Unbounded TextTrackCue end time #5953

rjksmith · 2020-09-27T21:09:47Z

Allow unbounded text track cue duration, as discussed in whatwg/html issue #5297.

Summary

It is proposed that a TextTrackCue.endTime value of Infinity be used to represent an unbounded time, i.e. an unspecified future time. This is a simple extension of the existing HTML standard where media.duration = Infinity represents the duration of an unbounded stream, which is consistent with the definition of unbounded time.

Implementer Details

At least two implementers are interested (and none opposed):
- Chromium
- Gecko
- WebKit
Tests are written and can be reviewed and commented upon at:
- Tests for unbounded cue end time web-platform-tests/wpt#28394
Implementation bugs are filed:
- Chrome: https://bugs.chromium.org/p/chromium/issues/detail?id=1145620
- Firefox: https://bugzilla.mozilla.org/show_bug.cgi?id=1675317
- Safari: https://bugs.webkit.org/show_bug.cgi?id=218567

(See WHATWG Working Mode: Changes for more details.)

cc @chrisn

/acknowledgements.html ( diff )
/media.html ( diff )

foolip

This change looks good, a pretty straightforward expansion of the allowed values that I think ought to work. The setter needs some changes, but that's it.

foolip · 2020-10-21T09:08:51Z

source

-  a <span>media element</span>'s <span>list of text tracks</span>, and the <span>media
-  element</span>'s <span>show poster flag</span> is not set, then run the <i data-x="time marches
-  on">time marches on</i> steps for that <span>media element</span>.</p>
+  <code>TextTrackCue</code> object represents, in seconds or positive Infinity for an


Because the IDL type of the attribute is now unrestricted double, the setter here needs to also handle -Infinity and NaN. I would suggest throwing a TypeError, which is what would currently happen. Run new VTTCue(0, 1, '').endTime = Infinity to see this in action.

https://html.spec.whatwg.org/#dom-input-valueasnumber has an example of this: "On setting, if the new value is infinite, then throw a TypeError exception." (You'll probably need to massage it a bit to fit into this paragraph.)

No reference to "unbounded text track cue" ought to be needed here in the end, because that's defined in terms of what is being set.

Thanks for your feedback and apologies for the delay. I've added a check "on setting" to throw TypeError for -Infinity and NaN as you suggest, and have removed the reference here to "unbounded text track cue".

foolip · 2020-10-21T09:10:34Z

source

+  in a <span>text track</span>'s <span data-x="text track list of cues">list of cues</span>, and
+  that <span>text track</span> is in a <span>media element</span>'s <span>list of text
+  tracks</span>, and the <span>media element</span>'s <span>show poster flag</span> is not set, then
+  run the <i data-x="time marches on">time marches on</i> steps for that <span>media element</span>.


Yep, looks like this is the only change really needed. https://html.spec.whatwg.org/#time-marches-on tests for "whose end times are greater than the current playback position" and that'll work for infinity.

Added support for unbounded TextTrackCue - see whatwg/html#5953 Whitespace removed by Atom

Update for TextTrackCue unbounded endTime proposed in PR whatwg/html#5953

gkatsev · 2021-03-10T17:21:14Z

Looks like TextTrackCue has tests in wpt here https://github.com/web-platform-tests/wpt/blob/master/html/semantics/embedded-content/media-elements/interfaces/TextTrackCue/endTime.html

Added tests for unbounded TextTrackCue endTime changes proposed in whatwg/html#5953 & w3c/webvtt#493

rjksmith · 2021-04-07T13:34:12Z

Added unbounded cue tests in web-platform-tests/wpt#28394

rjksmith · 2021-04-15T11:20:21Z

@annevk I believe the recent addition of web-platform-tests/wpt#28394 completes the information required for this issue, but I still see a failing check.

Participation Pending — @rjksmith participates on behalf of an unverified entity

Please advise if there are further actions I need to take to resolve this. Thanks.

annevk · 2021-04-15T11:52:08Z

Hey @rjksmith, thanks! We'll resolve that when this is ready to merge as per https://github.com/whatwg/participant-data/#maintenance. It does seem like you'll need to rebase this PR and @foolip needs to review.

Fixes whatwg#5297

Fixes whatwg#5297  - [ ] At least two implementers are interested (and none opposed): * … * … - [ ] [Tests](https://github.com/web-platform-tests/wpt) are written and can be reviewed and commented upon at: * … - [ ] [Implementation bugs](https://github.com/whatwg/meta/blob/master/MAINTAINERS.md#handling-pull-requests) are filed: * Chrome: … * Firefox: … * Safari: … (See [WHATWG Working Mode: Changes](https://whatwg.org/working-mode#changes) for more details.)

Added type validation for unrestricted TextTrackCue.endTime & removed reference to unbounded text track cue.

rjksmith · 2021-04-16T12:32:24Z

Rebased to main as requested

Update for TextTrackCue unbounded endTime proposed in PR whatwg/html#5953

Added tests for unbounded TextTrackCue endTime changes proposed in whatwg/html#5953 & w3c/webvtt#493

rjksmith · 2021-04-16T13:51:11Z

Also rebased w3c/webvtt#493 and web-platform-tests/wpt#28394 for associated VTTCue and Web Platform Tests changes respectively

foolip

I have but one remaining nit. I can rewrap the result if you don't feel like messing with it. (But feel free to.)

foolip · 2021-04-16T14:31:42Z

source

+  <p>An <dfn data-x="unbounded text track cue">unbounded text track cue</dfn> is a text track cue
+  with a <span>text track cue end time</span> set to positive Infinity. An active <span>unbounded
+  text track cue</span> cannot become inactive through the usual monotonic increase of the
+  <span>current playback position</span> during normal playback (e.g. a metadata cue for a chapter in a live


Good example!

Thanks to @chrisn for that. Further use case discussion can be found in w3c/webvtt#496 which has been decoupled from this change.

source

Address https://github.com/whatwg/html/pull/5953/files#r614888723

foolip · 2021-04-16T16:13:26Z

@rjksmith it turns out that I can't push the rewrap directly to you branch. Since it's a bit tedious, here it is for you to copy-paste directly, if you could push another commit that'd be great:

  <p>The <dfn><code data-x="dom-TextTrackCue-endTime">endTime</code></dfn> attribute, on getting,
  must return the <span>text track cue end time</span> of the <span>text track cue</span> that the
  <code>TextTrackCue</code> object represents, in seconds or positive Infinity. On setting, if the
  new value is negative Infinity or a Not-a-Number (NaN) value, then throw a <a
  href="https://tc39.es/ecma262/#sec-native-error-types-used-in-this-standard-typeerror">TypeError
  </a> exception. Otherwise, the <span>text track cue end time</span> must be set to the new value.
  Then, if the <code>TextTrackCue</code> object's <span>text track cue</span> is in a <span>text
  track</span>'s <span data-x="text track list of cues">list of cues</span>, and that <span>text
  track</span> is in a <span>media element</span>'s <span>list of text tracks</span>, and the
  <span>media element</span>'s <span>show poster flag </span> is not set, then run the <i
  data-x="time marches on">time marches on</i> steps for that <span>media element</span>.</p>

Address whatwg#5953 (comment)

rjksmith · 2021-04-16T17:11:36Z

@foolip Thanks for the text. Updated as requested

foolip · 2021-04-16T17:22:53Z

Now we just need the WebVTT change. It doesn't have to be merged at the same time, but be approved at least so it's not too far apart.

rjksmith · 2021-04-16T21:31:26Z

w3c/webvtt#493 updated as requested

foolip · 2021-04-17T10:53:45Z

@rjksmith I've reviewed that, suggesting some changes.

rjksmith · 2021-04-20T13:29:24Z

Updated implementation bugs for Chrome, Firefox and Safari with recent progress.

foolip · 2021-04-20T14:09:45Z

OK, I'm going to bet on w3c/webvtt#493 being merged soon, and merge this + web-platform-tests/wpt#28394 now.

@rjksmith can you keep an eye on the WebVTT change, and circle back here if it doesn't end up merged within a week?

Added tests for unbounded TextTrackCue endTime changes proposed in whatwg/html#5953 & w3c/webvtt#493

…only Automatic update from web-platform-tests Tests for unbounded cue end time (#28394) Added tests for unbounded TextTrackCue endTime changes proposed in whatwg/html#5953 & w3c/webvtt#493 -- wpt-commits: 786c430165d916bdab740ab491ac541afb3f8bf5 wpt-pr: 28394

rjksmith · 2021-04-27T16:03:53Z

@foolip WebVTT change is still not merged.

There's an agenda item to resolve this in TTWG Meeting on 29th April 2021.

WebVTT
Added unbounded TextTrackCue.endTime w3c/webvtt#493
There have been a couple of requests to merge this - any reason why not?

gkatsev · 2021-04-27T22:40:57Z

It's mostly unmerged because I haven't had a chance to get back to it yet, unfortunately. I believe there isn't anything that'll block it from being merged on the TTWG side, though, I'll wait for the final resolution from the meeting.

rjksmith · 2021-04-28T12:54:06Z

@gkatsev I can attend the TTWG meeting on 29th April to respond to any concerns raised. If that would be helpful, please let me know how to join. Thanks.

himorin · 2021-04-29T05:42:09Z

@gkatsev I can attend the TTWG meeting on 29th April to respond to any concerns raised. If that would be helpful, please let me know how to join. Thanks.

I'll send you information via email.

rjksmith · 2021-04-30T12:26:03Z

@foolip I can confirm that w3c/webvtt#493 has now been successfully merged to support web-platform-tests/wpt#28394 which concludes the required changes for this PR.

I've also updated the implementation bugs for Chrome, Firefox and Safari accordingly.

Many thanks to all those who have contributed and especially to @chrisn, @eric-carlson, @annevk, @foolip and @gkatsev for their invaluable support.

foolip · 2021-04-30T13:58:47Z

Thanks @rjksmith! Just to know what to expect, will you be doing any work on any implementation here?

rjksmith · 2021-04-30T16:39:10Z

@chrisn and I have been discussing ideas to encourage implementation. I'm considering a code contribution to Mozilla/Firefox.

rjksmith mentioned this pull request Oct 2, 2020

WebVMT: Investigate optional endTime in HTML5 TextTrackCue interface w3c/sdw#1106

Open

annevk requested a review from a team October 6, 2020 11:57

annevk mentioned this pull request Oct 7, 2020

PR Preview is not retrying tobie/pr-preview#82

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rjksmith mentioned this pull request Oct 9, 2020

Video geotagging format (WebVMT) w3c/strategy#113

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foolip reviewed Oct 21, 2020

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foolip mentioned this pull request Oct 21, 2020

Add TextTrackCue end time representing end of media #5297

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rjksmith added a commit to away-team-software/webvtt that referenced this pull request Nov 4, 2020

Added unbounded TextTrackCue.endTime

e09f617

Added support for unbounded TextTrackCue - see whatwg/html#5953 Whitespace removed by Atom

rjksmith mentioned this pull request Nov 4, 2020

Added unbounded TextTrackCue.endTime w3c/webvtt#493

Merged

rjksmith added a commit to away-team-software/webvtt that referenced this pull request Nov 20, 2020

Update for proposed TextTrackCue unbounded endTime

17626fd

Update for TextTrackCue unbounded endTime proposed in PR whatwg/html#5953

Base automatically changed from master to main January 15, 2021 07:58

rjksmith added a commit to away-team-software/wpt that referenced this pull request Apr 7, 2021

Tests for unbounded cue end time

8b40bc6

Added tests for unbounded TextTrackCue endTime changes proposed in whatwg/html#5953 & w3c/webvtt#493

rjksmith mentioned this pull request Apr 7, 2021

Tests for unbounded cue end time web-platform-tests/wpt#28394

Merged

chrisn and others added 3 commits April 16, 2021 13:21

Allow unbounded text track cue duration

c3644af

Fixes whatwg#5297

Update source

17ef7f3

Added type validation for unrestricted TextTrackCue.endTime & removed reference to unbounded text track cue.

rjksmith force-pushed the unbounded-cue-end-time branch from d348935 to 17ef7f3 Compare April 16, 2021 12:27

annevk requested a review from foolip April 16, 2021 13:03

rjksmith added a commit to away-team-software/webvtt that referenced this pull request Apr 16, 2021

Update for proposed TextTrackCue unbounded endTime

abe1287

Update for TextTrackCue unbounded endTime proposed in PR whatwg/html#5953

rjksmith added a commit to away-team-software/wpt that referenced this pull request Apr 16, 2021

Tests for unbounded cue end time

279033b

Added tests for unbounded TextTrackCue endTime changes proposed in whatwg/html#5953 & w3c/webvtt#493

foolip approved these changes Apr 16, 2021

View reviewed changes

Address reviewer comment

a00d1cd

Address https://github.com/whatwg/html/pull/5953/files#r614888723

Update reviewer comment

dd843c3

Address whatwg#5953 (comment)

foolip approved these changes Apr 16, 2021

View reviewed changes

foolip merged commit 0864a02 into whatwg:main Apr 20, 2021

foolip pushed a commit to web-platform-tests/wpt that referenced this pull request Apr 20, 2021

Tests for unbounded cue end time (#28394)

786c430

Added tests for unbounded TextTrackCue endTime changes proposed in whatwg/html#5953 & w3c/webvtt#493

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