RKC (File Format)
RKC Files are files downloaded by Mario Kart Wii using the WC24 download engine. The RKC file contains data and a U8 file with a new KMP for the competition. The RKC file is part of the DISTMAP.BIN file, which is stored inside the wc24dl.vff file in the savegame.
The maximum file size for a RKC file in the unmodified game is 20480 bytes. It might be possible to change the maximum size by finding the call to malloc() which allocates the space for the RKC data in the game's memory.
The RKC files contain multiple headers, they are all explained here.
The RKCT header, or the main header, is 0x10 bytes long:
|0x00||String||File magic. Always RKCT in ASCII.|
|0x04||UInt32||Length of the data in bytes.|
|0x08||UInt32||Length of all file headers (offset to the beginning of the U8 file).|
|0x0C||UInt32||Unknown, always 0x640. Maybe a version number?|
The RKCO Header contains all information for the competition. Stuff like Course ID, CommonObj that gets loaded and other information. The header is 0x3C bytes long:
|0x00||String||Section magic. Always RKCO in ASCII.|
|0x07||Byte||Engine class. 0: 50cc, 1: 100cc, 2: 150cc, 3: battle.|
|0x08||Byte||Amount of laps (laps, so triggered with checkpoints, not scores).|
|0x0A||UInt16||Vehicle restriction. 0: karts only, 1: bikes only, 2: no restriction.|
|0x0C||UInt16||Camera angle. 3: normal camera, 7: camera from above.|
|0x0E||UInt16||Minimap object. Defines an object to be shown on the minimap.|
|0x10||UInt16||Always empty, but read by the game.|
|0x12||UInt16||Always empty, but read by the game.|
|0x14||UInt16|| Cannon flag. If a track has no cannon, this is set to 0. If a track has a cannon and its |
setting is 0xFFFF, it is set to 0, too. Otherwise, it is set to the value of the cannon setting.
|0x16||UInt16||Amount of CPU players.|
|0x18||Byte|| Driver and vehicle settings for CPU players. First byte driver, second byte vehicle. |
0xFF for random driver / vehicle or unused slots.
|0x2E||Byte||Controller. 0x00 for free choice, 0x01 for Wii-Wheel only.|
|0x30||UInt16||Common object files to load. Bit field for the different files.|
|0x32||UInt16||Score (amount of gates, amount of coins, etc).|
|0x34||Byte||Intro settings. Between 0x00 and 0x03, 0x00: no intro video.|
|0x36||UInt16|| Unknown, either 18000 (0x4650) for tracks with laps, or 36000 (0x8CA0) for tracks with a score. |
Not used by the game.
|0x3A||UInt16||This seems to be a checksum of the header.|
Here are the known game modes:
|0x00||Time Trial. No position tracker. 3 Mushrooms, multiple KTPT, MSPT.|
|0x01||VS Race. Position tracker, single KTPT (player last), CPUs, continuing racing after finish.|
|0x03||Many different objects.|
|0x05||Coins (, ).|
|0x0B||Battle. No Position tracker, single KTPT (player first), CPUs, MSPT.|
|0x0C||Battle. Position tracker, single KTPT (player first), CPUs, MSPT.|
In game mode 0x03, many different objects will give you a point when you destroy, hit or activate them. The objects are:
and probably some more.
There are a few more game modes (the ones which do not appear in the list of game modes above), but their meaning and usage is unknown.
This is the part of a RKC file that contains the actual data. It only contains a YAZ0 compressed U8 file with a KMP file and some object files which are neither in the course, the competition bases or in one of the CommonObj files.
This U8 file must contain the folders AIParam and ItemSlotTable, but both of them may be empty if you do not want to modify the AI settings or the items.
Replacing and ripping RKC files
NOTE: The data blocks which were previously known as "RSF Files" (this name was invented by khacker35000vr to name unknown data groups) are not part of the actual competition. If you extract the VFF file and not just open it in a hex editor, you can see that there is no data after the RKC file. The "trash data" (RSF) in the VFF file after the RKC data is just random data from the previous competition, because Nintendo just copies the new RKC file to the specific offset and does not clear the rest of the file. So, when a new competition is smaller than the old one, those trash bytes stay in the file, even though they are not needed.
- Search the RKC file in the VFF File.
- Copy and paste (overwrite old data) the data of your custom RKC file at the good offset
- If the new RKC file is larger than the older one this may not work. At the moment there is no tool to create larger VFF files.
- Use Riivolution along with the savegame xml when a competition is in progress, or copy your savegame to SD with tools like the Savegame Manager GX
- Extract the wc24dl.vff with "vffdump.py".
- Open the file "DISTMAP.BIN" in a hex editor and search for "RKCT"
- Check the size and copy that amount of bytes to a new file (RKC)
- Custom tournaments are able to be made, and can be added to Leseratte's competition system for Wiimmfi.
- All downloaded contents (competition and other players' ghost data) for Mario Kart Wii are saved in wc24dl.vff.
The following tools can handle RKC files:
A kaitai format description file can be found on this GitHub repository.