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Recovering FLAC's deleted from hard drive, deleted FLAC's and then recoverd turn out corrupted
eveafterdark
post Jan 20 2013, 19:43
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Hello everyone
some time ago I had - amongst other stuff - a part of my flac collection (ca. 200 gb) accidentally deleted from my external hard drive (don't ask how, I "experimented" with some drivers for my VAIO bluetooth and suddenly on opening one, I just noticed files being deleted - just saw as folders disappear one by one in the hard drive window, only managed to plug out the disk to limit my losses).
anyway, I bought a software which I used to recover photos, mp3's, videos in different formats, lots of kinds of other files/formats and the problem is with the flac files.
first of all, the recovery software sees all the flac's (and other lossless) as "probably overwritten." this is strange because for instance some of the albums were copied to the disk just before the deletion, and generally, this was just a storage disk, not much copy/cut/paste/delete/save was going on there, except from putting the stuff there once and for good.
of course, I know that some of the files must be overwritten, I mean, properly overwritten but my point is, some of the files can't just be overwritten (in terms of how saving on hd works). besides, inside the same music folders where the flacs appear corrupted, there's bunch of other files, like art work for example which are not corrupted and were recoverd completeley.
now, I don't know how about the recovery software seeing the FLAC (and other lossless) files as "probably overwritten" I asked that question to the manufacturer, but haven't got the answer.

SO, my question to you guys is: are FLACS,APE's etc prone to getting corrupted when deleted and recovered? (maybe because of how they're built - MD5, CRC - these are just my guesses) and therefore the damage is permanent? anyone had similiar experience? or is there a way to repair lossless files?

Some details on what I tried:
- any action in foobar (like opening such flac, veryfying integrity) just gives me :(Unsupported format or corrupted file)
- in dbpoweramp try to convert it to wave or test coversion: Information converting to Wave, md5 did not match decoded data, file is corrupt.
- in dbpoweramp try to convert it to flac: Error input channel count more than FLAC can handle. [clEncoder::BeginConversion]
- audio tester - 1 file scanned, 1 file failed: (LOST_SYNC @ 0m 00s); the same with FLAC TESTER.
- FLAC FRONTEND: even with the errors option ticked it says: Run-time error '75 path/file access error

also I opened the flacs (but only e few of them, because this is where chinesse begins to me ;-) and simply lost hope ) with hex editor looking for the flac sequence numbers but I couldn't find one proper sequence

I'll be happy to know if I'm just wasting my time
thx in advance
eveafterdark
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eveafterdark
post Jan 20 2013, 22:31
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thank you guys.
the disk where the files got deleted is an external HD, and was used to store data and for playback (as I kept archiving stuff, I just saved it to that disk, just added stuff, and did not do much else - of course, there were things I deleted, changed names, etc, sometimes edited and saved, but not that much).
I recovered deleted files straight to my VAIO hd, so no portions of the old files have been overwritten on the external hd. to make it clear - no save/delete/copy/cut etc has been done on the external hd since the deletion.
I willll certainly try out Powerdatarecovery and Photorec, thx for that. also maybe I have to look at RAW recovery, the software I use does this, I just didn't look at it since I got the whole folders tree in the first place.
I also received an answer from the software developer - I asked them if the software may "see" deleted files like flac,ape etc. as 'probably overwritten' because of their specific structure (compressed , MD5 sum, CRC and so on). And the answer is that for such files "correctness" of the "head" is not chcecked /correctness of the file/. (not sure if "head" is a proper word, since it's my translation to ENG, but I think they meant the "beginning" of the file.) They also said this means that the recovery software simply can not decide whether the files are overwritten or not, so I think this strictly refers to the way data is saved on a hd.
They also suggest to use a hex editor on the corrupted file and on the original file and compare them.
As I mentioned before I did some hex editor checking because I read about it in other thread (corrupted files due to some bad MM tagging, I think it was some old thread).
But if I got that right though, there shoud be this "fLaC" sequence at the begining of every flac. And the sequence is 66 4C 61 43.
Well, I searched for such a string on a couple of corrupted flac files and I could not find it. I found parts of it , for instance the middle 4C is missing or I got "fL" only
Doesn't this mean such files are definitely lost?

This post has been edited by eveafterdark: Jan 20 2013, 22:42
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