I've finished my documentation and program for the NPA file format used in Nitro+/Nitro+CHiRAL games since late 2006. I know crass can already extract the archives but it can only do that and it's without docs. My tool allows you to extract and create NPA archives. Currently Django and Lamento Trial are not working because the formats are slightly different but I plan to support them later.
download (bin):
http://www.mediafire.com/?28loj4xpo3dggpd
download (src):
http://www.mediafire.com/?t4fz2piq52ng50a
docs:
http://www.tsukuru.info/nipa/npadoc.html
Code:
usage:
General
-h - Help. Displays this information.
Extraction
-x (file) - Extract NPA archive
-g (id) - Game ID for encryption (if applicable). Defaults to ChaosHead if no encryption is entered
Creation
-c (folder) (output file) - Create archive
-z - Compress files
Examples
-x nss.npa - Extract nss.npa into the folder "nss"
-xg nss.npa MuramasaTr - Extract nss.npa into the folder "nss" using the Muramasa Trial encryption
-c nss nss.npa - Create an archive out of the folder "nss"
-cz nss nss.npa - Create a compressed archive out of the folder "nss"
(Type -h in the program to see the list of game IDs to use for decryption/encryption.)
DO NOT compress a CG folder. There is little change in size by doing so and it messes up the engine. This is a problem with the engine and Nitro+ doesn't compress their CG files because of it.
Please report any bugs. I'm also not a technical writer so let me know if there's something unclear in my documentation.
If you are having troubles with locales, try Tsukiko's modified version:
https://github.com/Wilhansen/nipa/downloads