How to Fix gpSP Crash & mGBA Audio Crackling in RetroArch — Pokémon Unbound

Running a heavy CFRU-based ROM hack like Pokémon Unbound v2.1.1.1 on RetroArch can cause issues if using low-accuracy cores like gpSP, or high latency configuration on mGBA.

1. Known Bug: Antisis Sewers Black Screen

The gpSP core relies on lightweight Dynamic Recompilation (Dynarec). Due to Unbound's complex dynamic memory mapping and custom VRAM allocations, entering the south side of Antisis Sewers triggers a silent freeze, locking players out. This issue is highly documented across communities.

On mGBA, while high accuracy avoids locks, low-power handhelds (like Miyoo Mini or RG35XX) face severe audio crackling and frame drops down to 45 FPS during complex menus or screen transitions.

2. The Core-Swapping Workaround (Antisis Sewers Fix)

If you are stuck on a gpSP black screen, follow this procedure to hot-swap cores without losing progress:

1. Create a native in-game physical save (SRAM save) right before entering the sewers. Do NOT rely on Save States (.state files).
2. Access your device's file manager or insert the SD card into a PC.
3. Navigate to the gpSP save directory (e.g., /Saves/CurrentProfile/saves/gpSP/) and copy your Pokemon Unbound.sav.
4. Paste it into the mGBA save directory (e.g., /Saves/CurrentProfile/saves/mGBA/) and rename its extension to .srm (e.g., Pokemon Unbound.srm).
5. Delete any existing mGBA save states (.state) for Unbound to prevent clock/RAM mismatches.
6. Open RetroArch, select mGBA as the core, load the game, play through the Antisis Sewers, make an in-game save, and transfer the save back to the gpSP folder (renaming it back to .sav) to return to optimal FPS on low-power devices.

3. Recommended RetroArch Performance Settings