ASB

ASB (Animation Sequence Binary) is a file format used to store animation sequences for actors in recent Nintendo EPD games such as The Legend of Zelda: Tears of the Kingdom and Nintendo Switch Sports. This article is primarily aimed at the version that appears in Tears of the Kingdom (v0x0417). ASB files can be found in the AS folder of the romfs as well as the AS folder of certain pack files.

File Structure

ASB is a little endian format which consists of node pathways triggered by AS commands. When an AS command is called, it runs the sequence of nodes connected to it which trigger and control animations and animation logic. Nodes are arranged in an array and referenced and accessed by their array index.

All string offsets in the file are relative to the start of the string pool and name hashes are 32-bit murmur3 hashes. There are six possible parameter types: string, int (32-bit signed integer), float (32-bit floating point number), bool, vector3f, and pointer (object pointer).

Section Order

1. File Header (0x6C bytes in version 0x417, 0x68 bytes in version 0x40F)
2. AS Commands
3. Nodes
4. Event Entries Offsets
5. Node Bodies
6. 0x38 Section Indices
7. 0x38 Section
8. 0x2C Section
9. Events
10. Transitions (possibly the wrong description)
11. Command Groups
12. Local Blackboard Parameters
13. 0x34 Section (possibly animation slots)
14. Bone Groups
15. 0x40 Section
16. Tag List
17. Expression Binary
18. String Triplets
19. Tag Groups
20. 0x68 Section
21. 0x28 Section
22. String Pool

Sections

File Header

Offset	Size	Type	Description
0x00	0x04	char[4]	Magic - "ASB "
0x04	0x04	u32	Version (0x0417 in Tears of the Kingdom, 0x040F in Nintendo Switch Sports and Splatoon 3)
0x08	0x04	u32	Filename Offset
0x0C	0x04	u32	AS Command Count
0x10	0x04	u32	Node Count
0x14	0x04	u32	Event Count
0x18	0x04	u32	0x34 Section Entry Count
0x1C	0x04	u32	0x38 Section Entry Count
0x20	0x04	u32	Local Blackboard Parameters Offset
0x24	0x04	u32	String Pool Offset
0x28	0x04	u32	0x28 Section Offset
0x2C	0x04	u32	0x2C Section Offset
0x30	0x04	u32	Event Entries Offset Array Offset
0x34	0x04	u32	0x34 Section Offset
0x38	0x04	u32	0x38 Section Offset
0x3C	0x04	u32	0x38 Section Indices Array Offset
0x40	0x04	u32	0x40 Section Offset
0x44	0x04	u32	0x40 Section Entry Count
0x48	0x04	u32	Bone Groups Offset
0x4C	0x04	u32	Bone Group Count
0x50	0x04	u32	String Pool Size
0x54	0x04	u32	Transitions Offset
0x58	0x04	u32	Tag List Offset
0x5C	0x04	u32	String Triplets Offset
0x60	0x04	u32	EXB Offset (empty if section does not exist)
0x64	0x04	u32	Command Groups Offset (empty if section does not exist)
0x68	0x04	u32	0x68 Section Offset (version 0x417 only)