Is there any official .cso compressor?

[LunaMoo]

@Livy there are many tools for cso, but most of them use pretty limited, old and potentially buggy cso commandline tool. If you want a good program which handles it natively use Leecherman's Ciso Multi Compressor it's very simple, but has a batch conversion, you can choose different output folder, supports iso's above 2gb and multithreading which makes it really fast, nothing more of such tool is really needed. Also Leecherman is pretty known in the scene and his tools are very reliable.

Just an extra note - PPSSPP does not handle ripped iso's converted to cso's too well, so I don't recommed ripping with programs like umd gen at all.