Bug 202846 – AudioContext stops playing when suspended on visibilitychange

• Component: Web Audio
• Status: NEW

[Jesper van den Ende]

Created attachment 380740 [details]
demonstration of the issue

When suspending an audio context in the visibilitychange event of a document, resuming the audio context does not start playing audio.
Check the attached file for a demonstration.

-open the file on safari on iOS 13.1.2
-tap the resume button
-close safari
-note how the audio stops playing
-open safari again
-note how the audio does not resume, the current time stays the same even though the state of the audio context is still "running"
-tapping the resume button doesn't do anything
-only after tapping the suspend button and then the resume button, the audio context starts playing
-when 'suspend on visibility change' is unchecked, the problem does not occur.
-the problem also does not occur on iOS 12, though on iOS 12 the audio keeps on playing when the checkbox is not checked.

I wasn't able to reproduce this issue in the simulator on iOS 13.1, I was not able to download the iOS 13.1.2 simulator.

[Jesper van den Ende]

A temporary workaround for this issue is to put the ctx.resume() call of the visibilitychange event in a setTimeout with about 300ms.

[Radar WebKit Bug Importer]

<rdar://problem/56194169>

[John Doe]

The setTimeout of ≈ 300 is also required for resuming the audioContext on pageshow, as it seems.

Though I'm not sure why I need to call resume on pageshow, shouldn't that be done automatic by the browser as it suspends the audioContext when leaving the page?