UDF conversion
I have several personal DVDs in UDF format and I want to convert them to, say, quicktime or movie, to make clips. How do I do that?
Do you mean that you have several DVD-Video home movie discs that you created with a DVD-Video authoring program? DVD-Video discs normally encode video using MPEG2 and store it in the [.VIDEO_TS] directory in the form of .VOB (Video Object) container files and other miscellaneous files.
The contents of commercial DVD-Video discs are usually encrypted, but if you're converting home videos, that won't be an issue.
https://en.wikipedia.org/wiki/DVD-Video
I think you can find software to do this conversion, but it may take a little searching. For instance, a Google search turned up this old Apple Community thread. It recommended using a tool called Handbrake to convert the data in the .VOBs into .MP4 format.
Best way to import homemade DVD to iMovie - Apple Community