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.