Just a couple of notes of what worked for me to transform a DVD I bought (incidentally zone 1) where I thought it was a zone 2. So I had to transform it in order to be able to see it on my non free-zone player.
First I used the excellent ffmpeg to transform the VOB video files from NTSC format into PAL format:
mkdir AUDIO_TS VIDEO_TS
for i in /media/dvd/VIDEO_TS/*.VOB; do j=`basename $i`; rm -f $j; ffmpeg -i $i -sameq -target pal-dvd $j; done
I created 3 chapters, one per original set of VOB files (corresponding to the movie, the trailer, and the making of). Then in each of those titles, I added each of the VOB files concerned. For each, I entered in the advanced options submenu, and went to the last Misc tab (Divers for me). And each time I checked the 2 first boxes (File already MPEG-PS and recombine sound and video without re-encofing).
After that I asked Devede to create for me an ISO image I tested and then I burnt with k3B. And voilà !
There are probably multiple other ways to achieve the same result. I still need to fix a language issue as only the movie had a french track so I have no sound for the trailer and the making of. Should have forced the english one + subtitltes but that’s for the next time😉