Aces Replay Converter

Convert Minecraft 1.21.1 ReplayMod recordings into Flashback replays from inside the game, with support for recorded Simple Voice Chat data.

Report a problem

Open a bug report.

Include your converter version, Flashback version, mod loader, recording Minecraft version, and relevant log or crash report. For modded recordings, tell us whether the recording was made with the same modpack version used for playback.

Requirements

• Minecraft 1.21.1, Java 21+.
• Fabric Loader 0.18.4+, Fabric API.
• Flashback by Moulberry, installed separately from Modrinth. Tested with Flashback 0.39.10; supported range: 0.39.5–0.39.10.
• Simple Voice Chat for supported recorded voice playback.

For NeoForge, Sinytra Connector is required. This mod is a Fabric JAR and has been used successfully on NeoForge through Connector.

Use

1. Install the converter alongside Flashback and its dependencies.
2. Open Flashback's replay selection screen.
3. Click Convert from replay mcpr.
4. Select a Minecraft 1.21.1 .mcpr recording and confirm conversion.
5. Open the converted .zip replay in Flashback.
   
   

Compatibility

Version 1.0.0 is based on the working 0.1.4-dev build and targets native protocol 767 recordings. Conversion from other Minecraft versions is not supported by this Aces release.

Recordings from older modpack versions can fail during playback because mod packet formats and registry mappings differ. Conversion success alone does not guarantee playback compatibility. This release does not restore omitted NeoForge registry snapshots automatically.

Only audio present in the source recording can be converted.

The conversion code is identical to 0.1.4-dev. That build passed Java 21 JVM and ASM verification, converted a 257,694-packet test recording, and was reported working during playback.

This is designed for our modpack, therefore updates are unlikly unless needed,
other version support is not currently planned

Credits and source status

Based on Flashback Converter by Byzantonia, with the Aces native 1.21.1 fixes maintained by AcesGamingUK.

The local patch sources are repair and verification utilities, not a complete standalone Gradle source tree. The linked Byzantonia repository is the upstream project; it does not contain the Aces-specific release changes.

The distributed mod is GPL-3.0-only, with upstream credits and third-party notices retained. See the bundled license and notice files.