dd to ISO from disc drive makes unmountable / unburnable image?

I'm trying to dd from a disc in my DVD drive on my MacBook to an ISO, but the image always ends up as unmountable and unburnable. The disc is unmounted when I start the process.

I've used dd many times before - in OSX and in various Linux distros - without any problems. Am I doing something wrong?

The syntax I'm using is dd if=/dev/disk1 of=~/Desktop/image.iso

With CDs and DVDs on Mac OS X, the /dev/diskN entry seems to be the raw disc contents (i.e. it includes things like media error correction data). For imaging, you want /dev/diskNs0 (or sometimes /dev/diskNs1 etc, especially on a multisession disc). If the disc has a partition table, the mountable volumes will actually be e.g. /dev/diskNs1s2.

BTW, you can also create iso-style images from the GUI with Disk Utility: select the session from Disk Utility's sidebar (note: the session will be the item directly under the disc drive in the sidebar; if the disc has a partition table, there volume will be listed separately under that, and it's not what you want), then go to the menu and select File > New > Image from . Then, select CD/DVD Master for the image format. It'l name the image with a .cdr extension, but the format is the same as a typical .iso image.