Is CD->Apple Lossless->CD bit-for-bit identical?

Discussion in 'Mac Apps and Mac App Store' started by bigwig, Jan 11, 2008.

  1. bigwig macrumors 6502a

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    Sep 15, 2005
    #1
    That is, if I import a CD into iTunes using Apple Lossless, then burn a CD, will the newly burned copy be bit-for-bit identical to the original CD? One might think that "lossless" implies this, but from what I understand this isn't necessarily so.
     
  2. Killyp macrumors 68040

    Killyp

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    Jun 14, 2006
    #2
    Lossless files are as they say, lossless. They result in an identical checksum to the original PCM...

    What I'm not sure about is just how reliable the iTunes CD burning underpinnings are.
     
  3. OldCorpse macrumors 65816

    OldCorpse

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    compost heap
    #3
    Good question! I have some 5000 CDs. I've ripped around 1200 of them so far to an external hard drive which I have hooked up to my stereo. Now, since I like to hear music at high fidelity (I can clearly tell when I'm listening to a lossy MP3), I ripped them to Apple Lossless format, to save space. If I'd ever like to burn a mix CD for a trip, I'd want to do it from the ripped library. And I wonder what the results would be. So, this question is very interesting to me. Regardless, I'm glad I have the original CDs - somehow I'm superstitious and I don't entirely trust the Apple Lossless format :)
     
  4. Mr.Texor macrumors regular

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    Apr 20, 2007
    #4
    in short an audio CD has a special format.

    when you transfer your music into apple lossless, you get files that are different than what it's in the CD.

    Therefore, you can not just burn the apple lossless files into a CD. If you do so, you will get a data CD with apple lossless encoded files in it.

    To create an audio CD, you have to specify the burner app to do so. theoretically, a CD burned from apple lossless should sound exactly as the original audio CD.
     
  5. djejrejk macrumors 6502a

    djejrejk

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    #5
    Or just can just burn in iTunes... or Toast. Its not rocket science.
     
  6. macffooky macrumors regular

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    #6
    The iTunes ripping routine is not secure which means that any errors will not be corrected. In practice this means that undamaged CDs are likely to produce flawless rips and less pristine discs are still very unlikely to have any audible defects. There are ripping programs for OS X, mostly built around the Unix program CD Paranoia (or cdda2wav) but their error correction routines are rendered pointless if the disc drive caches audio, as nearly all drives do. These programs such as xACT, Max etc do have the advantage of logging potential errors, whereas iTunes leaves you blissfully ignorant. Unfortunately it's still necessary to boot into Windows and run EAC or dbPowerAmp for maximum security, though the Linux app RubyRipper is supposed to be runnable under OS X (won't compile for me :().

    Assuming a perfect rip from iTunes you still won't be able to burn an exact copy with iTunes, Toast or any other burning app I'm aware of, as no OS X apps are able to compensate for your drive's read/write offsets. This is really the world of the super anal as no modern drives have an offset which could ever produce any audible difference between the original and the burned copy.
     
  7. lostless macrumors 6502

    Joined:
    Oct 22, 2005
    #7
    It may not be bit for bit, but all that matters is the PCM waveform, which will be identical. No lossy loss is lost like mp3 or aac. Every frequency in the original cd will be there. As others say, it all depends how well itunes reads/burns the cd, where minor errors could occur, which for all purposes, a sample or 2 of errors in a row will not be heard. There are 44 thousand of them per second.
     
  8. QuarterSwede macrumors G3

    QuarterSwede

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    Oct 1, 2005
    Location:
    Colorado Springs, CO
    #8
    Actually the CD drive circuitry will correct any errors that do occur on playback, so what you'll end up hearing will be identical to the original CD. CD error correction is an amazing science. iTunes does include error correction for ripping; it just takes 30 minutes to rip instead of the quick ... 6 at most.

    Even if there was a chance that there were some errors that slipped through* I guarantee the errors would be so small the human ear (and mind) wouldn't notice a difference.

    *impossible since it would just stop playing if that happened ... scratched disc anyone?

    In Short:
    You'll hear the exact same thing from PCM (wav or aif[f]) > Apple Lossless > PCM (wav or aif[f]). Again using that method, any errors that do occur from ripping will NOT be heard on playback. Human ears just aren't that good. Any perceived difference is psychological.
     
  9. macffooky macrumors regular

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    May 13, 2004
    Location:
    The 51st State
    #9
    The bottom line is that unless a disc has pressing errros or is significantly damaged you are extremely unlikely ever to hear any hear any difference between the original and an iTunes-ripped copy but I think it's necessary to point out that iTunes is *not* a secure ripper.

    The error correction routines it runs are undocumented and we can only speculate but the consensus is that it's likely to involve C2 should your drive support it. It most definitely does not have any method of defeating a drive's audio caching mechanism. I've run exhaustive tests on damaged discs by making multiple rips of the same discs with iTunes, Toast, xACT, EAC RubyRipper and simply dragging to the Finder and the only reliable (as far as possible) methods were EAC and rubyripper.
    You must be lucky enough never to have come across anything with that annoying clicking diginoise from a duff rip :)


    Once again it has to be said that the differences were utterly inaudible and with commercially available recordings there's absolutely no problem. In the live/unofficial taping community which relies on accurate extraction to preserve the integrity of recordings for posterity, iTunes is not considered an acceptable ripper. That said, the overwhelming preference is for the circulation of the original lossless recordings as data files (FLAC etc) rather than extractions but where that isn't an option we're still waiting for an OS X option. I've been trying to get the bloke that coded xACT to whip up a GUI for RubyRipper but he can't get the damn thing to compile either.

    It's anal and really de trop for 99% of need but it's like that stuck pixel that you'd never noticed...once you know it's there, well....;)
     

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