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Calls of 4 to 8

Calls of 2 or 3 people go directly between Macs. From 4 people, a call goes through Cloudflare's Realtime SFU, a media server that forwards each person's audio and video. A call holds up to 8 people.

Why a media server

In a direct call, your Mac sends your audio and video to each person separately. With 4 or more people that's a lot of upload. Through the SFU, your Mac sends one copy, and the SFU forwards it to everyone else.

What changes in the call

The switch happens on its own when the fourth person joins. Each connection moves to the SFU once both sides are sending through it, so the audio doesn't drop or double while it switches. A call that has switched stays on the SFU until it ends, even if people leave.

If the SFU fails, the call goes back to direct connections for the rest of the call.

Not end-to-end

The SFU can decrypt what it forwards. Founder Hud marks these calls: a notice under the faces says "Not end-to-end with" and the names of the people you reach through the SFU. Point at it to read why.

Neither we nor Cloudflare record call media. See Encryption and your data.

What works differently

  • Screen sharing. The SFU sends two versions of a share, full size and half size. Everyone gets the same versions, so the quality picker on a share only shows on direct connections.
  • Transcripts. Transcript lines travel only on direct connections, never through a server. People you reach through the SFU don't get your lines. See Transcripts and notes.
  • Remote control. It travels only over a direct connection, never through a server. People you reach through the SFU can't control your Mac, and you can't control theirs. See Remote control.

Turn it off

Settings > Calls > Network > Use media servers for calls of 4 or more is on by default. Turn it off and your Mac stays connected directly to everyone, which uses more upload. The change applies from your next call.