Nero will not verify disc due to "inaccessible" file.

[franco]

I'm burning four DVDs and I will be keeping these as backups in case I lose my data or anything. However, on the final disc Nero will not verify the data. It give me the message:

"Total files = 19, identical = 18, different=0, inaccessible=1, skipped=0

Data verification failed"

Does anyone know what I can do about this. Is there any way to sort out this file or find out why it is inaccessible?

[rkr1958]

What happens if you try to open the file or copy it to your harddrive?

[franco]

Hi Rkr, Well I don't really know because I don't know which file is the inaccessible one. The situation is I have 4 short films or about 30 minutes each on my hard drive, which I author with TMPGenc DVD then burn to DVD with Nero. I don't know which movie file contains the inaccessible file, but I have played the DVD on my PC and it seems to play fine, although it is more inclined to freeze for a few seconds when I fast forward through the footage with my Power DVD player.

I had a hard drive crash a few weeks back, but was able to transfer all of these movies from my old hard drive, which was overheating. I don't know if that is part of the problem.

I am going to be sending these discs out to people and the most important thing is that they play fine. However, I always use the "verify data" function for peace of mind. If that doesn't work then I'll always be sending the DVD out without knowing for sure. Alternatively I'll have to keep checking it manually by playing it.

[rkr1958]

I've personally gotten both false verification failed and passed reports from Nero burns. I've learned not to trust them. One easy thing you could try is to copy the contents of the burned disc to your harddrive. If the files copy alright then they're readable on the disc. This is a necessary BUT NOT sufficient condition for the burned disc playing correctly on a standalone DVD player (if that's your intention). Media brand and type are significant factors for playing correctly in standalones.

[VegasBud]

An "inaccessible" file is one that can't be opened (on the dvd), so it can't be compared with the original on your hard drive. It's just another way of saying the burn failed. It has nothing to do with the integrity of the files on your hard drive.

As far as figuring out which file couldn't be accessed, you could just try opening them one at a time. When one can't be opened, you've found the problem file. It shouldn't really matter, though, unless the same file is inaccessible every time you try a burn. An example would be if the last file burned was consistently "inaccessible", in which case the media might be crapping out as it approached the outer edge of the disk. In that case, better media would probably solve the problem.

The only times I've personally gotten an "inaccessible" file, just burning it again was all it took.

[franco]

I've tried burning it about 7 times now and always get the same result. Anyway, the disc does play so I ripped the burned disc back to the hard drive with DVD Decrypter.

I then tried burning the folder DVD Decrypter made back to disc to see if Nero would burn and verify that folder but it wouldn't.

I might try that thing where you open each VOB file although I am not sure what program you need to open the vob files.

[Nelson37]

I disagree with what VegasBud said. It is certainly possible that a corrupted file on the Hard drive could result in an unreadable file on the disk. Particularly taking into account the Hard Drive crash.

Are these video or just Data disks? What is the total file size of what you are burning? Have you tried burning one-half of the folder to one disk, and one-half to another? If this works, would indicate you are having a problem burning the last part of the disk, burner or media problem and nothing at all wrong with the files. If this fails again, means a definite problem with a particular file. Re-doing the same operation only proves the problem is repeatable, now you need to Isolate and Identify the exact problem.

Since you made them, you should be able to do a simple copy back to the PC. No need for Decrypter. Copy all files and compare to the disk, or to the original folder on the hard drive that was burned. There should be one file missing. Whatever it is, it doesn't seem to be important.

Did you have the complete DVD structure on the old drive when it crashed, or just the MPG movie? What I am trying to find out is Did the invalid file exist on the drive that crashed? If you just had MPG and created structure AFTER the crash, since the disk plays that means the MPG is OK and the file is something else which was created on the new drive. However, if you had the entire structure, that would mean that the invalid file did indeed exist on the bad drive, and is potentially corrupt. ANY FILE which existed on the crashed drive should be considered suspect.

What form that corruption would take and what effect it would cause is like asking "how high is up?"

Depending on what you have to work with, start over using ONLY the Main Movie VOB files and completely re-author. The Main Movie VOB files being the only ones you cannot do without, and everything else being suspect.

[VegasBud]

franco,

VirtualDub-MPEG2 or VirtualDubMOD are both freeware that can open a VOB file.

You should probably try creating an ISO of the files with ImgTools Classic, and then burning with ImgBurn (with verification turned on). If that works, it was a Nero problem, and you're done. If it doesn't work, keep reading.

When you say you've "tried burning it about 7 times now and always get the same result", did you just use the one batch/brand of blank disks, or different brands of disk? If all the failed burns were using only one batch/brand of blank disks, you should try a different brand to rule out the disks being the problem. If you did use different brands (at least one high quality) and still got the same results, then we can rule out disk error.

To speed thing up a little, let's assume you did try different brands, and got the same burn failure (an "inaccessible" file), so the disk isn't the problem. The next step would be to try burning at a slower speed. If you are still failing to get a good burn, that pretty much just leaves the burner as the problem.

Nelson37,

Anything you burn to a disk should be an exact bit for bit copy of the original, if the burn worked correctly. A corrupted file on the hard drive should be a corrupted file on the burned disk...corrupted in the same way, at the exact same place(s). An "inaccessible" file means that the file can't be opened for reading. If the burning program was able to open the file on the hard drive, it should be able to open the file on the burned disk...if the burn was successful. If the burning program couldn't open the file on the hard drive, it would have thrown an error, and either skipped the file, or notified the user of the problem (stopped the pre-burn process). The fact that the verify function is trying to verify the "inaccessible" file means that the burning program was able to open the file on the hard drive, and thought it had burned it to the disk, but now can't open the copy on the burned disk for reading. That's a burn failure, and why Nero is reporting it as a verification error.

[Nelson37]

I still disagree. What a program should do and what it actually does are two different things. As for a bit for bit copy, just for starters the sector size is different, so no, it is not.

You have a message on screen stating "the file is unreadable". This means the program has enocuntered a condition for which the programmer decided to put that message on the screen. What that condition actually is we have no way of knowing. Does the verify check the entire file, just the first 10 bytes, file size only, use checksums? We do not know. Only way to make sure is use several different, independent methods to check the file. I have video on my HD right now that prog A will say is corrupt, prog B will play with glitches, and prog C will play with no visible problems. So is the file good, or bad? It is both, or neither. It is a file that Prog A will not handle, Prog B will handle with some problems, and Prog C will handle with no visible errors. Is prog C better at handling this particular problem, or is it just ignoring it?

When diagnosing a PC problem the simple rules are to reduce the procedure to most elementary components, and to eliminate all unknown factors, using only factors that are KNOWN to be good. Files from a crashed HD are certainly not KNOWN to be good, for that matter, neither are files from an HD that is working perfectly. When not one, but at least two or three progs are able to perform complex operations on that file can we be reasonably certain the file is good.

It is quite possible, and I have seen it happen, to copy a questionable file using different methods and get different results, depending on the software used, procedures it follows, and type of file corruption. All copy methods should theoretically be the same, but in the real world, they are not. How a prog will react to a corruption is as random as the corruption itself.

I most definitely agree that different media should be tried, that is one of those things that I just assume would be done in such a situation. Cutting the job in two halves should also effectively test this, though the problem could be with the final write-out rather than the total size.

[VegasBud]

Nelson37,

There are a few things I think we can agree on.

For example:
A file is comprised of a sequence of bits, arranged in a specific order. Each bit can only contain a 0 or a 1, a byte can only contain a value from 0 to 255. Files can have a header, be arranged in records, or have any other specific nature, but they are all just a sequence of bytes with the same range of values.

Sector size only concerns how the file is stored on a given medium. The actual sequence of bytes is unchanged regardless of how (or where) the file is stored. A file stored on a floppy is bit for bit identical with the same file stored on a cd, despite the fact that the media are storing it in different sized chunks.

Corruption in a file only causes unpredictable behaviour in a program when the data file is used. Whether an original file is corrupt or not doesn't matter to Nero. It doesn't attempt to use the file, just precisely reproduce a sequence of bytes, so no matter how corrupted a file is, it should have absolutely no effect on Nero's ability to burn a copy of it.

[Nelson37]

I agree that it shouldn't, but not that it won't.

At this point, we don't actually know that it did NOT copy correctly, just that Nero is indicating that it did not. Exactly how Nero is coming to this conclusion, we do not know.

Example - many progs, when trying to copy a file, will attempt to read multiple times, not just once. What if multiple read attempts yield an accurate copy, but the verify step only tries once to read the original file, and in that one attempt is unable to do so. Is an Unverifiable file deemed unreadable? I would not think so, but I have learned not to trust any one software package to make such determinations, there is simply too much variation in how different programs handle different problems. Perhaps the "unreadable" is referring to the file on the HD in the one attempt scenario, not on the DVD at all.

If the OP would do a straight, simple copy back to the HD, that will yield a lot of useful info.

Nero could be re-encoding or processing the original files in any number of ways, no definite info that it is not. So these data files may in fact be "in use". OP states he is burning a disk of Video, is he burning a Video disk in Nero? Two very different scenarios.

I guess I just don't trust a single program to give accurate info when some sort of unexpected result occurs, I want multiple confirmations, most particularly from simple, single-step, absolutely no manipulation whatsoever type programs and procedures.

[franco]

Hi guys, thanks for the replies. The discussion is an entertaining read, but much of it is above my head. OK, first of all I am authoring in TMPGenc and the size is listed as 4337MB. I am burning with Nero using the UDF/ISO option and I am using what I suppose are second grade media - RiDisc. I think it is important to mention I have other TMPGenc authored discs on my computer and they all burn fine to this media. I have previously burned about 35 or more discs with the same media and they work fine every time at any speed.

The files are MPEG2 files which were originally DivX files, but I changed them back to AVI and encoded to MPEG with AC3 audio. They were actually converted to MPEG files on my old hard drive. I was luckily able to get them from that drive.

OK, so what I managed tonight was to transfer all the files indiviually from a burned disc to my hard drive. Every one of them transferred OK, so they were exactly as they look in the original folder on my hard drive. I tried to burn the files I had manually transferred back to another disc, but got the same "data verification failed" error.

I then downloaded Imgburn. I read the file as an ISO with Decrypter, (maybe I should have used IMGTools as you said ) then burned the ISO to another disc with "verify" checked, and it burned fine. It did not give me any "verification failed" error in ImgBurn.

OK, so tomorrow - if you guys think it worth it - I will try and see if the VOB files open in VirtualDub.

By the way, how do I author a disc with just the VOB files and nothing else?

[VegasBud]

franco,

I'm glad to hear you got a good burn. Congratulations.

If I was you, I think I would go ahead and check the VOB files. It would be better to know now if there's a problem than after you author the dvd.

As far as authoring goes, I've been using DvdLab so long, I can't remember what else I used to use. You would probably be better off starting a new thread with a title like "Need help authoring dvd". That way you'll attract the authoring gurus, who should be able to lay out all your options, and offer better advice.

Good Luck.

[anzimike]

My 2 cents. It sounds like you are making some progress with the excellent advice above. You are burning 4337mb, which, I believe is pushing very near to the edge of the disc. Most medium to poor quality discs fail at the outer edge, where the dye can get patchy, (it's visible on my last batch of prodisc media)so you may want to try higher quality blanks or reduce file size just a bit. Also, though it's been criticized by some members on this site, I have found the TDA built-in burner to give excellent results on single and dual layer burns. Best of luck with your project.