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There are a lot of differences in the quality of CD/DVD drives and their ability to recover data from a disc.

I was wondering why some drives fail to read a disc when others have no problem. While watching a regular DVD on my TV, it kept skipping. Even after squirting the drive with compressed air and wiping the disc clean with Monster Screen clean, the disc still failed to stop skipping. I then finished watching it on my computer's CD/DVD combo drive/burner with no problems at all. Good thing since the disc is out of warranty as it took too long to watch three years of the Greatest American Hero. All other DVDs on my player do not skip. By the way, most of my DVDs are TV shows. What does someone do if they scratch disc five in an eight disc set and they don't want to re-buy the entire set for one disc or buy used?

In this excerpt from Answercast #46, I look at why CDs and DVDs might not play in a certain player and problems around making backups.

Sensitive discs

As it turns out, CDs and DVDs are fairly sensitive to a number of different factors that we normally don't need to think about.

  • Things like the calibration or the accuracy of the laser in the reading device.

  • The same for the calibration and the accuracy of the laser that was used to create the DVD, if it's a read/writable one that was created in a PC.

  • It's also the case where some lasers are simply better than others.

Some DVD drives that do the reading are simply better than others and able to tolerate a higher level of error in the data.

CD data files

The data actually is encoded in such a way so that a certain amount of problems can be recovered from. But, of course, there is a point of no return. There is a point where things get bad enough that it doesn't really help and it's not possible to recover.

But yes, bottom line:

  • Some CD/DVD drives and readers are simply better than others;

  • Some CDs and DVDs are simply manufactured better than others;

  • And some CD and DVD material (the blank DVDs or the raw, unburned material) is often better than others.

So a number of things can come into play that end up resulting in exactly what you see.

Replacing a commercial CD

Now, the real question is what happens if you lose CD #5 out of an eight CD set (or you know, DVD #5 out of an eight DVD set)?

Unfortunately, there's no real answer to that. It's very much like having a three-volume printed book set and losing the second volume. There really are no options for replacing that volume other than what you've described:

  • Either ordering a completely new set;

  • Or finding a volume on a secondary market; or what have you.

Backing up CD/DVD sets

Now, the interesting thing with CDs and DVDs is that we have the technology to quickly make copies of them. Whether or not that's legal is where things come into play.

  • I'll stop and say that I'm not a lawyer; this is in no way legal advice!

With that caveat out of the way, it's my understanding that:

  • Even copying a DVD for personal backup purposes (in other words, a DVD that you own);

  • Because it involves decrypting the encrypted data on that DVD... that's actually a violation of some law somewhere.

I personally don't think that's right. I certainly believe that individuals should – as consumers who have already purchased the DVD (in order to avoid the exact scenario that you're describing) – be able to make personal copies.

So, I will leave it to you and your conscience (and in fact, the laws wherever you happen to live because it does vary from country to country) to be your guide as to what steps you might want to take (or not) to proactively prevent this from becoming a problem at some point in the future.

But those are the solutions:

  • Pretend it's a paper book.

  • You can't copy it beforehand (it's just not worth the effort of copying a paper book);

  • So if you lose the second volume of a three volume series, you're kinda-sorta out of luck.

The way the things are structured right now:

  • That same scenario pretty much maps to what's allowed to happen on DVDs and other digital material.

The fact that we have the technology to make a backup copy starts walking us into this grey area of what is legal or not; what is ethical or not; and to some degree, what is moral or not. So, that's the best I can offer you there.

End of Answercast #46 Back to – Audio Segment

Article C5731 - August 23, 2012 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

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9 Comments
Mark J
August 24, 2012 10:32 AM

You might find the series in a public library.

GREG JACKSON
August 24, 2012 8:19 PM

How about this scenario. My Toshiba Satellite P305 laptop DVD/CD drive, rarely used [less than 30 hours], now suddenly wont play or record any disk whatsoever. Occasionally, it will play an installation disk....so it does actually does work. Drivers and firmware are up to date, and I reinstalled. Under DVD/CD properties it states device is working.

The only thing that seems odd is its location.
Location: Location 0 (Channel 0, Target 0, Lun 0)
Could this be the problem? All zeros worry me for some reason.

Comments......anyone?

Sri
August 24, 2012 9:11 PM

Some producers of such CDs/DVDs do provide the facility to replace a damaged piece with a duplicate on showing the purchase proof and payment of media & shipping costs.

So, it won't do you any harm to write to the producer of that DVD along with a scanned copy of the purchase proof, asking for a duplicate of #5, and stating that you would pay the media & shipping cost.

fredpickles
August 26, 2012 8:35 AM

Greg: 0's are usually always the location so don't worry about that. I am a computer technician and there are a number of ways to troubleshoot DVD players that don't work but actally I don't spend too much time doing that as you can get a replacement drive for very cheap. If I were you I would just go out and but one and make sure it comes with a data cable just in case the cable in your PC is the problem. Having said that....you could always try swapping out parts with parts from other PC's if you want to find out exactly what the trouble spot is. Software problems are the most difficult and too involved to go through here. hope that helps.

fredpickles
August 26, 2012 8:37 AM

Greg: oops, I should read more closely. You have a laptop and replacing parts in those is not always cheap and should probably be done by a tech. My advice? Take it to your local computer tech. If it's still under warranty it won't cost anything.

DDDes
August 27, 2012 7:40 PM

Can We Readily Identify At Point Of Purchase Quality CD/DVD's Etc Ie Is There a Distinguishing Stamp or Code ?

connie
August 28, 2012 9:35 AM

@DDDes
I'm thinking it'll be stamped with a higher price! hee hee

Art
August 29, 2012 7:18 AM

There are a number of businesses out there these days that resurface dvd and cd media. The most expensive I've seen is about $6.00 a disc. Start with Game Stop, I believe their a somewhat lower cost. Also try looking for local video game stores in your area. Most are starting too offer this service. We all know how poorly people (kids,ect) handle media. Even in cases where the media is not visibly damaged (scratched,ect) its well worth a try.

steven
August 30, 2012 7:22 PM

I once bought one of those resurfacing devices and found out the hard way it remove scratches by removing the coating. I thought it would fill in the scratches. If you keep removing material, the disc will get thinner and thinner and shatter.

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