BFSAR (File Format)
A BFSAR file is an archive containing sound effects. In NSMBU, it also contains all music streams, but I don't think this is the case for MK8.
See the RHCafe page for much more detailed documentation of the file format.
I found this information by reverse engineering NSMBU and analyzing the bfsar files of NSMBU, SM3DW and Splatoon. I think the same applies to MK8, but since I don't have MK8's files, I can't assure this.
|0x04||2||UInt16||Endianness. 0xFEFF is big endian, 0xFFFE is little endian|
|0x06||2||UInt16||Header size. Always 0x0040.|
|0x0C||4||UInt32||File size of the entire file.|
|0x10||2||UInt16||Section count. Always 3.|
|0x14||3 × 12||SectionInfo||Section info. 3 structures describing the offsets to and sizes of the bfsar sections.|
|0x38||8||?||Unknown, possibly alignment. Always 0.|
|0||2||UInt16||Identifier. Specifies which section it describes. 0x2000 is the STRG section, 0x2001 is INFO and 0x2002 is FILE.|
This section contains a string table and data about the string.
|0x00||4||ASCII identifier ("STRG")|
|0x08||4||Unknown. Always 0x24000000|
|0x0C||4||String table offset, relative to field 0x08 of the STRG section.|
|0x10||4||Unknown. Always 0x24010000|
|0x14||4||Offset to lookup table, relative to field 0x08 of the STRG section.|
The string table contains structures that point to null terminated strings. All offsets are relative to the start of the string table. It starts with a string count and then contains:
|0||4||Unknown. Always 0x1F010000.|
|4||4||Offset to null terminated string.|
|8||4||Size of null terminated string.|
This table is used to get the string table index and other data for a string. It starts with 8 bytes of data:
|0x00||4||Index of the table entry where it starts.|
|0x04||4||Unknown. Seems to be some kind of index too. Must be higher than the other index.|
|0x18||4||Count of audio names.|
And is then followed by 0x14 byte structures:
|0x00||2||Endpoint. 0 if this is an entry that links to another list entry. 1 if the string has been found and the entry contains data about it.|
|0x02||2||String bit. This bit in the string that's being searched for decides with which entry the search should continue.|
|0x04||4||This is the table index of the next entry if the string bit is 0.|
|0x08||4||This is the index of the next entry if the string bit is 1.|
|0x0C||4||String table index if this structure is an endpoint.|
|0x10||1||Data about the file. 1 if it's an audio file (SE/WSD/STRM), 2 if it's a WSDSET or SEQSET, 3 is a BANK, 4=PLAYER and 6=GROUP.|
All offsets in this header are relative to the start of the INFO section + 8.
|0x04||4||Size of INFO section.|
|0x08||4||Unknown. Always 0x21000000|
|0x0C||4||Audio list offset (SE/WSD/STRM)|
|0x10||4||Unknown. Always 0x21040000|
|0x14||4||Audio set list offset (WSDSET/SEQSET)|
|0x18||4||Unknown. Always 0x21010000|
|0x1C||4||Bank list offset|
|0x20||4||Unknown. Always 0x21030000|
|0x28||4||Unknown. Always 0x21050000|
|0x2C||4||Group list offset|
|0x30||4||Unknown. Always 0x21020000|
|0x34||4||Player list offset|
|0x38||4||Unknown. Always 0x21060000|
|0x40||4||Unknown. Always 0x220B0000|
Each list starts with the amount of list entries and is then followed by these structures:
FILE contains all of the audio data in the BFSAR.
|0x04||4||Size of FILE section.|
There isn't a whole lot else to document about the FILE partition, since the data in it will most definitely vary depending on the game.
There are multiple FILE partitions, but only 1 of them is the 'main' FILE partition (it's the one you get from the BFSAR header). The 'main' FILE partition contains all of the other sub FILE partitions.