MultiView — merge multi-player Flashback replays

MultiView is a Fabric add-on for Flashback. Each player records their own POV with Flashback; MultiView fuses those recordings into one unified replay that behaves as if a single omniscient observer had captured the whole session.

✅ Every chunk explored by any POV is included
✅ Every recording player is visible at the same time
✅ Every entity and event seen by at least one POV is kept
✅ Free camera or Spectate Player on the merged replay
✅ Tick-perfect time alignment, atomic rollback on failure

Who is this for?

Content creators — SMP recaps, PvP tournaments, machinima with multi-angle coverage from a single replay file.
Server staff — multi-angle review of incidents, anti-cheat investigations from every involved player's POV.
Cinematographers — free camera through a multiplayer scene with no information loss.

How to merge two replays

Each player records their POV with Flashback during the same session.
Drop the resulting .zip files into <gameDir>/flashback/replays/.
Launch Minecraft with Flashback + MultiView installed.
Click the camera icon → Select Replay.
Tick the checkbox to the right of each replay (minimum two).
Click Merge N Replays in the top-right corner.
The merged replay merged_<timestamp>.zip appears in the list once the progress screen finishes.

Compatibility

Minecraft	Flashback	MultiView
1.21.9 / 1.21.10	0.39.x	`0.3.2+mc1.21.9`
1.21.11	0.39.4	`0.3.2+mc1.21.11`
26.1 / 26.1.1 / 26.1.2	0.40.0	`0.5.x+mc26.1`

Requires Fabric API. Java 21 on 1.21.x, Java 25 on 26.1+.

Features

N-way merge — works from 2 up to many POVs.
Tick-perfect alignment via ClientboundSetTimePacket with metadata fallback.
Cross-source deduplication — chunks (SHA-256 128-bit content hash), player info, system chat by visible text, entity moves.
Multi-dimension — secondary POV dimension changes preserved as markers.
Aggregated markers from every POV on a single timeline.
Atomic write — .part file + atomic rename; a failed merge never destroys an existing replay.
Bounded memory — LRU-capped chat dedup, cryptographic chunk hashing, safe on multi-hour sessions.
i18n — French and English.

Known limitations

Secondary POVs appear as regular player entities (Flashback only supports one local player; the camera follows the first POV to start recording).
4+ POV merges may produce minor visual artefacts in zones where conflicting chunk versions overlap.
Full technical limitations and roadmap in SPEC.md.

License

MIT — free to use, modify and redistribute. Flashback remains under its proprietary license by Moulberry; MultiView is a fully independent add-on and does not redistribute any Flashback code.

Also available on Modrinth

MultiView - Flashback Addon