Image file definitions


i have some questions about some image file types (i hope this is the right forum)

I think you know the following image types:

clone cd images (img,ccd,sub)
alcohol 120% images (mdf,mds)

So know i spend my time to google for specifications/structure defintions of these image files but without look.

So now, does somebody know where i can get some information (the support of the software said it is not for public), because i am wondering how other free tools get this working?

Thanks for help.


I’m not an expert, but for what I know both CloneCD and Alcohol image file formats are proprietary and I don’t think that Companies will give you detailed specifications about their commercial products :wink:

If I’m not wrong, you can find detailed information only for public formats like ISO.

Yes and thats the problem and why i am wondering how other “normal people” get those functions in their free products ?

Nobody has an idea ?

These images or image files are files composed of data that has been organized within the structure of a file system. Operating systems need some kind of a file system to be able to make sense of data on a medium; to be able to read from it and write to it. Windows uses the FAT32 and NTFS file systems for hard drives. Unix and derivatives use other kinds of file systems for hard drives. The files systems that have been agreed upon by manufacturers for optical discs (CDs & DVDs) can be recognized by all these operating systems. It makes them very portable.

So you can burn data to CDs or DVDs in any form you want. But unless you organize the data into one of the agreed upon file system standards for optical discs, your operating system will not be able to recognize the data on it and you will not be able to do anything with it nor will anyone else.

The 1st file system for optical discs was created for CDs. It’s most often referred to as the Yellow Book Standard. It’s also called the ISO9660 Standard. Image files structured according to this standard are often called ISOs and have the file extension of dot ISO. It doesn’t matter what file extension it has. You could use dot xyz as long as your burner software will accept it. The ISO9660 fs is also widely used for burning non-video data to DVDs.
You can download the specifications for this file system at

The 2nd major file system created for optical discs was the Universal Disc Format (UDF). It was supposed to be the promised land of file systems for CDs and especially DVDs. But in the cold cruel world things haven’t worked out that way and pure UDF is the least used of the file systems for optical discs. You can download the specifications for this file system at

The 3rd major file system was created exclusively for DVD-Video. It is a hybrid of the first two; that is, in a highly simplfied way, a UDF wrapped in an ISO9660. There are several flavors of this format. You can download the specifications for one of the flavors at

So now you have all the information you need to code up your own CD/DVD image file creator program. But it helps to have a few examples of how to do it. There are a number (small) of open source programs that create ISOs.
You could peruse these to see how it’s done. The ones I know about are all for Linux. But optical disc file systems are independent of operating systems so technically it shoudn’t matter. But if you need it for windoze, you have to parse out the Linux APIs and use Win APIs.

One example of an open source program that can make ISOs is the libburnia project at
… google for more examples.

if you google on mdf, mds you will find information on them …

img is probably an ISO file for a CD with ccd and sub being separate
files containing the sub channel and other information.


Re : clone cd images (img,ccd,sub) and alcohol 120% images (mdf,mds)

I don’t support programs from these software companies that take and use open source freely published standards and then create their own proprietary formats from them and sell it for profit. Their formats, based on my use anyway, are no better than the published standards, they are just different so that you must use their program to burn them with.

Don’t support these programs. There are so many freeware (if not open source) programs that will do everything and more than most/any ? of these
commercial CD/DVD programs you don’t have to.


Are you sure that free specifications support storing DPM or Twin sectors information ?

No. You are right. Of course none of the digital protection schemes for either CD-Audio or DVD-Video are openly published. That’s their whole idea ; )

But most, if not all, of these schemes have been cracked and are available in freeware (if not open sourced) programs.

Again regarding the original posters question about files of type
img, ccd, sub, mdf, mds
one example of a freeware program that handles all these is
Lightning UK’s ImgBurn program at
www dot imgburn dot com


Oggi here’s some stuff I found
I was curious about these file formats myself

Alcohol 120% mds, mdf

MDS= Media Descriptor Sheet - A file created which holds a description of a
CD image file
MDF= Media Descriptor File - Holds the image of a CD

“On copy-protected CDs/DVDs, one common technique in copy-protection is to use intentionally defective sectors on the CD/DVD. The .mdf/.mds format allows defective sectors to be stored, whereas other popular formats such as .iso, .bin and .nrg do not.” quote from a forum – forgot which

a description and API of the contents of mds/mdf files can be found at

clone cd img, ccd, sub

img = standard ISO 9660 format file
sub = raw sub channel information
ccd = clone cd control file

“CCD is the data information for the image file, in CloneCD format. It’s kind of like a proprietary version of a CUE file in a CUE/BIN set. The IMG is the actual data, kind of like the BIN file in a CUE/BIN set. The SUB file is a copy of the subdata track; in an audio CD this is usually used for timing data, so when you fast forward your CD player knows where it is in the song. A lot of game companies screw around with this data, and use it for their copy protection; if the program doesn’t get the subdata codes its looking for, it knows you’re not using the original CD.” quote from another forum – again forgot which

a little more information on the contents of a .cdd file can be found at