Sorry, I should've been more specific. FindVUK used to be able to dump the VUK for AACS 1.0 discs but I believe only UK were ever available for AACS 2.0 discs. The consistent availability of AACS 1.0 device keys has effectively mitigated the loss of dumped AACS 1.0 VUK.
MakeMKV requires the keydb.cfg file contain the VUK for the relevant title even though it would be sufficient for the keydb to contain only the UK(s). This is distinct from VLC and libaacs which will happily playback/decrypt content using only the UK.
My expectation here is that FindVUK would've grabbed the volume ID from the DVDFab product, derived the MK via publicly available AACS 1.0 DK, combined the two to get the VUK and decrypt the UK with the VUK to get a complete record. As the resulting keydb entry contained the VUK, you were able to produce a decrypted backup with MakeMKV.
Wow, thank you for this very thorough explanation !
If you created an encrypted backup with MakeMKV I would expect VLC to be able to play the backup using only the UK.
I am fairly sure I told MakeMKV to create a decrypted backup, also it was able to open the disc and offered me to make MKV files of it. Not to mention I can just mount the ISO file I made from the MakeMKV backup and access the M2TS video files with the file explorer, as well as copy them and convert them to mp4 with ffmpeg with no issues (I actually used this to copy the "menu movie" onto my iPhone, just for fun).
Which particular UHD title were you attempting to backup? It would be interesting to see which keys it had available at that point in time.
I will try to answer this to the best of my ability.
This UHD disc I own is from "Kaamelott-Deuxième volet (Partie 1) Édition épique limitée [DVD du film, Blu-Ray du film, Blu-Ray 4K du film, DVD Bonus, Making-of, Table Ronde, 22 cartes personnages et 4 visuels Collector] " (see Amazon, if you're curious.)
In the keydb, it should be listed as KAAMELOTT 2 PARTIE 1. I believed I received the package in my mailbox on the 28th of February at around 11:19 France time. IIRC, throughout the day, I attempted to get rid of the FindVUK warning messages for this disc by using FindVUK (1.82, I think) several times. I believe I used both DVDFab and Passkey for this.
I do not remember the keydb entry for this UHD disc even existing before I used FindVUK on my disc, although I could be misremembering things, I suppose.
(For the record, I don't know if this will help you, but I believe I am also the one who turned the Legacy entry for the *regular, non-UHD* disc of this movie into a Meta entry, with the same computer, with FindVUK 1.83. I did so very recently.)
The *last* time I attempted to sync the keydb with the unit keys from this disc was, I believe, on the 28th of February at around 18:48 France time, and my full (and likely decrypted) backup was ready at 20:49:34 on the same day (still the 28th of February).
This means I likely started creating the backup near 19:49, since it takes my drive approximately an hour to make a backup of a ~91 GiB UHD disc.
(EDIT 2 : Ah, now I remember that I re-downloaded KEYDB.cfg straight from the website right before doing the backup, I believe... Of course, I placed it inside the MakeMKV config folder, and likely replaced the one inside the aacs config folder as well.)
EDIT : By the way, I'm not sure if this is related to the FindVUK warnings I got about possible missing title keys, but there is a visual glitch during the second opening sequence shortly before the menu shows up. When I play the two M2TS files for the opening sequences manually, I get no visual glitch, but there seems to be two extra unreadable M2TS files inside the folder. Apparently, this might be a known issue even with TV-style Blu-ray players, as some 4K discs of this movie (or possibly even all of them) seem to be flawed. People are known to have issues with this 4K disc, including sometimes not being able to hear the audio track. I'm just glad that aside from this minor visual glitch, my backup works flawlessly.
