Tech Goes Boom

Bigger CDRs from the Finder

In response to this hint over at macosxhints.com, I thought I would offer a better way to get bigger CD burns in the finder. The poster is suggesting just going around the finder and using command line utilities for burning. Pssshha I say. Let's make the finder bend to our wills.

The finder uses proxy disk images for determining burn sizes on CDs. They are located in:

/System/Library/CoreServices/Finder.app/Contents/Resources/

There you will find a bunch of proxy images with multiple CD sizes indicated by minute length and even one for DVDs. As the complaint goes, the 80 Minute CDR image offers only 670MB of burnable space. There is some consideration here for HFS overhead, but 30MB seems a little extreme. So let's make a new disk image to replace our 80 minute proxy image. Be sure to backup the proxy image to intend to mess with. Now to the good stuff. Bust open the terminal and type in the following:

hdiutil create -megabytes 700 ~/Desktop/cdrproxy.dmg -layout NONE

this creates a 700MB image on the desktop. It will actually be 700MB so make sure you have enough room.

hdid -nomount ~/Desktop/cdrproxy.dmg

This pseudo-mounts the image at a device location (/dev/something) to let us put a file system on it. Take note of the /dev/disk number that is returned as we'll be using it next.

newfs_hfs -v Untitled /dev/disk#

This puts our filesystem on the disk image where # is the number of the disk device we were given. It also names the volume Untitled.

hdiutil eject /dev/disk#

Eject our disk so we can convert it.

hdiutil convert -format UDZO ~/Desktop/cdrproxy.dmg -o ~/Desktop/cdr80-proxy.dmg

This will convert the image to read only compressed UDIF format which is required by the finder. It also gives the new image the correct name. You now have the image you need. Now you just have to move it into place.

sudo cp ~/Desktop/cdr80-proxy.dmg /System/Library/CoreServices/Finder.app/Contents/Resources

This moves the image into the right spot. It will ask for an admin password at this point.

sudo chmod 655 /System/Library/CoreServices/Finder.app/Contents/Resources/cdr80-proxy.dmg

This changes the permissions to the correct settings for the image.

sudo chown root /System/Library/CoreServices/Finder.app/Contents/Resources/cdr80-proxy.dmg

This changes the owner of the image to root as god intended. Now pop in a disc and revel in the extra space. This gives us a writable disc size of 689MB or about 19MB more than with the stock image. I tried making an 720 MB image and the finder failed with an error, so there will be no over-burning discs unless someone wants to break into the discburning framework and play around in there.