Windows CD-RW Recording FAQ

posted: June, 19 2003

By Jeff Sauer, Matt McMakin & Becky Waring

We know you've got questions about CD-RW, especially about how it compares to regular CD recording, and its compatibility with various players. CD-RW is one of the hottest topics newsletter readers ask about. So we've collected all the answers for you in this handy guide. Read on to become a CD-RW expert!

What is CD-RW?

Once informally dubbed "CD-Erasable," CD-RW is the official acronym for CD-ReWritable. CD-RW uses a phase-change technology that allows a drive's laser to change the state of the recording layer and thus the physical properties of a disc in order to write and rewrite data to the same disc. CD+RW is a slightly different physical recording format supported by certain drive hardware, but the discussion here applies to both CD-RW and CD+RW.

What does the phase change change?

To the casual eye, CD-RW discs look much the same as CD-ROM or CD-R discs, but they are made of an alloy base and a polycrystalline recording layer. That polycrystalline layer can exist in either an amorphous or crystalline state, similar to how water can exist as either liquid or solid ice. When recording data, a CD-RW drive's laser literally heats the polycrystalline and changes it to an amorphous state. At lower power levels, the laser "erases" the disc, returning the polycrystalline to its crystalline phase. At its lowest power level, the laser simply reads data, much like a CD-ROM drive.

How does CD-RW compare with CD-R?

While CD-R, or CD-Recordable, is a "Write-Once, Read-Many" format, CD-RW discs have the potential to be written, then erased, then written to again. CD-RW media is generally more expensive than that of CD-R (from 50 to 200 percent more, although CD-Rs are often extremely inexpensive when on sale), but are reusable. Burning CD-R discs is faster, though how much depends on the specific drive.

Which CD type is best to use when burning computer backups, CD-R or CD-RW?

For permanent archiving, CD-R is preferable. Discs are less expensive and cannot be erased accidentally. However, CD-RWs are excellent for frequent rewriting of your newest data over previous backups, in addition to intermittent full archives. If speed is an issue, CD-Rs are faster.

Can I use a CD-RW disc to make audio CDs?

Relatively few audio CD players, especially those manufactured prior to 2000, can read CD-RW discs. Some newer players, particularly DVD/AudioCD players, carry a CD-RW compatibility label and can play audio CDs recorded onto CD-RW media. However, CD-RW drives can also burn CD-R discs for creating audio CDs. So it's best to use CD-R for audio unless you know your player supports CD-RW, and you expect to want to rewrite the disc in the future.

Where can you play back CD-RWs?

Generally, CD-RW discs can only be played back in CD-RW drives, "MultiRead" CD-ROM drives, and specific DVD players carrying the CD-RW compatibility logo. CD-RW drives, on the other hand, can read and write CD-Rs and read CD-ROMs and Audio CDs.

Do you need to "format" a CD-RW first? How?

If you are writing standard ISO 9660 data to a CD-RW using Easy CD & DVD Creator, there is rarely a need to format a disc prior to use. A small percentage of new discs, however, come pre-formatted for UDF and these would need to be erased prior to use in Creator. Indeed, the more common usage of CD-RW discs is as UDF-formatted discs that appear in the Windows Explorer as typical disc volumes, supporting drag-and-drop and deleting individual files. Easy CD & DVD Creator 6.0 includes a packet-writing application called Drag-to-Disc that is available from the Creator home window, and from the taskbar or Start menu. Drag-to-Disc allows users to record information to a CD or DVD simply by dragging and dropping files to the Drag-to-Disc application icon, or to the drive letter of your recorder. Drag-to-Disc will automatically format a CD when you first copy information to it.

What is the difference between recording a CD-RW within Easy CD & DVD Creator 6.0 and with Drag-to-Disc?

Creator effectively treats CD-RWs the same as it does CD-Rs, recording ISO 9660 data onto them, with the significant exception of being able to erase the entire disc and start again. Drag-to-Disc, on the other hand, is a UDF formatting utility that allows CD-RW discs to appear in the Windows Explorer just as if they were a floppy or hard disk drive, supporting all the same drag-and-drop functionality, and the ability to delete individual files. Creator itself does write to UDF volumes.

What happened to DirectCD, and how is Drag-to-Disc different?

Drag-to-Disc is backwards and forwards compatible with DirectCD, a similar UDF writing utility included with earlier versions of Easy CD Creator. This means that discs written with DirectCD are readable with Drag-to-Disc, and vice versa. However, some media types (such as DVD-RWs) are supported by Drag-to-Disc that may not be supported by earlier versions of DirectCD.

What is UDF?

Universal Data Format is an ISO-compliant file system, endorsed by the OSTA (Optical Storage Technology Association), and used by packet-writing and other optical recordable disc technologies, like DVD. Drag-to-Disc uses UDF 1.5 and packet writing to give CD-R and CD-RW drives the effective usability of a large floppy disk. Computers require UDF reading software in order to read UDF-formatted discs. (Roxio's Drag-to-Disc for Windows includes a UDF reader, but you may not be able to read UDF discs on a Mac without special software, so be careful if you need to exchange data cross-platform. More on this below.)

What is packet writing?

Packet writing is a method of writing data in small increments surrounded by run-in and run-out blocks, rather than in a single large block as was the case with early CD burning. Packets can be a variable or fixed size depending on the application. The small increments are what allow the CD recorder to be used like a floppy drive.

Where is Drag-to-Disc, and how do I get it to work?

Drag-to-Disc is available from the Creator 6.0 home window, and from the taskbar or Start menu. You can also also select Drag-to-Disc from the pop-up menu by right-clicking the drive letter of your recorder. Drag-to-Disc also has an application icon that can be made to appear on the user's desktop.

What operating systems do Easy CD & DVD Creator 6.0 and Drag-to-Disc work with?

Windows 95/98/Me/NT4/2000/XP. A minimum of Easy CD Creator version 5.1 is required for Windows XP.

What is the difference between Formatting and Erasing a CD-RW?

Formatting a CD-RW typically refers to formatting the disc for UDF. Depending on your recorder and media (some come preformatted for UDF), you may or may not be asked to format when inserting a blank disc. If not, it happens automatically. Erasing a CD-RW returns the entire disc to its native crystalline phase, thus removing all data.

Can I erase/replace individual files on a CD-RW in the Windows Explorer?

Yes, if the disc is formatted with Drag-to-Disc.

When are the files actually written?

With Drag-to-Disc formatting, files are written to disc on the fly as you drag-and-drop them from the Windows Explorer.

Do I have to "finish" a CD-RW disc?

There is no manual finish to CD-RW discs; both Easy CD & DVD Creator and Drag-to-Disc finish discs automatically. In Creator this is done as the final stage of burning a disc. With Drag-to-Disc-formatted discs, a small amount of finishing data is written to the disc whenever it is ejected.

I've read that Easy CD & DVD Creator can't use CD-RW discs that have been formatted by Drag-to-Disc. If that's true, what is the use of Drag-to-Disc formatting?

Drag-to-Disc formats discs for the UDF file format. Doing so allows those discs to be recognized by the Windows Explorer as typical disc volumes, supporting all the same drag and drop functionality and the ability to delete individual files. You can physically use Drag-to-Disc formatted discs in Easy CD & DVD Creator, but you will need to completely erase them first to remove the UDF formatting. However, the more common usage of CD-RW discs is as UDF volumes.

If I have formatted a CD-RW disc with Drag-to-Disc, can I work directly from that disc; opening documents on the disc, making changes, then saving back to the same disc?

In theory, a Drag-to-Disc UDF-formatted CD-RW disc should be usable just like a giant floppy or other rewritable volume, supporting direct use from within desktop applications. And, most of the time this does work flawlessly in practice. However, working directly from within applications can occasionally produce errors and corrupt files. To be safe, it is still advisable to save important data to a local drive, then move it to a CD-RW disc from the Windows Explorer.

In general, what are the things to note about using CD-RWs within Easy CD & DVD Creator, as opposed to CD-Rs?

Most confusion about this topic stems from the two formatting methods for CD-RW: treating them as "CD-R-like" ISO 9660 volumes in Creator, or formatting them for UDF with Drag-to-Disc and then working with them in the Windows Explorer. A formatted UDF disc cannot be used in Easy CD & DVD Creator without being re-formatted and vice versa.

How can I exchange discs with Mac users and those without CD-RW drives?

If you expect to share your UDF CD-RW discs, you can add information before ejecting that makes them readable on other systems. Choose Settings from the Drag-to-Disc window, and check the box marked "Make this disc readable on any CD-ROM or DVD-ROM drive." Then click the Advanced button. Next, choose UDF if you will only be sharing with other Windows users, and ISO if you will be sharing with Mac or UNIX users. ISO is also readable by Windows, of course.