Need help: playback stops in background/when screen off on mobile?

[ltguillaume]

2020/08/07

The issue: mobile browsers tend to stop playback in the following cases:

• When the screen is off and the song is ended (Android / iOS)
  • Seems to be working fine in Chromium-based browsers (first successful test 2023/04/30).
• When the browser is pushed out of memory by bringing other resource-heavy apps to the foreground (Android / iOS??)

The problem is that JavaScript execution is prevented under those conditions under the guise of saving battery life.

Firefox for Android seems to be less likely to stop playback (I can play music for hours on my S5 with LineageOS, while trying this on Bromite will stop playback after a single song).

There seem to be some hacks available, such as constantly playing a (fake-ish) video in the background, but they're messy. If there's a proper solution, I'd love to be pointed towards it.

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@sbncbot @OoLunar @Invictaz @xRadio-us
I found that for some people on mobile devices playback tends to stop a while after the screen is turned off. I'm not sure whether the cause is due to resource management of the device itself, or a crappy network connection (or whether these are two separate issues). The playback tends to stop in between songs, so it could be caused by JavaScript not being run when the screen is off.

So, playback of the next song stops when:

• Screen is off, or perhaps even when the browser (or just the music player's tab) is put to the background
• Tends to immediately start playback again when I press the pause button :/

My questions to you:

• Have you have experienced a similar issue and what were the exact conditions?
• Can you easily reproduce it? If you can, does enabling crossfade improve the situation?
• Do you know of possible causes and/or solutions?

Some links to information on a possibly related issue:
https://stackoverflow.com/questions/22061280/javascript-halts-in-inactive-android-chrome-tab
https://developer.mozilla.org/en-US/docs/Web/API/Page_Visibility_API
https://stackoverflow.com/questions/15959244/is-it-possible-in-javascript-to-detect-when-the-screen-is-turned-off-in-the-an

[OoLunar]

On my app, it only turns off if it's on a different app, i.e the home page, or my contacts, etc. I have not tried enabling Crossfade, but I will take a look into it. The only solution I know is to turn off the screen while I'm still on my app.

EDIT: Enabling Crossfade does not help

[OoLunar]

Also, having a bad internet connection doesn't really seem to be an issue. I took some back roads for a trip, while choosing my songs with no reception, it kept playing (although I believe that's because it preloaded the song, and attempts to preload the next song while the current one playing. Very clever) almost all the way through

[OoLunar]

Service workers?
https://stackoverflow.com/a/50309148

[OoLunar]

No sleep JavaScript? Looks more promising than it sounds.
https://github.com/richtr/NoSleep.js/blob/master/README.md

[ltguillaume]

On my app, it only turns off if it's on a different app, i.e the home page, or my contacts, etc. I have not tried enabling Crossfade, but I will take a look into it. The only solution I know is to turn off the screen while I'm still on my app.

EDIT: Enabling Crossfade does not help

Thanks for reporting! So, to be clear, you mean it will stop playback after song X (not during song X?!) if you went to another app during playback of song X?

Also, having a bad internet connection doesn't really seem to be an issue. I took some back roads for a trip, while choosing my songs with no reception, it kept playing (although I believe that's because it preloaded the song, and attempts to preload the next song while the current one playing. Very clever) almost all the way through

Yes, you can always use the interface after it's loaded, but it will load the songs only after the previous has finished playback. When crossfade is enabled, it will start playing the next song ~10 seconds before the current has finished. As such, there is no real preloading yet, but it is planned (by using the same code as for crossfade, but by staying paused until the previous song has finished).

Service workers?
https://stackoverflow.com/a/50309148

I have no experience with Service Workers yet (and in my desktop browser I have disabled them), but if the very first comment I read in your link is anything to go on, it's not really useful for this problem:

SW are grate but not perfect, it's mostly limited to push notification, network event and caching things. It's no good at staying alive and will force close after 10min or so if things are preventing it from going idle. It have no control over playing music, geo monitoring or p2p stuff :(

[OoLunar]

Shame SW don't work. Crossfade will just end the song normally while fading out.

[ltguillaume]

Shame SW don't work. Crossfade will just end the song normally while fading out.

That's so odd... If it really fades out, that means that JavaScript is still working. This could be because if audio is still being played, the browser will NOT stop JavaScript (Tabs which are playing audio are considered foreground and aren’t throttled. - source). But if that's the case, it should also load the next file AND start playback, all during playback of the last 10 seconds of the current song. If so, there will always be an audio track playing, so JavaScript can't be stopped. So why wouldn't it continue?

[ltguillaume]

@OoLunar Could you tell me exactly how you provoke that it stops playback? I've been trying on an old Galaxy S5 while another app was opened, the screen off (and without crossfade), but it played for several hours without a problem (then I stopped it manually). I was using https://www.bromite.org as a browser on LineageOS 16 (Android 9).

Also, were you using the latest commit? (or just tell me the date of the music.* files, that should be enough of an indication for which commit you use).

[OoLunar]

May 4th.
As for the playback thing. Go and download my app, click a song of your choice, leave the app, and turn off the screen. By the end of the song, it stops.

[OoLunar]

Also, I know this is related what-so-ever to this issue, but can you help me with some Javascript related 10 line code? Send me an email at lunar@forsaken-borders.net if you want to help.

[ltguillaume]

Thanks for the quick reply. Hmz, I'm guessing you need the actual Google Chrome for your app: when I click "listen to music" it just opens a browser pick dialog. When I pick Bromite (which is just an "ungoogled" Chrome), it still works (but not as a Custom Chrome Tab!): I started several other apps, then turned off the screen, and still it continued playback with at least 4 songs... It might depend on how aggressively the manufacturer has set the phone to kill background apps (more info at https://dontkillmyapp.com), but I just don't know for sure... What a mess...

[OoLunar]

That's rough then. I haven't have any clue on how to solve this.

[ltguillaume]

I've installed Chrome on an old phone, let's see how it works. I did see that if I force-closed your app, playback also stopped. So perhaps you could try to exclude your app (and Chrome?) from battery optimization: https://www.makeuseof.com/tag/androids-battery-optimization-harm-good/

For now, it keeps playing on my phones.

[OoLunar]

Ah. I've already tried this on the Pixel 3. Doesn't seem to work. Instead I'm just am going to put the required .html, .js, and .php files into the app, basically turning it into a web app. Maybe then it'll work.