I have a series of a 21 disk (no copy protecton issue) series. When I first got them, I made a back up of all 21 disks w/no problems. Since that time, I have made more copies and each time I make them, I get progressively more errors.

I was under the impression that since they are digital, digital copies would be an exact duplicate of my "original" as opposed to the degradation which comes from copies of copies of copies or VHS or such. And all my secondary copies have been off my original copy.

At first, it was one error on one disk only but getting into the next few copies, I got more errors on more dksis. Mostly the errors relate to something like "cycle redundency" or such. Also, I have checked and they are clean and with almost no scratches other than normal handling which do not appear to be anywhere near "bad."

Any ideas of what would cause this degredation over several times copying?

Thanks

No matter what you are using, tape, dvd, cd, whenever you make a copy, you will have some kind of loss or degredation. And for each copy of the copy that you make that will continue to decline. If you want a new copy, go back to the original, or as close to it as you can (ie the first copy that you made.)

Off hand you may think that a digital copy wouldn't degrade, but they do. The problem is no copy is 100% identical to the original. With a digital copy there is some data on the disk that is bad, then when you copy it again you will get a few more pieces of data that are bad. If you do a quality scan you will find each copy gets worse.

for the best results make a backup from the original.

I may not have been clear. I received 21 different disks. I then made a copy from each of my "original" copies and they were OK. I then made another copy of each of my originals (not a copy of the copy) and there were problems on those copies. I made a third copy of each disk, again, from my original, and there are yet more errors.

So assuming no damage to my "original" disks, what would cause some to go bad? And I don't do copy after copy so I don't think it's a heating probmem but I can't say for certain. Any kind of testing I can do?

You could scan the discs with Nero CDSpeed - that will show you if you have errors on your originals - I have to ask, are the originals pressed DVD or DVD-R's?

What media?

No matter what you are using, tape, dvd, cd, whenever you make a copy, you will have some kind of loss or degredation. And for each copy of the copy that you make that will continue to decline. If you want a new copy, go back to the original, or as close to it as you can (ie the first copy that you made.)

true for VHS taps as well as DVDs

There is some bad information being given here. Suggesting something such as 'a copy of a copy of a copy' will contain more and more errors is false. Copying a DVD is not analog, it's a digital format. If it copies it 1:1, it creates an EXACT copy, the data is identical. Do a proper backup without read errors and you can make 10,000 copies of a copy and the 10,000th copy will be identical to the original disc. Example: Successfully rip a DVD as an ISO image, all that you are retaining is the data on the disc, nothing else.

To the original topic, for whatever reason the discs are degrading. Could be poor handling or storage, poor media. Discs CAN and WILL degrade, whether they are pressed or burned media, and it goes without saying that poor quality media will have more issues with degrading.

Rip each of the discs using DVD Decrypter and make a backup of each disc onto good media. If DVD Decrypter gives you errors, increase the number of retries in DVD Decrypter or try ripping the discs with ISOBuster.

burn a copy using the same media same burner and check the check the results with nero speed test.
Digital copies of digital media is not 1 for 1.

This would be true if everything were exactly perfect. But nothing in life is perfect. A slight variance in the wattage of the laser, a speck of dust, a slight imperfection in the media, static electricity, media degrading, your anti virus starting or a spike in your system tasks, buffer problems, all can and will effect the process. Can it be done (Answer is yes). Can it be done 100% of the time (Answer is no). Too many variables.

DVD is a digital format, it copies it 1:1 unless you have read errors. A very simple and obvious way to prove theories otherwise incorrect would be to take a crappy, but readable, disc such as an old Princo with high PI/PIF errors but no PO failures. Those are RECOVERABLE errors that exist on ANY disc. Rip that disc and burn it to something higher quality, such as a TY disc. There is no difference between either disc, the data is IDENTICAL. Of course the TY disc is not going to retain the high PI/PIF levels of the original Princo disc.

AGAIN, DVD is a digital, 1:1, format. Don't confuse DVD with analog such as VHS. Variations you described will affect PI/PIF levels of a burn on a burn to burn basis, but as long as your PI/PIF levels are within recoverable specs, the data to be extracted is identical. Only when you have a burn with unrecoverable errors do you get a 'copy' with changes occuring in the data.

These are not pressed disks I'm sure.

I have had a couple of people suggest I rip my "original" as an ISO image but (remember, I'm a Newbee at this), I have been unable to find how to rip/save as ISO. If anyone would give it to me using the KISS method, that will be appreciated. I'll do the CD-DVD Speed and see where that takes me and report back.

Download DVD Decrypter, insert disc, 'Mode'-'ISO Read'. It will copy the entire disc to the Hard Drive as a single, .ISO file. You can then use DVD Decrypter to write that .ISO image to a new disc. 'Mode-ISO Write'.

Get DVD Decrypter here

As others here of expressed you will never get a perfect copy of the original disks, its impossible. You have so many variables in DVD recording and media differences as was mentioned in recent posts. Included in these varibles is digital jitter which is much higher on recorded media than a commercial DVD.

The other point I would like to make about this subject is that it's true the DVD does not degrade from copy to copy like analog but it does degrade. Digital information is a repersentation of the original analog signals. On DVD it is 16 bits of resolution. During the read process a DVD player may not read all 16 bits and have errors every once in awhile which when it is ran through a 16 bit D/A converter inside your player it will affect quality because the converted analog signal will be distorted from the original analog signal. If you make a copy of a disk that has such errors it's going to get even worse on future copies. Sorry for going on this subject, but I don't think I gave bad information about what happens on multiple DVD copies. If you can spare the discs try the test. Copy an original and then make a copy of a copy of a copy and run it through Nero CDtest you will see the error get worse on every copy. Ok I guess I will get off the soap box about this subject (it could be discussed in another thread).

Anyways back to the root problem. I have to ask did you change your media recently? What is the media? Just curious...

This 'copy of a copy of a copy' getting worse with each copy is only applicable with uncorrectable errors, CRC errors/PO failures on discs. As I've pointed out each time, unless you get actual read errors then the disc is a 1:1 copy and you can copy it an infinite number of times with zero variation in the data from one disc to the next. In ANY other circumstance, to claim that a copy of a copy of a copy of a.... has anything less than an exact 1:1 copy of the data of the original disc, any such claim is entirely false.

Otherwise, as I stated earlier, just to prove this theory bogus all you have to do is make a copy off of a disc with high PI/PIF (correctable) errors onto a higher quality disc. If your suggestion were true, copying a crappy disc like a Yi Jhan with 10,000 PIF to a TY disc would not only retain those 10,000 PIF, but it would even increase. Of course this is completely false.

Ultimately, talosian needs to run the discs through a program such as DVD Decrypter when ripping the discs, or if they are in worse shape then something such as ISObuster. Unless he encounters unrecoverable errors in those programs, the discs can be copied exactly, 1:1.

I think as far as the copy conversation goes scoobiedoo and I will have to agree to disagree on this subject. I think he is coming more from what he has seen on scans and copies and I am coming 100% from an electrical standpoint. DVD's, A/D converters, Microprocessors, FPGA's, ASICS they all have error bit rates and digital jitter (along with other nasty stuff) that will come into play with any electronic device. Bottom line is the data is never 100% the same, thats why we oversample everything to get the resolution in the high 98%. In optical drives it's not unusual to oversample 4X. BTW oversample means that the same data is read 4 times before it's acutally written. This is a very common practice in all digital designs. I think that it would take a lot of copies before you start having major problems, but the degrading is real.

I do however think that it's a great idea to go for DVD decrypter. It's a free tool and works well.

Give

Robo,

There are two issues at play here:

1. Will you get a 100% identical copy?

Clearly no. No two burns are exactly the same.

2. Will you get the exact same data off the copy?

Yes. Provided that all write errors are recoverable, you can read (make ISOs from) both discs and end up with the exact same file on your hard drive.

----------------

You're concerned with number 1, and you're correct. Scoobie is concerned with number 2, and he's ALSO correct. Don't agree to disagree, just agree that you're discussing different things.

----------------

ORIGINAL POSTER:

In your case, your copies degraded with TIME and HEAT, not with successive reads (although reading involves spinning which involves heat so I suppose...) of the disc.

Yes you are correct, although I've pointed this out in agreement with you as well, if worded differently, in each of my posts. As I've said, UNLESS you encounter read errors, the data is an exact 1:1 copy of the data. The limitations of the physical media will contain varying amounts of recoverable errors, which is what PI/PIF tests are reporting. Of course PI/PIF error levels will vary with every single disc, I've pointed that out several times already. But UNLESS you have actual read errors from PO failures (too many errors in one spot leading to an unrecoverable portion of data), the data remains identical.

To make this even simpler, all that DVDs are is a bunch of data files. Let's say you copy a disc containing 'x1gk3' as its data. Of course the copied disc is also going to contain 'x1gk3' as its data, the data remains identical. If you encounter a disc with read errors, that data will be altered and could be replaced with anything, depending on whatever program you are using decides to insert for the unreadable data. But unless you have unreadable portions of disc, the data of the files remain IDENTICAL, even if you copy it a million times. And what this also translates to is that you can be using TY, Princo, MCC, whatever discs you want, and as long as your DVD Player can read back the data on the disc properly, the end result remains IDENTICAL. The disc will play back just the same regardless of jitter levels, PI/PIF error levels, etc. If the player can read the data properly, the playback will be identical. If it can't, you get skipping, stuttering, etc.

TRUE. Anyone thinking that the data will degrade from copy to copy in the digital world believes in fairy tales.

The MEDIA can degrade and bring low-level errors, but as long as there is no actual data error when reading, the copy will always be 100% the same as the original, data-wise. That's the LAW of digital world, for God's sake! You guys who think that copies are not 100% identical data-wise, how do you explain that your documents (datasheets, text etc..) are the same when you copy them to floppies, HDs, CDs, whatever? Have you already found a character replaced by another one after 20 consecutive copies of a Winword document? *LOL* - my oldest documents have 20 years and I have yet to encounter ANY so-called "degradation" even after they've been transferred from HD to HD to CD to floppy to DVD and back to HD.
And what about defragmentation? Have you thought about that? ALL your data COPIED from an area of the HD to another? Do you think that it degrades??? *LOL* - the DISK does. NOT the data.

BUT the CD/floppy/DVD (and yes, even HD) copy can actually be inferior for other reasons. The data will be the same, but if the media is of poor quality, the readability will be problematic (jitter, low-level errors etc..) and bring issues. That's a totally different thing. The data IS THE SAME. Unless there is a reading error, and then you CANNOT retrieve the data. And the copy FAILS.

The copy succeeds and the data is identical, or the copy fails. Period.

Now, @Talosian: you don't explain what "errors" you get. But I bet you have readability problems with your copies, and these are probably caused by poor burns (bad media/burner combination). Use good media and your problems will go away.

Of course, my comments above refer to 1:1 purely digital copies, i.e. retrieving data (copying files - this includes ISO images).

Any "copy" involving some kind of transcoding (digital>analog>digital for example) is subject to unavoidable and irreversible degradation even in the very best conditions. But this is a totally different story.

You may find this other post of mine interesting.

If you mean can discs go bad with use then this part of the question is clear.

Yes if the media gets damaged in some way then it will go bad. Obviously the more a disc is handled the greater the risk. Error correction can often recover for damaged areas so you can make another copy but when all else fails you sometimes can retrieve most of the data by using bios level hardware access that bypasses windows safeguards. There are programs specifically written to do this.

This part generated some confusion because some weren't sure if you meant... Do successive generation copies of a dvd degrade more with each copy?

That would imply that generation 1 is good, generation 2 is still good but now has some errors. Generation 3 is like 2 but now has new errors.
That would make no sense. Either copy 2 is good or it is not. It cannot posess errors and be good. It can have areas that require error correction to kick in because the disc has a physical or burn flaw and is hard to read but if you make another copy and are successfull it will not pass on the reading flaw. Let's not get confused with a burn that is good but somehow through deterioration of the physical disc, dirt, scratches, exposure to heat, warping etc... suddenly cannot be read or . There is error correction on each disc and if data can't be read then error correction will be attempted. That is not because it was stored bad but because it had a problem being read.
Lets say I have a read error on generation 3 and lets say that error correction works when I am making a copy of generation 3 to generation 4. Generation 4 is good because the same physical flaw that caused the error and difficulty reading on 3 is not on generation 4. Generation 4 is good and the data is the same but the physical disc itself is easier to read so to you it is better not worse than 3 but it's also the same as generation 1 and 2. In the language of 1's and 0's (or pits, reflectance and prepits) the data from disc 1 to disc 4 is identical.

Unless I am using a blind read and write with no error checking I can't pass on errors to the next disc. But some will argue I have bad video frames isn't that bad data. No. Digital writing passes whatever crap you feed it. If I copy garbled video that won't play from my hdd to a dvd disc it will be written just as it was on my hdd and still will be garbage but an exact copy. There is a possibility of data corruption being introduced by a badly written burning program. lets say the burning app looks at a character on the source disc and somehow passes a different character to the target disc then that data corruption is introduced by a bad program but not by deterioration of the data. An application like that won't last long.
So will a disc get worse from generation to generation? I can't see how that's possible unless you deliberately bypass error correction and create errors between copies.

//Edited by Womble
No Flaming, PERIOD

Aaaaah! Thanks! Comprehensive and sensible way to put things!

Call me when you need me

Download DVDDecrypter (if you can't find it PM me). Put a DVD in the drive, launch Decrypter, choose mode>ISO>read, choose the destination and start the rip.
When it's done, put a blank in the drive, choose mode>ISO>write, browse to the .ISO (or .MDS, doesn't make any difference) that has been saved on the HD during ripping, select it, and start the burn.

It's a breeze - can be done with Nero too, but the explanations are longer