Re: [MLUG - DISCUSSION] dvd db

[Mark Rages <EMAIL:PROTECTED>]

On Mon, Jun 09, 2003 at 08:09:43PM -0500, Michael wrote:
> > The first part of a DVD contains things like navigation data, so most
> > likely that's what you're checksumming, not movie data.  I can imagine
> > a case where the movie files differ, but the nav information is exactly
> > the same. Imagine something with simple menus like from a set-top DVD-R
> > recorder. at default settings.  Movie information would surely be
> > "uniq" but you'd probably need to mount the DVD (or use libdvdread) to
> > read it.
> 
> Hrm. In what case would two commercial DVD's of different movies have the
> same navigation information? I can see where it could happen in your case
> since it's possible to just stamp out the same exact menus for differing
> content but I can't see it for commercial movies. Just judging by the
> strings that come out of a head /dev/dvd it doesn't look like menu data
> but it's possible that it is.

Actually, we don't have any simple set-top recorders.  The authored 
DVD's that we make have different menus, just like ocmmercial discs.
 
> > You may want to check out MPUcoder's site:
> > http://mpucoder.kewlhair.com/DVD/ There's space in the spec for textual
> > data, but I don't know how often it's used.  There's a DVD-navigation
> > library, which I think is now part of libdvdread, whose source code may
> > be interesting to you.
> 
> I'll give it a look. Have yet to find any other data that lists any
> positive id information as being on a DVD but then it's not something that
> is documented in a way that schmucks like me can easily grok.

It's more sinister than that.  To peek at the spec is something 
like $15k and a book-length NDA.  So we have MPUcoder and the Ogle guys 
reverse engineering things, and books like DVD Demystified, which are 
great but don't have the detailed descriptions of the spec.

Regards,
Mark
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