Seeing the speaker

A receiver must see the speaker.

This is the single point where visibility and audibility are not independent, and it does not originate in Mumble Server Runtime.

A protocol constraint

Before buffering a voice frame, the Mumble client looks up the sender’s session in the model it holds. A frame whose sender is unknown is discarded.

An audio edge landing on a receiver who cannot see the sender would therefore deliver nothing. It is not a policy question but a fact about the client, and declaring such an edge is silence with extra steps.

A corollary worth stating: there is no separate right to speak. Speaking somewhere implies being visible there.

Checked on the render’s output

The condition is verified when a render is finished, against what each connection can see. A render declaring an edge that violates it is refused whole, and the previous view stays in place.

Visibility here means either route: through the shared view, when the sender’s scope is comparable to one the receiver observes, or through that receiver’s own overlay. Someone placed by an overlay counts as being there.

Two orderings carry the rule at runtime

The rule holds on the render’s output, but a transition takes time to reach a client, so two orderings keep it true in between.

The routing table is published before any view. Revocation therefore takes effect immediately, which is always safe: cutting a route early costs a lost packet, never a leak.

A granted route stays inert until the receiver has been told. Each speaker in the table carries the version at which it became visible, and a receiver whose position in the history has not reached that version is given nothing. The gate is one comparison on the voice path, with no shard involved.

Control and voice share one queue per connection. The message introducing a speaker is therefore written before that speaker’s tunnelled audio, rather than racing it.

Text inherits the same rule

A recipient who cannot see the speaker is skipped when a message is relayed. A text message naming a session the recipient does not hold would break the same client-side assumption that audio breaks, so the constraint is not specific to voice.