Timed Text Working Group Teleconference

28 Jul 2016

See also: IRC log


Nigel, Pierre, Glenn
Mike, Andreas


This meeting

nigel: [goes through agenda] Looks like our topics for today will be TPAC and TTML. AOB?

all: no AOB

TPAC 2016


<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> http://www.w3.org/AudioVideo/TT/tracker/actions/475

nigel: No progress to report on this so far
... We're set to meet on Monday and Tuesday.

TTML1 & TTML2 issues, actions, PRs, editorial actions etc

glenn: No actions to report on for me. I did have a chance to do a quick review of the
... wiki page on timing. Thanks for doing that. I think it will help organise some of our
... discussions on this area. I'm going to start augmenting that page with some additional
... information for example providing some historical context on some of the terms to
... help us see where things were and how they developed. That may help us resolve some
... mistaken text or understandings that have been introduced. The last part of that had
... an example with dur on body and end on an element underneath which appears to
... be longer than the dur on body. That would be handled by the SMIL timing semantics
... but as you point out they're difficult and they're not expressed anywhere in TTML and
... maybe, though I'm almost fearful of doing it, in the TTX application of the TTT project
... is implemented some timing semantics as we attempted to interpret it which may or
... may not be right. So at least I have a working example. So my thought was to try to
... use that as well as that the documented SMIL semantics to maybe describe the process
... that we implemented and put it into the wiki to use as a point of departure for maybe
... helping document that more thoroughly.

nigel: Thanks that will be really helpful.

glenn: By the way on that example, in SMIL end does not express begin+dur.
... So dur specifies a simple duration where end specifies the end of the active duration
... which are different things.

pal: These subtle issues are missed by 99.999% of implementers so I really like the idea
... of getting a baseline based on what you've implemented at least as a starting point.
... That's an excellent idea.

glenn: I definitely mean it as a starting point because I wouldn't stand by a statement that
... we have implemented it all correctly either. We can try to refine it based on other
... implementations and common understandings.

nigel: I wonder if there are any SMIL folk we can talk to about the details?

glenn: Thierry and I were on the SMIL group but couldn't answer for the technical details.
... The guy who did the main work was Patrick Schmitz - I think he attended some of our
... early meetings, but he was probably the only guy who understood the spec in my opinion.
... There was another guy who wrote a book on SMIL, whose name I can't remember right now.
... He might be another resource. There's a third person, Eric Hodge, who was at Real
... Networks. I suspect asking him about any of this now would mostly draw a blank.

nigel: Slightly related to this is the new issue I added: https://github.com/w3c/ttml2/issues/169

glenn: I saw that and thought it was reasonable.
... I also think we should add something for timing on break elements, which we added
... in TTML2 and wasn't in TTML1, so some implementations may not support it.

nigel: Agreed. I also wondered about a feature designator for nested timed elements, since
... some profiles disallow those for simplicity.

glenn: I'm generally open to adding new features, since they don't cost much. Noting that
... one of the uses of features is to drive the tests and implementation report. So if we
... list a feature there then it's harder to make a case that we have two implementations
... of it than if we have a broader feature definition.

nigel: Agreed. In this case since there are already processors subject to these restrictions
... I think we're fairly safe.
... Regarding the Safe Crop Area proposal I mentioned last week that I intend to
... raise an issue and a PR for the proposal unless there are any objections to that.

glenn: I don't see any problem with that. If there are any problems with the PR then you
... could always address them in the PR branch.

nigel: yes, of course. My plan is to put the SCA signalling in the ttp parameter namespace.

Profiles registry

nigel: Mike has told me that although he's begun work on the edits for this he hasn't
... yet managed to complete it, so there's a bit more work to do there.
... We're out of agenda topics for today so we'll finish ahead of time. Thanks! [adjourns meeting]

Summary of Action Items

Summary of Resolutions

[End of minutes]

Minutes formatted by David Booth's scribe.perl version 1.144 (CVS log)
$Date: 2016/07/28 14:39:25 $