>    andreas: I would also hope for a liaison to respond to this.
>
>    glenn: We can note that the algorithm for content height is not
>    concretely defined and that
>    ... browsers do behave the same with current CSS
>    implementations and will introduce a gap.
>    ... If we do want a new TTML1 feature we could write a short
>    specification introducing a
>    ... ttsx namespace style that is interpreted in a particular
>    way.
>
>    andreas: Ideally if there is a proper parameter to control this
>    it should be defined in this group.
>
>    nigel: +1
>
>    glenn: That would be an official extension to TTML1, which we
>    could say maps to a particular
>    ... syntax and semantic in TTML2.
>    ... That might be an approach.
>
>    pierre: If there is an urgent need to address real problems we
>    should address it in IMSC 1.1.
>
>    glenn: I've heard 3 things: 1. Clarify TTML1 with an errata -
>    we can do that non-controversially.
>    ... 2. We can define new mechanisms in TTML2 - we can do that
>    no problem.
>    ... 3. More controversially, define a new extension style for
>    TTML1. That creates another fork
>    ... in the implementation space.
>
>    andreas: The target when this was discussed was an IMSC 1.1
>    version. If that is possible we
>    ... should do that.
>
>    pierre: Absolutely. The question is if there is an urgent need
>    to resolve an industry problem now.
>    ... The worst thing would be to make a change that does not
>    solve the problem.
>
>    andreas: HbbTV has solved this for now - it would be
>    interesting to know if this breaks
>    ... current implementations.
>
>    pierre: it would be good to have a formal communication with
>    HbbTV about this issue.
>    ... It is essential that HbbTV is encouraged to communicate
>    their requirements to this group and we should be welcoming of
>    this, even if we make the initial communication.
>
>    andreas: We should also be clear that it is needed for
>    interoperability to establish this communication channel.
>
>    nigel: Notes that independent of HbbTV the BBC raised this
>    issue on TTML2 and andreas opened the equivalent on TTML1.
>    ... I want to come back to what we can do here.
>
>    andreas: There's the formal comms with HbbTV, an errata for
>    TTML1, and a discussion about
>    ... how to fix for TTML2. If there is no formal requirement for
>    this then it will not happen in IMSC 1.
>
>    pierre: BBC has raised this for TTML2, but the timescale for
>    that is very different than for TTML1.
>    ... To make a change on TTML1 requires a higher threshold, so
>    if there is a group such as
>    ... HbbTV that needs this in the short term then we should do
>    it.
>
>    <scribe> ACTION: nigel Draft a liaison to HbbTV requesting
>    further information and proposing an option e.g. to extend IMSC
>    1 to allow signalling of background height on span, and request
>    timelines etc. [recorded in
>    [24]http://www.w3.org/2016/09/19-tt-minutes.html#action01]
>
>      [24] http://www.w3.org/2016/09/19-tt-minutes.html#action01]
>
>    <trackbot> Created ACTION-478 - Draft a liaison to hbbtv
>    requesting further information and proposing an option e.g. to
>    extend imsc 1 to allow signalling of background height on span,
>    and request timelines etc. [on Nigel Megitt - due 2016-09-26].
>
>    nigel: Okay, that works; I would also still like to see the
>    erratum on TTML1 to provide the context
>    ... for any update to IMSC 1 to allow signalling this
>    behaviour.
>
>    glenn: I have added a comment on the issue at
>    [25]https://github.com/w3c/ttml1/issues/209#issuecomment-247973
>    673
>
>      [25] https://github.com/w3c/ttml1/issues/209#issuecomment-247973673
>
>    nigel: Thank you!
>
>    glenn: Of course that doesn't explain what to do about it, but
>    that's for [26]https://github.com/w3c/ttml2/issues/150
>    ... We have consensus in TTLM2 to solve this?
>
>      [26] https://github.com/w3c/ttml2/issues/150
>
>    nigel: Yes please!
>
>    glenn: I have a bpd content proposal where I define 7 possible
>    values.
>
>    nigel: That may be more than we need - let's review.
>    ... Thanks for the good discussion everyone, let's adjourn for
>    lunch and return at 1400.
>
> TTML2 Pull Requests
>
>    nigel: First up, [27]https://github.com/w3c/ttml2/pull/177 Add
>    tts:background{Clip,Extent,Origin}
>
>      [27] https://github.com/w3c/ttml2/pull/177
>
>    glenn: This is for image rendering support - I missed a couple
>    of items from CSS: there is
>    ... an editorial note to add them.
>    ... I ended up using backgroundExtent rather than
>    backgroundSize for consistency.
>
>    nigel: Just a note on reviewing the PRs - they don't include
>    the built HTML so it's hard to
>    ... review or diff. I'd like a CI tool to build the HTML
>    automatically so we can review it.
>
>    glenn: I could do the build and check in the built HTML but
>    then on pulling I would have to
>    ... remove it and build it again for gh-pages.
>    ... I'll go ahead and make a change to make these easier to
>    review.
>
>    <glenn>
>    [28]https://www.w3.org/TR/css3-background/#the-background-origi
>    n
>
>      [28] https://www.w3.org/TR/css3-background/#the-background-origin
>
>    nigel: So now we have backgroundOrigin as well as
>    backgroundPosition?
>
>    glenn: We may want to rename these!
>
>    nigel: (notes that this looks analogous to origin and position
>    but is not)
>
>    glenn: backgroundOrigin defines where the background is drawn
>    relative to the content.
>    ... This is as defined in CSS3 backgrounds and borders - it's
>    the same semantic.
>    ... I took off the -box suffix that's on CSS3.
>
>    nigel: I sense that there are some changes needed here to clear
>    up the names and make them
>    ... less potentially confusing. Also I'd encourage review of
>    this in the context of IMSC 2
>    ... if we want to support image placement in more detail.
>
>    pierre: This does not express how you would use SMPTE
>    background image in IMSC 1.
>
>    glenn: That's actually mapped to the image element.
>
>    pierre: yes.
>
>    glenn: However we did define background image also in TTML2 and
>    these attributes
>    ... I believe fully define the semantics for background images.
>    ... In the case of a foreground image these don't come up
>    because they define the content
>    ... rectangle. There's never a box in which to position it -
>    that only applies when the image
>    ... is used for the background. Also bear in mind that
>    background images may be repeated
>    ... in x and y directions, which can never happen with
>    foreground images.
>    ... For foreground image size you would use bpd and ipd rather
>    than backgroundExtent.
>    ... I need to think if it would ever be applicable to have the
>    same semantic as backgroundExtent
>    ... on a foreground image. I want to see if CSS allows that
>    property on the image element
>    ... in HTML and what does it mean.
>
>    nigel: Just considering the use cases for this - one that comes
>    to mind is the use of a
>    ... graduated fill background image that is animated to move
>    along behind foreground text
>    ... for karaoke usage. Do these semantics support that?
>
>    glenn: Yes I think you could animate the x and y positions,
>    either discretely or continuous.
>
>    nigel: The conclusions for the time being are 1) that more
>    thinking is needed for the names
>    ... and 2) whether backgroundExtent can apply to foreground
>    images.
>    ... For the hard of thinking, some example images etc would
>    really help, since the terminology
>    ... has a lot of repetition that makes it hard to understand
>    the differences.
>    ... I've added some notes to the issue.
>    ... Moving on to Add support for rounded borders by introducing
>    <border-radii> compone…
>    ... [29]https://github.com/w3c/ttml2/pull/179
>
>      [29] https://github.com/w3c/ttml2/pull/179
>
>    nigel_and_glenn: [discussion of single value processor
>    semantics for border radii without consensus emerging]
>
>    glenn: The more interesting case is the one raised in the issue
>    [30]https://github.com/w3c/ttml2/issues/176
>
>      [30] https://github.com/w3c/ttml2/issues/176
>
>    nigel: explains images in issue
>
>    glenn: I would suggest an optional token for this and a default
>    behaviour in case nothing is specified.
>    ... We also have to set up some context for when it might apply
>    - it would not apply when
>    ... all the line areas are the same length - you are proposing
>    a process for merging the
>    ... background areas.
>
>    nigel: Yes
>
>    glenn: Would you allow me to merge this PR and address your
>    issue as a later iteration?
>
>    nigel: Yes, that allows progress.
>
>    glenn: I agree with the issue - I might consult others in CSS
>    land for their opinions too.
>    ... It may even be in background and borders 4, I need to check
>    ... How to specify merged background areas with radii when
>    there is no corner is harder
>    ... to specify - I'm sure it's possible but it requires a bit
>    of thought.
>
>    nigel: Agreed!
>    ... Okay, next one is Add missing two component expression to
>    <position> value syntax.
>    [31]https://github.com/w3c/ttml2/pull/180
>    ... I added a comment about the ambiguity here.
>
>      [31] https://github.com/w3c/ttml2/pull/180
>
>    glenn: The ambiguity is resolved by the two value to four value
>    mapping tables.
>    ... The last entry is ambiguous I agree since it does not
>    distinguish the lengths
>
>    nigel: Even if this is normative and clear I would prefer at
>    least note to point people at the
>    ... order preference.
>
>    glenn: I'll see what I can do while I'm also dealing with the
>    last line in the table.
>
>    nigel: Let's take a break - back here at 1545
>    ... Next is Remove cea{608,708} prefix from named items.
>    [32]https://github.com/w3c/ttml2/pull/182
>
>      [32] https://github.com/w3c/ttml2/pull/182
>
>    glenn: I had the same question in my mind as Nigel, whether or
>    not any of the deprefixed
>    ... names had any similarity to the non-prefixed name. The
>    programName and programType
>    ... seem to be likely, the others not.
>    ... The ones that had cea prefixes need to be syntactically
>    compatible with SMPTE-TT.
>    ... I can not simply remove the reference to 608 or 708 from
>    the definition of them without
>    ... sacrificing syntactic specificity.
>
>    nigel: And there's an editorial task to add the source
>    definitions?
>
>    glenn: That's right.
>    ... I'm pretty sure that programName is just a string and no
>    more restricted. The originalProgrammeTitle
>    ... is probably the same semantic.
>    ... We also need to check with Mike Dolan since he was involved
>    in defining these in
>    ... SMPTE-TT. I think we should be able to merge programName
>    and originalProgramTitle
>    ... probably. We have to choose which token to end up with - I
>    don't have a strong preference.
>    ... My preference is to add a prefix back, but just make it cea
>    or cta (remove the 608 or 708)
>    ... and we could add it for EBU also.
>
>    nigel: An observation here is that building the named items
>    into the TTML2 spec gives us a
>    ... potential problem in that it makes it harder to update the
>    list later. A common pattern
>    ... is to reference an external list or classification scheme
>    which can be updated independently.
>    ... Since none of these named items normatively affects
>    processing this should be okay.
>    ... This is a bit like the role registry approach in TTML1.
>
>    glenn: In TTML1 we had a requirement to prefer Dublin Core, and
>    after much debate we took
>    ... a minimalist approach and hardly defined anything. Then
>    SMPTE-TT came along and defined
>    ... a whole bunch of metadata items for 608 and 708 that were
>    thought to be important.
>    ... Since one of the nominal driving factors for TTML2 is to
>    support all the extensions in
>    ... SMPTE-TT we ended up adding these in.
>
>    andreas: I think the most practical solution is to reference a
>    document that we maintain that
>    ... defines our unqualified namespace items and informatively
>    links to other sources of
>    ... namespace qualified items in other organisations'
>    namespaces.
>
>    glenn: That sounds like a plan.
>
>    nigel: Same here.
>
>    glenn: I think we should leave in usesForced and
>    alternativeText
>
>    nigel: Even those we do not need to be in the specification
>
>    glenn: I think we want to refer to them elsewhere in the spec
>    so I'd like to keep those two
>    ... unqualified names in the spec.
>
>    andreas: Ok, if they depend on these.
>
>    glenn: Others that we have not defined yet we can bind to a
>    namespace and offer a template
>    ... for the future to define new named items.
>    ... That would simplify this work quite a bit.
>    ... I'll add a note to the issue with that plan.
>    ... I didn't abbreviate alt text so I had it as alternateText -
>    what's the view?
>
>    pierre: Keep it as close as possible to IMSC 1.
>
>    nigel: yes, happy with altText.
>
>    glenn: ok
>
>    nigel: We have essentially covered Add alternateText named
>    metadata item (#107). [33]https://github.com/w3c/ttml2/pull/183
>
>      [33] https://github.com/w3c/ttml2/pull/183
>
> IMSC 2
>
>    pierre: We are beginning to get industry feedback from IMSC 1
>    implementation.
>
>    nigel: There seem to be some preconceptions in the wild about
>    what IMSC 2 will be. I'd like
>    ... us to collate requirements.
>
>    pierre: I would happily collate requirements for IMSC 2.
>
>    glenn: I think there will be a continuing requirement for
>    images to deal with internationalisation
>    ... cases that not all clients will be able to support.
>
>    <scribe> ACTION: pal Refactor the IMSC repository in
>    preparation for future versions of IMSC. [recorded in
>    [34]http://www.w3.org/2016/09/19-tt-minutes.html#action02]
>
>      [34] http://www.w3.org/2016/09/19-tt-minutes.html#action02]
>
>    <trackbot> Created ACTION-479 - Refactor the imsc repository in
>    preparation for future versions of imsc. [on Pierre-Anthony
>    Lemieux - due 2016-09-26].
>
>    glenn: Having them in one repository helps with issue tracking
>    but you should use labels of
>    ... some kind to distinguish between the different versions.
>
>    pal: At the root will be a roadmap document for all the
>    versions of IMSC.
>    ... As soon as I get requirements for IMSC 2 I will start a
>    requirements document too.
>
>    nigel: It's not from BBC but Ruby seems obvious.
>
>    pierre: Yes I hear that a lot, also HDR and tate chu yuko.
>    Disparity is another one.
>
>    nigel: Also Wide Color Gamut?
>
>    pierre: Yes. Also background area between lines.
>
>    nigel: I would add the safe crop area stuff too.
>
>    andreas: As well as asking for requirements it would be good to
>    ask for the use case and the
>    ... problem that needs to be solved, in some detail.
>
>    pierre: So yes, HDR, all east asian layout.
>
>    rohit: Any mention of the condition attribute?
>
>    pierre: No not yet. I've heard people wanting to do responsive
>    design, but I'm not sure we're there yet.
>
>    nigel: What about continuous animation?
>
>    pierre: Not yet.
>
>    nigel: Seems strange to me based on historical BBC research to
>    have disparity but not continuous animation.
>
>    andreas: We should check what east asian organisations need to
>    do.
>
>    dae: I'd like to know if there are any parts of TTML2 that folk
>    think might need to change. Ruby for example?
>
>    pierre: I'd like to be really specific about all the Ruby
>    features in a pedantic way.
>
>    glenn: All the TTML2 layout features were driven from existing
>    content in lambda cap. it is
>    ... easy to say what was not driven from lambda cap.
>    ... It is easy to enumerate all the different Ruby features -
>    look at TTML2 from
>    ... §10.2.30 tts:ruby to §10.2.37 tts:rubyPreserve also
>    §10.2.40 tts:textCombine
>    ... §10.2.41 tts:textEmphasis and §10.2.43 tts:textOrientation.
>    ... All those were directly driven by lambda cap. There are a
>    couple that were not:
>    ... rubyOverflow, rubyOverhand and rubyOverhangClass.
>
>    rohit: Also rubyReserve?
>
>    glenn: Yes. Overflow and overhang came out of the Japanese
>    requirements as well as how
>    ... to handle some cases that were not obvious.
>
>    pierre: Thanks!
>
>    nigel: Do we have feature designators for these yet?
>
>    glenn: There's an editorial note in E.1 for adding those.
>
>    group: [discussion of structure of specification, areas of
>    TTML2 that may be relatively more 'risky', how to make progress
>    etc.]
>
>    dae: Can we revisit the initial construct in TTML2 tomorrow?
>
> Agenda bash
>
>    group: plans ahead for tomorrow, updates agenda.
>
> TTML2 implementation work
>
>    glenn: Skynav's TTT set of tools could be viewed as 1-3
>    implementations. It's a layered
>    ... system - the validation layer at the bottom could be
>    considered a transformation implementation.
>    ... TTX above that has one module that translates into an ISD
>    sequence. For example it can
>    ... take IMSC1 or SMPTE-TT documents and turn them into TTML2
>    ISDs. Then the next
>    ... layer is TTPE that implements formatting semantics.
>
>    rohit: At Netflix we are building a TTML2 oriented pipeline.
>    The idea is to take TTML2 source
>    ... documents, convert them into a canonical form (probably
>    TTML2 ISD) and then use them
>    ... to generate output formats including WebVTT and rendered
>    subtitles.
>    ... Depending on the test vector set for TTML2 Netflix may be
>    able to meet 40-50% of the
>    ... tests for implementation.
>
>    glenn: I'd also like to add: in terms of presentation semantics
>    implementation in TTPE for
>    ... TTML2 features, the only new features it does not yet
>    support are the use of referenced
>    ... external fonts, audio and disparity. Everything else that's
>    new in TTML2 it supports already
>    ... from a presentation semantic. There might be some fine
>    points to some of the features
>    ... that we are still tweaking. We have test content for all of
>    those features that we are using
>    ... to generate presentable output in either images or SVG. So
>    we are way ahead on implementation
>    ... of presentation and we have test content for most all of
>    it. Our schedule for finishing
>    ... implementation work on TTML2 is scheduled to be finished
>    early March 2017.
>
>    thierry: The horizontal review groups request review
>    opportunity as soon as possible.
>
>    nigel: In fact I should trigger that process straight away.
>    ... Wide review is even wider than that.
>
>    thierry: We should start to initiate that to make sure there is
>    enough time.
>
>    glenn: I'd like to have a version ready for a new WD by early
>    October.
>
>    thierry: Remember that we can limit the scope of review only to
>    the additional features in
>    ... TTML2 that are new relative to TTML1.
>
>    pierre: Remember also for wide review you have to factor in
>    time to respond to comments.
>    ... For the east Asian text layout there's an action to contact
>    ARIB specifically.
>
>    nigel: We will also need horizontal review. As a minimum I
>    should contact the horizontal review groups and request time on
>    their schedule for a new document early November.
>
>    <scribe> ACTION: nigel Request schedule time for horizontal
>    review of TTML2 [recorded in
>    [35]http://www.w3.org/2016/09/19-tt-minutes.html#action03]
>
>      [35] http://www.w3.org/2016/09/19-tt-minutes.html#action03]
>
>    <trackbot> Created ACTION-480 - Request schedule time for
>    horizontal review of ttml2 [on Nigel Megitt - due 2016-09-26].
>
>    glenn: Why don't I give you a list of new features to start
>    reviewing?
>
>    nigel: Good idea.
>
>    <scribe> ACTION: gadams Provide nigel with a list of new
>    features in TTML2 to begin reviewing [recorded in
>    [36]http://www.w3.org/2016/09/19-tt-minutes.html#action04]
>
>      [36] http://www.w3.org/2016/09/19-tt-minutes.html#action04]
>
>    <trackbot> Created ACTION-481 - Provide nigel with a list of
>    new features in ttml2 to begin reviewing [on Glenn Adams - due
>    2016-09-26].
>
>    glenn: How would it be if we have a solid working draft for
>    wide review by Nov 1?
>
>    nigel: Sounds good to me.
>
>    glenn: And how about moving to CR by the end of the year?
>
>    nigel: It's ambitious but we can try.
>    ... Looking at the picture on
>    [37]https://www.w3.org/wiki/TimedText/Publications it shows
>    ... a FPWD of IMSC 2 back in June, but I think from today we
>    have decided to collate
>    ... industry requirements and then maybe base it on the TTML2
>    CR perhaps?
>
>      [37] https://www.w3.org/wiki/TimedText/Publications
>
>    pierre: We should aim to make IMSC 2 based solely on industry
>    requirements but we can
>    ... certainly set a new date - I'm comfortable with that,
>    partly as a challenge to folk who
>    ... want IMSC 2 - we need to get going on it.
>
>    nigel: Agreed. Shall we say IMSC 2 FPWD by Dec 1?
>
>    pierre: Sounds great to me, maybe even earlier.
>
>    nigel: Ok let's leave it at that for now and if we can make it
>    earlier, great.
>
>    dae: Can an implementation satisfy both TTML2 and IMSC 2?
>
>    nigel: Yes.
>    ... Ok we're out of time for today, thanks all. Time to adjourn
>    for tomorrow.
>
>    andreas: Can we make sure we cover IMSC 1 implementation work
>    tomorrow?
>
>    nigel: yes let's do that.
>    ... [adjourns meeting]
>
> Summary of Action Items
>
>    [NEW] ACTION: gadams Provide nigel with a list of new features
>    in TTML2 to begin reviewing [recorded in
>    [38]http://www.w3.org/2016/09/19-tt-minutes.html#action04]
>    [NEW] ACTION: nigel Draft a liaison to HbbTV requesting further
>    information and proposing an option e.g. to extend IMSC 1 to
>    allow signalling of background height on span, and request
>    timelines etc. [recorded in
>    [39]http://www.w3.org/2016/09/19-tt-minutes.html#action01]
>    [NEW] ACTION: nigel Request schedule time for horizontal review
>    of TTML2 [recorded in
>    [40]http://www.w3.org/2016/09/19-tt-minutes.html#action03]
>    [NEW] ACTION: pal Refactor the IMSC repository in preparation
>    for future versions of IMSC. [recorded in
>    [41]http://www.w3.org/2016/09/19-tt-minutes.html#action02]
>
>      [38] http://www.w3.org/2016/09/19-tt-minutes.html#action04
>      [39] http://www.w3.org/2016/09/19-tt-minutes.html#action01
>      [40] http://www.w3.org/2016/09/19-tt-minutes.html#action03
>      [41] http://www.w3.org/2016/09/19-tt-minutes.html#action02
>
> Summary of Resolutions
>
>     1. [42]If we do not move WebVTT to CR in this Charter period
>        then we will not include it in any new Charter.
>
>    [End of minutes]
>      __________________________________________________________
>
>
>     Minutes formatted by David Booth's [43]scribe.perl version
>     1.144 ([44]CVS log)
>     $Date: 2016/09/19 17:25:20 $
>
>      [43] http://dev.w3.org/cvsweb/~checkout~/2002/scribe/scribedoc.htm
>      [44] http://dev.w3.org/cvsweb/2002/scribe/
>
>
>
> *--*
>
>
> *Nigel Megitt*
>
> Executive Product Manager, BBC Design & Engineering
>
> Telephone : +44 (0)3030807996
>
> BC2 C1 Broadcast Centre, Media Village, 201 Wood Lane, London W12 7TP
>
>
>
Received on Monday, 19 September 2016 20:31:02 UTC

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