1412772 - website should handle rejected promise from video.play() properly when the pref "media.autoplay.enabled=false"

Status: RESOLVED INCOMPLETE

(Core :: Audio/Video: Playback, enhancement, P3)

Description

[Alastor Wu [:alwu]]

When set the pref "media.autoplay.enabled=false", we would stop any automatically play() invocation and reject the promise.

Websites should handle that rejected promise properly and then change their player UI to correct state.

It's defined by spec [1]

`If the media element is not allowed to play, return a promise rejected with a "NotAllowedError" DOMException and abort these steps.`

and we indeed reject the promise [2]

eg. Youtube would keep their controller's button as playing even we've prevented video playing

[1] https://html.spec.whatwg.org/multipage/media.html#dom-media-play
[2] http://searchfox.org/mozilla-central/rev/b52285fffc13f36eca6b47de735d4e4403b3859e/dom/html/HTMLMediaElement.cpp#4014

Comment 4

[Anthony Jones (:ajones, :kentuckyfriedtakahe, :k17e)]

There is nothing we can fix here aside from contacting sites.

Comment 5

[Alastor Wu [:alwu]]

Here is the list about the websites showing the wrong UI, see "Websites testing".

https://docs.google.com/document/d/1J0kgSHEOhb8aiRQTEPBxeKZGWni4gP7GiH0MGCUkNcU/edit#

Comment 6

[Eric Shepherd [:sheppy]]

Adding dev-doc-needed to be sure we fully document this recommendation.

Comment 7

[Chris Pearce [:cpearce (Not reading bugmail)]]

Closing. We intend to write a blog post documenting our autoplay behaviour.

Comment 8

[Eric Shepherd [:sheppy]]

I updated the page about HTMLMediaElement.play() with one specifically covering this scenario, and replaced the example on that page with one that covers this scenario.

https://developer.mozilla.org/en-US/docs/Web/API/HTMLMediaElement/play

Comment 9

[Chris Pearce [:cpearce (Not reading bugmail)]]

Looks good, thanks Eric.