[Debburn-devel] wodim -msinfo fails?

[scdbackup at gmx.net]

Hi,

Mike Cornelison:
> > genisoimage -R -q -print-size  /some/files   >>>  NNN
> > genisoimage -R /some/files | wodim -multi dev=/dev/dvd -tao tsize=NNNs -
Eduard Bloch:
> I would be surprised if TAO really worked with DVD.

Not with wodim. I made experiments about two months ago.

growisofs proved the pseudo-TAO capabilities of all single
layer DVD media quite a while ago.
I myself did not strive for anything inferior. I'm a TAO addict. :))

My own project cdrskin does not strive for the very convenient
multi-session stunts of growisofs with DVD-RAM, DVD+RW
or even with disk file based ISO images.
But it provides multi-session capabilities where MMC-5 and
the drives permit.

I.e. with DVD-R, DVD-RW or DVD+R the gestures attempted
by Mike Cornelison should succeed on cdrskin-0.3.4 or newer.
See
  http://scdbackup.sourceforge.net/man_1_cdrskin.html#EXAMPLES
  "Write multi-session to the same CD, DVD-R[W] or DVD+R:"
  "Get multi-session info for option -C of program mkisofs:"


------------------------------------------------------------------
Background info:

TAO-like behavior can be achieved with DVD-R[W] not by
Write Type 01h "Track-At-Once" in mode page 05h but by
Write Type 00h "Packet/Incremental" as 32 kiB fixed size
packet writing.
The write type with DVD+R is not controlled by mode page 05h
but is effectively a 32 kiB packet write.
On DVD+RW, DVD-RAM there is 2 kiB random access, on formatted
DVD-RW there is 32 kiB random access.
None of them needs a predicted track size.

On DVD+RW and DVD-RAM there is no notion of sessions and
tracks. So there is no way to learn about the last session
from any media structure.
In source file growisofs.c , Andy Polykov states that
in this case he interprets the existing ISO-Filesystem data
on media to find the start of the free space and that he
afterwards manipulates the existing ISO-Filesystem header
at the start of the disc to point to the newly added
pseudo-session.

> > wodim -msinfo dev=/dev/dvd  >>>  0,0

So there is only hope to get -msinfo for DVD-R, DVD-RW and
DVD+R ... unless one puts emphasis on ISO-9660 file systems.

For my collected knowledge about DVD writing on SCSI level see:
http://libburnia.pykix.org/browser/libburn/trunk/doc/cookbook.txt?format=txt


Have a nice day :)

Thomas