Replays

Elodin records simulation telemetry, metadata, schematics, and visual assets in an Elodin DB directory. The editor can serve and open that directory directly, so replaying a recording does not require a separate elodin-db process.

Record a simulation

Set ELODIN_DB_PATH when running a simulation to keep its database:

ELODIN_DB_PATH=dbs/apollo ELODIN_NON_INTERACTIVE=1 elodin run examples/apollo-lander/main.py

The recording includes a db_state file, component data, and an assets/ tree. Keep the whole directory when copying or sharing it.

Open a recording

Pass the database directory to the editor:

elodin editor dbs/apollo

The editor starts an embedded database server, connects to it automatically, and stops the server when the editor closes. The default Impeller address is [::]:2240; assets use port 2241 and gRPC uses port 2242. Use --addr to select another base address:

elodin editor dbs/apollo --addr 127.0.0.1:3000

The database directory cannot also be open by another elodin-db or elodin process on the same ports.

To serve the recording without opening an editor, use:

elodin run dbs/apollo

Replay mode

Replay mode reveals recorded data progressively as the playback marker advances, simulating a live session:

elodin editor dbs/apollo --replay

Without --replay, the full recorded time range is available immediately.

Choose a schematic

By default, the editor opens the active schematic stored in the database. Override it with a local KDL file:

elodin editor dbs/apollo --replay --kdl schematics/review.kdl

For details about bundled GLB files, images, skyboxes, and schematics, see DB Asset Server.