Re: [parchive-devel] Par2 Par3 comments.

[Michael N. <mik...@gm...>]

Re M. Niedermayer:

PAR + TAR/PkZip: Sorry, I must have been unclear.  I had, while working on
the Par2 spec, recommended getting rid of multi-file support and having
users use TAR.  However, the Par1 developers recommended strongly that I
keep multi-file support.  So, it was kept in.  I believe we should keep
multi-file support.  I think that supporting a few thousand files is fine;
if users need more than that, they can use TAR or PkZip.

Unicode: I think it is better to be backwards compatible and use 16-bit
Unicode than to be non-compatible and use UTF-8.

Use Cases:
* Streaming (e.g., NASA or multicast): These usually have burst errors.  The
best way to get around it is randomizing the order of the input slices (to
some extent) and by interleaving recovery slices before transmission.  I
don't think we should support streaming, but it is something to think about.
* User-level file system (as sister project): I've liked this idea for a
while, but I think it is well beyond the scope of PAR.  It only works well
with XOR-based LDPC, and it has many different requirements than PAR.
* Verification/redundancy for file distribution: I'm not sure my own ideas
were really clear. :)  My thinking was with people who distribute binaries
and indicate on a webpage that "the valid MD5 hash is XXXX:XXXX..." to
prevent malicious modification.  If someone included a Par2 file with the
binary, a person could just download and double-click on the Par2 file to
verify the binary and MD5 hash.  This is supported now by the file spec;
however, I don't know if GUIs or the reference implementation print out the
MD5 hashes of the files.

Neidermayer, your comments got truncated again.  I doubt it is my end
(Google Mail).  Do you know what might be causing it?

Mike



On Mon, Jun 14, 2010 at 4:04 PM, Michael Niedermayer <mic...@gm...>wrote:

> On Mon, Jun 14, 2010 at 12:48:21PM -0400, Michael Nahas wrote:
> > PAR + TAR/PkZip: I agree with P. Cordes, tools for using TAR on Windows
> > exist, as do tools for using PkZip on Unixs (Unices?).  If someone needs
> > more than 2^16 files, they can use one of those.  We don't need to say
> > which.
>
> I think i missunderstood the suggestion.
> The way i understood it was that we could support just 1 file in par3 and
> use tar for multiple file support (like for example gzip/bzip do as well).
> For this case using pkzip on windows and tar on linux would have meant a
> annoying incompatibilty.
> if its just for a rare case of >65535 files this is no longer a real issue
>
>
> [...]
>
^^^^^^^^^^^^^ Truncation?


> > UTF-8 Support: I wish it was easy as saying "Unicode has been around for
> > ages" to say that support exists.  Obviously, Java supports it.  It looks
> > like GNU has a C library.  (
> > http://www.gnu.org/software/libidn/manual/libidn.html#Utility-Functions)
>
>  ... [Cut by Michael Nahas]

> > Any others?  Any arguments in favor/against one of these?  Any ideas on
> how
> > to implement redundancy for a single-disk backup?  Should we have a
> sister
> > project for a user-level file system?  (Sounds expense with RS codes.)
> >
> > Also, the Par2 spec included optional packets for containing input file
> > slices.  So, people would not have to use a file-splitter, like RAR, for
> > Usenet or multi-disk backups.  Do we want to push to make those packets
> > mandatory?
> [...]
>
^^^^^^^^^^^^^^^^ Truncation?


>
>
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Breaking DRM is a little like attempting to break through a door even
> though the window is wide open and the only thing in the house is a bunch
> of things you dont want and which you would get tomorrow for free anyway
>
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.9 (GNU/Linux)
>
> iD8DBQFMFoszYR7HhwQLD6sRAq6xAJ9HZbLRYFa96bdIYy9uGbJVMkZKcwCdFeVq
> 74pvBmxzPFhxV56Ggw5/Ttg=
> =tEoX
> -----END PGP SIGNATURE-----
>
>
> ------------------------------------------------------------------------------
> ThinkGeek and WIRED's GeekDad team up for the Ultimate
> GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the
> lucky parental unit.  See the prize list and enter to win:
> http://p.sf.net/sfu/thinkgeek-promo
> _______________________________________________
> Parchive-devel mailing list
> Par...@li...
> https://lists.sourceforge.net/lists/listinfo/parchive-devel
>
>