Mounting and using DVD Videos

Jim Lesurf · External Since: Feb 06, 2010 Posts: 56

Some years ago I asked here (and elsewhere) about mounting home-recorded
Video DVDs that had been made on domestic video recorders. A specific
problem was that some discs (recorded by 'Panasonic' brand recorders)
showed up and mounted, but all their files and directories had the owner
'-1' and no permissions. So I couldn't access their contents.

The solution I was given was to add a suitable line to the fstab file that
over-ruled the ownership. This worked a treat at the time....

However I've recently been ungrading my various boxes to Xubuntu 11.10.
(They previously used Xubuntu 9.04.) Having done this I found that once
again I am having problems with the DVDs.

The symptoms are curious as they seem to vary according to the type of disc
(rewritables versus once-writable), by type ('+' or '-'), and from one
machine to another. (My laptop doesn't give quite the same behaviour as my
new Shuttle.) But the basic problem I had a few years ago is back.

According to notes I made at the time, the added entry I made to fstab was
as follows

/dev/scd0

/media/cdrom0

udf,iso9660

user,noauto,exec,utf8,uid=1000,mode=0755

0

0

Note that for the sake of clarity here I've put each of the entries on a
different line rather than having just one line with white space
separations.

In the past this gave me a 'cdrom0' entry in /media when I viewed it with
ROX filer. I could then use this to access the contents of a DVD and do
things like unmount or eject it.

But now I get no visible entry in the /media directory, and any attempt at
the filer level (e.g. using the icon that can - but does not always -
appear on the Xubuntu backdrop) fails because the "helper" /media/cdrom0
seems not to be found.

So is the above fstab entry incorrect? If so, can someone please tell me
how to correct it? My assumption is that either my notes have an error, or
Xubuntu 11.10 is sufficiently different to 9.04 for what worked then to
fail now, and need changing.

On the more general topic, the variations with disc type, etc, seem only to
affect the filer views. If I use VLC it can open and play discs which I
can't find via the ROX (or Xfce) filers on my laptop. I can also take an
iso image by using "cat /dev/dvd >> whatever.iso". And I can then usually
open the iso using the Xubuntu filer. But how do I make these discs
accessible via the filer in a more usual/general way? Some discs work, and
appear in /media with a name like 'Panasonic_DVD_RECORDER'. But others
don't.

Note that the discs are all finalised, and that none are CSS.

Thanks in advance for any help,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Martin Gregorie · External Since: Jun 26, 2009 Posts: 94

On Thu, 21 Jun 2012 13:51:50 +0100, Jim Lesurf wrote:

> Some years ago I asked here (and elsewhere) about mounting home-recorded
> Video DVDs that had been made on domestic video recorders. A specific
> problem was that some discs (recorded by 'Panasonic' brand recorders)
> showed up and mounted, but all their files and directories had the owner
> '-1' and no permissions. So I couldn't access their contents.
>
> The solution I was given was to add a suitable line to the fstab file
> that over-ruled the ownership. This worked a treat at the time....
>
> However I've recently been ungrading my various boxes to Xubuntu 11.10.
> (They previously used Xubuntu 9.04.) Having done this I found that once
> again I am having problems with the DVDs.
>
> The symptoms are curious as they seem to vary according to the type of
> disc (rewritables versus once-writable), by type ('+' or '-'), and from
> one machine to another. (My laptop doesn't give quite the same behaviour
> as my new Shuttle.) But the basic problem I had a few years ago is back.
>
> According to notes I made at the time, the added entry I made to fstab
> was as follows
>
> /dev/scd0
>
> /media/cdrom0
>
> udf,iso9660
>
> user,noauto,exec,utf8,uid=1000,mode=0755
>
> 0
>
> 0
>
> Note that for the sake of clarity here I've put each of the entries on a
> different line rather than having just one line with white space
> separations.
>
> In the past this gave me a 'cdrom0' entry in /media when I viewed it
> with ROX filer. I could then use this to access the contents of a DVD
> and do things like unmount or eject it.
>
> But now I get no visible entry in the /media directory, and any attempt
> at the filer level (e.g. using the icon that can - but does not always -
> appear on the Xubuntu backdrop) fails because the "helper" /media/cdrom0
> seems not to be found.
>
> So is the above fstab entry incorrect? If so, can someone please tell me
> how to correct it? My assumption is that either my notes have an error,
> or Xubuntu 11.10 is sufficiently different to 9.04 for what worked then
> to fail now, and need changing.
>
> On the more general topic, the variations with disc type, etc, seem only
> to affect the filer views. If I use VLC it can open and play discs which
> I can't find via the ROX (or Xfce) filers on my laptop. I can also take
> an iso image by using "cat /dev/dvd >> whatever.iso". And I can then
> usually open the iso using the Xubuntu filer. But how do I make these
> discs accessible via the filer in a more usual/general way? Some discs
> work, and appear in /media with a name like 'Panasonic_DVD_RECORDER'.
> But others don't.
>
> Note that the discs are all finalised, and that none are CSS.
>
If you can read them as ISOs, why not simply keep them as stored images
on disk? Have you tried writing such an ISO back to a blank DVD?
If so , did that help?

Being a dyed in the wool Redhat bloke, I don't know anything about
Ubuntu, but have one comment: since all block storage device handling
changed dramatically when UDEV replaced the older, traditional device
handling system, is there any chance that 9.04 used the older system
while 11.10 uses UDEV?

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Jim Lesurf · External Since: Feb 06, 2010 Posts: 56

In article , Martin Gregorie
wrote:
> On Thu, 21 Jun 2012 13:51:50 +0100, Jim Lesurf wrote:
[snip]
> >
> > Note that the discs are all finalised, and that none are CSS.
> >
> If you can read them as ISOs, why not simply keep them as stored images
> on disk? Have you tried writing such an ISO back to a blank DVD? If so
> , did that help?

I can (and do) sometimes read them as ISO images and then access them as
such. I can then write them back to another disc and it will play on a DVD
Video player/recorder. I'll check if one that initially 'hides' then shows
up. Good idea to try that.

For many purposes being able to make an iso file is fine. But sometimes I
simply want to do something like get at the audio track to analyse it. I
can normally do that using ffmpeg fed from the VOB files direct from the
DVD. It slows this down if I have to always make an iso image file first.
And I then have to open the iso and extract the VOB.

So since my old systems didn't have the problem (or rather, it seemed to
have been fixed by the fstab entry I listed) I'd prefer - if possible - to
have that again.

> Being a dyed in the wool Redhat bloke, I don't know anything about
> Ubuntu, but have one comment: since all block storage device handling
> changed dramatically when UDEV replaced the older, traditional device
> handling system, is there any chance that 9.04 used the older system
> while 11.10 uses UDEV?

Have to pass on that and see if someone can say. You may be right for all I
know. However one curio is that I now have Xubuntu 11.10 on both my main
Shuttle and the laptop, both installed from the same CDROM. Yet their
behaviours are slightly different, although the main problem remains.

I suppose one question I should be asking is: what does VLC do when asked
to play a 'disc'? It clearly doesn't make a complete iso image copy first.
So if I could duplicate that at the 'filer' level with a command I might be
able that way to get the DVDs to open up and show their contents.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

J G Miller · External Since: Dec 08, 2004 Posts: 360

On Thu, 21 Jun 2012 13:51:50 +0100, Jim Lesurf wrote:

> According to notes I made at the time, the added entry I made
> to fstab was as follows
>
> /dev/scd0

But does scd0 exist anymore on your system?

You may find that scdN is no longer in use and that the removable
medias all now go by srN (sr0, sr1 etc) under the libata regime.

So probably all you need do is replace scd0 with sr0.

Also remember that if you want some convenience symbolic links
eg cdrom, cdrw, dvd, dvdrw according to your preference you can
add udev rules to /etc/udev/rules.d to create them at kernel detection
time.

For example on this machine with two dvdrws, I have for convenience ...

#*****************************************************************************#
#|
#| file : /etc/udev/rules.d/70-persistent-cd.rules
#|
#*---------------------------------------------------------------------------
*#
#
SUBSYSTEM=="block", ENV{GENERATED}="1", ENV{ID_CDROM}=="?*", \
ENV{ID_PATH}=="pci-0000:00:04.1-scsi-0:0:0:0", \
SYMLINK+="cdrom1"
#
SUBSYSTEM=="block", ENV{GENERATED}="1", ENV{ID_CDROM}=="?*", \
ENV{ID_PATH}=="pci-0000:00:04.1-scsi-0:0:0:0", \
SYMLINK+="dvdrw"
#
#.............................................................................#
#
#
SUBSYSTEM=="block", ENV{GENERATED}="1", ENV{ID_CDROM}=="?*", \
ENV{ID_PATH}=="pci-0000:00:04.1-scsi-1:0:0:0", \
SYMLINK+="cdrom"
#
SUBSYSTEM=="block", ENV{GENERATED}="1", ENV{ID_CDROM}=="?*", \
ENV{ID_PATH}=="pci-0000:00:04.1-scsi-1:0:0:0", \
SYMLINK+="cdtooldev"
#
SUBSYSTEM=="block", ENV{GENERATED}="1", ENV{ID_CDROM}=="?*", \
ENV{ID_PATH}=="pci-0000:00:04.1-scsi-1:0:0:0", \
SYMLINK+="dvd"
#
#*****************************************************************************#

Obviously you need to change the pci-*scsi-* string to what is
appropriate for your machine.

Jim Lesurf · External Since: Feb 06, 2010 Posts: 56

In article , J G Miller
wrote:
> On Thu, 21 Jun 2012 13:51:50 +0100, Jim Lesurf wrote:

> > According to notes I made at the time, the added entry I made to fstab
> > was as follows
> >
> > /dev/scd0

> But does scd0 exist anymore on your system?

> You may find that scdN is no longer in use and that the removable medias
> all now go by srN (sr0, sr1 etc) under the libata regime.

/dev/scd0 still is present as a link, owner 'root'.

However /dev/sr0 is also present as a block device.

> So probably all you need do is replace scd0 with sr0.

Thanks. I'll give that a try. I've also noted the explanation you gave of
using udev. [snipped from below]

Cheers,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

J G Miller · External Since: Dec 08, 2004 Posts: 360

On Friday, June 22nd, 2012, at 15:10:29h +0100, Jim Lesurf explained:

> /dev/scd0 still is present as a link, owner 'root'.

Okay, some distributions may still create this as a convenience
link via udev rules in the same way as I suggested for other convenience
names.

Incidentally, cdtooldev is for the command line cdplay.

Also, the entries I have in /etc/fstab are as follows

/dev/sr0 /media/dvdrw iso9660,udf exec,noauto,user,utf8 0 0
/dev/sr1 /media/dvd iso9660,udf exec,noauto,user,utf8 0 0

So if you add your permissions settings to the options section (exec,noauto..)
that should work for you.

Change the mountpoint names, to whatever you prefer of course and
which exist on your system Wink

Jim Lesurf · External Since: Feb 06, 2010 Posts: 56

On 22 Jun, noise DeleteThis @audiomisc.co.uk wrote:
> In article , J G Miller
> wrote:

> > So probably all you need do is replace scd0 with sr0.

> Thanks. I'll give that a try.

Alas, that doesn't work, so I must still be doing something wrong. I'll
give the details in the hope it will help others spot my mistake(s).

Having put the line into fstab that now starts /etc/sr0 the behaviour as
follows.

If In put a DVD-RW into the drive and icon for an optical disc *does*
appear on the Xubuntu desktop backdrop. (I don't think that happened
before.)

However, still, no 'cdrom0' appears in /media when viewed by ROX filer.

If I click on the 'mount' menu option of the Xubuntu backdrop icon that
fails with

Failed to mount "DVD_VIDEO_RECORDER"...

which shows it can at least detect a video recorded disc at some level or
other

.... Exit code 1: Helper failed with mount: mount point /media/cdrom0 does
not exist.

As before I can "cat /dev/dvd >> test.iso" and get the content of the disc
copied into an iso file. But no sign of it being available via the filer,
either via xfce or rox.

Do I need to do something else to pre-create the mount point in /media? I
may have had to do that mumble years ago when setting up my old system. But
if so, I've forgotten the details and have note of it along with my notes
on the old fstab entry that worked then.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

J G Miller · External Since: Dec 08, 2004 Posts: 360

On Saturday, June 23rd, 2012, at 16:33:32h +0100, Jim Lesurf explained:

> Having put the line into fstab that now starts /etc/sr0 the behaviour as
> follows.

/etc ???? Please double check to see that you did put in /dev/sr0
and you were thinking "/etc/fstab".

> If In put a DVD-RW into the drive and icon for an optical disc *does*
> appear on the Xubuntu desktop backdrop. (I don't think that happened
> before.)

That will be the udev + dbus system detecting and mounting the disk.

If you do a right click on icon, can you bring up properties to
see where it has been mounted?

> However, still, no 'cdrom0' appears in /media when viewed by ROX filer.

Probably because it is not mounted as cdrom0 under /media or it
has been mounted somewhere else.

> ... Exit code 1: Helper failed with mount: mount point /media/cdrom0 does
> not exist.

Well that is your problem then -- as root go into /media and create directories
cdrom0, cdrom1 ord dvd0, dvd1 etc in order that mountpoints which you specified
in /etc/fstab exist, otherwise the thing will never mount there.

> Do I need to do something else to pre-create the mount point in /media?

Yes -- mkdir

Jim Lesurf · External Since: Feb 06, 2010 Posts: 56

In article , J G Miller
wrote:
> On Saturday, June 23rd, 2012, at 16:33:32h +0100, Jim Lesurf explained:

> > Having put the line into fstab that now starts /etc/sr0 the behaviour
> > as follows.

> /etc ???? Please double check to see that you did put in /dev/sr0 and
> you were thinking "/etc/fstab".

Yes, apologies, the above was a typo. The line in the file is as follows:

/dev/sr0 /media/cdrom0 udf,iso9660
user,noauto,exec,utf8,uid=1000,mode=0755 0 0

(all on one line in the file)

> > ... Exit code 1: Helper failed with mount: mount point /media/cdrom0
> > does not exist.

> Well that is your problem then -- as root go into /media and create
> directories cdrom0, cdrom1 ord dvd0, dvd1 etc in order that mountpoints
> which you specified in /etc/fstab exist, otherwise the thing will never
> mount there.

YES. Smile

Thanks. When I set this up on my earlier install I must have done
that. But I guess I thought it was so obvious that I didn't mention it in
my notes! I had to make myself root to create the /media/cdrom0 directory,
but that then does let me mount discs at that point. (I had been wondering
if I needed to create some kind of link. Hadn't occurred to me a directory
was needed.)

As soon as I made the directory it was shown by ROX filer as being a
mountable (ROX gives the directory icon but with an added blob whose colour
changes depending on if mounted.)

So the good news is that I can now mount and access DVD+/-Rs that way using
the filer.

The bad is that it gives me the old problem with DVD-RWs...

With a DVD-RW videos recorded in the Panasonic videorecorders I can open
the /media/cdrom0 'directory'. But the contents show not the expected Video
directory of VOB files. Instead what should be a directory is a file with
no permissions at all (---,---,---./---) and both owner and group are '-1'.
So it is impossible to access the actual contents.

This is the behaviour that I got with my old install about three years ago
which caused me to add the extra fstab line. I'd thought that the

user,noauto,exec,utf8,uid=1000,mode=0755

would fix this. But it doesn't. Am I I still missing something or doing
something wrong?

Two extra bits of info which may be diagnostically relevant fo all I know:

1) When I load a DVD+/-R I get the Xubuntu backdrop icon appear and can be
used to examine the contents (and, now, I can also do so via the filer
using /media/cdrom0). *But* when I load a DVD-RW the Xubuntu backdrop icon
just fleetingly appears and vanishes (and I get the above inability to
access via the filer because I seem not to have permission/ownership
despite my fstab line details).

2) Does fstab have to be owned by root? I noticed that I've managed to make
it owned by me as a user. It seems to work in that the system runs OK and I
now get access to DVD+/-Rs. But I am wondering if this is why it seems not
to over-rule the disc saying I don't have access to the disc contents.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Martin Gregorie · External Since: Jun 26, 2009 Posts: 94

On Sun, 24 Jun 2012 09:35:06 +0100, Jim Lesurf wrote:

> 2) Does fstab have to be owned by root? I noticed that I've managed to
> make it owned by me as a user. It seems to work in that the system runs
> OK and I now get access to DVD+/-Rs. But I am wondering if this is why
> it seems not to over-rule the disc saying I don't have access to the
> disc contents.
>
It and /etc/mtab are owned by root on my systems (Fedora 15 and 16) and
/etc/fstab is only writable by root in both. F15 and F16 are respectively
kernel 2.6.43 and 3.4.2 systems. In both cases /etc/mtab is a symlink to
/proc/mounts.

You may find out a bit more from 'df' - in both my systems df shows
'tmpfs' in the leftmost column alongside /media.

I can't help much more as I've never used any Ubuntu flavours, or
anything in the Derbian branch either. All I can add is that I've had no
issues such as you're seeing with either of my current installed Fedora
systems.

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Jim Lesurf · External Since: Feb 06, 2010 Posts: 56

A correction and an update...

On 24 Jun, noise DeleteThis @audiomisc.co.uk wrote:
> In article , J G Miller
> wrote:
> > On Saturday, June 23rd, 2012, at 16:33:32h +0100, Jim Lesurf explained:

> The bad is that it gives me the old problem with DVD-RWs...

I've now tried a wider variety of discs, and the problem seems to be back
to exactly the same as I had some years ago (and which was then fixed by
adding the line to fstab).

Discs recording on the *Panasonic* recorders I use give problems. Discs I
recorded in the past on *Philips* recorders don't give the problems.

For the 'Philips' discs I can load either R or RW discs and their contents
are fully accessible via either the Xfce backdrop icon or via the mount
point I've added at /media/cdrom0. Opening /media/cdrom0 shows the
directorie(s) on the disc and their content vob files, etc.

For 'Panasonic' discs I can load either R or RW and the backdrop icon only
appears briefly. They *can't* been accessed via the /media/cdrom0 mount
point by either the xubuntu desktop filer or rox. Opening /media/cdrom0
gives a 'file' inside that has no permissions or details.[1]

Yet in *both* cases I can cat /dev/dvd >> something.iso and then can
use/play/open the iso image file. I can also have VLC open and play the
disc in the drive with no problems.

So methods like cat /dev/dvd and VLC seem to bypass a problem that stops my
mount point from accessing the 'Panasonic' DVDs... This is the problem I
had years ago. But for some reason this time the mod to the fstab file
doesn't seem to fix it, although it gives access to the 'Philips' discs
just fine.

FWIW as a long shot I used chown to make the fstab file root:root ownership
again as earlier on I'd unintentionally made the edited file mine as a
normal user. But that doesn't solve the problem.

Slainte,

Jim

[1] This, I guess, underlines that "everything is a file" since I know a
'directory' *is* a file. But in this case, one that doesn't even reveal
that it should act as a directory! :-/

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
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Audio Misc http://www.audiomisc.co.uk/index.html

Nix · External Since: Jul 29, 2004 Posts: 746

On 24 Jun 2012, Martin Gregorie spake thusly:

> On Sun, 24 Jun 2012 09:35:06 +0100, Jim Lesurf wrote:
>
>> 2) Does fstab have to be owned by root? I noticed that I've managed to
>> make it owned by me as a user. It seems to work in that the system runs
>> OK and I now get access to DVD+/-Rs. But I am wondering if this is why
>> it seems not to over-rule the disc saying I don't have access to the
>> disc contents.
>>
> It and /etc/mtab are owned by root on my systems (Fedora 15 and 16) and
> /etc/fstab is only writable by root in both.

Having /etc/fstab be writable by anyone non-root is a security hole
which essentially makes that user (or group, or everyone *shiver*)
equivalent to root.

--
NULL && (void)

J G Miller · External Since: Dec 08, 2004 Posts: 360

On Sunday, June 24th, 2012, at 09:35:06h +0100, Jim Lesurf wrote:

> Hadn't occurred to me a directory was needed.

Yes whenever you mount a device with a directory structure you have
to have a directory already in existence in order to mount it.

If you use autofs, then that automagically createst the necessary
directory under the autofs controlled directories as specified
in the auto.* files.

> I'd thought that the

user,noauto,exec,utf8,uid=1000,mode=0755

> would fix this. But it doesn't.

I do not know why it does not. After doing the mount, you need
to provide the information given by

mount | egrep cdrom0

and

ls -Fls /media

assuming you have mounted it on a directory under /media

plus the relevant line from /etc/fstab

> *But* when I load a DVD-RW the Xubuntu backdrop icon
> just fleetingly appears and vanishes

Sounds like it is trying to mount it and fails.

> 2) Does fstab have to be owned by root?

No, but it should be for security reasons, eg

-r--r--r-- 1 root root 2368 2007-01-01 00:00 /etc/fstab

or rw by root if you like.

J G Miller · External Since: Dec 08, 2004 Posts: 360

On Sunday, June 24th, 2012, at 09:35:06h +0100, Jim Lesurf wrote:

> Hadn't occurred to me a directory was needed.

Yes whenever you mount a device with a directory structure you have
to have a directory already in existence in order to mount it.

If you use autofs, then that automagically createst the necessary
directory under the autofs controlled directories as specified
in the auto.* files.

> I'd thought that the

user,noauto,exec,utf8,uid=1000,mode=0755

> would fix this. But it doesn't.

I do not know why it does not. After doing the mount, you need
to provide the information given by

mount | egrep cdrom0

and

ls -Fls /media

assuming you have mounted it on a directory under /media

plus the relevant line from /etc/fstab

> *But* when I load a DVD-RW the Xubuntu backdrop icon
> just fleetingly appears and vanishes

Sounds like it is trying to mount it and fails.

> 2) Does fstab have to be owned by root?

No, but it should be for security reasons, eg

-r--r--r-- 1 root root 2368 2007-01-01 00:00 /etc/fstab

or rw by root if you like.

Jim Lesurf · External Since: Feb 06, 2010 Posts: 56

In article , J G Miller
wrote:
> On Sunday, June 24th, 2012, at 09:35:06h +0100, Jim Lesurf wrote:

> > I'd thought that the

> user,noauto,exec,utf8,uid=1000,mode=0755

> > would fix this. But it doesn't.

> I do not know why it does not. After doing the mount, you need to
> provide the information given by

> mount | egrep cdrom0

that gives

/dev/sr0 on /media/cdrom0 type udf
(ro,nosuid,nodev,utf8,uid=1000,mode=0755,user=jim)

and is the same for two discs I tried (one which is a 'Panasonic' disc and
shows the access problem, the other an older disc that I can access fine).

> and

> ls -Fls /media

that gave

total 2
2 dr--r--r-- 3 jim 4294967295 88 2012-06-21 17:45 cdrom0/

for the 'doesn't access properly' disc, and

total 2
2 dr-xr-xr-x 4 jim 4294967295 136 2000-01-01 00:00 cdrom0/

for the disc that is fine.

> assuming you have mounted it on a directory under /media

> plus the relevant line from /etc/fstab

That is as mentioned

/dev/sr0 /media/cdrom0 udf,iso9660
user,noauto,exec,utf8,uid=1000,mode=0755 0 0

So it seems like the ownership is being asserted, but not actually being
enacted!

> > *But* when I load a DVD-RW the Xubuntu backdrop icon just fleetingly
> > appears and vanishes

> Sounds like it is trying to mount it and fails.

That is what I was suspecting. But I am baffled as to why.

This is particularly odd since I can still use cat /dev/dvd to get an iso.
*And* I can then open the iso using the Xubuntu filer and access the
contents whose permissions are then set with me being the owner.

So the problem doesn't - in the end - prevent me accessing the disc. And
they play as discs using VLC. But it means if I want to access the disc
content to, say, rip the audio from the VOB files, I have to first make an
iso file copy. All baffling as I'm sure the added fstab line sorted the
problem with the earlier distros!

One thing occurs to me. There are two possible filing systems. one being
utf, the other iso9660. (Or am I muddled?) The above seems to say I'm being
given a mount via udf. Might iso9660 be better and is being used by other
routes, so works for, say, VLC? If so, can I set that I prefer iso9660 over
udf if both are present? i'm wondering if this is a result of Panasonic
furtling about with the root filing info on the discs...

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
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Audio Misc http://www.audiomisc.co.uk/index.html

J G Miller · External Since: Dec 08, 2004 Posts: 360

On Monday, June 25th, 2012, at 10:11:17h +0100, Jim Lesurf wrote:

> that gave
>
> total 2
> 2 dr--r--r-- 3 jim 4294967295 88 2012-06-21 17:45 cdrom0/
>
> for the 'doesn't access properly' disc, and
>
> total 2
> 2 dr-xr-xr-x 4 jim 4294967295 136 2000-01-01 00:00 cdrom0/

So you can see that the problem is that the problem disc is
mounted without the execute permission bit set.

Thus when you try to ls the contents of the directory it
will not work because in order to do that it needs the "x"
bit set.

> That is what I was suspecting. But I am baffled as to why.

I suggest that it does mount it, but that it cannot list
the contents because of the lack of "x", hence why the
icon disappears.

> This is particularly odd since I can still use cat /dev/dvd to get an iso.

But that is different -- you are going via the raw device and not
via the mounted file system.

> *And* I can then open the iso using the Xubuntu filer and access the
> contents whose permissions are then set with me being the owner.

I do not understand to what you are referring by the Xubuntu filer.

I was just about to suggest doing chmod 755 on the directory which
is almost guaranteed to fail, and then it occurred to me you are
doing something wrong.

You most definitely cannot mount an iso file system, nor udf I think, as
writeable, so your permission 0755 is wrong and should be 0555

This could possibly be the cause of the problem because when it
tries to mount the problem disk as writeable it fails and falls
back to readonly, and thus does not set the needed "x" as well.

So change the fstab line from 0755 to 0555 and see if that works.

> So the problem doesn't - in the end - prevent me accessing the disc. And
> they play as discs using VLC.

Again because VLC is accessing via the device /dev/sr0 and does
not mount the device as file system for reading.

> One thing occurs to me. There are two possible filing systems. one being
> utf, the other iso9660.

UDF Universal Disk Format

UTF UCS Transformation Format (Unicode, UCS) (eg font formats)

> The above seems to say I'm being given a mount via udf.

Which is what you want for DVDs (although I have a feeling it
is possible to write an iso9660 file system to a DVD, and if
it is, is not advisable under normal circumstances becase you
will only be able to use it as a DATA DVD and not play it in
a CD player or DVD player).

> Might iso9660 be better

No because that is the file system use for CDs

Jim Lesurf · External Since: Feb 06, 2010 Posts: 56

In article , J G Miller
wrote:
> On Monday, June 25th, 2012, at 10:11:17h +0100, Jim Lesurf wrote:

> Thus when you try to ls the contents of the directory it will not work
> because in order to do that it needs the "x" bit set.

> > That is what I was suspecting. But I am baffled as to why.

<AOL>me too!</AOL> Smile

> > *And* I can then open the iso using the Xubuntu filer and access the
> > contents whose permissions are then set with me being the owner.

> I do not understand to what you are referring by the Xubuntu filer.

Sorry, I'm just meaning the desktop filer provided as part of Xubuntu. Not
sure if I should call it xcfe4, xfwm, or what... This is to distinguish it
from my preferred use of ROX filer. I had initially wondered if this was a
quirk with ROX. But I've now been trying both desktop filers and they give
the same behaviours. So I assume the problem is at another level.

> I was just about to suggest doing chmod 755 on the directory which is
> almost guaranteed to fail, and then it occurred to me you are doing
> something wrong.

> You most definitely cannot mount an iso file system, nor udf I think, as
> writeable, so your permission 0755 is wrong and should be 0555

> This could possibly be the cause of the problem because when it tries to
> mount the problem disk as writeable it fails and falls back to readonly,
> and thus does not set the needed "x" as well.

> So change the fstab line from 0755 to 0555 and see if that works.

Ok. I've now tried that but it still doesn't work. ls -Fls /media still
also says the permissions are dr--r--r--. But mount | egrep cdrom0 confirms
it is now mode=0555.

And the puzzle here is why old ('Philips' recorded) discs work fine whilst
newer ones don't. And why changing fstab worked fine on the old distro, but
not now.

>
> > So the problem doesn't - in the end - prevent me accessing the disc.
> > And they play as discs using VLC.

> Again because VLC is accessing via the device /dev/sr0 and does not
> mount the device as file system for reading.

> > One thing occurs to me. There are two possible filing systems. one
> > being utf, the other iso9660.

> UDF Universal Disk Format

Yes, sorry, another typo.

> UTF UCS Transformation Format (Unicode, UCS) (eg font formats)

> > The above seems to say I'm being given a mount via udf.

> Which is what you want for DVDs (although I have a feeling it is
> possible to write an iso9660 file system to a DVD, and if it is, is not
> advisable under normal circumstances becase you will only be able to use
> it as a DATA DVD and not play it in a CD player or DVD player).

> > Might iso9660 be better

> No because that is the file system use for CDs

I'm probably misremebering my reading of my 'Big book of DVD' some years
ago. But I think that said video DVD expected two different ways to give
the root file info. I was thinking they were iso and udf. But maybe one is
a simple serial equivalent of a 'boot sector' at the start of the disc.

Not directly relevant, but I'm now wondering why a saved disc image of a
DVD is an 'iso' image. Is that just a hangover from doing the same for CDs?
So it should really be called something else?

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

J G Miller · External Since: Dec 08, 2004 Posts: 360

On Monday, June 25th, 2012, at 12:18:37h +0100, Jim Lesurf wrote:

> Sorry, I'm just meaning the desktop filer provided as part of Xubuntu.

If you are using the default file manager under XFCE (the desktop) with
XFWM (the window manager), then it will be thunar.

The icon for this is a hammer.

> So I assume the problem is at another level.

Yes the problem appears to be deep down at I think the kernel level.

> I've now tried that but it still doesn't work.

Well it was worth trying just to see if the read-only versus read-write
conflict was the problem.

> But mount | egrep cdrom0 confirms it is now mode=0555.

So you did unmount then. The only thing I can think of trying to do
now to diagnose the problem is as follows.

Unmount the problem DVD and manually mount it with

mount -t udf -o mode=0444 /dev/sr0 /media/cdrom0

Then look at the output of mount | egrep cdrom0 and
look at the last few lines of dmesg to see if there
is any information there about the mounting.

Then do

mount -t udf -o remount,mode=0555 /dev/sr0 /media/cdrom0

and look at the output of mount | egrep cdrom0 and look
at the last frew lines of dmesg to see if there
is any information there about the mounting.

If the file system root on the disk is really 444 and not 555,
then it maybe you will never be able to mount it 555 and if you
did in the past, this may have been a bug that was "fixed" since
the standard is to mount as is, not mount as you want it to be.

> Not directly relevant, but I'm now wondering why a saved disc image of a
> DVD is an 'iso' image.

Probably just the extension name which is used as a convenient fiction,
but the file system is actually udf.

SACD images are often saved as .iso, but the file system is certainly
not iso9660.

J G Miller · External Since: Dec 08, 2004 Posts: 360

On Monday, June 25th, 2012, at 12:55:57h +0000, J G Miller instructed:

> Then do
>
> mount -t udf -o remount,mode=0555 /dev/sr0 /media/cdrom0

Further investigation reveals that mount has two "mode" options.

mode refers to files.

So that should be mode=0444

And for for directory permissions there is dmode, so you need both

dmode=0555,mode=0444

You may if you have time wish to read the discussion at

<https://bugs.launchpad.NET/ubuntu/+source/util-linux/+bug/10550>

Nix · External Since: Jul 29, 2004 Posts: 746

On 25 Jun 2012, Jim Lesurf uttered the following:
> /dev/sr0 /media/cdrom0 udf,iso9660
> user,noauto,exec,utf8,uid=1000,mode=0755 0 0

Uh, what? Can you use commas in /etc/fstab like that?

*digs in source code*

Aha! in guess_fstype_and_mount() there is indeed code to

/* Accept a comma-separated list of types, and try them one by one */
/* A list like "nonfs,.." indicates types not to use */

This appears to be documented nowhere but in that comment. How did you
figure out this was permitted? Is some distro using it by default, or
did you grovel through the source too?

(hm, clearly time to document it and submit a fix to Karel...)

--
NULL && (void)