WinMX Corrupt Downloads

[Capn_Yzerman]

Hi All,

I was hoping someone here could help me with a problem I have been running into lately. Whenever I download a large zip file and it completes and I try to open it, winzip reports that the zip file is corrupt and invalid.

This only happens when I download large zip files. MPEGs, AVI's, small zip files all work fine. Kaza Lite and EDonkey zip files are just fine. Anyone have any ideas? My theory is that since this is only happening to large zip files (600 + Megs) in WinMX that somehow, the files get corrupted when the computer shuts down.... The smaller files (avi's mpegs and small zips) usually get completed within 12 hours (that is usually how long I leave WinMX on) but the larger ones of course are not complete, so when I shut down, I am thinking that is what is doing it. I have tried to make sure that I shut down WinMX properly and everything, I don't just turn off the computer or reboot it. It is still happening though.....

Any ideas guys? Recently I upgraded to Windows XP Pro from Win ME and then a day later I upgraded to the current version of WinMX.

My computer is:

P3 933
384 megs of ram
Cable Modem
Running Windows XP Pro

Any ideas would be appreciated guys.

Thanks,
CY

[SiANiDE]

Okay ... corrupt .zip files! First of all, here is a bit of background into some (but not all!) of the reasons why a zip file maybe corrupt:

1. Some b*stard has sent you a fake file ... we all hate it!

2. The file has corrupted an download because:

(a) the dowload has been broken due to a dropped connection ie when your dialup times out/your Alcatel Speedtouch goes mad/you disconnect the plug in the wall/your computer crashes/ et cetera ad infinitum.

(b) this may sound mad, but - when your download rate is too high ... on very fast connections ie >4mbit the information can corrupt due to the sheer speed of the rate at which it is received (i promise you this is a fact i have discovered first hand and has been subsequently verified on the net by various sources)

(c) the file was corrupt on the other users computer before it even got to yours

Anyway, enough of the theory, what can you do about it?

You can't do anything about a fake file, the data simply isn't there! What you can do to prevent this though, is once some of the file has downloaded, and the transfer is labelled as incomplete, to open the zip file in WinRAR. WinRAR is more intelligent than winzip, and if a zip file is corrupt or incomplete, it will still open the file and you can browse the contents. If winRAR doesn't allow you to view the file names of the files within the corrupt archive, you can pretty much guarantee it is a fake. To double check, drag and drop the file over mediaplayer (most people make fake files by renaming a movie or an mp3 track) ... if this is the case, a crap movie/song will play! I'll bet my MP3 collection that these are the most effective ways of checking a file's integrity.

If the file has corrupted on download, there is a neat little trick which I taught myself to kinda repair the file [ (c) SiANiDE ;-) ] :

Open the file in winRAR, and click the test button. Make a note of at what point in the test process the file was corrupted (as a percentage). Multiply the percentage - 2% by the total file size, and divide by 100. Using a file splitting program, truncate the file to the size which you have just calculated above. Resume the file from this point ... hey presto! a working file! Obviously, if the file corrupts after say 1%, just delete the file and start again. :-(

The reason why this tends to happen to compressed archives more than mp3/mpeg files is because every time you open a zip file, a very brief check is done to ensure the file is legit (CRC verification is the next step). With media files, AFAIK, there is no such checking. This is because data integrity is not as vital with media files (let's face it, your ears/eyes can't pick up errors half as well as your PC can ...)

Anyway, that's enough waffle from me!

[Snifer]

may be the file has the wrong extension... if it's a large file, then may be it's a .iso file. i think i've seen .iso files renamed to .exe in kazaa (fasttrack) so they'll appear in the software searches, may be it's something similar in winmx. try renaming it to .iso and open it with the latest version of winrar.

[SiANiDE]

errr ... don't yah mean open the .iso file in fireburner/nero? I didn't know winRAR could open ISO images! What version of winRAR are you using? winRAR 4.0?



;-)

[Snifer]

Originally posted by SiANiDE
errr ... don't yah mean open the .iso file in fireburner/nero? I didn't know winRAR could open ISO images! What version of winRAR are you using? winRAR 4.0?



;-)

well... if you want to burn a .iso you can use your favorite cd-burning app... but if you want to check if it's a valid .iso only and you have winrar installed, then use it!

from whatsnew.txt (winrar 3.00):

12. Added support for ISO9660 (.iso) file format, which is widely used to store CD images. WinRAR is able to browse and unpack contents of ISO files. WinRAR also supports Joliet extension of ISO9660 and displays long file names inside of Joliet CD images.

[SiANiDE]

Ok, so you have just d/l'd an .ISO image ... you try to open it in winzip ... it don't open ... why do you want to check it is uncorrupt? Surely just burn the mudda and free up some harddrive space for your next app? Like so what if it is corrupt and you lose a CD-R out of it? Faster than verifying it! How much is your time worth? i think for 20p I'll just burn it thanks.

No offence, but be logical ... In the world of filesharing ...

Time is MONEY!


;¬)

[Capn_Yzerman]

Thanks for all the help guys. I was hoping to hear that this was a bug in WinMX though. Damn. :-)

I will try everyones suggestions. It just seems that if I exit Win MX, whatever zip files I was D/Ling and not complete at the time will be corrupt, the ones that complete without being interupted by me shutting down/rebooting, are fine.

I am going to re-install Win MX
ChkDsk my drive

and see what happens.

Thanks for all the help, everyone.

On a good note, I have been able to leave Win MX up for 4 days without a crash. This version and XP rock.

CY

[basementwaste]

Hi,
I originally posted about this about a month and a half ago here:
http://www.zeropaid.com/bbs/showthread.php?threadid=2528

The problem only started once I upgraded to 3.3. For me its not if I have to shut down the program, and resume the download. I downloaded a 1,003,124,325 bytes size file in one night without shutting down winmx, and its still corrupt. Lots of people have it, so its gotta be real. There wouldnt be 50+ people who would keep a non working 1GB file. I open it in winrar. There are 3 ISOs, but CRC fails on every one of them if I try to extract or test.
It downloaded at 80kb/s at the fastest, so its not corrupted by downloading too fast. I have had no problem with this ever until winmx 3.3, 3.31. I'm gonna try a few more random things, but I cant think of anything really to help. I do think its a winmx problem, though.

I am using AMD Athlon XP 1700+, 512 MB DDR, WinXP Pro, Comcast Cable

[SiANiDE]

I've had a think about this problem which some users seem to be having with corrupt zip files, and there seems to an obvious issue which hasn't been raised yet.

Everything, yes even with computers, is based upon probability. If we take the situation of downloading a file (ie a zip file), then, for every byte which is downloaded, there is a probability that one of those bytes will be corrupted. Maybe, we could say, a 1 in 10,000,000,000 chance (I don't know exactly what it is, but we use an approximation). That basically means for a 1gb file, there is a 10% chance that one of those bytes is corrupt. As mentioned in a previous reply, if just one byte of a zip file is corrupt, it could wreck the entire archive (unlike, say mp3 files or avi files).

Now then, you notice that most users complain about large files being corrupted, the reason why this is, is because the more bytes downloaded per file, the greater the probability of the file being corrupted. It may just be that users don't complain about smaller files, since they are easily redownloaded in a shorter time. Is that the case? Do users suffer from CRC problems with small files? I, for one have never had a CRC error on a small files (and only maybe three times ever on a >1gb file).

At the time of writing this, winMX has only been out nine days, which I don't think is a long enough period to give it a fair trial. Maybe after a few more weeks of use, a better informed decision could be made.

Let's face it, the corrupt files could just be an unlucky run! Remeber ... it's all down to probability.

[SiANiDE]

Originally posted by basementwaste
I downloaded a 1,003,124,325 bytes size file in one night without shutting down winmx

Did you download off just one user or were you multisourcing?

[basementwaste]

I was multisource downloading.

The thing is, though I've downloaded at least 20 ISOs in the past. This means a file size of between usually 350 - 750 MB and I've never had a problem before. I even downloaded a decent amount of large multisource downloads with v3 Beta through 3.2 with no problems. I tryed downloading this 1GB file both with 3.3 and 3.31, and both times it was corrupt.
Another good example would be that I multisource downloaded a certain ISO with v3.2, and it was good. I told a friend of mine he should grab that copy of the file, since I know its good. He multisource downloaded it with 3.3, and when he finally got it it was corrupt.
It definately has something to do with probability, since every 500 - 1000MB file corrupt 90% of my 100 - 400 MB downloads are corrupt, about half of my 50 MB downloads are corrupt, and every now and then I'll get a corrupt less than 10MB file. But, it didnt happen with other versions of winMX, or other file sharing programs (eDonkey2000, Direct Connect, WinMX 3.2 and lower)

It might have something to do with multisource downloading in 3.3+, since when I download a large file, I end up getting it from a few different people. When I download a small file, it usually finishes before another source starts.

My other concern is if all files are actually getting slightly corrupted every time they get downloaded, but zips need to be exact. Mp3s and movies can have messed up bits here and there and be OK, It would be bad though if all downloads are actually getting slightly corrupt because over time, through many downloads, the files could get more and more messed up.

-Dave

[SiANiDE]

OK ... I have a suggestion as to how you can get around your problem. This definitely works, because I've tried it myself (albeit quite some time ago). It's especially useful if you have downloaded the file twice (which I assume you have).

1. Run a CRC check on your corrupt files (using winRAR).

2. Make a note of where each file is corrupt, say at 35% in file #1 and 45% in file #2.

3. Using a file splitting program, split the files into 10 parts each.

4. You now have twenty files, lets call them File1.000 to File1.009 and File2.000 to File2.009

[File1.000 contains the first 10% of file #1, therefore, File1.003 contains between 30 and 40% (roughly) which is the corrupt segment]

6. Delete File1.003, and rename File2.003 as File1.003

7. Rejoin the File1.00* set.

8. Test the CRC of the archive. I bet you it's not corrupt!

Important notes:

a) Do not use winrar to split the files into rar archives, I've just tried it, and it doesn't work
b) Ensure error checking in your splitting program is OFF (otherwise you will receive CRC errors when rejoining)
c) It's worked for me a few times but isn't guaranteed!

There is also a more subtle issue covered by this practice. In the first step, if you get a CRC error at exactly the same point in both files, then it is more than likely (though not a sure-fire) that the source file is corrupt. Also, when you download the file for the second time, try to use a different source.

[x71us]

BlindWrite Suite , Nero, & a bunch of others will open Iso files. If you want to see whats in the Iso just download & use Win Iso. Its on Donkey.

[Capn_Yzerman]

basementwaste,

I will let you know if I here of anything that can help us out. I still use WinMX for Audio/Video, but for programs, I now use EMule, which has been working great for me. Consistant 10K to 20K download speed consistantly. I usually get stuff fairly quickly with EMule.

I wish every compressed file (Zip & Rar) I downloaded from WinMX was not currupt. I've tried many different files over 300 Megs and they have all been corrupt, for me it is a 100 percent chance thing.

CY

[basementwaste]

Thanks,
If I happen to figure anything out, here will be the first place I will post it. I'll check back in this thread if thers any new posts in it too.

As far as the advice from SiANiDE, unfortunately, I deleted the first corrupt file before I started downloading the second one, so I cant try to fix the file this way. But thanks for the detailed description, so I can possibly try this in the future.

Thanks to all who helped

-Dave

[fyz]

Hi,

I think you can try an utility called Advanced Zip Repair (http://www.datanumen.com/azr/) to repair your Zip file. It works rather well for my corrupt Zip files. But it is not free, so can be used in the end.

Alan