[TriLUG] why can't I dd an audio CD?

[Joseph Tate]

On Fri, Dec 26, 2008 at 12:13 AM, Joseph Mack NA3T <jmack at wm7d.net> wrote:
>>> I would assume then that video DVDs are also different from
>>> data DVDs in much the same ways.
>>
>> Fortunately they got it right with DVD-Video.  It's just a
>> restricted case of DVD-ROM and uses the same, strong error
>> correction.  You *can* "dd" a DVD-Video disc.
>
> hmm Commercial DRM'ed DVD movie
>
> dd if=/dev/dvd of=foo.out
>
> about 2M of output
> .
> .
> Error: Illegal request
> Read of scrambled sector without authentication.
>
> I take it that you're talking about DVD-Videos you make
> yourself then
>

A couple of years ago, DVD producers (Pixar and Disney were the first
I encountered) created an abomination of the standard called ARccOS,
(see http://en.wikipedia.org/wiki/ARccOS_Protection).  This rendered
the UDF file system busted for file system access, but most players
are able to skip the injected bad blocks without users noticing.  This
is probably what you're seeing.  Of course it didn't take long for the
DVD ripping software makers to bypass this misfeature.


-- 
Joseph Tate
Personal e-mail: jtate AT dragonstrider DOT com
Web: http://www.dragonstrider.com