Timed Text Working Group Teleconference -- 24 Apr 2014

<trackbot> Date: 24 April 2014

<scribe> scribeNick: nigel

TPAC 2014

https://www.w3.org/2002/09/wbs/34314/TPAC2014Planning/results

RESOLUTION: We will have a face to face meeting at TPAC, probably 2 days

nigel: looks like meeting on Monday and Friday as last year would work best.

RESOLUTION: We'll meet on the Monday and Friday

glenn: It may be worth discussing generic track apis, datacue and texttrackcue, with HTML WG.

nigel: I'll take this offline with David (who suggested meeting HTML WG)
... Agenda topics: obviously TTML2 makes sense - we can work on the rest of the agenda later.

F2F

action-281?

<trackbot> action-281 -- Nigel Megitt to Talk to frans about hosting a meeting -- due 2014-04-24 -- OPEN

<trackbot> http://www.w3.org/AudioVideo/TT/tracker/actions/281

nigel: I'm waiting for a response from Frans - he may be away.

MPEG liaison re MIME @codecs parameter

action-282?

<trackbot> action-282 -- Nigel Megitt to Add MPEG liaison to agenda for 24/3 TTWG meeting -- due 2014-04-24 -- OPEN

<trackbot> http://www.w3.org/AudioVideo/TT/tracker/actions/282

glenn: what procedure would the recipient adopy to make use of this parameter? I can imagine a processor wanting to avoid looking inside a TTML document because it knows that there are some formats it cannot process.
... This looks like being a content profile claim. Could be a signal of processor profile required too - two sides of the same coin.
... a list of designations in the MIME types to identify profiles seems feasible. I don't think we want to create a second order set of names to map to those URIs.
... We could advocate creating a registry that associates 4 character short labels with specific well-defined URIs with normative references available.

nigel: that seems to fit well with the MPEG approach - we could even suggest that one codec value map to multiple URIs.

pal: Is MPEG asking how to do this or what values should go into the codec parameter value?

nigel: I don't know.

pal: this group could recommend a set of profiles that should have codec values associated, and MPEG can then work out how to do that mapping.

dsinger: W3C owns the root of the TTML tree, so the obvious thing to do is to have a registry for the various dialects and short identifiers that name them.

glenn: It's possible that documents may adhere to multiple profiles, so would these short identifiers be expressed as a list or would the registry need to map short identifiers to lists?

dsinger: it would be cleaner to have a list in the codecs parameter, which I think is possible.

glenn: That sounds much better.

dsinger: I think MPEG would say that the type is 'something derived from W3C TTML' and then the codec parameter would be delegated to the W3C registry. We should talk to W3C staff about that. Or IANA could do it.

glenn: there are a number of registries in W3C based on wiki pages.

dsinger: that would work.

glenn: That would be easy to set up quickly.

dsinger: Just call it 'short identifiers for TTML profiles'.

nigel: Does MPEG need a long term commitment?

dsinger: No, it's up to the managing organisation to look after the list.
... You should use characters that can be used in a MIME type.

glenn: so a 4 character alphanumeric identifier would be sufficient.

pal: 4 characters might not be sufficient. I'd go for more than that.

glenn: 4 alphanumeric digits is 62^4 which should be more than enough.

dsinger: It just needs to be a 'short' string, so 5, 6 characters should be fine too.

pal: I'm considering it from the human perspective.

RESOLUTION: W3C to create wiki page holding this Registry

<scribe> ACTION: nigel and dsinger to respond to MPEG liaison [recorded in http://www.w3.org/2014/04/24-tt-minutes.html#action01]

<trackbot> Created ACTION-283 - And dsinger to respond to mpeg liaison [on Nigel Megitt - due 2014-05-01].

<scribe> ACTION: glenn to create the registry page [recorded in http://www.w3.org/2014/04/24-tt-minutes.html#action02]

<trackbot> Created ACTION-284 - Create the registry page [on Glenn Adams - due 2014-05-01].

close action-282

<trackbot> Closed action-282.

IMSC FPWD

pal: we're on track to publish

tmichel: I need 2 days between requesting publication and the actual publication

nigel: I presume if you made the request on Tuesday and some hitch arose then we could pull the process?

tmichel: yes. I'll request publication this Tuesday then.

action-279?

<trackbot> action-279 -- Pierre-Anthony Lemieux to Add [imsc] subject header in the imsc draft -- due 2014-04-24 -- OPEN

<trackbot> http://www.w3.org/AudioVideo/TT/tracker/actions/279

tmichel: that's done.

nigel: please could you add to the Notes on the action a link to the edit revision before setting to Pending Review?

pal: sure!

Action Items overdue

action-246?

<trackbot> action-246 -- Nigel Megitt to Take deliverables of draft charter to TAG for scrutiny -- due 2014-04-17 -- OPEN

<trackbot> http://www.w3.org/AudioVideo/TT/tracker/actions/246

action-246: I've been looking into this and think it may become a no-operation, still reviewing. It seems that we are not defining anything that will affect the architecture of the web.

<trackbot> Notes added to action-246 Take deliverables of draft charter to TAG for scrutiny.

action-254?

<trackbot> action-254 -- Glenn Adams to Add errata note for ttml1 pointing at constraint in smil prohibiting dur of zero, add normative text to ttml2 -- due 2014-04-01 -- OPEN

<trackbot> http://www.w3.org/AudioVideo/TT/tracker/actions/254

glenn: SMIL specifies that dur attributes must be non-zero. I'm now of the opinion that we should permit zero durations and add an explicit note to say so.
... The lack of prohibition is in TTML1 and used in tests. In SMIL even in the discussion it refers to implicit zero durations. All of the math in the timing calculations continues to work with explicit zero durations.
... There doesn't seem to be any need for it, although I suppose I could bring it up with the SMIL authors. My current thinking is to add an explicit permission of zero durations.

nigel: there may be utility here in terms of event generation if an entry and exit event need to be generated without making an on-screen change.

glenn: that could be the case. In cue and out cue events are permitted to have identical times.

RESOLUTION: We will permit zero dur attribute values.

issue-304?

<trackbot> issue-304 -- Non-standard unqualified attributes not permitted -- open

<trackbot> http://www.w3.org/AudioVideo/TT/tracker/issues/304

glenn: A user asked why we can't use an unqualified attribute name that is not in the TTML namespace. The spec doesn't quite say what we meant, so we need to add a note clarifying that "any attribute not in default or any TT namespace" should
... say "any qualified attribute..."

<scribe> ACTION: glenn to implement proposed errata in issue-304 [recorded in http://www.w3.org/2014/04/24-tt-minutes.html#action03]

<trackbot> Created ACTION-285 - Implement proposed errata in issue-304 [on Glenn Adams - due 2014-05-01].

glenn: I need to verify in the TTV that it's checking this. I'm pretty sure the schema would reject unqualified attributes so there may be no work needed.
... we haven't formally announced the TTV web page on the W3C website.

<scribe> ACTION: glenn to send an email to public-tt describing the TTV hosting site at W3C [recorded in http://www.w3.org/2014/04/24-tt-minutes.html#action04]

<trackbot> Created ACTION-286 - Send an email to public-tt describing the ttv hosting site at w3c [on Glenn Adams - due 2014-05-01].

<Dsinger_> Still here

close action-279

<trackbot> Closed action-279.

- DRAFT -

Timed Text Working Group Teleconference

24 Apr 2014

Attendees

Contents

TPAC 2014

F2F

MPEG liaison re MIME @codecs parameter

IMSC FPWD

Action Items overdue

Summary of Action Items

Scribe.perl diagnostic output