Jsystem

What Jsystem is

Jsystem is a dev lib that nintendo used around the gc/wii era for devlopment before being replaced by NintendoWare toolkit later in the wiis life. and is not only used in pikmin 1 and 2 but is also used for games such as twilight princess and super mario sunshine.

Header

Offset	Type	Name	Description
0x00	char[4]	Subsystem Version	Some code for the JSYSTEM library that this file is used in, along with a version, like "J3D2" or "JPA2". Sometimes this is a generic code, like "MESG" for BMG files.
0x04	char[4]	File Type	The kind of file used by this subsystem, like "bmd1", "bmg1". Usually the same as the file extension of the file.
0x08	int	File Size	The total size of the file.
0x0C	int	Chunk Count	The number of "chunks" that follow.
0x10	char[4]	(Optional) Subversion	"SVRn" with some number might appear, or it might be 0xFF padding like below. It is ignored. It is hypothesized that this was a marker was used to track data migration during the development of the game.
0x14	char[12]	Padding	This was likely reserved space in case they wanted to expand the header later. It is ignored. Official files have it as 0xFF padding.

Chunk Data

Offset	Type	Name	Description
0x00	char[4]	Chunk Type	A FourCC code describing the contents of the chunk. This is chunk-specific.
0x04	int	Size	The size of the chunk, including this header. In some cases, this has been known to be off slightly and run off the end of the file. It is used to locate the next chunk.

Each chunk is aligned to a 0x20 boundary, and the size is the aligned version. If the data does is not aligned to 0x20, then Nintendo's official tooling uses a custom string to fill the remaining chunk contents. The longest known version of this string is:

This is padding data to alignme

The rest of the data is file and chunk-specific. See the format's page for further information.

Name Tables

Name tables are pools of strings used by multiple different JSYSTEM files, under the class name JUTNameTab. They collect all strings used in a chunk or section so that multiple references to the same string can be referenced by an index into the name table. A name table is laid out like this:

Offset	Type	Name	Description
0x00	int	Name Count	The number of names in this Name Table.
0x04	JUTNameTabEntry[Count]	Entries	A variable-length set of entries.

Each entry consists of the following.

Offset	Type	Name	Description
0x00	short	Hash Code	A hash code of the string for fast lookup.
0x02	short	String Offset	An offset, relative to the start of the name table, containing the string contents followed by a NUL byte.

Known JSYSTEM libraries

JUtility

Utility toolkit with various bits and bobs. Contains JKernel, which are the core routines for doing I/O from disc, and memory management.

Extension	JSYSTEM Class Name	Description
szs	JKRDecomp	Yaz0 Compression
SZP	JKRDecomp	Yay0 Compression
ARC	JKRArchive	File Archive
BTI	JUTTexture	Binary Texture Image
BFN	JUTResFont	Binary Font

J3DGraph

J3DGraph is a 3D rendering library.

J3DGraphBase

Extension	JSYSTEM Class Name	Description
BMD	J3DModelData	Binary Model
BDL	J3DModelData	Binary Display List
BMT	J3DMaterialTable	Binary Material Table
BLS	J3DClusterLoader	Binary cLuSter (Alternate vertex cluster shapes)

J3DGraphAnimator

J3DGraphAnimator is a helper library that can animate various parts of J3D objects. Most animations come in two forms, "full", where each frame of an animation is serialized its entirety, and "key", where only key frames are serialized, and the runtime interpolates between key frames.

Extension	JSYSTEM Class Name	Description
BTK	J3DAnmTextureSRTKey	Texture SRT Animation (Key)
BCK	J3DAnmTransformKey	Joint Animation (Key)
BRK	J3DAnmTevRegKey	Texture Register Animation (Key)
BPK	J3DAnmColor	Color Animation (Key)
BTP	J3DAnmTexPattern	Texture Palette Animation (Full)
BCA	J3DAnmTransformFull	Joint Animation (Full)
BVA	J3DAnmVisibilityFull	Visibility Animation (Full)
BLA	J3DAnmClusterFull	Cluster Animation (Full)
BLK	J3DAnmClusterKey	Cluster Animation (Key)
???	J3DAnmColorFull	Color Animation (Full) (No Known Usages)
???	J3DAnmVtxColorFull	Vertex Color Animation (Full) (No Known Usages)
???	J3DAnmVtxColorKey	Vertex Color Animation (Key) (No Known Usages)

J2DGraph

J2DGraph is a 2D rendering and UI library.

Extension	JSYSTEM Class Name	Description
BLO		Binary Layout
BMG		Binary Message
BMC		Binary Message Color (?)

JParticle

JParticle is a particle and effects system.

Extension	JSYSTEM Class Name	Description
JPC	JPAEmitterArchiveLoaderDataBase	JParticle Archive
JPA	JPAEmitterLoaderDataBase	Particle

JAudio

JAudio is a music and audio system, which encompasses audio and music playback.

Extension	JSYSTEM Class Name	Description
AAF		Audio Archive File
BAA		Binary Audio Archive
BMS		Binary Music Sequence
AW		Wave Archive

Maybe also BAS (Binary Animation Sound)

JStudio

JStudio is a cutscene recording & playback library able to sequence and play back prerecorded animations for multiple actors, objects, lights.

Extension	JSYSTEM Class Name	Description
STB	JStudio::TParse	JStudio Binary

JMap

JMap is a helper library for serializing map layouts. It has been seen in Luigi's Mansion and Super Mario Galaxy 1 and 2.

Extension	JSYSTEM Class Name	Description
BCSV	JMapInfo	Binary CSV, a miscellaneous serialization format.

Credits: GameCubing8619,cloudmodding