View source for NKit/NKitFormat


The NKit Format is a non-lossy format for shrinking and restoring Wii and GameCube images. It supports clean / Redump images as well as scrubbed and hacked images. Some corrupt and bad images are supported too, although these quite often error.

There are 2 NKit output formats, raw (iso) and compressed (gcz). Both were designed with 1:1 preservation, size and playability in mind. Hardware support for Wii was sacrificed for smaller images. WBFS is currently the best available and Recoverable to Redump where not hacked or corrupt.

{| class="wikitable"
|-
! System !! Format !! Hardware Supported !! Dolphin Supported !! Restorable 1:1 !! Notes
|-
| GameCube || nkit.iso || Yes || Yes || Yes || Same as compacted GameCube iso
|-
| GameCube || nkit.gcz || No || Yes || Yes || GCZ is Dolphin's own block seekable compression format
|-
| Wii || nkit.iso || No (Dev Kit?) || Yes || Yes || RVT-H format only playable in Dolphin or a Dev Kit (Untested)
|-
| Wii || nkit.gcz || No || Yes || Yes || RVT-H in GCZ playable in Dolphin only
|}

NKit Format images contain the bare minimum of data. All junk and scrubbing is removed. Non-uniform data is preserved in 256 byte blocks with a 4 byte header. Wii encryption and hashes are fully recreatable and removed. Meaning any remaining data is as compressible possible.

== Header ==

NKit places its header at 0x200 in the Wii and GameCube disc headers.

{| class="wikitable"
|-
! Offset !! Length !! Name
|-
| 0x200 || 0x4 || NKit Header 'NKIT'
|-
| 0x204 || 0x4 || NKit Version ' v01'
|-
| 0x208 || 0x4 || Source image original CRC32
|-
| 0x20C || 0x4 || NKit CRC - makes the NKit file CRC32 equal the source CRC at 0x208 (at 0x4 in GCZ)
|-
| 0x210 || 0x4 || Source image length 
|-
| 0x214 || 0x4 || Forced Junk ID (When Disc ID differs - rare - GameCube only) 
|-
| 0x218 || 0x4 || Wii Update partition CRC32 if removed when converting
|}

NKit also modifies the Wii header to set the bytes at 0x60 and 0x61 to 0x1. This indicates to a Dev Kit and Dolphin that the encryption and hashes aren't present.

== GameCube ==

The disc header (Boot.bin) length is 0x440. It's modified as detailed above. The [[NKit/Discs#GameCube_Disc_.2F_Wii_Raw_Partition_Data|other items]] remain untouched.

The [[NKit/NKitFormat#FileSystem|filesystem]] and fst.bin are modified when converting to NKit.

== Wii ==

The disc header length is 0x50000. The partition tables are modified to point to new partition offsets.

==== Removed Update Partition ====
The update partition may have been removed in order to save space. In this case offset 0x218 in the disc header will be the CRC32 of the removed partition. The removed partition will have been backed up in the 'Redump' recovery folder or in the 'NkitExtracted' recovery folder if it's not a known partition.

The original partition table is backed up at 0x50000. The next partition (Data or Channel) is located at 0x58000

=== Partitions ===

<coming soon>

== FileSystem ==

Both the GameCube and Wii use the same code to encode the filesystem. The only real difference is that Wii FST file offsets and lengths  must be multiplied by 4 when mapping to files. The NKit Format uses a custom Run Length Encoding (RLE) to remove the gaps between files and shrink gaps to 4 bytes in most cases.

<te be added>