[Linux-disciples] The loop device

[Stephen R Laniel]

Kind of relatedly: I copied a DVD to a disk image via

dd if=/dev/hdc of=image_file.iso

or something similar, where /dev/hdc is the DVD reader. I
can now mount it via

sudo mount -o loop -t iso9660 image_file.iso /mnt/dvd/ 

and I get a proper directory listing:

(15:01) slaniel at TheloniousMonk:~$ ls /mnt/dvd
total 10K
dr-xr-xr-x    1 root     root         2.0K 2004-08-19 12:16 .
drwxr-xr-x   10 root     root         4.0K 2005-01-03 14:28 ..
dr-xr-xr-x    1 root     root         2.0K 2004-08-25 08:41 audio_ts
dr-xr-xr-x    1 root     root         2.0K 2004-08-25 09:13 video_ts

(as an aside, I think the loop device must be doing some
kind of magic, because the .iso file itself is only 202
megs, but du'ing /mnt/dvd shows that it contains 7.7 gigs of
files)

Now how do I play this DVD? I tried

mplayer dvd://1 -dvd-device ~/image_file.iso

and got

Playing dvd://1.
Reading disc structure, please wait...
There are 9 titles on this DVD.
There are 14 chapters in this DVD title.
There are 1 angles in this DVD title.
libdvdread: Invalid title IFO (VTS_01_0.IFO).
Cannot open the IFO file for DVD title 1.

I have libdvdcss2 installed:

libdvdcss2/unstable uptodate 1.2.8-0.0

Any idea what the problem could be? I get the sense that
maybe the issue is the loop device, but I don't understand
it well enough to know whether that's the problem.

-- 
Stephen R. Laniel
steve at laniels.org
+(617) 308-5571
http://laniels.org/