BYAML File Format

AL / LP > Binary YAML

These files are similar to regular YAML files, but are encoded in binary form. They usually have the file extension .byml or .byaml.

Header

Offset	Size	Description
0x0	2	Magic number / BOM (BY: big endian, YB: little endian)
0x2	2	Version number

Version 1:

Offset	Size	Description
0x4	4	Offset to dictionary key table
0x8	4	Offset to string table
0xC	4	Offset to binary data table
0x10	4	Offset to root node (array or dictionary)

Version 2:

Offset	Size	Description
0x4	4	Offset to dictionary key table
0x8	4	Offset to string table
0xC	4	Offset to root node (array or dictionary)

Changelog

Version	Changes
v1	Initial file format
v2	- Unsigned integers were added (0xD3) - Binary data was removed (0xA1). Binary data is stored as a string instead (0xA0).
v3	64-bit values were added (0xD4 - 0xD6).

Node Types

ID	Type	Version
0xA0	String	Any
0xA1	Binary data	1
0xC0	Array	Any
0xC1	Dictionary	Any
0xD0	Bool	Any
0xD1	Integer	Any
0xD2	Float	Any
0xD3	Unsigned integer	2+
0xD4	Integer (64 bits)	3+
0xD5	Unsigned integer (64 bits)	3+
0xD6	Double	3+

The following node types may not be used in an array or dictionary. They are only used by the header.

ID	Type	Version
0xC2	String table	Any
0xC3	Binary table	Any

Arrays and dictionaries reserve 32 bits per element. Because not all node types fit into 32 bits, they are stored as follows:

Type	Value
0xA0	An index into the string table (see header).
0xA1	An index into the binary data table (see header).
0xC0 and 0xC1	An absolute offset to the node.
0xD0 - 0xD3	Simply the value.
0xD4 - 0xD6	An absolute offset to the value.

Array

If the number of elements is not a multiple of 4, additional null bytes are inserted between the type table and the data table such that the data table is aligned to 4 bytes.

Offset	Size	Description
0x0	1	Node type (0xC0)
0x1	3	Number of elements (N)
0x4	N	Type table
	4 x N	Data table

The type table contains one byte per element that indicates its node type.

The data table contains either an absolute offset to the node (for container nodes), or simply the value of the array element (for primitive nodes).

Dictionary

A dictionary contains key / value pairs. The pairs must be sorted by their keys, because a binary search algorithm is used to look them up.

Offset	Size	Description
0x0	1	Node type (0xC1)
0x1	3	Number of pairs (N)
0x4	8 x N	Pair table

Every pair is stored as follows:

Offset	Size	Description
0x0	3	Index into dictionary key table (see header)
0x3	1	Node type
0x4	4	Value

Just like array elements, the value is either a primitive or an absolute offset to a container node.

String Table

Offset	Size	Description
0x0	1	Node type (0xC2)
0x1	3	Number of strings (N)
0x4	4 x (N + 1)	Address table
		Null-terminated strings

The address table contains offsets to the strings, relative to the start of the string table node. It also contains an offset that points to the end of the string table (right behind the last string).

The address table and strings must both be sorted, because a binary search algorithm is used to find them.

Binary Table

Offset	Size	Description
0x0	1	Node type (0xC3)
0x1	3	Number of binary blobs (N)
0x4	4 x (N + 1)	Address table
		Binary data

The address table contains offsets to the binary data, relative to the start of the binary table node. It also contains an offset that points to the end of the binary table (right behind the last binary blob).

The address table must be sorted, because the size of a binary blob is calculated from the difference between two offsets.