Thank you wgk.derdicke and DWreck1995 for sharing your experience. It seems all more complex than I supposed. If you lose part of the Dolby Vision, I'm no longer interested.
I always make a copy of my original films. I keep the original disc and to watch it I use the copy (many are cartoons and if you have children .....). My intention was to replace the disk copy with a copy on hard disk and play it from my NAS. Perhaps the best solution remains the copy on another disk.
By the way, DVDFab offers two options to copy one is "full disk" and the other "clone"
What are the differences between them?
masterlogic
You can keep Dolby Vision with the MP4 container but the audio has to be re-encoded. That is the compromise. For the Dolby Vision movies you own, you could just clone to another disc. For all the others, you can just do one of the passthrough methods I mentioned in my previous reply or play from ISO. Unless you're cool with just making physical copies of all your movies.
To add from what wgk.derdicke said, the "Full Disc" mode is generally used to compress the movie to fit onto smaller discs. It maintains all features of the movies, just like the original, but allows it you to have a smaller output. This is useful if you want to save money on discs or have limited storage. Technically, you could select the same output as the source to. But that defeats the purpose unless you plan to alter the settings. wgkderdicke is also right about the audio data having to be altered for Cinavia removal.
The "Clone/Burn" mode, as wgk.derdicke pointed out, just gives you an exact 1:1 ISO or a cloned disc. You cannot compress or alter the settings (other than decryption) like you can in "Full Disc" mode. This is the best option for maintaining the original quality.
