I need to do a media comparison between a data DVD and the .iso file 
that purportedly contains the image of the exact DVD (including any 
bootable or autoload binary files, not for an Intel instruction set 
architecture).

When burning to the DVD, applications such as K3B and Nero (for Linux) 
will do a verify of the burned media.  My understanding is that these 
applications go through the device driver and device controller 
hardware/firmware that may be applying error correction to the raw bit 
stream; any such detected "hardware media" errors typically are reported 
by the driver to a log file, but typically (if corrected) do not cause 
the application to fail.

If one mounts the .iso file, by a command similar to that below,

# mount -t iso9660 -o ro,loop=/dev/loop0 /files/dvdimage.iso 
/media1/virtualdisc

and likewise has the physical DVD in the DVD drive and mounted from, 
say, /dev/sr0

will a diff /dev/loop0 /dev/sr0 suffice?

Is there a utility that will do the same thing that Nero would do as it 
verifies after burning, but not requiring the burn -- that is, verify a 
DVD against an ISO image file?

If /dev/sr0 were mounted on, say, /media/someDVD, and the ISO image file on
/media1/virtualdisk , is there a utility or script to do a "bit by bit" 
comparison via the mount points (not just the "raw" mount as /dev/sr0 )?

Yasha Karant