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Topic: Can a image of Audio CD be considered an exact copy (Read 2899 times) previous topic - next topic
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Can a image of Audio CD be considered an exact copy

That is the thing that came to my mind and wanted ask some folks who know more about those things - can an image made by audioCD in formats like .iso( i.e IMGBurner), .nrg (i.e Nero) or .ddp (Hofa) be considered exact, bit to bit copy of an actual audio CD?Can such image file, either burned back on CDr disc or loaded in virtual drive be an alternative to EAC rip?

Re: Can a image of Audio CD be considered an exact copy

Reply #1 –
http://www.accuraterip.com/
Quis custodiet ipsos custodes?  ;~)

Re: Can a image of Audio CD be considered an exact copy

Reply #2 –
Yes, the audio data can be exact.   That's the wonderful thing about digital!   You can make a copy-of-a-copy-of-a-copy for a million generations and the last copy can be identical to the first (as long as nothing goes wrong).

And in general, digital is just darn-reliable...    My usual example is - If there's a spelling error in this post you can be sure it was my error and not some kind of data-error through all of the connections around the world.

If you burn a copy there might be an offset difference (which doesn't affect the sound) and...   I'm not an expert but I'm pretty sure there's something on the "blank" CD indicating that it's burned,  not pressed, (which also doesn't affect the sound).      And since burned discs are "different", some older CD players couldn't play burned CDs. 

Audio CDs can have errors (or damage, etc.) and the data-format doesn't have the same error detection and error correction as your hard disc or computer-files burned onto a CD. so you don't always know when there's an error.    But in some ways that's good  because an audio CD will usually just read-through any errors instead of stopping and reporting an error.   (And there is some error-correction and "error hiding" and not all errors are audible anyway.

Re: Can a image of Audio CD be considered an exact copy

Reply #4 –
Quote from: anc on
can an image made by audioCD in formats like .iso( i.e IMGBurner), .nrg (i.e Nero) or .ddp (Hofa) be considered exact, bit to bit copy of an actual audio CD?

There's no guarantee that it will be bit exact.

Re: Can a image of Audio CD be considered an exact copy

Reply #5 –
Quote
It it's about conventional audio RIPPERS vs exact ones like EAC or dBpoweramp. It does not say anything about creating image file of whole CD
If AccurateRip shows no errors the audio data is identical and it doesn't matter if it's "packaged" in a WAV file or an image file.      (Audio CDs don't have WAV files with WAV headers, etc., but the audio samples can be bit-identical.)

If you're using a ripper that doesn't support AccurateRip it's not as easy to "prove" that you're not getting read errors but but yes, the underlying audio data can be byte-for-byte (or sample-for-sample) identical...   CD audio has 44,100 samples per second (x 2 channels) and each sample has a value between -32,768 and +32,767 and those values ALMOST NEVER get accidently changed or corrupted (unless there is a CD reading error).

Re: Can a image of Audio CD be considered an exact copy

Reply #6 –
Quote from: anc on
That is the thing that came to my mind and wanted ask some folks who know more about those things - can an image made by audioCD in formats like .iso( i.e IMGBurner), .nrg (i.e Nero) or .ddp (Hofa) be considered exact, bit to bit copy of an actual audio CD?

That question is too imprecise, actually. You give a clue here:

Quote from: anc on
Can such image file, either burned back on CDr disc or loaded in virtual drive be an alternative to EAC rip?

So I imagine that what you are after, is whether you can eliminate the need for ripping software like EAC by using cloning software instead, and then extracting audio from that.

The answer is no. The bits extracted by the cloners are no better than what they retrieve from the CD through, AFAIK, an ordinary a burst rip.
Surely a burst rip is often good enough, and with e.g. CUETools it is easier to verify after ripping - but if there is an issue where you "need" a secure ripper, you have replaced the right tool with the wrong tool.
You have given yourself extra work for something that is not improving, and will fail when there is an actual difference.


Also if your question was broader, you may or may not get another "oh there is a difference too". Your typical cloner will not copy subchannels and error codes. And for data sessions (EnhancedCD or the Playstation type), then I don't know whether cloning software is actually to put the data in precisely the same location on the CDr.
 

Re: Can a image of Audio CD be considered an exact copy

Reply #7 –
Quote from: Porcus on
And for data sessions (EnhancedCD or the Playstation type), then I don't know whether cloning software is actually to put the data in precisely the same location on the CDr.
I don't know if any existing software is so meticulous about it, but in theory one could burn a CD in raw mode with adjustments to account for the write offset. Getting an exact match would depend on the drive: not all of them support raw mode, and the ones that do support it might refuse to write unusual things like offset-corrected data.

And you still need an accurate read of the disc.