[openbeos] Re: ISO-9660 BFS filesystem extension
- From: "john 'soco' robinson" <soco@xxxxxxxxx>
- To: <openbeos@xxxxxxxxxxxxx>
- Date: Fri, 11 Jan 2002 09:59:19 +0100
> somehow as the vob files are the a/v streams) I didn't have the time to
> read through the 3-4 MPEG standards manuals. I just know the entire
it's not part of the MPEG standard. it's part of the DVD standard. the same
way that unlocking hte DVD media isn't part of the mpeg* standard.
> decoding process (not just the movie, the menu and options as well) is
done
> as a bitstream.
>
> example, I copied the first 100 MB of a DVD to a file via the dd command,
> the dvd decoder I was using (beta/experimental/no longer available to me)
> could play it just fine.. at least till it hit the 100MB mark. Now try
to
> do the same with a BFS partition.. dd the first 100 MB of the partition to
a
> file and try to mount and use it, no go. It's not designed to work like
lol. in theory if you have a decent decoder the same will happen
for all MPEG files including mp3. all are flat bitstreams and the
decoders are supposed to be designed to ignore bad blocks.
(even be's mp3 decoder could do it.)
i could make you a DVD where dd-ing the first 100megs of it won't do shit,
the same as the BFS didn't do anything. however, yes you can read it
straight
sector by sector until you run into the bitstream. when you start getting
things
like DVD+RWs and such with other things on them, it'd probably be a good
idea to actually comply with the spec. :) the dd-ing is hardly an accurate
test,
but if you truly want, you can ensure that a MPEG2 video player can work
with a VOB file on any filesystem if you just ensure that your data is for
sure
in the first 100 megs of space. (or whatever number of data you decide
to dd off)
i can't tell you exactly why UDF is part of the standard, i don't know. i
don't
know what things were planned for the future or what they were anticipating.
i just know it's required to be fully compatible with all DVD's, not just a
large
number of them. maybe it's to ensure i don't throw in my Suse DVD and try
to play it. i really don't know the answer. i can tell you that it's part of
the
standard for some reason.
-soco
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