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WAV to ALE to WAV
The Legioneer
post Nov 11 2006, 16:53
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I'm about to start ripping my entire CD collection with EAC. From there, the WAV files will be converted to Apple Lossless via iTunes. At this point, the WAVs will be deleted and the ALE files archived to DVD.

So I started thinking, what if I need to decode ALE back to WAV? I'm putting complete faith in iTunes that it will be able to restore the WAV files, just as if they were coming straight from EAC.

I had the idea to create an MD5 checksum of the WAV files right after I ripped them from EAC. I converted the WAVs to ALE, deleted them, then encoded the new ALE files back into WAVs with the iTunes WAV Encoder. When I ran the MD5 I created with the WAVs from EAC, it found no errors on the WAVs that had been converted to ALE and then back to WAV.

This would make them an 100% bit for bit perfect digital match, would it not? It would seem this would prove absolutely nothing was lost in the ALE conversions. Is this being way too paranoid keeping these MD5s hanging around with the album archive, or do you use similiar methods to check your own files? or is there a better way to do what I'm attempting?

Basically, at the end of the day, I just want to be sure that if need be, I could have exact copies of the WAVs that were ripped from EAC.
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spoon
post Nov 11 2006, 22:43
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Any lossless codec (Apple, Microsoft, FLAC, WV, Monkeys) should always decode the same as went in, your md5 is more likely to find hard disk errors than codec errors (perhaps).


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jcoalson
post Nov 12 2006, 00:13
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what kind of testing has been done on apple lossless to show that it's reliably lossless?

all the comparisons I've seen only compare times and ratios.
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jcoalson
post Nov 12 2006, 00:23
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nevermind, I think the question is interesting enough for it's own topic so I made one:
http://www.hydrogenaudio.org/forums/index....showtopic=50107
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The Legioneer
post Nov 12 2006, 03:10
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QUOTE (spoon @ Nov 11 2006, 16:43) *
Any lossless codec (Apple, Microsoft, FLAC, WV, Monkeys) should always decode the same as went in, your md5 is more likely to find hard disk errors than codec errors (perhaps).


I posted a similar question in another forum (here), about going WAV to FLAC to WAV and was given a response that lead me to be believe the audio samples from the two WAVs would be bit for bit identical, but that decoding a WAV from FLAC would add extra meta data that would result in a different file than the ones untouched from EAC. I don't know whether or not this is true, I haven't tested it yet.

Is there a better way to compare two files than the MD5 check and an EAC WAV comparison?
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Remedial Sound
post Nov 12 2006, 04:24
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QUOTE (The Legioneer @ Nov 11 2006, 21:10) *
I posted a similar question in another forum (here), about going WAV to FLAC to WAV and was given a response that lead me to be believe the audio samples from the two WAVs would be bit for bit identical, but that decoding a WAV from FLAC would add extra meta data that would result in a different file than the ones untouched from EAC. I don't know whether or not this is true, I haven't tested it yet.

Is there a better way to compare two files than the MD5 check and an EAC WAV comparison?

AFAIK decompressing flac to wav does not transfer the flac's metadata to the wav, because wav files do not natively support tagging. The two files should be identical.

If you use foobar2000, you can use the Binary Comparator component to compare files.
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