Sources

BDMV/ISO

Both of these formats contain the raw contents of a Blu-Ray disk. During remuxing this content is changed into a format that is more portable, and usable by platforms like jellyfin or plex

Retrieving Content

Numerous private trackers and indexers provide raw rips of disk

Personal Rips

Personal rips can be processed as well.

However some functionality depends on the naming of the file. So it's important that your rips have proper names.