W3C

Media Fragments Working Group Teleconference

15 Jun 2011

Agenda

See also: IRC log

Attendees

Present
Yves, Jack, Davy, Chris, Silvia, Raphael, Erik, Philip, (irc)
Regrets
Thomas
Chair
Raphael, Erik
Scribe
raphael

Contents


<trackbot> Date: 15 June 2011

<doublec> I get 'dispatch code is not valid'

<doublec> when trying to enter the conference code

<doublec> yes

<silvia> hmm… I am still at work and about to go home… am I needed in the meeting?

Chris announcing some nightlies to see part of media fragments in ACTION:-)

1. ADMIN

PROPOSED to accept the minutes of the last week telecon:

http://www.w3.org/2011/06/08-mediafrag-minutes.html

<davy> +1

<erik> +1

+1

<jackjansen> +1

minutes accepted

<doublec> +1

2. SPEC MAINTENANCE

ACTION-218?

<trackbot> ACTION-218 -- Jack Jansen to carrefully review the changes made by Davy that will most likely be all over the palce -- due 2011-04-20 -- OPEN

<trackbot> http://www.w3.org/2008/WebVideo/Fragments/tracker/actions/218

Jack: I'd like that people go through this list and address these comments
... going through my comments, the first one is actually about section 6.1.1
... it is indeed a typo, e should be > 0
... should we allow empty images or empty video files ?

Davy: no, no empty images, so we are right to write w>0 and h>0
... for consistency, we do the same for temporal, to e>0 (strictly greater)

Jack: harmonize the text, between play from x to y OR play from x until y ... and also specifiy if the last frame should or should not be played
... this is an open interval so the last frame shouldn't be played

Raphael: we should even have a test case that check this

Jack: this is important if we start combining media fragments
... we use width as opposed to right so it is clear which pixels are actually displayed
... this is clear, we can ignore this point
... #t=a, is illegal

Davy: yes per the ABNF and per the test case

Raphael: we should put it in the section 6.2.2 as a typical example of error case

<davy> http://www.w3.org/2008/WebVideo/Fragments/TC/ua-test-cases#TC0018-UA

Jack: problem with SMPTE time code adressing: are we always guaranteed to have frame accuracy

<foolip> I don't think the spec is anywhere near CR, it has no browser implementations yet. (I also don't know why the spec status is important.)

<foolip> I have no opinion on the name, id is fine by me.

Philip, CR does not mean implementations ... PR mean implementations

<Yves> foolip, CR is a call for implementations, so it's normal not to have implementation at that stage (and the end result might be going back to LC again)

<foolip> OK, no opinion on spec status

<Yves> in any case, we know that most implementers are aware of the status of the edcopy :)

Jack: perhaps we could let it explicitly as "implementation to be defined"
... if you do spmte addressing on smpte encoded media has a well defined behavior
... but if you do smpte addressing on non smpte-encoded media, then it is explicly undefined and we wait for implementation experience

<doublec> We have no plans to implement smpte timecods

Raphael: I think foolip does not plan to implement smpte addressing, correct foolip ?

<foolip> raphael, correct

Jack: that is fine, this not for browsers, this is more for editing programs

Silvia: gstreamer has a plan to implement media fragments with smpte time codes addressing for live streaming!

<silvia> flumotion

Davy: WebTV IG has also interest in frame accuracy

<Yves> but does editing programs needs identifying such timepoints using URIs ?

<silvia> Thomas van der Stichele from Fluendo

Davy: we should keep an eye on this group

Raphael: I will check if Thomas is subscribed to this mailing list

<Yves> ok, thanks Jack, the annotations is indeed a use case

Jack: the annotation use case is important, not only for playback, in an editing program that would use a URI to identify a frame

Davy: no we don't have test cases yet for a<s and b<s and various combinations (because smpte timecodes don't have to be zero-based)
... we removed them for npt since these resources cannot start with 0, but we should add them back for smpte

Jack: undefined for non contiguous smpte timecodes
... we need much more implementation experience

Raphael: I'm in favor of saying explicitly it is *undefined*

+1 from Jack and Davy

<silvia> +1

Raphael: going through the problem of track names discovery
... and errors on the track dimension

Jack: what's happen with #track=foo&t=10,40 ?
... and track foo starts at t=25
... an implementation will play this track from 25 to 40 ?
... or play all the tracks from 10 to 25 and start to play from 25 to 40 the track foo ?

Silvia: no, you just select the track, and return the sub part you have
... I wouldn't write anything about this, this is a general problem
... this is a corner case
... again an implementation quality issue

Jack: again, then I would be in favor of saying explicitly undefined
... if a track does not exist for the whole duration of the media, then what is happened is undefined
... a forthcoming WG could fix it
... 6.3.5: we should explicitly state what happens if you apply a chapter MF to a media format that doesn't support chaptering?

Davy: we have a test case for that

<Yves> yes, same defaulting behaviour as 'not found'

Davy: same behavior that the media format supporting chapters but the chapter is not found

close ACTION-217

<trackbot> ACTION-217 Edit the specification for precising what is the user experience when there is an invalid time range closed

ACTIO: davy to edit the specification and in particular section 6 to reflect this entire discussion

<scribe> ACTION: davy to edit the specification and in particular section 6 to reflect this entire discussion [recorded in http://www.w3.org/2011/06/15-mediafrag-minutes.html#action01]

<trackbot> Created ACTION-225 - Edit the specification and in particular section 6 to reflect this entire discussion [on Davy Van Deursen - due 2011-06-22].

ACTION-221?

<trackbot> ACTION-221 -- Davy Van Deursen to fix the #t=10, in Section 4.2.1 which is invalid -- due 2011-06-15 -- OPEN

<trackbot> http://www.w3.org/2008/WebVideo/Fragments/tracker/actions/221

close ACTION-221

<trackbot> ACTION-221 Fix the #t=10, in Section 4.2.1 which is invalid closed

ACTION-222?

<trackbot> ACTION-222 -- Davy Van Deursen to adapt Section 5.2.3 so that the server can also send back the mapping in terms of byte ranges -- due 2011-06-15 -- OPEN

<trackbot> http://www.w3.org/2008/WebVideo/Fragments/tracker/actions/222

close ACTION-222

<trackbot> ACTION-222 Adapt Section 5.2.3 so that the server can also send back the mapping in terms of byte ranges closed

3. Name of the 4th dimension

<jackjansen> I fully agree with Philip

<jackjansen> I disagree with "cue", the other ones are fine. "Cue" is a point, not an interval;

Raphael: chapter might not be a good dimension name for possible confusion with the chapter track

<jackjansen> lol

Silvia: segment?

Raphael: id

<jackjansen> range? area? part?

<doublec> bookmark?

<jackjansen> -bookmark: it's a point

<doublec> what do the users suggest as an alternative?

Silvia: I'm worried about the users, not the programmer

Jack: initally we talked about id but said it replaced all dimensions
... now we restrict it to only time ranges
... and renamed it chapter

<Yves> shortcut?

Jack: so if this is just a temporal range, chapter is good

Silvia: chapter in the context of HTML5 is made for navigational purpose

Jack: I'm in +-0

Raphael: I like "id" because it is general and can extended in version 2

<davy> +1

Erik: id I prefer

<foolip> perhaps our problem is that the best solution would be #nameofthingtoseekto, just like for HTML, but that unfortunately conflicts with something else we've made up :)

<silvia> #nameofthingtorestrictto

Yves: id also conflicts with HTML

<foolip> silvia, so you no longer think users should be able to seek outside of the given fragment? ;)

Jack: I disagree, id refers to a continuous section of a structured document
... and this is what we mean

Yves: id means point

<doublec> fragment?

Jack: no, a node that points to a subsection

<doublec> :)

Raphael: propose to switch back to ID

<doublec> I just noticed everyone was calling it a fragment

<jackjansen> +0

<silvia> +.5

<doublec> +1 to id

+1 for ID

<davy> +1 for id

<erik> +1 to id

<Yves> ~0 for id

<jackjansen> ~0? you mean 0xffffffff?

<Yves> yep!

<jackjansen> That's -1 to me....

<Yves> now use the right type, signed or unsigned...

<scribe> ACTION: davy to edit the spec again to switch back to "ID" for the 4th dimension [recorded in http://www.w3.org/2011/06/15-mediafrag-minutes.html#action02]

<trackbot> Created ACTION-226 - Edit the spec again to switch back to "ID" for the 4th dimension [on Davy Van Deursen - due 2011-06-22].

ACTION-224?

<trackbot> ACTION-224 -- Raphaël Troncy to send a reply to the 4 commenters -- due 2011-06-15 -- OPEN

<trackbot> http://www.w3.org/2008/WebVideo/Fragments/tracker/actions/224

4. CR transitioning

Yves: diff versions need to be prepared
... just run htmldiff between the two LC and the CR version

<Yves> see http://services.w3.org/xslt?xmlfile=http://www.w3.org/2005/08/01-transitions.html&xslfile=http://www.w3.org/2005/08/transitions.xsl&docstatus=cr-tr

Yves: the disposition of comments ?
... create an HTML page for this
... the comments between 1st LC, 2nd LC and CR
... I'm wondering if the whole section 5.2 should not be put aside in a different document with a note status ?

Jack: do we want a note or an extension to be a spec later on

Yves: a note would be better, it could be picked up by WG later on
... there are multiple ways of doing the same thing and I'm not sure it should be in the spec

Jack: it is a painful decision to make because we have devoted a lot of time in it
... but I think I agree with you

Silvia: I don't think this is fine. I believe implementers will need this part and consistently used

<silvia> it's about getting interoperable implementations

Jack: look at the audience of this document: end users, web designers, people doing implementations

Silvia: no, I disagree, we are targetting the URI spec readers

<Yves> rfc3986 is different from rfc2616

Raphael: I agree with Silvia, and I don't think we should throw away this part

Jack: this is clear that this part is nice for browser vendors, but it is not interesting for other readers

Raphael: I don't think that our spec is that *long* that we should bother with part targetted at a different audience

<Yves> I will take that to email

<silvia> a specification is there to create interoperable implementations

<silvia> it's not a communication tool for users - they can get their information from other websites that have created readable subparts from the specification

<erik> +1 to Raphael & Silvia ... if some are not interested in some parts, you just don't read it ... browser vendors are main players that will make this spec work (I think)

Rapahel: I will prepare the diff files and the disposition of comments

Yves: I will follow up this discussion by email + indicating the status of HTTP Bis and request for implementations from Marc Nottingham

5. AOB

none

meeting adjourned

<scribe> ACTION: double to announce a link to a nightly implementing part of the media fragment spec [recorded in http://www.w3.org/2011/06/15-mediafrag-minutes.html#action03]

<trackbot> Created ACTION-227 - Announce a link to a nightly implementing part of the media fragment spec [on Chris Double - due 2011-06-22].

Summary of Action Items

[NEW] ACTION: davy to edit the spec again to switch back to "ID" for the 4th dimension [recorded in http://www.w3.org/2011/06/15-mediafrag-minutes.html#action02]
[NEW] ACTION: davy to edit the specification and in particular section 6 to reflect this entire discussion [recorded in http://www.w3.org/2011/06/15-mediafrag-minutes.html#action01]
[NEW] ACTION: double to announce a link to a nightly implementing part of the media fragment spec [recorded in http://www.w3.org/2011/06/15-mediafrag-minutes.html#action03]
 
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$Date: 2011/06/15 10:14:58 $