Truecrypt unable to open MRL

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chiefengineer
Posts: 65
Joined: Mon 25 Mar 2013, 08:48

Truecrypt unable to open MRL

#1 Post by chiefengineer »

This is a quirky problem I have had for months:

1) I have terabytes of video on hard disk, each in its own Truecrypt volume. I simply mount the volume I want to see and drag/drop the VIDEO_TS folder into VLC, and it throws this error:

VLC is unable to open the MRL: 'dvd:///mnt/dm-0/VIDEO_TS/'

...and yet it clearly finds it: it starts playing the DVD Folder one VOB at a time skipping everywhere...each VOB plays serially like its own file...as from a list...requiring constantly resetting subtitles, sound, etc., making the experience unusable). I formerly blamed VLC for playing poorly with Truecrypt but that just doesn't make sense the more I test:

2) I thought maybe I needed a swap file (which I am reluctant to employ) or increase my 4GB RAM, but if I simply take the decrypted volume and copy the exact same VIDEO_TS folder to hard disk (no longer involving Truecrpyt) then drag/drop it into VLC, it plays the whole "DVD" as it was meant to: perfectly. Of course, this makes the whole encryption thing nonsensical to begin with.

3) This is true whether I use Truecrypt 7.0a, 7.1, turn off kernel cryptographic services (in which case DM-0 doesn't appear but I drag the folder from /mnt/truecrypt1 with the similar error), or whatever version of VLC I use and whatever advanced menu option I attempt to use to open the folder. It also behaves the same way regardless of the hard disk the Truecrypt volume physically resides on: fixed, removable, etc.

This is the ONE THING I am relegated to using Windows for anymore
(and on the exact same machine, and also with VLC and Truecrypt). I am what you could otherwise describe as super-Fatdog-happy.

I am guessing I am clueless about some missing mapping library that makes a Truecrypt volume behave as if it were an honest-to-God hard drive volume...

Any advice about this would be most enlightening and appreciated.

User avatar
Barkin
Posts: 803
Joined: Fri 12 Aug 2011, 04:55

#2 Post by Barkin »


chiefengineer
Posts: 65
Joined: Mon 25 Mar 2013, 08:48

Thanks

#3 Post by chiefengineer »

I had previously tried that script and couldn't
get it to execute/intefrace. It DOES seem like Truecrypt is
designed to interface with Nautilus which I thought
might be the problem with it finding paths in ROX in a flawed fashion.

Fatdog quite nicely creates an "DM-X" icon when a Truecrypt
volume is mounted so opening it as in Windows was never necessary.
But in revisiting your comments in that thread it would seem
like there might be something truncating names INSIDE my VIDEO_TS
folder. I will have to check the paths from the command line
and even try your idea of creating the same volume under
Windows and also Puppy, and alternatively open both.

Hopefully this will occur before I am to elderly to type.

chiefengineer
Posts: 65
Joined: Mon 25 Mar 2013, 08:48

Finally did some testing

#4 Post by chiefengineer »

Very carefully controlled the same files on the same disk (external USB hard drive) which play great under Win7/Truecrypt/VLC, but choke under Fatdog621/Truecrypt/VLC. However, the same folders not under Truecrypt on the same drive work identically in both systems (same machine). Making the DVD folders on either platform is moot as it turns out. Invoking VLC from the command line in Fatdog gives lots of errors, the most telling of which is it can't read the initial block of the decrypted/mounted device and guesses it isn't a DVD at all (which it isn't...it is folder on a hard drive...but Win7 figures that out). The error is thrown by VLC's call using libdvdcss. I tried a series of tests using both Truecrypt and cryptsetup to open/mount the archive, unmount it manually, then try to mount it as a psuedo DVD file system, but so far libdvdcss still chokes on it. Perhaps someone with familiarity with the code can give me a workaround? For instance, it appears to be probing in /root for mapping files it says don't exist but might give it more mapping intelligence?

chiefengineer
Posts: 65
Joined: Mon 25 Mar 2013, 08:48

Here are some lines from vlc opened on the command line:

#5 Post by chiefengineer »

libdvdread: Using libdvdcss version 1.2.11 for DVD access
libdvdread: Attempting to use device /dev/mapper/truecrypt1 mounted on /mnt/truecrypt1 for CSS authentication
libdvdnav: Can't read name block. Probably not a DVD-ROM device.
libdvdnav: Unable to find map file '/root/.dvdnav/.map'
libdvdnav:DVDOpenFileUDF:UDFFindFile /VIDEO_TS/VIDEO_TS.IFO failed
libdvdnav:DVDOpenFileUDF:UDFFindFile /VIDEO_TS/VIDEO_TS.BUP failed
libdvdread: Can't open file VIDEO_TS.IFO.
libdvdnav: vm: failed to read VIDEO_TS.IFO

libdvdread attempts to open the block device (at the mountpoint?) "for CSS authentication" then everything acts like the path is mythical. After that VLC finds a way to open each VOB one at a time. So it seems the path is correct.
That message is the fork compared to playing the same folder extracted/unencrypted. In other words there is no similar statement "Attempting to use device /dev/mapper/truecrypt1 mounted on /mnt/truecrypt1 for CSS authentication" when the path doesn't involve dm-mapper?

chiefengineer
Posts: 65
Joined: Mon 25 Mar 2013, 08:48

Update

#6 Post by chiefengineer »

Just a word about what I have been doing to resolve this:

1) Upgraded to Fatdog 630
2) Tested this against other Linux Ubuntu distributions
3) Ran the test inside pure upgraded DM-Crypt
4) Gone to the the VLC forums and asked advice and tried
all from command line to each menu option.

Result:
Dragging a VIDEO_TS folder from an encrypted archive
into VLC loses the path in every case in every Linux distribution (tested). Still works with all files
and hardware identical (in Windows (7)).

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