Does MP3 encoding cause artifacts?

Discussion in 'Computing' started by Guitarfreak, Sep 1, 2009.

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  1. Guitarfreak

    Guitarfreak Well-Known Member

    Feb 21, 2009
    Just beating a dead horse. Occasionally when I listen to my iTunes library there are very subtle pops and/or crackles. I want to find out if this is a codec compression issue or a faulty pair of monitors. It happens intermittently, like maybe it is only certain songs or certain parts of certain songs. It doesn't occur frequently enough for me to be worried that it is a monitor issue, but the question remains.
  2. Codemonkey

    Codemonkey Well-Known Member

    Dec 11, 2007
    Scotland, UK
    Artefacts in the form of pops and crackles, I don't think so.
    In the form of high frequency (~16KHz, the filter frequency) squeaks, yes.

    Maybe the songs distort a little?
  3. dvdhawk

    dvdhawk Well-Known Member

    Dec 18, 2008
    Western Pennsylvania, USA
    MP3 encoding is all about file compression (which is very different from audio compression), it's main objective is to reduce the filesize. It thins out information it deems redundant or unnecessary. The theory is, your ears and your brain can't concentrate simultaneously on 20Hz-20kHz over a wide dynamic range. So, the finished MP3 is a snapshot of what's going on musically at the moment and it thins out data that would be seen as background. It's calculated, so you might find you get a different result with the same bit rate etc. using a different program to do your encoding Each encoder probably has their own algorithm that determines what to keep and what to thin-out.

    Try a different encoder and see if you still have the same crackling and popping.

    Here's an analogy like you'd find on the SATs:

    Children's paint-by-numbers version of the Mona Lisa, is to DaVinci's original Mona Lisa

    / as /

    MP3 file of the Hey Jude is to the undigitized original musical masterpiece.
  4. djmukilteo

    djmukilteo Well-Known Member

    Nov 23, 2008
    Rainy Roads WA USA
    Maybe try your headphones to rule out the monitors. I would try and duplicate the problem....
    Like science experiments, duplicate and investigate....rule out and isolate...maybe its your audio converter?
  5. Guitarfreak

    Guitarfreak Well-Known Member

    Feb 21, 2009
    Good info. Regarding the last post, I never heard anything through my speakers or headphones. I assumed as much that they were hiding the flaws and that the monitors weren't as nice to the flaws, showing them to me like a trusty retriever dropping a bone at your feet :lol: I could be wrong.

    It very well could be my interface, that is a good point. It's only a PreSonus FireBox. It's not like I spent $500 or more on it. Speaking of which, they are discontinuing it. Apparently there is a new model on the way.
  6. jg49

    jg49 Well-Known Member

    Oct 16, 2008
    Frozen Tundra of CT
    It is possible that it is your monitors they were "B" stock which means it is likely they were returned once. They test them and resell possibly they missed something.

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