ciso is a simple commandline utility to compress PSP iso files.
This package is a (currently incomplete) port of a package provided by Ubuntu: http://packages.ubuntu.com/natty/ciso
To decompress a cso file:
ciso 0 infile.cso outfile.iso
To compress an iso file:
ciso level infile.iso outfile.cso
where level ranges from 1 (fast, poor compression) to 9 (slow, high compression).
Do Not Trust Your Data To This
While it appears that iso -> cso -> iso roundtrips are lossless, the generated cso is broken and existing csos that I have are not recognized by the executable.
Given the compilation warnings I get I am assuming it's buggy due to differences between Linux and MacOS libraries.