(This answer also covers “why unfinalised DVD doesn’t play on my DVD player”)

When you write to a DVD-R, DVD-RW, DVD+R, DVD+RW or other type of writable DVD without finalizing it, the directory information is written to a temporary area after the most recent recorded session. Players that can read unfinalized DVDs look at these areas in reverse order to get the most recent directory information.

You can always add more information to unfinalized DVDs, which is why it’s done this way.

However, in order to guarantee full read-compatibility with the majority of DVD players (including DVD writers, DVD burners and DVD recorders), the directory has to be written to the standard place on the disc. This process is called “finalization” and once the disc has been “finalized” (or “finalised”) it can’t be added to.

Windows Media Player 10 calls the process of finalisation “closing” instead (and doesn’t give you the opportunity to bypass it).

There’s more we could say about the process of finalization, but to keep it short- for best compatibility, write everything you want to the disc, then finalize it.

Session Close on CD Discs

The term “finalise” is also sometimes used to refer to the process of “closing” a session on a CD-R disc. When writing to CD-R discs you can have multiple writing sessions, but each session must be closed, or the data in that session won’t be readable on CD-ROM and other CD reader drives. (Audio CDs only usually support one session anyway.)

Some very early CD-ROM drives only read one session and won’t read data later added to a multisession disc- however, we don’t really consider this an issue as most such drives would be over 15 years old now!

Other CD compatibility issues

Note also that some older audio players simply can’t play CD-RW media, regardless of how they’re created. This is often due to the physical nature of the disc- the underside of CD-RW (rewritable CD) discs is less reflective than CD-R and prerecorded CD discs and older players weren’t designed with that in mind.

Have any more questions about recordable DVDs, blank CDs or anything else we sell? Add it to the comments below and we’ll consider writing an article on it!