- From: David Ronca <dronca@netflix.com>
- Date: Mon, 19 Sep 2016 13:50:51 -0700
- To: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
- Cc: Nigel Megitt <nigel.megitt@bbc.co.uk>, Public TTWG List <public-tt@w3.org>
- Message-ID: <CAMjV-FjK9daJCvtn5ZjNphv+Zjd4orPjPr6wRcghKnXO-1_KDA@mail.gmail.com>
CR requires 2 implementations of every feature in the specification,
correct?
D
On Mon, Sep 19, 2016 at 1:30 PM, Silvia Pfeiffer <silviapfeiffer1@gmail.com>
wrote:
> 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 20:51:25 UTC