Difference between revisions of "AST file"
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| − | WARNING: The PCM16 data is stored in BIG-ENDIAN! Don't forget to byteswap each sample you read or your sound will be pure junk! | + | WARNING: The PCM16 data is stored in BIG-ENDIAN! Don't forget to byteswap each sample you read or your sound will be pure junk!<br> |
Note: there's sound data for one channel only. Stereo mixing is performed by the Wii's DSP. | Note: there's sound data for one channel only. Stereo mixing is performed by the Wii's DSP. | ||
Revision as of 20:01, 23 September 2009
AST files contain PCM16 (16-bit signed) sound data. They're used in Super Mario Galaxy for musics, and possibly in other games.
They contain an header followed by a BLCK 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.
AST header
The header is 64 bytes long. Here's a description of it:
| Offset | Size | Description |
|---|---|---|
| 0x0000 | 4 | "STRM" (0x5354524D) |
| 0x0004 | 4 | Size of the BLCK chunk |
| 0x0008 | 4 | Unknown (0x00010010) |
| 0x000C | 4 | Unknown |
| 0x0010 | 4 | Sampling rate in Hz (typically 0x7D00 = 32000 Hz) |
| 0x0014 | 4 | Unknown |
| 0x0018 | 4 | Loopstart position in samples, from beginning of BLCK chunk |
| 0x001C | 4 | Unknown (typically same as entry 0x0014) |
| 0x0020 | 4 | Block size? (typically 0x2760) |
| 0x0024 | 28 | Unknown |
BLCK chunk
The BLCK chunk directly follows the AST header. It contains a 32-byte header, followed by the PCM16 sound data.
Here's a description of it:
| Offset
(from beginning of BLCK chunk) |
Size | Description |
|---|---|---|
| 0x0000 | 4 | "BLCK" (0x424C434B) |
| 0x0004 | 4 | Block size? (typically 0x2760) |
| 0x0008 | 24 | Padding (zero) |
| 0x0020 | variable | PCM16 data |
WARNING: The PCM16 data is stored in BIG-ENDIAN! Don't forget to byteswap each sample you read or your sound will be pure junk!
Note: there's sound data for one channel only. Stereo mixing is performed by the Wii's DSP.