Does Face Swap Keep Working When You Switch Tabs or Share Your Screen?

You start a call with a face swap on, then you need your notes, a link or a slide deck. Does the face hold when you click away? We measured it. The first time, it didn't: the swap froze after a few seconds in the background. Here is what we found, why it happened and what changed.

What happens to the face swap when you switch tabs?

With version 2.4.1, nothing changes: the swap keeps updating 18.7 to 20.1 times a second with the call tab in the background, as fast as with it in front (19.8 in our test). With version 2.4.0, nothing changed for about 9 seconds after we brought another tab to the front; then the rate fell to exactly 1 a second and stayed there until we switched back.

The call itself never noticed. Facecam Virtual Camera kept sending 30 frames a second the whole time, so there was no black screen and no "camera off". But with the swap updating once a second, most of those frames repeated the same picture: the other people saw a swapped face holding still, then jumping to a new position once a second, with lips that didn't follow the words.

Why did the face freeze in a background tab?

To save battery, Chrome slows down tabs you can't see, and a minimised window or a tab behind another tab counts as one you can't see. The camera kept delivering 30 frames a second to the extension the whole time; what slowed down was one step after it. Before each frame goes to the swap server, the extension compresses it to a JPEG, and Chrome only runs that kind of work when the tab has spare time. A tab that has been hidden for about 10 seconds never gets spare time, so Chrome made each frame wait its 1-second fallback.

Version 2.4.1 compresses frames straight away while the call's tab is hidden, instead of waiting for spare time. It's the same work as before, so it uses no more battery; it just isn't put off.

Which setups keep the swap at full speed?

With 2.4.1, all of them. Here is every case we measured, 30 seconds each, with both versions:

We also left another tab in front for 7 minutes with 2.4.1. The swap stayed connected and averaged 19.5 to 20.2 updates a second every minute, including after the 5-minute mark, when Chrome throttles background tabs harder. With 2.4.0 the same test ran at 0.96 a second from start to finish.

How do I get the fix?

Chrome updates extensions by itself, usually within a few hours of a new version. To check, open chrome://extensions and click Details under Facecam: version 2.4.1 or later has the fix. To update right away, turn on Developer mode at the top right of that page and press Update.

Does the face swap keep working when you share your screen?

Yes. When you share a tab, Chrome brings that tab to the front for you, which hides the call tab if both are in the same window. With 2.4.0, that slowed the swap to one update a second 10 seconds later; with 2.4.1 it kept full speed (18.9 updates a second). On an older version, click back to the call tab and the swap is live again, while the share carries on.

1. 1

   Open what you'll present

   A tab in the call's window works. A separate window (drag the tab out, or press Ctrl+N, Cmd+N on a Mac) lets you see the call and your slides side by side.

2. 2

   Share that tab or window from the call

   In our test, the swap kept full speed whether Chrome showed the shared tab or the call: 18.9 and 19.1 updates a second with 2.4.1.

3. 3

   Glance at your own video

   Your preview in the call shows what the others see. If the face looks frozen there, check that the extension is on version 2.4.1 or later.

What about the Live Face Swap page on facecam.ai?

The try-out page works differently on purpose. Live Face Swap is a real-time face swap that lets you look like anyone you choose: try it with your webcam on facecam.ai, then use it as a virtual camera in Google Meet, Zoom on the web, Discord in the browser and other sites in Chrome with the extension. When the facecam.ai page's tab is hidden, the page stops sending frames altogether, so nothing runs and nothing is used up, and it picks up again when you come back. For calls, use the extension, which keeps going in the background as measured above.

What didn't we test?

We ran Chromium on a Mac without a visible screen, driven by a script, and our call was a test page using the same browser camera and WebRTC tools Meet and Discord use, not those apps themselves. The swap server was a stand-in that replayed our GPU's real output, so this measures what Chrome and the extension do, not GPU speed; about 20 updates a second was this machine's limit with the stand-in. We didn't test a window fully covered by another window (Chrome can treat that as hidden too, which 2.4.1 handles the same way), Meet's own picture-in-picture, Windows, or ChromeOS.