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 and Mario vs Donkey Kong (v0x0417). Other ASB versions include 0x304 (Ring Fit Adventure), 0x3FB (Labo Toy-Con 04 and Game Builder Garage), 0x407 (Animal Crossing: New Horizons), 0x40F (Nintendo Switch Sports), 0x410 (Splatoon 3), 0x418 (Super Mario Bros. Wonder), and 0x41A (Nintendo Switch Online: Playtest Program). 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. Despite the presence of animation events in ASB files, these events do not appear to be used by the game.

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, this is not actually possible in ASB, only usable in AINB).

Documentation is still sparse, refer to this repository for more details (names may not match exactly).

Section Order

Version 0x417

1. File Header (0x6C bytes in version 0x417, 0x68 bytes in version 0x40F)
2. AS Commands
3. Nodes
4. Event Entry Offsets
5. Node Bodies
6. Sync Data Entry Indices
7. Sync Data
8. State Transitions
9. Events (in games that use BAEV, these events are non-functional)
10. Transitions
11. Command Groups
12. AS Blackboard Parameters
13. Partials
14. Bone Groups
15. Calculation Result Cache
16. Valid Tag List
17. Tag Groups
18. Expression Binary
19. AS Markings
20. Material Blend Settings
21. Enum Resolve Table
22. String Pool

Structures

Helpers

AsbString

Represents a u32 offset relative to the start of the file's string pool.

AsbPtr <T>

Represents a u32 absolute offset from the start of the file to the struct of type "T" enclosed by <>.

AsbArray <T>

Represents a u32 absolute offset from the start of the file to:

Offset	Size	Type	Description
0x0	0x4	u32	Count
0x4		T[Count]	Array of struct of type T. Note; asb files only use 32-bit aligned types.

File Header

File Header (0x417)

Offset	Size	Type	Description
0x00	0x04	char[4]	Magic - "ASB "
0x04	0x04	u32	Version (0x0417 in Tears of the Kingdom)
0x08	0x04	u32	Filename Offset
0x0C	0x04	u32	AS Command Count
0x10	0x04	u32	Node Count
0x14	0x04	u32	Event Count
0x18	0x04	u32	Partial Count
0x1C	0x04	u32	Sync Data Entry Count
0x20	0x04	u32	AS Blackboard Parameters Offset
0x24	0x04	u32	String Pool Offset
0x28	0x04	u32	Enum Resolve Table Offset
0x2C	0x04	u32	State Transitions Offset
0x30	0x04	u32	Event Entries Offset Array Offset
0x34	0x04	u32	Partials Offset
0x38	0x04	u32	Sync Data Offset
0x3C	0x04	u32	Sync Data Indices Array Offset
0x40	0x04	u32	Calculation Result Cache Offset
0x44	0x04	u32	Calculation Result Cache 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	Expression Offset (empty if section does not exist)
0x64	0x04	u32	Command Groups Offset (empty if section does not exist)
0x68	0x04	u32	Material Blend Settings Offset (version 0x417 only)

File Header (0x41b)

Offset	Size	Type	Description
0x0	0x4	u32	Magic - "ASB "
0x4	0x4	u32	Version - (0x41b in Nintendo Switch Online: Playtest version 021)
0x8	0x4	AsbString	Name Offset
0xc	0x4	u32	Command Count
0x10	0x4	AsbPtr<Command[Command Count]>	Command Array
0x14	0x4	u32	Element Count
0x18	0x4	AsbPtr<Element[Element Count]>	Element Array
0x1c	0x4	u32	Event Count - The pointer and count are erroneously present, but the section is not actually written in applications that support the baev file format.
0x20	0x4	AsbPtr<Event[Event Count]>	Event Array
0x24	0x4	u32	Parts Count
0x28	0x4	AsbPtr<Parts>	Parts Region - Pointer to start of parts region.
0x2c	0x4	AsbPtr<u32[Parts Count]>	Parts Index Array - Array of indices to parts
0x30	0x4	AsbPtr<Blackboard>	Blackboard
0x34	0x4	AsbPtr<char>	String Pool
0x38	0x4	u32	Float Property Ex Count
0x3c	0x4	AsbPtr<Float Property Ex[Float Property Ex Count]>	Float Property Ex Array
0x40	0x4	u32	Bone Blend Count
0x44	0x4	AsbPtr<Bone Blend[Bone Blend Count]>	Bone Blend Array
0x48	0x4	u32	Partial Skeleton Count
0x4c	0x4	AsbPtr<Partial Skeleton[Partial Skeleton Count]>	Partial Skeleton Array
0x50	0x4	u32	String Pool Size
0x54	0x4	AsbPtr<Transition Array>	Transition Array
0x58	0x4	AsbPtr<AsbArray<u32>>	Transition Partial Skeleton Array
0x5c	0x4	AsbPtr<AsbArray<AsbString>>	Tag Array
0x60	0x4	AsbPtr<AsbArray<External Action>>	External Action Array
0x64	0x4	AsbPtr<AsbArray<Exb>>	Exb
0x68	0x4	u32	Transition Group Array
0x6c	0x4	AsbPtr<AsbArray<Material Blend>>	Material Blend Array

Property<T>

Property types include s32 (can be an enum), bool(32-bit), float, AsbString, and Vector3f.

Property<T>

Offset	Size	Type	Description
0x00	0x04	u32	Flags and Index
0x04	0x04 or 0x0C	T	Value

If the top bit of the flags is set, then the bottom two bytes of the flags become an index value. If it is not set, then the provided value is value of the parameter. If flags & 1 << 0x18 != 0, then the index is an expression index (EXB) and the normal value field becomes the input value for the expression. If flags & 1 << 0x1e != 0, then the index is a calculation result cache index (this stores the previously evaluated value and calculates the new value from the cached value on subsequent accesses). Note, this is only applicable if the parameter is a float. Otherwise, if flags & 1 << 0x19 != 0, then the index specifies the command data type. 0 is the current frame normalized (i.e. (current_frame - start_frame)/total_duration), 1 and 2 are random float values between 0.0 and 1.0, 3 is an unknown string value, 4 is the command's fade in frame, and 6 is an unknown float value. Note, this only applies if the parameter is a float or a string. In all other cases, the index is a blackboard index and value of the parameter is the value of the corresponding blackboard parameter. For float parameters specifically, flags >> 0x1a & 3 specifies the exact parameter source. 0 is a float blackboard parameter while 1, 2, or 3 are a vector3f blackboard parameter with 1, 2, and 3 being the x, y, and z components respectively.

Command

Defines a command that can be played by an as::Controller. The command is composed of a behavior tree of elements.

Command (0x417)

Offset	Size	Type	Description
0x00	0x04	u32	Name Offset
0x04	0x04	u32	Tag Entry Offset (version 0x417+)
0x08	0x08	Property<float>
0x10	0x08	Property<bool>	Is Ignore Same Command
0x18	0x04	u32	Interpolation Type (uncertain, but 0 = unspecified, 1 = no model morph, 3 = enable local bone morph, 4 = enable inertial blend)
0x1C	0x10	u32	GUID
		u16
		u16
		u8[2]
		u8[6]
0x2C	0x02	u16	Child Node Index
0x2E	0x02	u16

Command (0x41b)

Offset	Size	Type	Description
0x00	0x4	AsbString	Name
0x04	0x4	AsbPtr<AsbArray<AsbString>>	Tag Array
0x08	0x8	Property<float>	Frame Count
0x10	0x4	u32	Debug flag for host io?
0x14	0x8	Property<InterpolationType>	Default Interpolation Type
0x1c	0x10	Guid	Guid
0x2c	0x2	u16	Element Id
0x2e	0x2	u16

Interpolation Type

Enum for (known) interpolation types.

Interpolation Type

Name	Value	Description
Default	0
None	1
Cross Fade	2
Local Bone	3
Inertia Local Bone	4
Parts	5

Element

Element (0x417)

Offset	Size	Type	Description
0x00	0x02	AsbNodeType	Node Type
0x02	0x01	u8	Sync Data Count
0x03	0x01	u8	Does Not Have State Transition
0x04	0x04	u32	Tag Entry Offset
0x08	0x04	u32	Node Body Offset
0x0C	0x02	u16	Calculation Result Cache Index
0x0E	0x02	u16	Calculation Result Cache Count
0x10	0x02	u16	Sync Data Index Array Index
0x12	0x02	u16	AS Markings Index (-1 for index)
0x14	0x10	u32	GUID
		u16
		u16
		u8[2]
		u8[6]

Element (0x41b)

Offset	Size	Type	Description
0x0	0x2	u16	Element Type
0x2	0x1	u8	Parts Count
0x3	0x1	u8	Is No State End
0x4	0x4	AsbPtr<AsbArray<AsbString>>	Tag Array
0x8	0x4	AsbPtr<ElementParam<Element Type>>	Element Param
0xc	0x2	u16	Float Property Ex Flags
0xe	0x2	u16	Float Property Ex Count
0x10	0x2	u16	Base Parts Index Id
0x12	0x2	u16	External Action Id
0x14	0x10	Guid

Element Type

Enum of element types.

Element Type

Value (Hex)	Value (Dec)	Node Type
0x01	1	FloatSelector
0x02	2	StringSelector
0x03	3	SkeletalAnimation
0x04	4	State
0x05	5	StateEnd
0x06	6	OneDimensionalBlender
0x07	7	Sequential
0x08	8	IntSelector
0x09	9	Simultaneous
0x0A	10	Event
0x0B	11	MaterialAnimation
0x0C	12	FrameController
0x0D	13	DummyAnimation
0x0E	14	RandomSelector
0x0F	15	StateEnd
0x10	16	PreviousTagSelector
0x11	17	BonePositionSelector
0x12	18	BoneVisibilityAnimation
0x13	19	InitialFrame
0x14	20	BoneBlender
0x15	21	BoolSelector
0x16	22	Alert
0x17	23	SubtractAnimation
0x18	24	ShapeAnimation
0x19	25
0x1a	26	TwoDimensionalBlender
0x1b	27

ElementPlugs

The plug struct provides relative offsets to "plug" data.

ElementPlugs (0x41b)

Offset	Size	Type	Description
0x0	0x1	u8	State Count
0x1	0x1	u8	State Base Index
0x2	0x1	u8	Unknown Count
0x3	0x1	u8	Unknown Base Index
0x4	0x1	u8	Child Count
0x5	0x1	u8	Child Base Index
0x6	0x1	u8	Exb Count
0x7	0x1	u8	Exb Base Index
0x8	0x1	u8	Event Count
0x9	0x1	u8	Event Base Index
0xa	0x1	u8	Frame Controller Count
0xb	0x1	u8	Frame Controller Base Index
0xc	0x4 * Frame Controller Base Index + Frame Controller Count	u32[]	Plug Data Offset Array - Offsets relative to start of plug table

Child Plug

Only known are listed.

Default

Offset	Size	Type	Description
0x0	0x4	u32	Child Element Id

FloatSelector, OneDimensionalBlender, BonePositionSelector Elements

Offset	Size	Type	Description
0x0	0x8	Property<float>	Min
0x8	0x8	Property<float>	Max
0x10	0x4	u32	Child Element Id

StringSelector Element

Offset	Size	Type	Description
0x0	0x8	Property<AsbString>	Value
0x8	0x4	u32	Child Element Id

IntSelector Element

Offset	Size	Type	Description
0x0	0x8	Property<s32>	Value
0x8	0x4	u32	Child Element Id

RandomSelector Element

Offset	Size	Type	Description
0x0	0x8	Property<float>	Value
0x8	0x4	u32	Child Element Id

PreviousTagSelector Element

Offset	Size	Type	Description
0x0	0x8	AsbPtr<AsbArray<AsbString>>	Tag Array
0x8	0x4	u32	Child Element Id

Event Plug

Offset	Size	Type	Description
0x0	0x4	u32	Event Element Id

Frame Controller Plug

Offset	Size	Type	Description
0x0	0x4	u32	Frame Controller Element Id

ElementParam<Element Type>

FloatSelector Element

Offset	Size	Type	Description
0x0	0x8	Property<float>	Select Value
0x8	0x8	Property<bool>	Is Slot Sync
0x10	0x4	u32
0x14	0xc + N	ElementPlugs	Plugs

StringSelector Element

Offset	Size	Type	Description
0x0	0x8	Property<float>	Select Value
0x8	0x8	Property<bool>	Is Slot Sync
0x10	0x4	u32
0x14	0xc + N	ElementPlugs	Plugs

SkeletalAnimation Element

Offset	Size	Type	Description
0x0	0x8	Property<AsbString>	Animation Name
0x8	0x4	u32
0xc	0x4	u32
0x10	0x8	Property<bool>	Is Offset Frame
0x18	0x8	Property<float>	Frame Offset
0x20	0xc + N	ElementPlugs	Plugs

State Element

Offset	Size	Type	Description
0x0	0xc + N	ElementPlugs	Plugs

OneDimensionalBlender Element

Offset	Size	Type	Description
0x0	0x8	Property<float>	Selector weight
0x8	0x4	u32	Easing Type (1 = ease)
0xc	0xc + N	ElementPlugs	Plugs

Sequential Element

Offset	Size	Type	Description
0x0	0x8	Property<bool>
0x8	0x8	Property<s32>
0x10	0x8	Property<bool>
0x18	0xc + N	ElementPlugs	Plugs

IntSelector Element

Offset	Size	Type	Description
0x0	0x8	Property<s32>	Select Value
0x8	0x8	Property<bool>	Is Slot Sync
0x10	0x4	u32
0x14	0xc + N	ElementPlugs	Plugs

Simultaneous Element

Offset	Size	Type	Description
0x0	0x4	u32	State End Type (0 = no children, 1 = first child state end)
0x8	0xc + N	ElementPlugs	Plugs

Event Element

Offset	Size	Type	Description
0x0	0x4	u32
0x8	0xc + N	ElementPlugs	Plugs

MaterialAnimation Element

Offset	Size	Type	Description
0x0	0x4	u32	Material Blend Id
0x4	0x8	Property<AsbString>	Animation Name
0xc	0x8	Property<bool>
0x14	0xc + N	ElementPlugs	Plugs

FrameController Element

Offset	Size	Type	Description
0x0	0x8	Property<float>	Play Rate
0x8	0x8	Property<float>	Loop Start
0x10	0x8	Property<float>	Loop End
0x18	0x4	u32
0x1c	0x8	Property<bool>	Is Kill Loop
0x24	0x8	Property<bool>
0x2c	0x8	Property<s32>	Frame Count
0x34	0x8	Property<s32>	Random Range
0x3c	0x8	Property<bool>	Is Local Random
0x44	0x8	Property<float>	Frame Offset
0x4c	0x8	Property<float>	Current Frame
0x54	0x8	Property<float>
0x5c	0x4	u32
0x60	0x8	Property<float>
0x68	0x8	Property<bool>
0x70	0x8	Property<bool>	Is Retarget Play Rate
0x78	0xc + N	ElementPlugs	Plugs

DummyAnimation Element

Offset	Size	Type	Description
0x0	0x8	Property<float>	Frame Count
0x8	0x8	Property<bool>	Is Looping
0x10	0xc + N	ElementPlugs	Plugs

RandomSelector Element

Offset	Size	Type	Description
0x0	0x4	u32	Judge Timing
0x4	0x8	Property<bool>	Is Slot Sync
0xc	0x8	Property<s32>
0x14	0x8	Property<>	Unknown
0x1c	0x4	u32
0x20	0xc + N	ElementPlugs	Plugs

PreviousTagSelector Element

Offset	Size	Type	Description
0x0	0x4	u32
0x4	0xc + N	ElementPlugs	Plugs

BonePositionSelector Element

Offset	Size	Type	Description
0x0	0x8	Property<AsbString>	Left Bone Name
0x8	0x8	Property<AsbString>	Right Bone Name
0xc	0x4	u32	Component Id - (0 = X, 1 = Y, 2 = Z) component to generate bone position difference from
0x10	0x4	u32	Judge Timing
0x14	0x8	Property<bool>	Is Slot Sync
0x1c	0xc + N	ElementPlugs	Plugs

BoneVisibilityAnimation Element

Offset	Size	Type	Description
0x0	0x8	Property<AsbString>	Animation Name
0x8	0x8	Property<bool>
0x10	0x8	Property<bool>	Is Offset Frame
0x18	0x8	Property<float>	Frame Offset
0x20	0xc + N	ElementPlugs	Plugs

InitialFrame Element

Offset	Size	Type	Description
0x0	0x4	u32	Initial Frame Type
0x4	0x4	AsbPtr<AsbArray<AsbString>>	Tag Array
0x8	0x8	Property<bool>	Is Share By Same Anim key
0x10	0x8	Property<AsbString>	Left Bone Name
0x18	0x8	Property<AsbString>	Right Bone Name
0x20	0x4	u32	Component Id
0x24	0x8	Property<bool>	Is Random
0x2c	0x8	Property<bool>	Is Fixed Random
0x34	0xc + N	ElementPlugs	Plugs

Initial Frame Type

Name
Start
FrameOffset
InvFrameOffset
Random
BonePosition
End
Frame
InvFrame
SlotSync

BoneBlender Element

Offset	Size	Type	Description
0x0	0x8	Property<AsbString>	Bone Blend Name
0x8	0x4	u32	Sync Child Id
0xc	0x8	Property<float>	Bone Blend Mode Value
0x14	0x4	u32	Bone Blend Mode
0x18	0x4	u32	State End Mode (0 = all, 1 = child 0, 2 = child 1)
0x1c	0xc + N	ElementPlugs	Plugs

BoolSelector Element

Offset	Size	Type	Description
0x0	0x8	Property<bool>	Select Value
0x8	0x8	Property<bool>	Is Slot Sync
0x10	0x4	u32
0x14	0xc + N	ElementPlugs	Plugs

Alert

Offset	Size	Type	Description
0x0	0x8	Property<AsbString>	Alert
0x8	0xc + N	ElementPlugs	Plugs

SubtractAnimation Element

Offset	Size	Type	Description
0x0	0xc + N	ElementPlugs	Plugs

ShapeAnimation Element

Offset	Size	Type	Description
0x0	0x8	Property<AsbString>	Animation Name
0x8	0xc + N	ElementPlugs	Plugs

TwoDimensionalBlender Element

Offset	Size	Type	Description
0x0	0x8	Property<float>
0x8	0x8	Property<float>
0x10	0x4	u32	Offset to key frame array relative to 0x10 of this struct?
0x14	0x4	u32	Offset to key data array relative to 0x10 of this struct?
0x18	0xc + N	ElementPlugs	Plugs