Minutes from Media Timed Events Task Force call 16 March 2020

Dear all,

The minutes from the Media Timed Events Task Force call today are now available [1], and copied below.

The next call is planned for Monday 20th April.

We are also discussing the WICG DataCue proposal [2] with DASH-IF. W3C members with an interest in DataCue are invited to join DASH-IF [3] calls every second Friday (the next call is this Friday, 20th March at 14:00 UTC). Please contact me for dial-in details.

Kind regards,

Chris (Co-chair, W3C Media & Entertainment Interest Group)

[1] https://www.w3.org/2020/03/16-me-minutes.html
[2] https://github.com/WICG/datacue/blob/master/explainer.md
[3] https://dashif-documents.azurewebsites.net/Events/master/event.html


Media Timed Events TF
16 Mar 2020


	Chris_Needham, Kaz_Ashimura, Rob_Smith, Francois_Daoust, Nigel_Megitt


Review open issues
Summary of Action Items
Summary of Resolutions

<scribe> scribe: tidoust

<cpn> https://lists.w3.org/Archives/Public/public-web-and-tv/2020Mar/0009.html

<scribe> Agenda: https://lists.w3.org/Archives/Public/public-web-and-tv/2020Mar/0009.html

cpn: Wondering if there's further work for the IG task force to do, or whether we should just fold the task force and go on with the DataCue incubation in the WICG.
.... It would be good to go through open issues and decide what to do with them on the way to publishing an update of the IG Note
.... Would like to talk about cues generated by user agent (~ in-band cues)
.... Also report on discussions I've had recently with DASH-IF folks.

# Review open issues

<cpn> https://github.com/w3c/me-media-timed-events/issues

cpn: https://github.com/w3c/me-media-timed-events/issues/39 #39 is I believe covered. Done through the HTML issue tracker to report the issue.
.... I don't think there's anything more to do on this particular issue;
.... I've added text to cover additional use cases that Mark raised

<kaz> draft wot minutes

kaz: FYI, the WoT group just had a meeting and discussed media use cases. You can review the minutes offline.

<cpn> https://github.com/w3c/me-media-timed-events/issues/36

nigel: The issue ended up with two new issues, but that's far from the actual title of the issue.

<kaz> https://github.com/w3c/me-media-timed-events/pull/46 PR 46

cpn: Pending pull request 46 is in response to #39. One part where I wanted Rob to provide feedback.
.... Essentially, once PR #46 has been merged, we can close #39.
.... With regards to #39 we made a corresponding proposal into the HTML spec..
.... The question I have is in relation with the second paragraph, updating event times.
.... Is this a proposal that we want to put forward? If it is, should it trigger change on any property update, not only on times?

RobSmith: With the existing interface, you can delete a cue and create a new one with the same identity.
.... The design for the cues is immutable currently.

cpn: No, the cues can be changed. At least, the timing can be changed.
.... So you don't have to do remove/add, you can just modify the properties directly.
.... I made some investigation. As I understand it, you can change any of the cue attributes. There is an implementation bug around an event that I raised with browser vendors.

<Zakim> nigel, you wanted to say there are no semantics associated with the ids and id usage in general in HTML

nigel: It would be unusual in HTML to use an ID for anything. The only place where it's really being used is for CSS selector. The TextTrackCue ID is really just an arbitrary string. The implication would be that the sender of the cues would need to be aware of the state of the client, which worries me a bit.

RobSmith: The purpose of setting the same ID is to be able to track it. Different implementations can do different things. The "onexit" and "onenter" could be linked to the identity. I may ignore them deliberately. Or not.

nigel: OK, I'm still worried about this because there's no uniqueness with the notion of ID.
.... Also, why wouldn't you want to update the cue directly instead of removing/adding a new one.

RobSmith: The system didn't seem designed to do that.
.... If you consider that to be immutable, then its lifecycle is basically added/deleted.

nigel: It's not the actual model. If it's immutable then it would have to say it.
.... The default for objects in DOM is mutable.

RobSmith: But then you have to define the interface to handle that

nigel: Yes, that's what need to be specified. I just note that the TextTrackCue interface does not say that the content cannot be changed. Implementations may not expect that to happen, but that would be a bug.

RobSmith: Such an implementation could easily say that the spec is not clear on the topic.

cpn: In terms of start/end time, then the spec defines behavior with regards to updating them.
.... If we talk about other properties, I'm less clear.

RobSmith: Also the problem of the asynchronous process processing the cue, you're never quite sure about what happens.

Summary of Action Items
Summary of Resolutions
[End of minutes]
Minutes manually created (not a transcript), formatted by David Booth's scribe.perl version 1.154 (CVS log)
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Present: Chris_Needham Kaz_Ashimura Rob_Smith Francois_Daoust Nigel_Megitt
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Agenda: https://lists.w3.org/Archives/Public/public-web-and-tv/2020Mar/0009..html

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Received on Monday, 16 March 2020 18:17:00 UTC