sts format

`sts` format

This is not official documentation. This is a reverse-engineered documentation of the sts format used in the Muse Sounds library. The original documentation is not available.

Muse Drumline uses a new format which haven’t been decrypted. It seems that the new format stores its TOC in the corresponding spx file, and the sts file only contains encrypted data. I haven’t found a way to decrypt the new format yet.

Structure

The file has three parts:

+--------+-------+--------+
| Header |  TOC  |  Data  |
+--------+-------+--------+

All numbers mentioned below are little-endian encoded.

A fixed 24-byte binary string. In hex:

14 00 00 00 53 41 61 66 66 50 61 64 20 53 61 6D
70 6C 65 20 46 69 6C 65

My understanding of the string:

An int32 number showing that the string after this number is 0x14 (18) bytes long
The human-readable text (StaffPad Sample File)

TOC (Table of contents)

This part is concatenated from a number of units. Before the units, there is a int32 number showing how many units are there.

The structure of each unit looks like this:

An int32 number showing the length of the file name.
File name, without a delimiter
An int64 number showing the begin byte of the file (inclusive) in this sts file
An int64 number showing the end byte of the file (exclusive) in this sts file

Example extracted from Piano.sts (hex):

1C 00 00 00 53 74 65 69 6E 77 61 79 5F 4D 69 78
65 64 5F 66 5F 75 70 5F 41 23 30 2E 6F 70 75 73
40 74 00 00 00 00 00 00 85 9D 05 00 00 00 00 00

Data

All files concatenated without a delimiter

Example extractor (Python)

#!/bin/python3
# sts-extractor.py
# Muse Sounds sts extractor
# See https://github.com/CarlGao4/Muse-Sounds

import pathlib
import struct
import sys

if len(sys.argv) != 2:
    print("Muse Sounds sts extractor", file=sys.stderr)
    print("Usage: sts-extractor.py [sts file]")
    sys.exit(1)

sts = pathlib.Path(sys.argv[1])
out_folder = sts.resolve().parent
f = open(sts, mode="rb")
assert f.read(24) == b"\x14\x00\x00\x00StaffPad Sample File"
last_len = 0
for _ in range(struct.unpack("<i", f.read(4))[0]):
    name_len = struct.unpack("<i", f.read(4))[0]
    name = f.read(name_len).decode()
    print(name, end="", file=sys.stderr)
    print(" " * max(0, last_len - len(name)), end="\r", file=sys.stderr)
    last_len = len(name)
    out = out_folder / name
    out.parent.mkdir(parents=True, exist_ok=True)
    begin, end = struct.unpack("<qq", f.read(16))
    back = f.tell()
    f.seek(begin)
    out.write_bytes(f.read(end - begin))
    f.seek(back)
f.close()

Example script to archive

See create-sts.py for an example script to archive files into sts format.

sts format