[Debburn-devel] Character sets in UDF

[Eduard Bloch]

#include <hallo.h>
* Florent Rougon [Sun, Jan 21 2007, 08:09:08PM]:
> Hi,
> 
> I'd like to create UDF filesystems for DVD-R that can be read correctly
> on Linux, Windows and possibly MacOS X. I'd like to use characters that
> are found in ISO 8859-15 (and therefore in Unicode), but if there is no
> portable way to do that with UDF, I may consider falling back to ASCII.
> 
> I read the genisoimage(8) section on character sets, but I'm still not
> sure if there is a way to do that (and I'm confused by the fact that
> ISO9660 and UDF are not treated separately; do Joliet and Rock Ridge
> extensions apply to UDF, for instance?). I have the impression that you
> can write your UDF file names with basically whichever charset and
> encoding you want, but the actual charset/coding used is not specified
> in the UDF filesystem (as metadata).

Uhm, that is the point of Unicode. If you know the encoding and it
covers the whole Unicode and this is the only allowed mode, what is the
point in additional metadata? In the current version, UDF code shares
many parts with Joliet code for filename conversion, therefore
(unfortunately) the 64/103 char filename length limit applies as well.
There are just some chars that you should not use with UDF even if they
are supported (like :\/), others including spaces should be ok.

> PS: I did read about the alpha status of UDF support in genisoimage(8).
>     I'm new to DVD writing and I thought UDF would be the right choice
>     for writing data (not DVD-Video) with potentially large files (more
>     than 2GB) to DVD-R media. But I saw there are several "competing"
>     packages for DVD writing. If you think there is a better tool to do
>     that in Debian, please comment. Thanks.

There is a problem with large files. 2..4GB are possible with UDF, but
then something goes wrong, looks like a subtle bug or design limitation
in genisoimage's code. You can disable the largefile prevention hook but
the resulting FS has broken files. I did not have time to investigate it
yet, somebody needs to step out and fix it. Competing tools like
commercial NeroLinux seem to do it well.

Eduard.
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