VLC is unable to open the MRL

[JamButty]

Something has changed recently with VLC and DVD playback. Codecs are good, been doing the

sudo apt-get install libdvd-pkg
sudo dpkg-reconfigure libdvd-pkg
bit for years after each new re-install. But now, DVDs I played without problem just a month or two ago pull this error as a popup

Your input can't be opened:
VLC is unable to open the MRL
and the VLC log reads:

-- logger module started --
main: Running vlc with the default interface. Use 'cvlc' to use vlc without interface.
filesystem error: read error: Input/output error
cache_read error: cannot pre fill buffer
mjpeg error: cannot peek

every online reference to this I find is concerned with VLC playing streaming media (youtube etc.), but these are standard commercial DVDs playing from the main CD/DVD tray. The log output is the same whether auto-opening the DVD on mount or trying to play initial files in VIDEO-TS directly, but the pop-up only appears when trying to play the VIDEO_TS files directly.
I am stumped.

[#&thj^%]

What shows here:

apt policy libdvdcss2
Or

dpkg -l *libdvdcss* | grep ii
Also with DVD playing run:

DVDCSS_VERBOSE=2

may give more information.
Other Steps to take:
Reset your preferences. (you would be suprised how often this fixes problems)
If that dose not solve the issue.>>>Use a script:
first download this script: https://github.com/videolan/vlc/blob/master/share/lua/playlist/youtube.lua
Lets find our file with:

locate youtube.luac
Mine was here:

/usr/lib/x86_64-linux-gnu/vlc/lua/playlist/youtube.luac
/usr/share/doc/vlc/lua/playlist/youtube.lua.gz ###Don't worry about this line

copy and paste it to a text file, named example "youtube.luac"
now replace this with the new youtube.luac file.

sudo cp ~/Downloads/youtube.lua /usr/lib/x86_64-linux-gnu/vlc/lua/playlist/youtube.luac
Should be Good to Go.

[JamButty]

$ apt policy libdvdcss2
libdvdcss2:
Installed: 1.4.2-1~local
Candidate: 1.4.2-1~local
Version table:
*** 1.4.2-1~local 100
100 /var/lib/dpkg/status
$ dpkg -l *libdvdcss* | grep ii
ii libdvdcss-dev:amd64 1.4.2-1~local amd64 library for accessing encrypted DVDs - development files
ii libdvdcss2:amd64 1.4.2-1~local amd64 library for accessing encrypted DVDs
$ DVDCSS_VERBOSE=2
$


I could not run "DVDCSS_VERBOSE=2" while DVD is running as no DVD file will run at all, so I ran it immediately after attempting a VLC play. I did reset the VLC preferences. All that did was make my log file disappear. I went through a song and dance about a year ago just to force VLC to even produce a logfile I could easily find, so I need to research again to see/remember how I did that.
I am still trying to process what the script is about.
Thanks.

[JamButty]

Also tried removing snap-VLC and installing non-snap version - no change.

[#&thj^%]

I am still trying to process what the script is about.
Thanks.
Simply "youtube.lua", was preventing videos with copyright-claimed material from being played. (This changes more often than one would expect)
Back-up your old one first then, add the New one and enjoy.
If not then there is something else wrong.
Side Note Snap Version of VLC just not an option for me. (Snaps just leave a bad taste in my usage).

[JamButty]

sooooo...since the "youtube.lua" file at that address is text and VLC is expecting a binary LUAC file, I assume I would need to compile it, which I have no idea how to do, me being a basic user, not a programmer. Also unclear why a module designed to mediate streaming online data would mediate commercial DVDs.
I got the logfile going again, changed the output level to "debug" and got reams of output, most of which I understood nothing of, but it seemed clear that even when it found files it needed (e.g. meta fetcher module, art finder module, access_demux module, meta fetcher module etc.) it either did not find the portions inside each it needed or was entirely unable to open them.
Since some of the online solutions aimed at Windows users mentioned file ownership issues as a possible problem, I had a hunch that running VLC from the command line (as root if needed) might help. Hey presto! Tested several DVDs and all work running from the command line (even without root privs). Further the logfile now shows VLC happily finding files it could not find before and even autostarting VLC on mount now works for some DVDs, not all. Can't say I understand it, but it works.

TL; DR- running VLC from the command line eliminated problem.

[#&thj^%]

sooooo...since the "youtube.lua" file at that address is text and VLC is expecting a binary LUAC file, I assume I would need to compile it, which I have no idea how to do, me being a basic user, not a programmer. Also unclear why a module designed to mediate streaming online data would mediate commercial DVDs.

As I said **any** It's preventing videos with copyright-claimed material. (DVD's fall in here)
Not sure why running from the terminal would make a difference though, unless left-over stuff from Snap version is lingering.
And no you don't have to compile anything, the changed script should be enough.

[JamButty]

I am baffled too - why it suddenly became inoperable and then why a command line start without root privs helps. But it works. Thanks for your input.

[JamButty]

I am baffled too - why it suddenly became inoperable and then why a command line start without root privs helps. But it works. Thanks for your input.