- From: Nigel Megitt <nigel.megitt@bbc.co.uk>
- Date: Thu, 19 Jun 2014 16:05:18 +0000
- To: TTWG <public-tt@w3.org>
- Message-ID: <CFC8C896.1F436%nigel.megitt@bbc.co.uk>
Available at: http://www.w3.org/2014/06/19-tt-minutes.html
[1]W3C
[1] http://www.w3.org/
- DRAFT -
Timed Text Working Group Teleconference
19 Jun 2014
See also: [2]IRC log
[2] http://www.w3.org/2014/06/19-tt-irc
Attendees
Present
pal, nigel, glenn, tmichel, plh, jdsmith
Regrets
mike_dolan, frans_de_jong
Chair
nigel
Scribe
nigel
Contents
* [3]Topics
1. [4]Actions
2. [5]Issues
3. [6]Change Proposals
4. [7]AOB
* [8]Summary of Action Items
__________________________________________________________
<trackbot> Date: 19 June 2014
<scribe> scribeNick: nigel
Actions
action-297?
<trackbot> action-297 -- Glenn Adams to Soften language about
'willful violation' regarding treatment of duration zero -- due
2014-06-12 -- PENDINGREVIEW
<trackbot>
[9]http://www.w3.org/AudioVideo/TT/tracker/actions/297
[9] http://www.w3.org/AudioVideo/TT/tracker/actions/297
close action-297
<trackbot> Closed action-297.
action-300?
<trackbot> action-300 -- Glenn Adams to Add note to issue 263
explaining how ttml2 additions for @{extends,restricts}
(partially) addresses this issue -- due 2014-06-19 --
PENDINGREVIEW
<trackbot>
[10]http://www.w3.org/AudioVideo/TT/tracker/actions/300
[10] http://www.w3.org/AudioVideo/TT/tracker/actions/300
issue-263?
<trackbot> issue-263 -- profile feature set may not match
intended feature constraints -- pending review
<trackbot>
[11]http://www.w3.org/AudioVideo/TT/tracker/issues/263
[11] http://www.w3.org/AudioVideo/TT/tracker/issues/263
glenn: I added the note.
close action-300
<trackbot> Closed action-300.
Issues
issue-263?
<trackbot> issue-263 -- profile feature set may not match
intended feature constraints -- pending review
<trackbot>
[12]http://www.w3.org/AudioVideo/TT/tracker/issues/263
[12] http://www.w3.org/AudioVideo/TT/tracker/issues/263
glenn: Implemented since May 21. Initially raised by Mike Dolan
so we may need him to review it.
... There's a question: should we update SDP-US. We don't
normally update notes, so this is a process issue.
... What I implemented potentially resolves the issue raised.
... We should probably check with Mike and call for consensus
to the group requesting input and close if no objections
otherwise we'll see if someone wants to file an issue to update
SDP-US in some way.
ack
nigel: I understood that though this is a problem surfaced by
SDP-US it's really something for use in future specifications.
... I'm happy to leave this pending review and seek input as
proposed.
pal: Glenn, if you could crystallise your thoughts on how this
would work that would be helpful.
glenn: There's no formal way in TTML1 so the only option is to
write it into prose.
... However if you write a profile that uses an existing
feature and then says in the prose that it's a restriction or
extension without defining a new feature that would be
problematic.
... Right now the way people have been writing profiles has not
included defining new features or extensions. For example
CFF-TT and EBU-TT they just say 'use this feature' but we're
restricting it semantically or syntactically.
pal: That's true in SDP-US too?
glenn: That's right. This leads to an ambiguity because the
formal definition of the features is not restricted.
pal: In the context of TTML1 how important/tolerable is this?
glenn: The consequence, for TTML1 processor profiles, is that
the profile asks for more support than is required by the
content. Color is an example. The profile definition in SDP-US
... requires all colors to be supported by the processor but
the prose only requires support for a limited subset.
... In TTML2 we're handling this differently but that's the
discrepancy in TTML1.
issue-295?
<trackbot> issue-295 -- Remove code point restrictions from
IMSC -- pending review
<trackbot>
[13]http://www.w3.org/AudioVideo/TT/tracker/issues/295
[13] http://www.w3.org/AudioVideo/TT/tracker/issues/295
pal: The two actions have been closed so if there's no new
information this can be closed.
close issue-295
<trackbot> Closed issue-295.
issue-296?
<trackbot> issue-296 -- Remove xml:lang placement restrictions
from IMSC -- pending review
<trackbot>
[14]http://www.w3.org/AudioVideo/TT/tracker/issues/296
[14] http://www.w3.org/AudioVideo/TT/tracker/issues/296
nigel: notes that Pal has posted some edits.
... This is related to issue-237 which is closed.
pal: The proposal was accepted and implemented in November.
close issue-296
<trackbot> Closed issue-296.
issue-308?
<trackbot> issue-308 -- It is unclear how a document is
associated with a related video object -- pending review
<trackbot>
[15]http://www.w3.org/AudioVideo/TT/tracker/issues/308
[15] http://www.w3.org/AudioVideo/TT/tracker/issues/308
nigel: I still have an outstanding issue not resolved in §4.4
because the intention to display and remove ISDs on specific
video frames remains.
... I think I'm happy with the time expressions part though.
pal: There's also issue-317
... Which is about frame alignment.
... Issue-308 doesn't make the link between Related Video
Object and Related Media Object and that's been fixed. Also 308
implies that IMSC documents have to be authored for a
particular frame rate,
... which is not true unless frame rate is used.
nigel: agrees that Issue-317 is separate and that this edit
fixes Issue-308.
close issue-308
<trackbot> Closed issue-308.
issue-309?
<trackbot> issue-309 -- Image profile needs to permit text
equivalent -- pending review
<trackbot>
[16]http://www.w3.org/AudioVideo/TT/tracker/issues/309
[16] http://www.w3.org/AudioVideo/TT/tracker/issues/309
nigel: There's ongoing discussion of this issue on the email
reflector, including participants not present here.
pal: How will we resolve this?
nigel: John Birch is working on an edit proposal.
pal: I believe IMSC already deals with text equivalence.
nigel: I don't think IMSC deals with this strongly enough at
present.
... I believe we must allow alternative text representations
alongside images, for content providers to optionally use.
pal: Must is a strong statement - we need to get understand why
this level of requirement applies here given that content
providers can generate whole alternate documents.
... This depends on the application. The technology supports
all the applications.
nigel: The specification only defines the contents of a single
document, and if that document has image representations
there's no accessible equivalent.
pal: IMSC satisfies that.
nigel: I disagree that IMSC satisfies that.
pal: If you multiplex the documents that becomes a single
document. All applications I know of support multiple tracks
already.
nigel: We aren't defining the application just the document
format. IMSC does not support multiplexing at the moment.
pal: All applications I know of for IMSC already support this
and other things too.
... I'm not opposed to informative metadata as John has pointed
out, that can be useful for debugging. That's probably a good
idea. I see potential harm but no requirement in specifying a
less flexible and rich profile than text profile.
nigel: I agree and propose that documents should be able to
contain both text profile and image profile and a selectivity
mechanism for the processor to choose which representation to
use.
... It's broken now because it doesn't satisfy the W3C's own
guidelines for accessibility.
glenn: Historically it has never required a separate document
to satisfy the requirement for alternate text representation.
pal: I believe the guidelines are intended to be more general
but I did not see in the recommendations anything that points
to a single document even if that's how it's been implemented
so far.
glenn: Most 'lay people' would say that these requirements do
apply. It may be worth getting a sense from someone e.g.
involved in WCAG.
... Technically you could just put metadata in, which would be
a non-standard solution and probably not adequate, but it would
be useful to get input to ward off future objections.
pal: Why would metadata not satisfy the recommendations?
glenn: it might, but I can't answer this.
plh: We're talking about backgroundImage. Why would you require
alternate content?
glenn: This is using backgroundImage for the content.
nigel: This originated in SMPTE-TT.
plh: The use of backgroundImage in CSS wasn't intended for
this. In CSS it wasn't supposed to carry content that needs to
be made accessible.
... If it's really part of the content then we should address
the naming and we do need a text alternative for that.
pal: There's at least one digital cinema application when a lot
of the time subtitles are delivered as image. They can also be
delivered as text. These are displayed on screen for hard of
hearing.
... In parallel there's another document for captions that uses
the same format with a different profile, and it's always text,
and is used for captioning devices.
... This is done because you typically want more control over
the display of the text for captioning devices than you could
by a simple alt tag on an image. This is how cinema meets
accessibility requirements.
... Sometimes there are two subtitle tracks, one for language
translation, another for description of sounds.
plh: I think glenn is right - we should ask. I'm wondering if
it's even meaningful.
... Here those persons can hear what is there, so if they can
hear the video then will they still need to have the
subtitling.
... It's not just about text alternatives, but a lot more, so
it would need a dedicated track.
pal: This is the only way to provide a good experience.
plh: In that case we should put some guidelines in that section
that says by the way we recommend that this is not used for
non-sighted applications.
pal: I really want to understand the use cases and am happy to
follow up with W3C folk.
<scribe> ACTION: plh Contact W3C Accessibility expert re
Issue-309 [recorded in
[17]http://www.w3.org/2014/06/19-tt-minutes.html#action01]
<trackbot> Created ACTION-301 - Contact w3c accessibility
expert re issue-309 [on Philippe Le Hégaret - due 2014-06-26].
pal: I'm happy to help, as this is a different use case than
HTML.
nigel: There are use cases that aren't just for non-seeing and
non-hearing folk, e.g. touch-based. I've also mentioned the
issue of the attribute name showBackground in the email thread.
glenn: It's possible that we can meet these genuine
requirements with separate documents. We should also consider
the use cases of search and information processing.
nigel: adjourn for 2 minutes until 16:03 please
issue-312?
<trackbot> issue-312 -- forcedDisplay attribute is metadata so
should be in ttm not tts namespace -- pending review
<trackbot>
[18]http://www.w3.org/AudioVideo/TT/tracker/issues/312
[18] http://www.w3.org/AudioVideo/TT/tracker/issues/312
nigel: For me the edit in §4.5.3 has not addressed the issue
since all content is expected to be displayed anyway.
glenn: We should change the name of this issue as it's not the
path we want to go down.
pal: It isn't a metadata element, and is not in the ttml
namespace, but is in the imsc namespace as discussed before.
nigel: I will change it.
pal: Please propose an alternative and see the example
nigel: I see no example in 4.5.3
glenn: Rather than feature designator it should be an extension
designator.
pal: §4.5.3 references an example.
nigel: That example describes the use case but not the
semantics of the attribute.
... This is very different from the current system model in
which a document is being processed only if the content is to
be shown.
glenn: The second para in §4.5.3 that describes forcedDisplay
talks about SHOULD be displayed regardless of etc. This
disregards the semantics of the visibility property and timing
and the display property, and the mapping to a temporally
active region.
... Additionally the region itself could be made invisible.
This doesn't factor in all of those aspects of display into the
equation so I'm concerned about how this reaches down inside
the content
... and defines 'display regardless of everything else'.
pal: It's more 'don't display the other stuff' unless this
setting is true.
glenn: I'm more of the opinion that this maybe should be
metadata, as it's a higher level protocol that's outside of the
scope of the current semantics of TTML. I'd be a lot more
comfortable
... if this were defined in a metadata namespace. The language
needs to be characterised as a higher level protocol, and it
would be useful to have examples of ignoring and not ignoring
content tagged with
... specific languages, for example Spanish and English, where
some higher level processor is selecting one of those languages
to display.
reopen issue-312
<trackbot> Re-opened issue-312.
issue-313?
<trackbot> issue-313 -- Presented Region section is informative
only -- pending review
<trackbot>
[19]http://www.w3.org/AudioVideo/TT/tracker/issues/313
[19] http://www.w3.org/AudioVideo/TT/tracker/issues/313
glenn: showBackground and visibility also apply to region.
ACTION nigel to re-review issue-313
<trackbot> Created ACTION-302 - Re-review issue-313 [on Nigel
Megitt - due 2014-06-26].
issue-306?
<trackbot> issue-306 -- Appendix N.2 omits fractional time
expressions -- raised
<trackbot>
[20]http://www.w3.org/AudioVideo/TT/tracker/issues/306
[20] http://www.w3.org/AudioVideo/TT/tracker/issues/306
glenn: My intention was that if there were a fraction component
of seconds then it would be interpreted in the seconds part.
open issue-306
reopen issue-306
<trackbot> Re-opened issue-306.
issue-314?
<trackbot> issue-314 -- Temporally active is not defined for
regions -- raised
<trackbot>
[21]http://www.w3.org/AudioVideo/TT/tracker/issues/314
[21] http://www.w3.org/AudioVideo/TT/tracker/issues/314
reopen issue-314
<trackbot> Re-opened issue-314.
glenn: I'm not sure if I agree with this but we can consider
it. Before I would agree with that I'd like a use case.
nigel: There's an error in the issue - it should say
showBackground="always" rather than "true"
glenn: I guess in this case "always" is semantically qualified
by temporal activity. I agree it should be made explicit. The
ancillary question is should we make "always" unqualified.
nigel: A use case is if region backgrounds should be painted
even when no text is selected into them.
reopen issue-314
<trackbot> Re-opened issue-314.
issue-321?
<trackbot> issue-321 -- typo - s/ttp:feature/ttp:extension/ in
5th paragraph of 6.1.5 -- raised
<trackbot>
[22]http://www.w3.org/AudioVideo/TT/tracker/issues/321
[22] http://www.w3.org/AudioVideo/TT/tracker/issues/321
reopen issue-321
<trackbot> Re-opened issue-321.
glenn: This is a copy paste error.
issue-322?
<trackbot> issue-322 -- Formula for dropNTSC time expressions
is incorrect. -- raised
<trackbot>
[23]http://www.w3.org/AudioVideo/TT/tracker/issues/322
[23] http://www.w3.org/AudioVideo/TT/tracker/issues/322
reopen issue-322
<trackbot> Re-opened issue-322.
reopen issue-315
<trackbot> Re-opened issue-315.
reopen issue-317
<trackbot> Re-opened issue-317.
reopen issue-319
<trackbot> Re-opened issue-319.
Change Proposals
nigel: change proposal 2
[24]https://www.w3.org/wiki/TTML/changeProposal002 was
discussed last week and amended
... I believe a further edit is in the queue from CP2
[24] https://www.w3.org/wiki/TTML/changeProposal002
jdsmith: I think so.
nigel: There are Ed Notes in 9.3.2 and 9.3.3 but not in 9.3.5
to add an elaborated example.
glenn: expresses concern that over-complicating the examples
makes them less useful.
... We also might consider a section in the wiki that has more
examples rather than putting them all in the spec itself.
nigel: What CPs would folk like to work on in the future?
glenn: It would be useful to prioritise. An additional column
to indicate priority 1, 2 and 3 might be useful. The owner can
tweak the priority.
<scribe> ACTION: nigel Add priority column to Change Proposal
Index [recorded in
[25]http://www.w3.org/2014/06/19-tt-minutes.html#action02]
<trackbot> Created ACTION-303 - Add priority column to change
proposal index [on Nigel Megitt - due 2014-06-26].
glenn: We should maybe put a mark in the sand for the change
proposals we want to finish before we go to FPWD.
nigel: agrees.
plh: We need to do a call for exclusions at FPWD.
nigel: We set a schedule in March to get to LC in August, and
haven't got to FPWD yet.
glenn: Maybe August is not impractical for FPWD at this point.
nigel: Let's aim for that.
AOB
nigel: Regrets from me for next 2 weeks.
... As noone has volunteered to chair then I propose that we do
not meet until our next on 10th July.
Summary of Action Items
[NEW] ACTION: nigel Add priority column to Change Proposal
Index [recorded in
[26]http://www.w3.org/2014/06/19-tt-minutes.html#action02]
[NEW] ACTION: plh Contact W3C Accessibility expert re Issue-309
[recorded in
[27]http://www.w3.org/2014/06/19-tt-minutes.html#action01]
[End of minutes]
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Received on Thursday, 19 June 2014 16:05:50 UTC