unable to dd dvd

[Patrick Asselman]

On 2013-05-01 06:08, JD wrote:
> On 04/29/2013 04:38 AM, Patrick Asselman wrote:
>> On 2013-04-28 03:40, JD wrote:
>>> Tried multiple dvd drives.
>>> dd if=/dev/sr0 of=dvd.iso bs=2k
>>> always results  in
>>> dd: reading `/dev/sr0': Input/output error
>>> 1+1 records in
>>> 1+1 records out
>>>
>>> Tried on sr1, and sr2  all fail in the same way.
>>>
>>> And yet the movie plays just fine with vlc and smplayer!!
>>>
>>> This the first time I see this.
>>> I never had this issue on Fedora.
>>
>> Could it be that the DVD is copyrighted and has intentionally 
>> corrupt sectors on it?
>> The media player simply plays the list of sectors given to it, so it 
>> will never encounter those bad sectors, whereas dd will attempt to 
>> read all sectors, so it will run into problems.
>>
>> Best regards,
>> Patrick Asselman
>>
>>
> What's somewhat interesting is that some movies I buy and back up 
> using
> dd have no problem at all. And some do, as I stated in my post.
> I would have thought that all commercial movie dvd's sold in the US 
> follow
> the same method? policy? of production.
> But I found a method to get around the problem.
>
> Thanx,
>
> JD

No, there is a whole ratrace going on between the copyright protectors 
and the people trying to circumvent it. New methods are invented all the 
time, sometimes even leading to problems for people who legally bought 
the copyrighted material (due to standards not being adherred to). This 
is why some producers have now decided to stop trying to protect the 
materials using technical solutions, thus saving money and no longer 
causing nuisance to legitimate customers.

To get some idea about the protection schemes, have a look here:
http://en.wikipedia.org/wiki/List_of_Compact_Disc_and_DVD_copy_protection_schemes

Best regards,
Patrick Asselman