See also: IRC log
<scribe> scribe: nigel
nigel: We are low on numbers today for various reasons. What are we quorate to discuss?
mike: Perhaps a brief update on the IANA registration
Andreas: TPAC
... Also the lineHeight, background height issue and the need
for a solution.
nigel: Okay, I'd also maybe like to come back to the Safe Crop Area proposal.
nigel: Note that the hotel
closest to the venue is getting low on availability: I just
tried booking and failed!
... So it's worth booking accommodation soon.
Andreas: Regarding the conflict
(for some) with the Web & TV IG meeting on the Monday
... and the TTWG meeting on the Monday and Tuesday. There is
some overlap of interest
... so this is unfortunate. It may be difficult to change this,
but we should ask the Web & TV IG
... at least about their agenda so we can have a basis for
setting our agenda topics.
... Also we thought about a combined meeting with the Web &
TV IG. I'm not sure if this
... is still of interest for others. There's clearly an overlap
in what they are working on,
... and also the members are I think interested in progress on
the subtitle front. It could
... be a possibility to discuss the issues about WebVTT and
TTML and the adoption of
... IMSC.
nigel: For the last few years we
have provided an update to the Web & TV IG who are
... indeed interested in our progress, so I think it makes
sense to ask for some joint time
... with them so that we can do the same this year. I'll give
myself an action.
<scribe> ACTION: nigel Contact the chair of the Web & TV IG to ask about schedule and joint meeting time. [recorded in http://www.w3.org/2016/07/21-tt-minutes.html#action01]
<trackbot> Created ACTION-475 - Contact the chair of the web & tv ig to ask about schedule and joint meeting time. [on Nigel Megitt - due 2016-07-28].
mike: That's a good idea - I won't be there by the way.
davidr: Dae will be there for Netflix - I don't really have an opinion on it.
mike: If you go to the
interaction with IANA link, there's the old one a year or two
ago,
... but nothing in there that indicates that we have any open
engagement with IANA. I
... thought plh had done that but it looks like not. We've had
no response from IANA either.
nigel: Okay, it looks like
something's "stuck". I have prompted plh but it's unclear
what's happening.
... Ideally he'd be on the call...
... I've sent him a message to see if he is available to join.
If he can let's come back to this.
nigel: Andreas, I think you wanted to mention lineHeight etc?
andreas: We discussed this for 3
weeks with a lot of discussion and comments, then
... other discussions took over. I think it's important that we
look for a solution because
... HbbTV has now published an update to their spec and they
have some normative
... text that clarifies this issue and I think they also are
waiting for clear guidance from
... W3C or EBU that they could reference, but because they have
to publish sooner they
... needed to include some text. I think it's important for us
to check this change and
... also to work on the solution and decide if there's an
errata needed for TTML1 or an
... update to IMSC 1 and how in general this should be solved
for TTML2.
... It may also be important but out of scope for W3C that
HbbTV starts a liaison with W3C
... on this issue.
nigel: Can you recall what HbbTV did?
andreas: They made a lightweight
addition, based on a request that a transparent gap
... should not appear between line backgrounds. So the solution
is that for lineHeight <= 125%
... when the background is set on consecutive rows there should
not be a gap between
... the line backgrounds, without explaining how the renderer
should make that happen.
... The solution for how this conceptually and theoretically
would be done in TTML is still
... outstanding and the task of this group.
nigel: Even this group may not be
the best place to fix it - sometimes we have to do so
... when nobody else will fix it, but it seems like it should
be fixed in CSS and then we should
... align with that, otherwise it's a bit backwards.
andreas: It would be good to have
a pragmatic solution as soon as possible so that the
... different standards are compatible with us, e.g. by an
errata with TTML1. Going back
... to the discussion we had there was I think not a really
clear view of the group how this
... case should be handled so there seems to be a gap in TTML1
how it should be handled.
... If this is the case that there is some room for
interpretation then there can be an errata
... in TTML1. If this is not the case then it would be good to
have a solution in the next
... upcoming spec, which could be an update to IMSC 1.
davidr: I've seen that separation
between backgrounds of multiple lines of text is a
problem
... on iOS with WebVTT.
... For our TTML clients we don't specify backgrounds.
nigel: Our BBC subtitle
guidelines take the opposite approach - a black background
is
... required and there must not be gaps between lines, so this
is a real issue for us.
... Thank you for raising the profile of this once again.
plh: I started the review - IETF
says we have to start the review on their TIES mailing
list
... first. You have to do a complete submission every
time.
... Once we're done we send the request to IANA.
nigel: Is the IETF review period open ended or will it close?
plh: It is open ended; it's been
more than a month but I would think that is enough.
... I would not worry about the time period. But I would ask if
we addressed the comments?
mike: The status is: we received 2 comments from W3S; one was rejected by the WG
plh: I'm not aware of W3S comments on the IETF list.
mike: I'm not aware of any
comments from the IETF list.
... There was a comment from Eric Prud'hommeaux and Paul
Libbrecht who posted to the public TTWG reflector
... and those are the only two comments.
plh: [looks on the IETF list] If the comments are not on the IETF list then they are not a concern.
<plh> https://lists.w3.org/Archives/Public/public-tt/2016Jun/0012.html
plh: That's my request on June 16, which I sent to the IANA media types list, as required.
<plh> https://lists.w3.org/Archives/Public/public-tt/2016Jun/0014.html
<plh> https://lists.w3.org/Archives/Public/public-tt/2016Jun/0015.html
plh: So one comment was rejected?
mike: We decided not to proceed with the Mac clipboard type request.
<plh> answer to Paul: https://lists.w3.org/Archives/Public/public-tt/2016Jun/0018.html
mike: Nobody expressed any interest or practice that we could codify.
plh: So did you do what is needed to address the comments?
mike: Eric's comment was
editorial, but I didn't want to edit the document until the
review
... period is over.
plh: At this point I need the
document to be updated so I can submit the registration
to
... IANA itself.
mike: Okay I'll make the changes via issues and PRs and send you an email when I'm done.
plh: Then let me know when you're
done and email me until I've sent it to IANA!
... The form I will fill is at:
<plh> http://www.iana.org/form/media-types
plh: Sometimes the hardest
question to answer is "encoding consideration" so if you
think
... it is perfectly answered in your document then you're
fine.
<plh> "Encoding Considerations"
mike: All the comments are on the
note not the media type registration. We didn't touch
... that aside from adding a codecs parameter.
... I can't understand why the same answer would be a concern
now when it wasn't before.
plh: Understood. When I send the
form to IANA then, according to my most recent
experience,
... they're pretty fast in processing it.
mike: I understand the steps - I'll make the edits and send you an email later.
plh: Thank you.
nigel: Thanks both - great to unlock that.
nigel: I'd like to come back the
BBC's Safe Crop Area proposal - noting that the people
... present today are a mutually exclusive set relative to
those present last week when we
... discussed it.
... I don't know if anyone has had a chance to look through it.
Mike, thank you for
... sending through the links to smpte documents.
... I think they help to explain how the problem arises but do
not solve it.
... [outlines problem of trying to maintain positional
registration and complete display]
mike: There's both a display
problem and an authoring problem.
... There used to be something like a safe area in the video,
not directly solving the
... problem for subtitles and captions. The active format
descriptor and bar data help
... to describe the status for video, and SMPTE is in the
process of updating those.
... It helps solve the video problem and may provide a
framework for how we want to fix
... it for TTML. There's also ISO/IEC 14496-30 corrigendum 1,
which tries to provide
... some signalling outside the document, which we should look
at.
nigel: It was unclear to me what that corrigendum actually means for the decoder.
mike: It's about the aspect ratio
of the TTML and the active format descriptors describe
... how to ignore deliberately black areas even though they're
encoded in the video.
nigel: What this proposal does is
to defer some of the solution space but provide extra
... information to allow decoders to do a better job.
davidr: At this point we don't deal with the use case of subtitle registration differing from how it is authored.
nigel: Okay, well I encourage
everyone to look at the proposal document
...
https://lists.w3.org/Archives/Public/public-tt/2016Jun/0003.html
... direct link to PDF:
https://lists.w3.org/Archives/Public/public-tt/2016Jun/att-0003/Subtitle_Safe_Crop_Area_BBC_submission_2016-06-09.pdf
... If there are no adverse comments then I intend to raise
this as an issue and possibly a PR on
... IMSC 1 for a future update, because that is where it would
be most useful for uptake.
... Thanks all [adjourns meeting]