Sequences (.bfseq, .bcseq)

Sequences play notes from a particular bank. This can be used for sound effects, level music, or anything else.

The Main File

The main file consists of a standard File Header, a Data Block, and a Label block. Each block is padded to be 0x20 bytes. The file data is the same for each version, with the standard being 1.0.0.

Type	Description
FileHeader	Standard File Header (Magic: FSEQ or CSEQ. Always contains 2 blocks)
Block	Data Block (Reference Type: 0x5000)
Block	Label Block (Reference Type: 0x5001)

Data Block Body (Magic: DATA)

Contains only raw sequence data. See the Sequence Data Specification for details. Padded to 0x20 bytes. It’s important to note that the sequence data is always big endian for the Wii U and 3ds, but little endian for the Switch.

Offset	Type	Description
0x00	u8[Block size - 8]	Raw sequence data
—-	—	Padding for alignment

Label Block Body (Magic: LABL)

Contains labels to jump to in the sequence data.

Offset	Type	Description
0x00	Table<Reference>	References to each Label (Reference Type: 0x5100)
0x04 + 8 * Table Count	Label[Table Count]	Labels referenced earlier
—-	—	Padding for alignment

Label

Contains the label name and offset to data in the sequence data. Think of a label as an entrypoint in the data, like a door. Each label is padded to 0x4 bytes.

Offset	Type	Description
0x00	Reference	Reference to start in raw sequence data (Reference Type: 0x1F00)
0x08	u32	Size of the label name
0x0C	char[Size of label name]	The name of the label. There is still a null terminator after this for whatever reason
—-	—	Padding for alignment

Summary

A tree to sum up the structure of the file:

SEQ File:
|-File Header
|
|-Data Block
|    |-Raw sequence data.
|
|-Label Block
|    |-Reference table to labels.
|        |-Label with reference to data entrypoint, and name.
|
|-Files