I seem to have read that the life expectancy of CD’s is about 25 years. I’m trying to remember, but I think I bought “Ramsey & Nancy” (Ramsey Lewis and Nancy Wilson) and “Digital Works” by Ahmad Jamal about 25 years ago.
They seem to sound OK but am I kidding myself? Has their digital information taken a rest and I’m listening to junk? Am I on a downward spiral where time is systematically taking my collection into the junk heap and I am condemned to listening to crap unless I replace it with new CD’s that I can somehow verify were produced in recent years?
I don’t know exactly how error correction on the CDs fits into this, but if you can still hear the CD, you’re probably hearing the same thing you would have 25 years ago. Unless I’m misunderstanding the technology behind it, you either hear the CD or you don’t. When the CD has degraded, they’ll be noticeable skips and gaps in the audio, if the CD is at all playable.
I think Cecil did a column about it. The gist of it was approximately this:
The actual recording will be good for a long time. However, the players are becoming outdated technology, making way for new formats. A couple of decades from now you’re going to have trouble finding a working CD player that can play your discs.
Case in point: I’ve still got a 20 year old copy of Douglas Adams’ computer game *Bureacracy *on the 5¼-inch inch floppy disk. I never did complete it. I couldn’t get past the numbered rooms in the jungle. I’d love to play the game again, but when was the last time you saw a 5¼-inch disk drive? And would it be compatible with my PC?
Audio CD’s are not all-or-nothing WRT data loss. There is an error detection/correction code so some bits can be dropped and still play fine. If more bits are dropped, the fact the the data is bad is known, and the missing data can be estimated by an interpolation scheme.
Thus it is possible that the sound could degrade some but still be listenable.
Most of the above does not apply to MP3 files. The compression process greatly increases the entropy of the data, and interpolation isn’t going to work to fill in the holes.
I don’t think the CD is doomed… yet.
The floppy disks were replaced by incompatible formats (3 1/2 inch floppy, CD-R) but the CD was replaced by the DVD, which is backwards compatible with CDs. The DVD will be replace with HD-DVD or Bluray, both still backwards compatible with CDs and DVDs. CDs will continue to be used until a new incompatible format is established. The format could be flash memory based, or more abstract like the MP3 “format,” or it could simply be a smaller form of the optical disc. As long as the standards remain backwards compatible, the standard CD will not become obsolete.
I’ve got one right here under my desk. It dual-boots DOS/Win3.1 and Win98.
As long as your PC has a free 5¼-inch bay and an IDE channel, yes. You can buy them on eBay, BTW, that’s how I got mine. Beware, though: you’ve probably forgotten how noisy they are. I know I had.
Actually, DVDs are in no significant sense “backwards compatible” with DVDs.
What has happened is that because the cost of software (iand integrated electronics & lasers) is relatively low, it’s economically possible to create a DVD player which also knows how, using completely separate software and partly seperate hardware, to handle CDs.
But don’t think that just because they look the same to the unaided eye that they are in any sense compatible below the level of gross physical characteristics.
I do think that in general, the original audio CD format & the others based on that same physical disk form factor will have a much longer half life than did, say, cassette tapes or 8 track cartridges.
But that means it may last 30 years, not 100. And 20 of those 30 have already gone by. The march of music from iTunes-to-iPod with no physical artifact is well underway. That is only going to get bigger. CD’s days are numbered.
The good news is it’s not like one fine day they’ll suddenly be unplayable for lack of compatible players. As CD players start to fade from the marketplace you’ll have plenty of ways to copy the content to whatever new storage technology is current.
Just don’t wait waay too long, like the guy upthread with the 5-1/4" game he now wants to play.
Right in front of me, actually. The Win 3.1 box I got in 1986 is the base for my monitor, and it has both 5¼ and 3½ floppy drives in it (Not to mention a 10-meg hard drive). It’s there because it was handy and also for any transcribing duties I might need.
The last time I used it, about three years ago, I stuck in a left-over blank 5¼ disk as a sacrifice (to clean any accumulated dust out) then copied a friend’s old floppy to a 3½ disc. Now, if the next box I get has no 3½ floppy drive in it I’m screwed. I guess I’ll have to keep the present one around for a two-stage conversion, 5¼ to 3½ to USB flash.
Yeah, I suspected there was some of this at work. However, how much data can you lose and still have a playable CD? A bit here and a bit there, and I suspect listeners won’t even notice the difference. But I don’t get the feeling they degrade like cassettes do, where you can hear the sound get worse and worse after years and repeated playings.
Tape degrades because it’s dragging against a head and running through rollers. It physically wears down. Eventually, the tape will get thin and stretch out of shape or break, or the magnetic part of the tape will become exposed and start to come off and you’ll have a useless tape.
I understand that. I’m asking whether a CD has a similar degradation in sound as more and more error correction is being applied–and what exactly is the limit of that error correction and how perceptible is it?
It probably depends on where and when they were manufactured. I occasionally hear about bad production runs at specific plants that are subject to premature failure.
Another issue is storage conditions. I’ve hear horror stories about the quick demise of CDs in high-temperature and high-humidity conditions like the tropics. There are microorganisms that will eat parts of the CD.
