Questions about FLAC, ALAC and XLD

Discussion in 'iPod' started by Simon Young, Feb 14, 2009.

  1. macrumors member

    Joined:
    Feb 1, 2008
    #1
    1) Converting from FLAC to ALAC, should the result be identical to the original?

    2) Converting from ALAC to ALAC, should the result be identical to the original?

    3) Does XLD's ALAC encoding quality differ from iTunes' encoding quality?

    4) Does XLD's method of tagging differ from iTunes' method?

    5) Does XLD's method of adding album art differ from iTunes' method?
     
  2. macrumors 65816

    Joined:
    Mar 17, 2007
    Location:
    Canada
    #2
    Doubt it the file sizes when I do it are always a little bigger on the .m4a.
    Your not converting anything there.

    Should be the same anytime I ever looked at the file(s) in Jaikoz it says Converted with XLD using Quicktime which is what iTunes would be using.

    It uses the same as far as I can tell.

    See above.
     
  3. macrumors 6502a

    Joined:
    Aug 6, 2007
    #3
    The file size between the FLAC and the ALAC are different because they're using different algorithms, but they're both still lossless, so they're storing exactly the same data in the end.
     
  4. macrumors 65816

    Joined:
    Mar 17, 2007
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    Canada
    #4
    Impossible different algorithms by definition means different results in the file created they will not be exact copies identical to each other...
     
  5. macrumors 6502a

    Joined:
    Aug 6, 2007
    #5
    ...but they are. That's the point of using a lossless codec.

    If you take a WAV file and make FLAC and ALAC copies of it, you can do null tests on them and they are exactly the same.

    Think of it like a ZIP file VS a RAR file. They'll produce archives of different sizes, but you can put exactly the same data in them, and get exactly the same data out.

    With lossless codecs, what goes in comes out on the other end exactly the same, period. The way it gets there varies from codec to codec, but the result is the same.
     
  6. macrumors 65816

    Joined:
    Mar 17, 2007
    Location:
    Canada
    #6
    I understand what your saying but they are not exact binary or other copies they are different files the results achieved may be the same in the end but the files are not.

    Edit: I would add that a "lossless" codec are not comparable to either the zip or rar or some files they compress the data that is contained in them then expand it back to the original an audio lossless codec does not contain the same data as the original .wav they are compressed and some data is lost no matter what they claim it is damn close to the original but it is not it exactly.

    Edit: New version is there when I went to start it jst now with a rather nice looking batch function that will go through your directories recursively allowing you to convert an entire directory tree of files .
     
  7. macrumors 6502a

    Joined:
    Aug 6, 2007
    #7
    Not only did you contradict yourself, but your second statement is wrong.

    At first you said the end result is the same...that is accurate. Also accurate is that the FLAC and ALAC binaries aren't going to match...using different algorithms, they wouldn't.

    However, the statement that lossless codecs produce files that are "damn close" to the original but are "not exactly" the same is categorically wrong. FLAC and ALAC share exactly the principle as ZIP and RAR files. Exactly what goes in, comes out.

    You can prove this by doing a null test. Take a wav file and a FLAC or ALAC copy of the wav file. Load both into a multitrack program. Invert the phase of either of them. As long as they are lined up exactly, they will cancel each other out into absolute digital silence. By doing this, you prove the end result is exactly the same, bit for bit. This goes for any lossless codec vs the input source, obviously provided it's working properly.

    I don't mean to be harsh, but spreading misinformation doesn't help anybody.

    Lossless = NOTHING is lost. If you want more information on how FLAC achieves this, read the associated sections here: http://en.wikipedia.org/wiki/FLAC
     
  8. macrumors 65816

    Joined:
    Mar 17, 2007
    Location:
    Canada
    #8
    Yeah I was really talking about the files produced after reading that page I see what you mean about the other point you were making I missed.. On another note if any one uses the recursive feature make sure you don't allow the files to stay in the same directory as the ones being converted it seems to give you a copy for every directory it has to go down into. Setting a base directory and preserving the directory structure gives you a single copy of the file however.
     

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