Picture-in-picture

Every app can keep the call in a small window on top of other apps. Each platform has its own API for it, and they differ a lot in what they allow.

Screenshot to add

Chrome on a desktop with another tab or app in front, and the call's floating picture-in-picture window on top: the other person's video, your small tile and the mic, camera and hang up buttons.

File: docs/public/media/pip-web.png

Platform	API	What the window shows
Web (Chrome, Edge)	Document Picture-in-Picture	A mini call: remote video, your tile, mic, camera and hang up
Web (other browsers)	Video picture-in-picture	The remote video only
Android	Activity picture-in-picture	The remote video
iOS	AVPictureInPictureController, video call PiP	The remote video (1:1 calls only)
macOS	An always-on-top NSPanel	Remote video, your tile, controls on hover
Windows	CompactOverlay window	Remote video with mute, camera, back and leave

In a group call the window shows the active speaker, else the first person with a camera.

Web

usePictureInPicture.ts uses the Document Picture-in-Picture API where it exists (Chromium desktop) and falls back to video picture-in-picture.

• documentPictureInPicture.requestWindow() opens an always-on-top window. The page's stylesheets are copied into it, and PipView.vue is rendered there through <Teleport>. Its animations are CSS only, because the tab that owns the Vue app is hidden and its requestAnimationFrame doesn't run.
• While a peer is connected, the page registers the enterpictureinpicture Media Session action. Chrome 134 and later then opens the window by itself when you switch to another tab, like Google Meet. Switching to another app doesn't, the button (or P) does.
• Other browsers put the remote <video> itself into picture-in-picture (requestPictureInPicture(), or webkitSetPresentationMode('picture-in-picture') on iOS Safari).

Android

CallActivity declares supportsPictureInPicture and handles size changes itself, so entering and leaving the window never recreates it.

• Once a peer is connected, setAutoEnterEnabled(true) on Android 12+ moves the call into the window on the home gesture. Older versions do the same from onUserLeaveHint.
• The window's aspect ratio follows the remote frame, clamped to the 1:2.39 to 2.39:1 range the system accepts.
• In the window only the remote video is shown. The local tile is hidden rather than removed, so it keeps its corner.
• Closing the window ends the call, since nothing keeps the camera and microphone alive in the background.

iOS

The call uses video call PiP: an AVPictureInPictureController with an activeVideoCallSourceView content source and an AVPictureInPictureVideoCallViewController (PictureInPicture.swift).

• The system window can't show the Metal video view, so a second sink on the remote track feeds an AVSampleBufferDisplayLayer. Hardware-decoded frames go in as they are. Software-decoded I420 frames, which is what VP8 produces, are copied into pooled NV12 pixel buffers.
• canStartPictureInPictureAutomaticallyFromInline is on while a peer is connected, so leaving the app opens the window.
• The camera session turns on isMultitaskingCameraAccessEnabled where it is supported, so the other person keeps seeing you while the call is in PiP.

macOS

The Mac has no system PiP for calls, so FloatingCallWindow.swift is an NSPanel at floating level that joins all Spaces. It shows the remote video with a mini self view and hover controls, and opens by itself when you minimize the call window.

Windows

The window switches to the CompactOverlay presenter: a small always-on-top window with the remote video and mute, camera, back and leave buttons. In a group call it closes by itself when the last person leaves.