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You can put a bunch of files on a CD-R today, play them all week, then put more files on the same CD-R next week.
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Al Fasoldt's reviews and commentaries, continuously available online since 1983

T e c h n o f i l e
How to treat CD-Rs as if they were CD-RWs


July 27, 2003


By Al Fasoldt
Copyright © 2003, Al Fasoldt
Copyright © 2003, The Post-Standard

   Blank CD-R disks are incredibly cheap. But CD-RWs, the "read-write" erasable blank CDs, usually cost a lot more. Wouldn't it be great if you could treat a CD-R like a CD-RW and record on it again and again?
   Do I have good news for you. And, well, bad news, too. CD-Rs can be used just like CD-RWs in many ways. You can put a bunch of files -- MP3 music tracks, let's say -- on a CD-R today, play them all week, then put more files on the same CD-R next week. You can do that week after week until the disk fills up, recording on it over and over again.
   The bad news? You can't erase a CD-R. Once it fills up using this multiple-recording-session technique, it's full forever.
   And I probably ought to tell you the other bad news. This method doesn't work for audio CDs. You can't make them dribble by dribble.
   But in most other ways, "multi-session" CD recording works fine, but practically nobody seems to know about it.
   I think I know why. Back in the early days of CD recording, CD burners were extremely expensive -- maybe $3,000 at first, dropping down to a "mere" $1,200 after a few years -- and blank CDs were insanely out of sight. I remember my utter joy back in the early 1990s when I located a store that was selling blank CDs at a discount; I was able to buy them for $14 a disk.
   So everybody who made their own CDs treasured them as if they were gold. The idea of wasting any space on a CD was considered crazy, and the companies that made CD recorders came up with an amazing improvement. Instead of recording a CD in one session, CD burners were reengineered to allow multiple recordings on a single disk. All that was needed was to hold off on a crucial step in the recording process until the disk was finally full.
   That crucial step is called "closing the disk." When you've added all the files you want to a multi-session CD, you use a menu item or toolbar button in your CD-burner software to close the door on any more recording sessions.
   Is that cool or what?
   In the bad old days, many CD-ROM drives had problems dealing with multi-session disks, but not any more. Any computer, whether it is running Windows, Mac or Linux, should be able to handle multi-session CDs without a problem.
   Your CD-writing software should have an option for recording a session instead of a full disk. The first time you do it is actually the hardest time, because all CD-burner software is able to recognize a partially recorded CD-R disk and should ask if you want to add another session when you put such a CD into the burner.
   Aside from the two drawbacks I mentioned earlier, you should know about two other little problems:
   Each time you record another session on a CD, you waste 13 megabytes of space on the disk. That's the overhead needed when the software creates a new directory.
   Multisession CDs can sometimes confuse CD and DVD players in your home stereo system. As I pointed out, you can't make audio CDs this way, but you can make MP3 CDs as multisession disks. If your DVD player is less than a year old, it probably can play MP3 CDs, too. Make a standard MP3 CD (without multiple sessions) and try playing it. Then make one multisession MP3 CD and try it out before you make any more.