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Yet another FLAC recovery problem thread
andoru
post Jan 25 2013, 03:33
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Just as the other thread in this sub forum, I've had accidentally deleted a FLAC collection of mine and I went to recover it. Unlike the previous user most of my FLAC files turned out undamaged when recovering them but some were overwritten. Although I decided to recover the damaged files too, it went successfully and most of the FLAC files came intact. I played a few of them and I noticed one track that had a problem. When playing it in foobar (tried VLC also), at some random points it produces a unpleasant very loud screech (white-noise like). Now, as I had quite a few FLAC files in that collection, I would like to check them all for those errors, and preferably not through playback as that could be quite painful to the ears XD
I tried to run the -t parameter in the CLI flac encoder on the file, but it reports no errors. Any suggestions on what to use to detect those mishaps? (if it can do it in batch mode that's a plus! )

Software used:

Recording/Encoding - Audacity/libFLAC 1.2.1 20070917
Playback - FooBar, VLC
Recovery - Recuva
File System - NTFS
OS - WinXP SP3 x86

If anyone needs a sample of the problematic file, I can upload it somewhere, it's not copyrighted.

Thanks in advance ^^



This post has been edited by andoru: Jan 25 2013, 03:35
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andoru
post Jan 25 2013, 15:14
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QUOTE (EagleScout1998 @ Jan 25 2013, 09:16) *
Would Foobar2000's File Integrity tool work for this?


Where would that tool be? I can't find it in fb2k's menus.

QUOTE (db1989 @ Jan 25 2013, 11:18) *
On a file that produces a loud burst of static? Thatís very odd. Assuming of course that thereís a reason for that in the data itself, flac.exe should notice it and report an error in the overall MD5 at the very least, if not also the individual block(s) housing the change. Of course, itís possible youíve defied the odds and found a hash collision, but yíknow, probably not! tongue.gif So, Iím very curious about this. Have you tried the test on more than one file?


It could be in the data itself, maybe Recuva found this file as being damaged for having a few bytes (or blocks as you say) missing and it attempted to plaster those missing bits and make it checksum intact. Yes, I tried multiple files and some do expose the same problem. I forgot to also mention that the original audio (before deletion) didn't have those loud screechy bits (BTW, they aren't static, as they change in waveform and in the spectrum).

QUOTE (lylew @ Jan 25 2013, 12:09) *
you may be able to "correct" the audio with Audacity.

if the tracks at not copyrighted, just try to find a legal download (hopefully not violating TOS). no copyright does NOT always equal free.


I don't think I can fix the audio anymore, what I'm trying to do is to detect the faulty files and replace them (by recording again). There is no download for this file as it's recorded by myself.

QUOTE (ktf @ Jan 25 2013, 12:14) *
Yes please, I would like to see the file. If this is true, it might be a *very bad* bug which needs fixing soon, as the devs are working towards a new release of FLAC smile.gif


Here you go. It has ~7sec of silence in the beginning, beware not to set your speakers too loud if you attempt to listen to it =P

Also here's the spectrogram:



And a close-up:



This post has been edited by andoru: Jan 25 2013, 15:16
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