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Should SHA1 hashes of audio CD tracks burned from image match original CD tracks?


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Posted

I used the current ImgBurn v2.5.2.0 to create an image of an audio CD on my HDD, then successfully burned and verified a copy of the CD from the image (and the copy seems to play just fine). I didn't realize ImgBurn had the ability to calculate and compare MD5 hashes, so I used CDCheck to generate SHA1 hashes of all the tracks.

 

I thought hashes of the tracks on the burned copy would match the hashes of tracks on the original CD, but none of them matched. Am I confused or misinformed about the nature of audio CD images and CD copies burned from those images?

 

I no longer have the CD copy to do any further testing, but I still have the original CD and the image on my HDD, and I just now re-verified the orignial CD against the image on my HDD with ImgBurn, and got matching MD5 hashes, so I'm even more puzzled.

 

I can set ImgBurn to calculate and compare MD5 hashes, burn another CD copy, and submit the logs if necessary (including the logs for the actions described above), but I thought I should make sure I even understand what to expect before I confuse myself further.

 

Should hashes for the copied CD tracks match hashes for the original CD tracks?

 

Thanks! :)

Posted

Unless you have a LiteOn drive or apply the correct offsets when reading/writing, no.

 

Drives don't burn audio data exactly where you tell them to. I've no idea why, they just don't.

 

Everything gets offset by a few bytes either way (depends on the drive), so checksums won't match unless you apply those same offsets when you read/write the data.

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