[openbeos] Re: ISO-9660 BFS filesystem extension
- From: "Jonathan Tarbox" <jtarbox@xxxxxxxxxxxxx>
- To: <openbeos@xxxxxxxxxxxxx>
- Date: Thu, 10 Jan 2002 19:44:26 -0600
Yes, I do understand the difference between the /dev device of the disc
and the file system that is on it.
If you read my last post I did mention that the UDF file system access
and the dvd decoding via a bit stream are both possible, just two different
points of view. I just know how it was done via the bitstream and when I
asked 'what about the file system, don't we need a file system driver', the
engineer replied "nope.. the dvd is read directly as a bitstream, no need
for a file system driver" Whether or not the UDF file system is part of
that, encompasses that, or is a seperate entity that points to a bitstream
on the DVD.. I don't know. (obviously it does point/wrap/encompass the data
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
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
that. DVDs are. What's my point? UDF, or more correctly put.. a UDF file
system driver, is not needed to play a DVD.
end of soapbox, no more replies from me on this.
-jtarbox
----- Original Message -----
From: "François Revol" <revol@xxxxxxx>
To: <openbeos@xxxxxxxxxxxxx>
Sent: Thursday, January 10, 2002 3:12 AM
Subject: [openbeos] Re: ISO-9660 BFS filesystem extension
That doesn't mean it doesn't parse the UDF data to jump to the first .vob
file
data...
Anyway the filesystem is not in the /dev/... driver, it is _in_ the data you
copy from it. (or developpers are getting more and more weird :))
That's why you can dd a bfs partition to foo.img and do things like
mkdir /foo
mount /boot/home/foo.img /foo
En réponse à Jonathan Tarbox <jtarbox@xxxxxxxxxxxxx>:
> Well.. whether or not UDF is used on the disc, the DVD decoding is done
> as a
> bit stream.. I have seen the source code, read a little of the
> official
> standards book (wow, two pages worth of it and I got a headache) Just
> going
> by what I saw.. Terminator running with overlay support within BeOS
>
> -jtarbox
>
> > > that's a personal opinion).. but most DVD decoders don't even use
> it. a
> > DVD
> > > usually is read as a raw bit stream from the device. it's quite
> > interesting
> > > reading, don't member the full details, but I'm not even sure what
> udf
> on
> > a
> > > dvd is used for.. prolly optional stuff.. /shrug
> >
> > not true. it's required of all DVD players to read basic UDF.
> > it's part of the standard.
> >
> > you can check out section 6.9 of the UDF2.00 specs (it's probably
> > a different number in other versions)
> >
> > "DVD-ROM discs shall be mastered with the UDF file system"
> > ...
> > "DVD-Video players expect media in UDF 1.02 format."
> > ...
> > "A DVD player shall only support UDF and not ISO 9660."
> >
> >
> > more importantly on this discussion...
> >
> > "Note: The disc may also include the ISO 9660 file system. If the
> disc
> > contains both UDF and ISO 9660 file systems it shall be known as a
> UDF
> > Bridge disc. This UDF Bridge disc will allow playing DVD-ROM media
> in
> > computers which may only support ISO 9660. As UDF computer
> implementations
> > are provided, the need for ISO 9660 will disappear, and future discs
> should
> > contain only UDF."
> >
> >
> >
> > -soco
> >
> >
> >
>
>
>
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