Interrupt autoplay when video element becomes invisible #2324

xxyzzzq · 2017-02-06T12:02:56Z

Allow the user agent to interrupt an autoplaying video when it becomes invisible.
Renamed the confusing name "autoplaying flag" to "autoplay on demand flag".

xxyzzzq · 2017-02-06T12:03:11Z

@foolip @mounirlamouri PTAL

mounirlamouri · 2017-02-06T12:38:32Z

This is also changing the behavior when a video starts autoplaying to no longer set the flag to false, right?

zcorpan · 2017-02-06T12:56:25Z

Is this web compatible?
Would it not be nice to have the ability to "auto pause" without autoplay?

xxyzzzq · 2017-02-06T13:53:31Z

This is also changing the behavior when a video starts autoplaying to no longer set the flag to false, right?

Yes, I feel the original flag "autoplaying flag" has some inconsistencies, so it is hard to tell what it really mean.

This is why I'm changing the name to "autoplay on demand flag" to "the element is in the autoplaying stage", so the user agent can autoplay it if they want if the flag is true.

If we keep the old behavior and set the flag to false, then we have to set it to true at some point (maybe when it becomes invisible). However I feel this is a bit overlapping with "eligible to autoplay" as it also checks the paused attribute.

xxyzzzq · 2017-02-06T14:04:26Z

Is this web compatible?

Yes, Safari on iOS already does this (using an equivalent implementation). So I think websites who care about the autoplay behavior should already know it.

Would it not be nice to have the ability to "auto pause" without autoplay?

Yes, it would be nice to have this. However we are targeting the autoplay attribute, which has very low percentage of usage compared to autoplay by play() method. Here we only want to improve the default implementation of the autoplay behavior if it is initiated by autoplay attribute. Websites who really care about the behavior could have their own implementations.

domenic · 2017-02-06T15:00:59Z

source

       <li><span>Notify about playing</span> for the element.</li>

-       <li>Set the <span>autoplaying flag</span> to false.</li>
+       <li>Optionally, if the substeps are triggered when a <code>video</code> element <span


As an editorial nit, I think this would be better as a separate paragraph (stating "when the element no longer..." instead of "wait until the element no longer...") introducing a second set of substeps, instead of as a step inside the autoplay substeps. Then you don't need to define the "substeps for interrupting autoplay" either (unless you were planning on using those from another spec?).

Done. It's a bit hard to rephrase without the substep set names as they reference each other (run the other set after one set is finished). However I managed to do it. PTAL

domenic

LGTM, although I'd like @zcorpan's signoff for media stuff if he has time.

foolip

Thanks, we should make this change, just a bit of tinkering needed.

foolip · 2017-02-06T21:42:28Z

source

+
+      <ol>
+
+       <li>Set the <code data-x="dom-media-paused">paused</code> attribute to true.</li>


I think this should use https://html.spec.whatwg.org/multipage/embedded-content.html#internal-pause-steps, but I guess that setting the "autoplay on demand flag" to false would prevent autoplay the next time the video intersects the viewport? It'd be fine to just say "invoke the internal pause steps and set the autoplay on demand flag to false" instead.

I think it would be good to point out that the steps for playing and pausing can be triggered many times. Because this inside an algorithm, my default assumption would be that one never jumps to an earlier step implicitly.

I agree, setting the paused attribute is a bit weird as it is intended to be used for reflecting instead of controlling the playback state.

It'd be fine to just say "invoke the internal pause steps and set the autoplay on demand flag to false" instead.

Did you mean "invoke the internal pause steps and set the autoplay on demand flag to true"?

Ah, yes, true is the default state :)

foolip · 2017-02-06T21:53:18Z

source

  <div w-nodev>

-  <p>All <span data-x="media element">media elements</span> have an <dfn>autoplaying flag</dfn>,
+  <p>All <span data-x="media element">media elements</span> have an <dfn>autoplay on demand flag</dfn>,


The old name was pretty bad, so allow me to bikeshed a little bit. In this context, I'd associate "on demand" with a user doing the demanding or perhaps video on demand as opposed to live. To call it "autoplay eligibility flag" would be an accurate and boring name. That's the best I can come up with, any other ideas?

That will be a bit confusing with the definition of "eligible for autoplay". Maybe name it "autoplay stage flag"? which is always true after loading and before the user explicitly call play() or pause(). The UA can autoplay at will if the flag is true.

Yes, one would have to pay attention to not confuse "eligible for autoplay" with the raw value of the flag. "The UA can autoplay at will if the flag is true" is precisely it, so maybe the "can autoplay flag"?

SGTM, will do.

xxyzzzq · 2017-02-07T00:02:53Z

Safari has an equivalent implementation. +@jernoble to look at this change and see if he's okay.

xxyzzzq · 2017-02-07T11:22:34Z

@foolip PTAL

…ps can be triggered multiple times

xxyzzzq · 2017-02-09T15:46:15Z

source

+      the viewport</span> and, if the element is still <span>eligible for autoplay</span>, run the
+      substeps above. Optionally, when the element stops <span data-x="intersect the
+      viewport">intersecting the viewport</span>, and if the <span>can autoplay flag</span> is still
+      true and the <code data-x="attr-media-autoplay">autoplay</code> attribute is still specified,


@foolip I tend to remove the paused attribute from the "eligible for autoplay", so we can use:

Eligible for autoplay and paused attribute is true for starting autoplay

Eligible for autoplay and paused attribute is false for pausing autoplay

Does it sound good?

foolip

I made a few minor things with punctuation and moved+clarified the note about multiple play/pause. @xxyzzzq, can you check if it's OK before merging?

foolip · 2017-02-09T16:16:06Z

I have filed web-platform-tests/wpt#4772 to track the fact that it's not possible to write shared tests for this.

foolip · 2017-02-09T16:21:17Z

Ping @jernoble to check if this is close enough to what WebKit does.

xxyzzzq · 2017-02-09T16:24:32Z

@foolip LGTM. Thanks for the fixes 👍

jernoble · 2017-02-09T17:10:33Z

@foolip, AFAICT, this is close enough to what WebKit does on iOS.

foolip · 2017-02-09T18:43:36Z

Implementation bugs:

Chromium: https://bugs.chromium.org/p/chromium/issues/detail?id=690468
EdgeHTML: https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/10886239/
Gecko: https://bugzilla.mozilla.org/show_bug.cgi?id=1338259
WebKit: None filed as @jernoble says it's already pretty close.

In this CL, when a muted video is autoplaying from attribute, we pause it when it comes off screen. Intent to implement and ship: https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/UtFM-kndhaI Spec PR: whatwg/html#2324 BUG=683141 Review-Url: https://codereview.chromium.org/2654123002 Cr-Commit-Position: refs/heads/master@{#450707}

alastor0325 · 2017-06-12T07:55:03Z

I think we should also consider whether the video is audible or not, because it's annoying that the audio track was also be paused when the video became invisible.

zcorpan added topic: media addition/proposal New features or enhancements labels Feb 6, 2017

interrupt autoplay when video element becomes invisible

726b535

xxyzzzq force-pushed the autoplaying_flag_fix branch from 2e0317c to 726b535 Compare February 6, 2017 13:35

domenic reviewed Feb 6, 2017

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moving intersection observing out from substeps

841a5b4

domenic approved these changes Feb 6, 2017

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foolip requested changes Feb 6, 2017

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addressed more comments from foolip

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foolip mentioned this pull request Feb 8, 2017

www.tsn.ca - mobile site is not usable webcompat/web-bugs#2803

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fixed the condition for pausing autoplay, and added note that the ste…

c73c403

…ps can be triggered multiple times

xxyzzzq commented Feb 9, 2017

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suggest a few editoral minor tweaks

0264b63

foolip approved these changes Feb 9, 2017

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foolip merged commit aba54ed into whatwg:master Feb 9, 2017

foolip mentioned this pull request Feb 24, 2017

Intervention change: allow autoplay of muted videos on mobile WICG/interventions#23

Closed


		<ol>

		<li>Set the <code data-x="dom-media-paused">paused</code> attribute to true.</li>

Interrupt autoplay when video element becomes invisible #2324

Interrupt autoplay when video element becomes invisible #2324

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xxyzzzq commented Feb 6, 2017

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