Timed Text Working Group Teleconference -- 01 May 2014

<trackbot> Date: 01 May 2014

<scribe> scribeNick: nigel

IMSC FPWD

nigel: We published the FPWD today

pal: the Latest version link doesn't work yet

plh: that's because it hasn't been officially published yet - the dated version does work, the latest will work later in the day

http://www.w3.org/2014/03/timed-text-charter.html

pal: Next step for IMSC is to collect comments and set a goal for LC based on level of comment received.
... In parallel let's work on IMSC2 based on the progress in TTML2
... The faster we move through IMSC1 the sooner we'll be able to put emphasis on IMSC2.
... Is it reasonable to set a target for LC for end of May?

mike: I'll make SMPTE and DECE aware of this.

nigel: I'll make EBU aware.
... Suggest we review the level of comments received in 2 weeks and assess the feasibility of an end of May LC then (on the 15th May)

Issue discussed over the past week

Issue-299?

<trackbot> Issue-299 -- dur must be greater than zero -- pending review

<trackbot> http://www.w3.org/AudioVideo/TT/tracker/issues/299

nigel: Would Glenn be able to contact Dick Bulterman re the reasoning behind 0 dur prohibition in SMIL?

glenn: yes, I will do that.
... On the other point re "willfully violated" I think we should stay with the same language as in HTML which has been extensively used in quite a few
... specifications, so it would be consistent to stay with it.
... we refer to SMIL normatively for the semantics but not the syntax so we could argue that we may define 0 to be permitted for dur in TTML syntax.
... However this could create some confusion on the part of readers if there is a discrepancy between them. We were silent on this in TTML 1 and did not discuss it previously.

plh: Re "willful" I would agree with nigel that it has negative connotations.

nigel: That's my argument too - my suggestion is "deliberately" in place of "willfully"

glenn: I notice that in TTML1 we use this phrase "without taking into account any semantics defined by this specification". I could try to reword it to make
... clear that we are overriding the semantics.

RESOLUTION: We will avoid the term "willful violation" in our documents.

issue-304?

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

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

action-285?

<trackbot> action-285 -- Glenn Adams to Implement proposed errata in issue-304 -- due 2014-05-01 -- OPEN

<trackbot> http://www.w3.org/AudioVideo/TT/tracker/actions/285

Action Item overdue and due next week

glenn: I do plan to use the same namespace in TTML2 as we used in TTML1. We did specifically specify the namespace in TTML1 to be mutable.

pal: I don't recall where that action idea came from but the discussion raises in my mind re actual implementation. Do we know what existing implementations
... will do if they find an attribute that they don't recognise in a namespace that they do recognise? Do we have any practical data points on this?

glenn: I don't know of any research to give an answer to this.

pal: Not having to define a new namespace is a really good idea but the assumption around disruption of existing implementations is of potential concern.
... I'm not sure there's much action to do other than to ask the question. If no objections we should go with the current plan. It's possible that introducing a new namespace will be more disruptive.

glenn: Agree with the point about introducing a new namespace.
... The processing rules would expose new names in the namespace to the processor. In the DFXP Viewer programme we coded it to effectively test for errors in the attributes that were used
... but I don't believe we did anything to reject the document. It was an informational warning. It's possible that if I fire that up with a TTML2 document with new attributes in the existing
... namespaces it may raise a warning. I haven't checked all the other implementations.
... TTML2 §4 also provides some wording on this.
... We may want to elaborate on that wording in TTML2 and add an errata to TTML1 to deal with this, but perhaps that's a different action item.

action-275: Closing as per discussion today, on the basis that we will extend the existing namespace and follow up with enhanced wording to §4 in a separate action.

<trackbot> Notes added to action-275 Review issues in cp12 and if one is needed for handling new attributes in ttml2 in same namespace as ttml1 then raise it, and link to issue-286..

close action-275

<trackbot> Closed action-275.

<scribe> ACTION: glenn to elaborate on wording in §4 on namespace extension in TTML2 and as an errata to TTML1 [recorded in http://www.w3.org/2014/05/01-tt-minutes.html#action01]

<trackbot> Created ACTION-287 - Elaborate on wording in §4 on namespace extension in ttml2 and as an errata to ttml1 [on Glenn Adams - due 2014-05-08].

F2F in September

action-281?

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

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

nigel: A room of up to 60 people has been reserved at EBU in Geneva on 16th and 17th September for us to use for this face to face meeting.

close action-281

<trackbot> Closed action-281.

nigel: The goal of this F2F is to work on our charter deliverable of a WebVTT <--> TTML mapping

MPEG liaison re MIME Codecs parameter

action-283?

<trackbot> action-283 -- Nigel Megitt to And dsinger to respond to mpeg liaison -- due 2014-05-01 -- PENDINGREVIEW

<trackbot> http://www.w3.org/AudioVideo/TT/tracker/actions/283

close action-283

<trackbot> Closed action-283.

mike: In MPEG a couple of weeks ago the DASH group asked for some help with the codecs parameter. We decided that W3C should manage this with respect to TTML and WebVTT in particular.
... MPEG meets every 3-4 months and not much happens in between meetings. This means that the response will not be until 2nd or 3rd week July.
... However the intent is that W3C takes ownership of this issue so we can act on this more quickly.
... Technically, there's a missing requirement. We need to indicate the presence of other namespaces since most profiles support foreign namespaces.
... I don't think it's a fundamental problem but we need to reconsider the labels to identify namespaces not profiles.
... On the second point the 4C code needs to be defined too [minutes incomplete]

glenn: I don't agree with Mike's point about namespaces. So we need to discuss this more.

mike: The MPEG group's intention was to signal namespaces.
... We can also do what we do in TTML2 with the document content profile but the codec string folk in the File Format group of MPEG felt that string would be too cumbersome and long.
... I agree with you that we should consider that mechanism.

glenn: Is the purpose of this to define what is required by the decoder or is it to define what the content adheres to?

mike: the latter, what the content adheres to.
... The way this works in DASH is that the manifest describes the content that is available and the decoder selects the best resources for its capabilities.

glenn: That describes a processor profile not a related content profile.

mike: I can see that point of view. The important thing is to provide an unambiguous identifier which is not too long a string.

glenn: If we assume that we can discuss and get folks to agree on profile designations, possibly a list of them, then it's simply a matter of creating short names to link to those
... profile designation URIs.

mike: I like it. We should talk about mapping it through to the mechanism we've already designed.

nigel: when the page has been created I will add a section on meaning and endorsement.

glenn: I've already got some prior work I can reuse for that.

mike: Additional to the short name and URI should we also encourage a resolvable link to the definition?

glenn: Yes we should encourage that and a reference to the specification.

mike: short name, profile URI, profile document URL, specification URL, schema/electronic representation URL would be a good set of columns.
... Everything after the short name and profile URI is encouraged but optional.

<scribe> ACTION: nigel to create issue for codecs parameter [recorded in http://www.w3.org/2014/05/01-tt-minutes.html#action02]

<trackbot> Created ACTION-288 - Create issue for codecs parameter [on Nigel Megitt - due 2014-05-08].

- DRAFT -

Timed Text Working Group Teleconference

01 May 2014

Attendees

Contents

IMSC FPWD

Issue discussed over the past week

Action Item overdue and due next week

F2F in September

MPEG liaison re MIME Codecs parameter

Summary of Action Items

Scribe.perl diagnostic output