Converting VOB Files To Other Formats

iMac (2.7 GHz Intel Core i5) running OSX 10.9.5

I have some home movies on old DVD's that were burned from even older VHS tapes. I'd like to convert them to something I can edit in iMovie. The videos appear to be VOB files averaging 800 MB each. The output file can be any decent quality video format. I've looked in the app store but can't find anything. I suspect this is because of copyright infringement issues but, again, these are personal home movies. I'd appreciate any suggestions. Thank you.