[Debburn-devel] iso from defined session

[Thomas Schmitt]

Hi,

i am not involved in cdrkit but interested in such problems
anyway.

> OS: Freedos v1.1

This might of course become a problem with getting practical advise.


> 1. please, tell me how to make iso,( or read files), only from defined
> session (multisession dvd-rw), by using only cdrkit, without use "dd"

If i get you right then you have a DVD-RW with e.g. 4 sessions
and you want to create an .iso file which shows the state of
e.g. session 3.

I doubt that cdrkit will be of help here, except for wodim -toc
which will tell you were sessions start and end.

You would have to do this:
- Copy to a file all data blocks of the DVD-RW from block 0 to the
  end of session 3 (on Linux this would be the job of dd)
Then you need to perform the growisofs superblock stunt:
- Copy a few kB from start of session 3 to the start of the
  .iso file.
- Add the number of pre-session-3 blocks to the size field in
  the copied superblock.

See for details
  http://libburnia-project.org/browser/libburn/trunk/doc/cookbook.txt
  "ISO 9660 multi-session emulation on overwriteable media"

This would work with the last session (4) too.


> when I, instead of "-M 0,1,0" write "-M previous.iso", it works, if only ONE
> previous .iso; but what you advice, when there is SEVERAL previous .iso?

You would have to pile them up in one file and direct
genisoimage to the block address where the desired previous
ISO session begins.
 -M complete_file.iso -C session_start,file_end

session_start would be the size of the file before appending
the desired input session, divided by 2048.
file_end would be the size of the complete file, divided by 2048.

The resulting session file would then be suitable to appended
to complete_file.iso.
But to activate the new session for mounting, you next have
to perform above growisofs stunt that installs the new superblock
near the file start.

The reward of the stunt would be that from then on you can
let genisoimage load the last session via -C 0,...
  -M complete_file.iso -C 0,file_end


Have a nice day :)

Thomas