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element-call-Github/docs/matrix_rtc_modes.md
Robin ede29bdf1b Remove MatrixRTC legacy mode
This is the mode in which we sent membership events with the 'oldest membership' transport selection algorithm, which stopped being the default back in version 0.21.0. Users will no longer be able to select this mode in developer settings, and admins will no longer be able to select legacy mode through the config either. The app will still continue to support *receiving* membership events with the 'oldest membership' transport selection algorithm from others, however.
2026-08-26 19:51:12 +02:00

2.0 KiB

MatrixRTC modes

Element Call is in the middle of a transition of how a call session is represented: from room state events (org.matrix.msc3401.call.member) to sticky events (MSC4354), which are a much better fit for the short lived, per-device nature of call memberships.

Not every homeserver supports sticky events yet. The two MatrixRTC modes controls whether Element Call uses them.

The modes

Mode Membership events SFU selection JWT endpoint
compatibility state events multi SFU legacy
matrix_2_0 sticky events multi SFU Matrix 2.0 (hashed identity)

compatibility — multi SFU, but still state events. Use it when the homeserver does not support sticky events. This is the default.

matrix_2_0 — the target state. Requires a homeserver that advertises MSC4354 and all clients on v0.17.0 or later. The local membership requests its token from the Matrix 2.0 JWT endpoint of the MatrixRTC Authorization Service and identifies the room by a hashed identity instead of a livekit_alias. (Remote memberships always try the new endpoint first and fall back to the legacy one, so remote participants can be on either.)

Selecting a mode

Users can choose a mode under Settings → Developer → MatrixRTC mode. The Matrix 2.0 option is disabled if the homeserver does not support sticky events.

A deployment can pin the mode for all its clients in config.json, which disables the Developer Settings choice:

{
  "matrix_rtc_mode": "compatibility"
}

Valid values are compatibility and matrix_2_0; an invalid value is ignored (with a warning) and the user's choice applies. Pinning matrix_2_0 on a homeserver without sticky event support makes joining fail with a "sticky events required" error.