CSS weirdness with dd, dvdbackup, and mplayer -- Can someone explain?

Question

Just wondering if someone could explain what's going on in the following circumstance.  This doesn't happen for all CSS-encumbered DVDs, but I can reproduce the pattern for DVDs that it does happen to.
dd if=/dev/sr0 of=~/somefile bs=2048
dd cuts off with an error at around the 4MB mark.
mplayer -dvd-device /dev/sr0 -identify -frames 0
dd if=/dev/sr0 of=~/somefile bs=2048
dd now completes
mplayer -dvd-device ~/somefile dvd://n
the video is messed up
dvdbackup -i /dev/sr0 -o ~/somedir -n somename -M
mplayer -dvd-device ~/somedir/somename dvd://n
the video is still messed up
mplayer -dvd-device /dev/sr0 dvd://n -frames 60
This seems to be the magic trick
dvdbackup -i /dev/sr0 -o ~/somedir -n somename -M
mplayer -dvd-device ~/somedir/somename dvd://n
Now works.
dd if=/dev/sr0 of=~/somefile bs=2048
mplayer -dvd-device ~/somefile dvd://n
Still messed up.
Last edited by BrainwreckedTech (2011-10-03 17:43:32)

Answer 1

Thank you Dr but the following is true:
I placed this code in the for loop before I posted the question :
for (int i = 0; i < numSpanTags; i++) { // Loop falls through here!
      System.out.println("Span tag (" + i + ") = " + spanTags.item(i));
}And I receive 29 (The correct number) of non-null references to objects (Node objects) in the NodeList.
When I replace the exact same for loop with this code :
for (int i = 0; i < numSpanTags; i++) { // Loop falls through here!
      System.out.println("Span tag (" + i + ") = " + spanTags.item(i).getTextContent());
}Nothing prints. This discussion has never been about "clever means to suppress exceptions" it has been precisely about why a loop that has the
exact same references, exact same indices prints one time and doesn't print the other and does not throw an exception. If you can answer
that question then I am interested. I am not interested in pursuing avenues that are incorrect, not understood and most importantly shot from the hip without much thought.