Read the title from a DVD?

You could use blkid for that:

DVD_NAME=$(blkid -o value -s LABEL /dev/dvd)

(you need to have read permission to /dev/dvd for that).

Or:

DVD_NAME=$(udevadm info -n dvd -q property | sed -n 's/^ID_FS_LABEL=//p')

for which you don't need any special privilege (udev (running as root) queries the label name using blkid and updates a device database which you query with udevadm).