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Comment by eriknstr | Hacker News Reader

I notice that the demo video stops when I switch tabs. Is this by design or by accident? Can I use JSMpeg but have it play in the background? Another thing; can I have video controls?

PS: That video has a very late nineties, early double-ohs feel to it indeed. Good choice of video :)

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Yeah. From the docs:

> pauseWhenHidden – whether to pause playback when the tab is inactive. Default true. Note that browsers usually throttle JS in inactive tabs anyway.

Supposedly, Chrome doesn't throttle background tabs where audio is playing.

JS hack idea! Play a silent sound to force Chrome to not throttle your page when it's not primary.

Please don't.

Also, Chrome puts a little speaker icon on the tab, so users might notice.

In the long run, the probability of this being exploited is approximately 100%. I'm surprised they left in such an obvious loophole.

I'm not sure how usurping this is an 'exploit'. It's used as a heuristic to save battery life.

and if you're trying to run down a user's battery I can think of better ways.

Well you can mine bitcoins or run some botnets on victims computer.

The goal isn't to run down the users' battery. The goal is to do whatever timer callback processing a tab is doing that got throttled in the first place.

Need to do some more testing, but I have suspicions that Chrome actually doesn't put the sound icon on the tab if it's playing silent audio.

Throw in an inaudible frequency once per second at a low volume. I doubt they're doing signal processing to decide if a human can actually hear the output.

Browsers (like Chrome throttle) the JS execution of background tabs drastically which would probably make the MPEG decode impossible.

They probably stop the video as a workaround.

Worth noting that Chrome won't throttle a tab that has audio playing.

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