Although I bumped the old request, I have created a new one because that open ticket is 14 years old...
I am requesting a filter for ecm data. This data is poorly compressible by most methods, but can be wiped and reconstructed in a lossless fashion.
Someone has kindly already built a plugin that encodes the input file as an ecm file - but this would be much better implemented as a filter.
Link to the plugin version: http://ajax16384.narod.ru./
Lastly, here is a github fork where you can see the algorithm in code:
https://github.com/alucryd/ecm-tools/blob/master/ecm.c
Please and thank you!
Iso7z plugin has RawSplitter codec. It uses the same principle.