BRSTM file
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BRSTM files contain ADPCM sound data. They are used for music in some games, such as Super Smash Bros. Brawl and Mario Kart Wii.
They contain a header, followed by a HEAD chunk, an ADPC chunk and a DATA chunk.
All the data in those files are big-endian, except where mentioned.
All the offsets are absolute (from begining of file), except where mentioned.
All the sizes are in bytes, except where mentioned.
BRSTM header
The header is 64 bytes long.
| Offset | Size | Description |
|---|---|---|
| 0x0000 | 4 | "RSTM" (0x5253544D) |
| 0x0004 | 2 | Byte Order Mark (BOM), usually 0xFE 0xFF for big endian. |
| 0x0006 | 1 | Major version |
| 0x0007 | 1 | Minor version |
| 0x0008 | 4 | Size of the whole file |
| 0x000C | 2 | Header size |
| 0x000E | 2 | Number of chunks |
| 0x0010 | 4 | Offset to HEAD chunk |
| 0x0014 | 4 | Size of HEAD chunk |
| 0x0018 | 4 | Offset to ADPC chunk |
| 0x001C | 4 | Size of ADPC chunk |
| 0x0020 | 4 | Offset to DATA chunk |
| 0x0024 | 4 | Size of DATA chunk |
| 0x0028 | 24 | Unknown/Padding (zero) |
HEAD chunk
The HEAD chunk contains information about the brstm file, including sample rate, loop information, volume, panning, and information on each of the ADPCM streams.
This chunk contains 3 internal parts.
Part 1 contains general information about the file such as loop information, sample rate, and data needed to deinterleave the audio stream.
Part 2 defines the tracks in the file, and contains volume and panning information for each of them.
Part 3 contains the information needed to decode the ADPCM audio, including the ADPCM coefficients, and history samples.
Any internal offsets in the HEAD chunk are based off of byte 8 in the header. e.g. Offset 0x40 would refer to offset 0x48 in the overall header.
HEAD chunk header
| Offset | Size | Description |
|---|---|---|
| 0x0000 | 4 | "HEAD" (0x48454144) |
| 0x0004 | 4 | Length of entire HEAD section. |
| 0x0008 | 4 | Marker? (0x01000000) |
| 0x000C | 4 | Offset to HEAD chunk part 1 |
| 0x0010 | 4 | Marker? (0x01000000) |
| 0x0014 | 4 | Offset to HEAD chunk part 2 |
| 0x0018 | 4 | Marker? (0x01000000) |
| 0x001C | 4 | Offset to HEAD chunk part 3 |
ADPC chunk
The ADPC chunk is typically 1216 bytes long. It seems to contain some other ADPCM table.
DATA chunk
The DATA chunk contains ADPCM sound data.