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  #1  
Old 2008-05-21, 06:40 PM
tWreCK51 tWreCK51 is offline
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Question FLAC file errors and integrity

Has anyone (other than myself) experienced random flac file errors -fingerprint checksum doesn't match or chunks/pieces missing? Usually it's a 2Mb block or so that's missing. Now here's the catch, all FLAC files were double checked upon download and they checked out 100% - but when I randomly pick out & check some flac files they don't check out 100% anymore which means they're not keeping their integrity. I usually (but not always depending on time) listen to each release at least once as well.

I don't back them up them up to other media such as CD-R/DVD either because of the simple fact that having 2 1Tb Seagate drives should be adequate for archiving.

So the problem is - FLAC files that once checked out perfectly later become corrupt or have pieces missing from them. This usually happens after a few weeks or so. The question is why?

If it were a hardware related issue (HD, memory, system bus, etc) then other files (compressed format) such as mp3/rar/avi would also be affected but this isn't happening. Those other file formats are keeping their data integrity. So this leads me to the conclusion that it's the FLAC files that are prone to errors/corruption but the question is why? Maybe you guys have some answers because I'm clueless at this point? I'm thinking it might have to do with the level of compression these flac files have been encoded with. Higher levels (8) might be more prone to these errors as opposed to files encoded with lower levels of compression (> 6).

For the record I tested my memory (Memtest86) and scanned my HD's for bad sectors and it all checked out fine. No SMART errors triggered or anything.

Sorry 'bout the long post but this issue is pissing me off - I don't want to constantly have to re-download flac files because they've become corrupt or otherwise. It becomes very time consuming to try and maintain everything 100% intact, not to mention impossible considering the amount of files residing on my drives.........
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  #2  
Old 2008-05-21, 06:48 PM
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direwolf-pgh direwolf-pgh is offline
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Re: FLAC file errors and integrity

its your hard drive (my answer for everything today )
run a full hard disk diag for bad sectors
files just dont 'go partially missing after a while'
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  #3  
Old 2008-05-21, 07:00 PM
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U2Lynne U2Lynne is offline
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Re: FLAC file errors and integrity

I had this happen when my memory was bad. I replaced the bad memory and the files tested out as fine again.
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  #4  
Old 2008-05-21, 07:25 PM
tWreCK51 tWreCK51 is offline
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Re: FLAC file errors and integrity

Thx for the reply

direwolf-pgh > I did run a full disk diag with Seatools and all drives checked out 100% - no bad sectors, no SMART actions triggered, absolutely nothing.

U2Lynne > I checked the memory as well with MemTest86 twice and both sticks checked out 100% as well. I also went to the manufacturers tech-forum (Corsair) and the reply I was given was if the memory checks out with Memtest86 then there is a 99% probability that they are fine.

If one of those (or both) were to be at fault don't you think other files residing on the drives would also be affected and not just the FLAC's?
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Old 2008-05-21, 07:31 PM
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U2Lynne U2Lynne is offline
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Re: FLAC file errors and integrity

Do you run md5s on the other files also periodically?

But yeah, if something were going wrong, it wouldn't just pick on flac files. But, I really can't think of why your flac files would get corrupted. What bittorrent client are you using? Is this happening to all file sets or just file sets that, um, you have burned? Or that have been sitting around for x amount of time? Or that _______ ? Have you noticed anything these bad files have in common?
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  #6  
Old 2008-05-21, 07:32 PM
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direwolf-pgh direwolf-pgh is offline
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Re: FLAC file errors and integrity

maybe your computer just hates your taste in music

flacs dont just dont 'go corrupt'..neither do md5
if it was bad memory..all your progs would crap out - and often.
hard drives - when they identify a bad block or sector - mark them & dont write back to that block/sector again.
get a prog that will stress test your computer..all components

http://www.burnintest.com/

Last edited by direwolf-pgh; 2008-05-21 at 07:37 PM.
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  #7  
Old 2008-05-21, 08:51 PM
tWreCK51 tWreCK51 is offline
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Re: FLAC file errors and integrity

Quote:
Originally Posted by direwolf-pgh View Post
maybe your computer just hates your taste in music

flacs dont just dont 'go corrupt'..neither do md5
if it was bad memory..all your progs would crap out - and often.
hard drives - when they identify a bad block or sector - mark them & dont write back to that block/sector again.
get a prog that will stress test your computer..all components

http://www.burnintest.com/
That might very well be the reason

I guess it wouldn't hurt to try a stress test on my whole system but there's really nothing wrong with it except for this odd behaviour.

U2Lynne > yes - I run (and create when needed) md5's as soon as I have downloaded any fileset be it mp3/avi/rar etc. I'm using utorrent 1.7.7

This behaviour is random and doesn't target any specific flac fileset and usually happens after x amount of time. I don't really see a pattern or anything in common between the files other than they are all flacs.....
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  #8  
Old 2008-05-21, 10:09 PM
MeFirst MeFirst is offline
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Re: FLAC file errors and integrity

I've had this problem saving files to external USB drives. Tried several different drives and cables, and all different USB ports on 2 different machines with the same results, decompressing with flac frontend would give errors on files randomly. Also had problems with other types of files, like DVDs having some corrupt spots from incomplete or corrupt downloads. And these aren't files that have been sitting around a while, these would be newly downloaded files.

Also, after they finished downloading and started seeding they would stay seeding fine, but if I removed the torrent and tried to open it again later to help seed, the check would only go to about 98 or 99% and would have to re-download some parts. Bottom line for me, I only use internal drives or external firewire drives.

I assume you're talking about an internal drive so I know my story is somewhat irrelevant, but I just thought I'd throw it out there to let you know you're not the only one with corrupt flac files.
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  #9  
Old 2008-05-22, 01:39 PM
tWreCK51 tWreCK51 is offline
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Join Date: Mar 2007
Re: FLAC file errors and integrity

They do mention on the official FLAC website that encoding/decoding flac errors highlights bad RAM, overclocking and/or other hardware issues. Have you checked your RAM with memtest86 and run a HD diag scan? If not, then do a few passes with memtest and run a scan on your drives to exclude them as the source of your troubles.......

Although my problems could still be a hardware issue (unlikely but still possible) I'm leaning more and more towards the theory that the FLAC compression itself is very sensitive and prone to corruption & errors when in archival for a period of time and when performing tasks such as burning, copying etc. It may also be a fluke/bug hardware/software incompatibility behaviour appearing on some systems and not others. While strange & unusual it's not the first time something like this has happened. Perhaps this needs to be brought to the attention and investigated further by the FLAC developers...........
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