Some surprise while "dd-ing" a video DVD...

Nancy Rudins nrudins at
Thu Jan 19 15:53:36 UTC 2006

On Thu, 19 Jan 2006, Andrea Giuliano wrote:

> First of all, thanks for you useful explanation.
> > All commercial video DVDs use UDF, not iso9660.  The linux kernel has 
> > supported UDF for several years, which is as long as it has supported DVDs.
> I believe in what you say, but actually I can mount a video DVD both as 
> UDF and ISO9660. As you say, Nautilus and "mount" unlock the DVD before 
> mount it, that's why I always can mount it.
> Yet, I don't understand why dd should not copy a stream of byte from a 
> device if they represent an encrypted video DVD. I mean, whatever the 
> bytes represents, dd should dump them. At most, you should get a big, 
> useless file, but that file should be exactly what was written on the media.
> But probably there's something I don't know. You said that mplayer (and 
> obviously xine, vlc and so on) unlocks the drive, and I guess you mean 
> "at the hardware level". If it's so, every tools like dd, tar, cpio and 
> such should fail reading the media.
> Am I right?

If I understand correctly, tar and cpio are file archiving tools.
dd does a byte-for-byte transfer, so it should capture everything
on the DVD, including encryption.

> Another question: is there something one can do before invoking dd to 
> accomplish the same without using mplayer? I have nothing against 
> mplayer, it's just curiousity.

I don't know, is there any way to mount it as a udf file system???

Kind regards,

Nancy Rudins    nrudins at

Take a sad song and make it better.  (lennon/mccartney)

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