AosTools
Commandline toolset for extracting and repacking .aos archives.
Creation year: 2023
Programming language: C#
Project
AosTools is a commandline tool for extracting and repacking .aos archives used by various visual novel producers with their in-house engine. This tool makes modding and translation of the game files possible.
This project made me delve deep into binary data and different methods of storing binary data. I also got to research different compression and encryption methods while figuring out how the different file formats were structured.
Part of the research also covered how the engine itself behaved so I got good amount of hours into assembly and scrolling through vast amounts of binary data.
For better or worse this project made me learn the .bmp file format inside out…
Key features
- Reading and writing archive files
- Script file compression and decompression using huffman coding algorithm
- Bitmap unpacking using run-length encoding (RLE)
- Custom animation format extraction
Formats the tool is able to extract or decode:
| Format | Description |
|---|---|
| .aos | Archive format used for storing files. |
| .scr | Huffman compressed text file used for storing scripts. |
| .bmp | Bitmap graphic. |
| .abm | Custom bitmap format that can be compressed or store multi frame animations. |
| .msk | Grayscale bitmap mask used for transitions and similar effects. |
| .ogg | Sound file. |
Repository
The public repository and release build was made during 2025 on my alt github.