Why a Nemi meeting stops at ten people

Most video calls you have been on went through a server. Your camera went up to it once, and it sent a copy to everybody else. Nemi Meet does not have one. When you join a call, your browser opens its own encrypted connection to every other person in it, and sends your camera down each of them.

That decision explains most of what Meet is. It is why a meeting needs nothing but the browser you already have open. It is why there is no server of ours that can see or hear what is said. And it is why there is a number on the pricing page that no plan, not even Business, can raise past ten.

What is a WebRTC mesh?

In a mesh, every pair of people has its own connection. Two people need one. Three need three. Ten need forty five, because each of the ten connects to the nine others and every connection is shared by two people: ten times nine, halved. The number of connections grows with the square of the room.

What matters to your laptop is the other number: how many copies of your own camera you are encoding and uploading. In a mesh it is everybody but you. Try it.

Why does video quality drop as more people join?

If every stream stayed at the quality of a two person call, the upload would climb in a straight line. At 1.4 Mbps per copy, a ten person call would ask every laptop for 12.6 Mbps of upload, every second, for the length of the meeting. Plenty of home connections cannot do that, and a phone on a weak mobile signal often cannot either.

So the camera steps down as people arrive: 1.4 Mbps for two, 800 kbps up to four, 500 kbps up to six and 300 kbps beyond that. The resolution the camera is asked for depends on how full the room is when you turn it on: 720p for two, 540p up to six, 360p beyond. That second part is the one people do not expect. Asking a camera for 720p and then starving it of bitrate gives you a soft, smeared picture; asking for 360p at the same bitrate gives you a sharp small one, and with eight faces on screen every tile is small anyway.

Mesh vs SFU: why is a call limited to ten people?

At ten people the ladder lands at 2.7 Mbps of upload for video. That is something an ordinary connection carries, and nine simultaneous encodes is something an ordinary laptop survives. Past ten the curve keeps going, and the only remaining lever is to make everybody's picture worse still.

The limit is not a price. It is the point where the honest fix is a different architecture.

That fix exists. It is called a selective forwarding unit: a server every browser uploads to once, which forwards the streams on. It is how large calls work everywhere. It is also a server in the middle of your meeting, which sees who is sending what to whom, and which we would have to run, secure and pay for per minute of everybody's call. For the calls Meet is built for, a team, a client, a family, ten is the right side of that trade. So the plans fit three, five, eight or ten people, and MEET_MESH_MAX clamps every one of them at ten, whatever a plan says.

Four lanes, fixed forever

The mesh has a second rule that nobody sees and everything depends on. Every connection in a Nemi call is built with exactly four media lanes, always in the same order: microphone, camera, screen, and the screen's own sound. Both sides create all four before anybody sends anything.

Turning anything on or off is therefore a track swap on a lane that already exists, never a renegotiation of the connection. That matters more than it sounds. A lane associates with the first unclaimed lane of its kind on the other side, in the order they were created, so if one browser added a lane the other did not expect, the receiver would play a screen share through somebody's face tile. Fixing the order fixes that for good.

Is a peer to peer video call private?

Every WebRTC connection is encrypted between the two browsers. In a mesh there is no box in the middle holding a key, so nobody at Nemi can watch or listen to a meeting, and there is no setting that would let us. On networks that refuse direct connections, usually corporate ones, the encrypted stream is passed along by a relay we operate. It forwards packets it cannot read and keeps nothing. The privacy policy says exactly this. What a meeting does leave behind is listed there too: the chat, who joined and when, and the whiteboard and meeting notes, which are ordinary documents that belong to the host, saved the way every Nemi document saves, and stored encrypted at rest.

So the mesh is a trade we made on purpose. You get a meeting with no middle, and you get a ceiling. We think that is the right trade for the meetings most people actually have, and the slider above is the whole argument. What each plan fits is on the Meet page, and the help centre shows how to start a meeting and send the link.