BRSTM (File Format)

Overview

A BRSTM (Binary Revolution STreaM) is the music format used by Mario Kart Wii and other games such as Super Smash Bros. Brawl.

File Header

Offset	Type	Description
0x00	String	File magic. RSTM in ASCII.
0x04	UInt16	Byte order mark (BOM): The value is always 0xFEFF. If value 0xFFFE is read, then the false endian is used. Mario Kart Wii uses nearly always big endian (bytes 0xFE,0xFF).
0x06	UInt16	Version. Always 0x0100.
0x08	UInt32	File size.
0x0c	UInt16	Header size. Always 0x40.
0x0e	UInt16	Section count. (Excluding HEAD).
0x10	UInt32	Offset to HEAD section.
0x14	UInt32	Size of HEAD section.
0x18	UInt32	Offset to ADPC section.
0x1c	UInt32	Size of ADPC section.
0x20	UInt32	Offset to DATA section.
0x24	UInt32	Size of DATA section.

HEAD

Offsets are relative to 0x08 of this header.

Offset	Type	Description
0x00	String	Section magic. Always HEAD in ASCII.
0x04	UInt32	Size of the section.
0x08	DataRef	Reference to Stream Data Info.
0x10	DataRef	Reference to Track Table.
0x18	DataRef	Reference to Channel Table.

Stream Data Info

Offset	Type	Description
0x00	Byte	Format. Enum Description 0x0 PCM8 0x1 PCM16 0x2 ADPCM
0x01	Byte	Loop Flag
0x02	Byte	Number of channels
0x03	UInt24	Sample rate.
0x06	UInt16	Offset to block header? Always 0.
0x08	UInt32	Loop start sample.
0x0C	UInt32	Loop end sample.
0x10	UInt32	Actual data offset.
0x14	UInt32	Block count.
0x18	UInt32	Block size.
0x1C	UInt32	Block samples.
0x20	UInt32	Final block size.
0x24	UInt32	Final block samples.
0x28	UInt32	Final block size with padding.
0x2C	UInt32	The interval (sample count) for writing data to the ADPC block.
0x30	UInt32	Size per channel for each interval where data is written to the ADPC.

Track Table

Offset	Type	Description
0x00	Byte	N = Track count.
0x01	Byte	Track Info type. (0 = Simple, 1 = Extended).
0x02	Byte[2]	Padding.
0x04	DataRef[N]	Reference to Track Info. Data type needs to match Track Info type.

Track Info (Simple)

With "simple" track info Track Volume is set to 127.

Offset	Type	Description
0x00	Byte	N = Channel count.
0x01	Byte[N]	Channel index info.

Track Info (Extended)

Offset	Type	Description
0x00	Byte	Track volume (0-127).
0x01	Byte	Pan (0-127).
0x02	Byte[2]	Padding.
0x04	UInt32	Reserved.
0x08	Byte	N = Channel count.
0x09	Byte[N]	Channel index info.

Channel Table

Offset	Type	Description
0x00	Byte	N = Channel count.
0x01	Byte[3]	Padding.
0x04	DataRef[N]	References to another DataRef referencing ADPCM Parameters Set. Value of 0 is second DataRef means no data.

ADPCM Parameters Set

This data is only available if ADPCM encoding is used.

Offset	Type	Description
0x00	UInt16[16]	Coefficients.
0x2C	UInt16	Gain.
0x2E	UInt16	Predictor + Scale.
0x30	UInt16	YN1. (Sample - 1).
0x32	UInt16	YN2. (Sample - 2).
0x34	UInt16	Loop Predictor + Scale.
0x36	UInt16	Loop YN1. (Sample - 1).
0x38	UInt16	Loop YN2. (Sample - 2).

ADPC

This section is only available if ADPCM encoding is used.
The ADPC chunk contains 2 PCM history samples per channel for every entry in the table. (UInt16)
The number of samples per entry is specified in the HEAD section.
Each entry in the table contains the final two samples from the preceding block.

Offset	Type	Description
0x00	String	Section magic. ADPC in ASCII.
0x04	UInt32	Size of the section.

DATA

The DATA section contains the ADPCM data, the sounds the file makes.

Offset	Type	Description
0x00	String	Section magic. DATA in ASCII.
0x04	UInt16	Size of the section.
0x08	UInt32	Offset to actual data.

Data needs to be 0x20 aligned and it's splitted in blocks.
Data stored with channel alternating every block unlike WAV format, where channels alternate every sample.
(Channel 0 Block 0 -> Channel 1 Block 0 -> Channel 0 Block 1 -> ...)

Data Reference

The Data Reference structure is used to point to other data types.

Offset	Type	Description
0x00	Byte	Reference type. (0 = Address, 1 = Offset).
0x01	Byte	Data type.
0x02	UInt16	Reserved.
0x04	UInt32	Value.