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Fixed mix-up of N' and N in description of file
AST files contain PCM16 (16-bit signed) sound data. They're used in Super Mario Galaxy for musics, and possibly in other games.
AST files contain PCM16 (16-bit signed) sound data. They're used in Super Mario Galaxy for musics, Legend of Zelda: Twilight Princess, and possibly in other games.
They contain an header followed by a BLCK chunk.<br>
They contain a header, followed by BLCK chunks which are divided in blocks (channels).<br>
All the data in those files are big-endian, except where mentioned.<br>
All the data in those files are big-endian, except where mentioned.<br>
All the offsets are absolute (from begining of file), except where mentioned.<br>
All the offsets are absolute (from beginning of the file), except where mentioned.<br>
All the sizes are in bytes, except where mentioned.<br>
All the sizes are in bytes, except where mentioned.<br>
| 0x0004
| 0x0004
| 4
| 4
| Size of the BLCK chunk
| Size of all the BLCK chunks (size of the file minus 64)
|-
|-
| 0x0008
| 0x0008
|-
|-
| 0x000C
| 0x000C
| 4
| 2
| Unknown
| Number of channels (typically 2 = stereo)
|-
| 0x000E
| 2
| Unknown (0xFFFF)
|-
|-
| 0x0010
| 0x0010
| 4
| 4
| Sampling rate in Hz (typically 0x7D00 = 32000 Hz)
| Sampling rate in Hz (typically 32000)
|-
|-
| 0x0014
| 0x0014
| 4
| 4
| Unknown
| Total number of samples
|-
|-
| 0x0018
| 0x0018
| 4
| 4
| Loopstart position in samples, from beginning of BLCK chunk
| Loopstart position in samples/bytes?
|-
|-
| 0x001C
| 0x001C
| 0x0020
| 0x0020
| 4
| 4
| Block size? (typically 0x2760)
| Block size for the first chunk? (typically 0x2760)
|-
|-
| 0x0024
| 0x0024
| 28
| 28
| Unknown
| Unknown (Usually all zeros except 0x0028, which is 0x7F)
|}
|}
=== BLCK chunk ===
=== BLCK chunks ===
The BLCK chunk directly follows the AST header. It contains a 32-byte header, followed by the PCM16 sound data.<br>
The BLCK chunks directly follow the AST header. They contain a 32-byte header, followed by PCM16 sound data.<br>
Here's a description of it:
Here's a description of them:
{| class="wikitable"
{| class="wikitable"
| 0x0004
| 0x0004
| 4
| 4
| Block size? (typically 0x2760)
| Block size (typically 0x2760)
|-
|-
| 0x0008
| 0x0008
| 0x0020
| 0x0020
| variable
| variable
| PCM16 data
| PCM16 data blocks
|}
The data is divided into blocks. There's one block per channel.<br>
The length of each block is defined by entry 0x0004 in BLCK chunk header.<br>
WARNING: The PCM16 data is stored in BIG-ENDIAN! If you aren't working on the Wii, don't forget to byteswap each sample you read or your sound will be pure junk!<br>
=== Block mapping inside BLCK chunks ===
{| class="wikitable"
|-
! Number of channels
! Type
! Block mapping
|-
| 2
| Stereo
| Left; Right
|-
| 4
| 4.0 Surround
| Left; Right; Surround left; Surround right
|}
Stereo is the most common type. Some music in SMG, such as the beach theme, are 4.0 Surround, though.
=== AST file structure ===
{| class="wikitable"
|-
! Element
! Size
|-
| AST header
| 64 bytes
|-
| BLCK chunk header
| 32 bytes
|-
| PCM16 block 1
| N
|-
| PCM16 block 2
| N
|-
| ...
|
|-
| PCM16 block N'
| N
|-
| BLCK chunk header
| 32 bytes
|-
| PCM16 block 1
| N
|-
| PCM16 block 2
| N
|-
| ...
|
|-
| PCM16 block N'
| N
|-
| BLCK chunk header
| 32 bytes
|-
| ...
|
|}
|}
Where:<br>
- N' is the number of channels (entry 0x000C in AST header)<br>
- N is the block size (entry 0x0004 in BLCK chunk header)<br>
[[Category:File formats]]