[Libcdio-devel] Re: Retrieving DATA session from multisession audio disc

[Thomas Schmitt]

Hi,

> Using isoinfo (NOT iso-info) it seems stuff is in place:
> [morituri-uninstalled] address@hidden trunk]$ isoinfo -N 207106 -i
> Ladyhawke\ -\ Ladyhawke/data.iso  -l

So the offset 207106 seems to be the right one.
(I found this helptext of isoinfo:
  http://www.herongyang.com/CD-DVD/Data-CD-ISO-9660-isoinfo.html
 "-N sector   Sector number where ISO image should start on CD"
)


> a) can I write this (wrong) iso as is to a mixed mode cd to make a
> perfect copy of my cd ?

You will have to put it exactly to offset 207106
so that it works unaltered.
Possibly one can do that with cdrecord -sao or
some -raw* option if one has suitable input files
for the tracks which come before the ISO track.

But that's outside of my own experience.


> I couldn't get this to mount either:
> address@hidden thomas]# mount -t iso9660 -o loop,sbsector=207106 dummy.iso 
> /mnt/iso/

Did you append the image to the end of a file of
exactly the right size ?
In this case:

   dd if=/dev/zero \
   bs=2K count=1 seek=207105 \
   of=cd_dummy.iso

Note that you have to seek to (207106 - 1)
and then write 1 block, to get 207106 blocks.

Does this cd_dummy.iso show with ls -l a size of
424153088 bytes ? (Before you append data.iso)


I just tried this with a multi-session CD on
Debian 5.04. Track start block is 109287,
track size is 3497:

  $ dd if=/dev/hda bs=2048 skip=109287 count=3497 of=track1.iso
  $ dd if=/dev/zero bs=2K count=1 seek=109286 of=cd_dummy.iso
  $ cat track1.iso >> cd_dummy.iso
  $ su
  # mount -t iso9660 -o loop,sbsector=109287 cd_dummy.iso /mnt
  # ls /mnt

shows lots of files.


------------------------------------------------

> > Adventurous testers could try losetup option -o
> > with a negative value or mount option "offset".
> What value would this be there ? I tried in a loop with lots of values,
> none worked.

I would have thought that this might work

  # losetup -f
  /dev/loop0
  # losetup -o -207106 /dev/loop0 data.iso
  # mount -t iso9660 -o sbsector=207106 /dev/loop0 /mnt

but on Debian 5.04 (with 109287) it doesn't.