md5 of /dev/acd0

[Christoph Kukulies]

I was trying to determine a md5sum from a DVD I had inserted into a 
FreeBSD 8.0
on my Dell Inspiron 9400 notebook.

I thought dd if=/dev/acd0 | md5 would work but I got "Invalid argument".

Trying dd if=/dev/acd0 bs=1048k | md5 worked  in so far that it didn't 
yield an error
but after the DVD stopped spinning the command  hung and I only could 
bail out using ^C.

Any clues?

--
Christoph