You don't have to write "proper" data to the disc... you can write arbitrary data by simply creating a file of appropriate size.
To start, let's assume we're using a CD to write on (rewritable hopefully, 'cause we're gonna make some coasters!!), so our desired data image size is about 700 meg.
Create a file with 10 meg chunks of alternating 0x00's and 0xff's.. this would show you the 'on/off' pattern of the data in a simple form.
Modulate the data in the image file... Disc's are written from the center out... so more data is contained in the outer (faster!) diameter than the inner, and you should be able to calculate the approximate point to change your data patterns in the image file by using some creative patterns.
Once you figure out the 'zones', you should be able to create even more complex data patterns to compensate for the rotational speed and data density on the outer 'track' (CD/DVD is actually just a tight spiral). Fun Fun Fun!!
Well... that's how I'd start, if I were looking to discover things about pattern writing on CD/DVD data surfaces.
(dang it... where's that old spindle of CD's I've never used...)
Oh yeah... the commands involved:
CD: wodim dev=/dev/sr0 -eject -v -data=MYIMAGE.img
DVD: growisofs -Z /dev/sr0=MYIMAGE.img