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File archiving, Lossless vs compressed folders, Other than space saving concerns.
HTS
post Apr 1 2011, 18:28
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To archive raw sound files, what is the more secure method? Using some lossless codec (FLAC, ALAC or WMAL) or putting them in some zip folder like winrar? The backup software like winrar have error checking features, they do that on extraction or anytime you decide to test the files. They also have recovery records.

What can the lossless audio codecs do?
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Soap
post Apr 1 2011, 20:20
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QUOTE (HTS @ Apr 1 2011, 12:28) *
What can the lossless audio codecs do?

Store metadata (commonly called "tags")

Be played.

Error-correction and detection varies greatly across the codecs so I won't make any blanket statement.

Offer better compression since they are designed with audio in mind.


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pdq
post Apr 1 2011, 21:22
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It was reported some time ago that WinZip was incorporating the algorithm from WavPack, but I don't know what became of that.

If true then you could zip your wav files and get good compression, plus get all of the error recovery in zip files.
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greynol
post Apr 1 2011, 21:30
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Since when did WinZip include a provision for data redundancy?


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HTS
post Apr 1 2011, 22:11
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So what kind of error checking/correction do WMAL and FLAC have?
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Lorem Ipsum
post Apr 2 2011, 00:09
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A FLAC file can include an MD5 fingerprint for error-checking of the Audio data, which is pretty much equivalent to integrity-checking of Zip & RAR files with their CRC fingerprint, AFAIK.
On the plus side, the fact that the MD5 fingerprint is relevant only to the Audio part of the file, you may still freely edit the metadata without re-encoding the file and still be able to check the file for integrity. That is, while the complete file's fingerprint will change, the Audio portion of it should not.

As far as error recovery goes - unless I'm really outdated, last I recall this was optional for RAR, and of course introduced extra data which needs to be calculated and incorporated into the archive. You could achieve the same effect using an external Parity set creator (e.g. QuickPar on the Windows side), and not be bound to a certain archive format with the files 'locked' within it.

As far as direct usability of the files goes, I feel I need not repeat what those above me already pointed out.

-- L. Ipsum

This post has been edited by Lorem Ipsum: Apr 2 2011, 00:13
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HTS
post Apr 2 2011, 04:54
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I encountered a strange problem with winrar. I compressed an archive with 10% setting, but it maxed out at 9%. So is it the case that for some files the recovery record doesn't need to be at 10%?

Edit: I see that the max recovery archive allowed is 256mb. Nevermind.

This post has been edited by HTS: Apr 2 2011, 05:12
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_mē_
post Apr 2 2011, 18:29
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WinRar error recovery is bad. I've seen multiple cases where it failed even though corruption was small, just unfortunately placed.
FreeArc has a similar feature, but it's barely tested, I'm not sure if I remember correctly, but I think it has the same problems as rar and I wouldn't trust it either.
There are some others with this feature (SQX came to my mind), but I don't know any details.
OptimFROG has it in the roadmap, but it's there for years already, so I wouldn't wait for it. It's error detection is slightly ahead of competition because it stores checksum of both compressed and uncompressed data, the latter is good for finding compression / decompression bugs, the former allows fast finding of silent corruption. Though it's a slight benefit compared to codecs that decompress fast, i.e. flac.
Parchive is field proven and should be reliable.
ZFS is also an option. The one I chose.

This post has been edited by _mē_: Apr 2 2011, 18:30
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HTS
post Apr 3 2011, 05:02
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Does adding files to a rar archive automatically delete the pre-set recovery record?
Windows has a "date modified" entry for every file. Is that a reliable way to tell if a file has been corrupted, or is that number just written when you tell windows to modify a file? (i.e. only legimate modifications of a file will result in a rewrite of the metadata, not some checksum at the background.)
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_mē_
post Apr 3 2011, 07:47
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QUOTE (HTS @ Apr 3 2011, 06:02) *
Windows has a "date modified" entry for every file. Is that a reliable way to tell if a file has been corrupted, or is that number just written when you tell windows to modify a file? (i.e. only legimate modifications of a file will result in a rewrite of the metadata, not some checksum at the background.)

The latter. And can be faked easily too, so it's almost meaningless.


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