I m not talking about the encrypted version which is common to all games (emulated or not), but the decrypted version actually used by the Nintendo s official emulator.
I extracted the N64 roms from the Wii virtual console titles. While the versions detected aren t the right one (for example pal Zelda 1.2 is detected as version 1.1), they work without modifications on mupen64plus fz.
However, the same can t be said about the save game data extracted from the Wii s filesystem. While some game games like Mario kart or Mario 64 works without modifications, for most games like 1080 the imported saved data isn t loaded.
The reason is simple. The save game format used by Nintendo for their Nintendo 64 emulators is almost the standard single file based format with optional bytes used for additionnal descriptions (I couldn t figure their purpose). That means the format is so simple that in some cases the emulated game s savedata don t need those descriptions.
Adding support for the official Nintendo s emulator savegame format would just be the matter of detecting and removing those additionnal bytes as the remaining works like with other emulators.