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Filtering digital

  • 03-06-2012 12:18pm
    #1
    naysayer
    Registered Users, Registered Users 2 Posts: 46 ✭


    Filtering digital audio

    // Might be better in Math/Physics forums, we'll see.

    // using c# .net

    I'm working with a short 16bit 44.1kHz wave (.wav) file, and have properly loaded it into an Int16 array or collection.
    The values in this array therefore represent the actual 16bit value of each sample.

    Suppose I would like to filter out audio frequencies above say, 1kHz,
    anybody know how might I go about it? It has me stumped.
    I'm not sure if I should be thinking about zero-crossings or coutours, or both.


Comments

  • #2
    carveone
    Registered Users, Registered Users 2 Posts: 1,306 ✭✭✭carveone


    naysayer wrote: »
    Filtering digital audio

    // Might be better in Math/Physics forums, we'll see.

    // using c# .net

    I'm working with a short 16bit 44.1kHz wave (.wav) file, and have properly loaded it into an Int16 array or collection.
    The values in this array therefore represent the actual 16bit value of each sample.

    Suppose I would like to filter out audio frequencies above say, 1kHz,
    anybody know how might I go about it? It has me stumped.
    I'm not sure if I should be thinking about zero-crossings or coutours, or both.

    Aha! The wide and scary world of DSP. You are looking for a digital implementation of a low pass filter (I assume!)

    The musicdsp.org website might help a bit here but finding a book on DSP might help more. This one: http://www.dspguide.com/ might be a bit high end but have a look...

    Edit: This wikipedia entry:
    http://en.wikipedia.org/wiki/Low-pass_filter#Algorithmic_implementation
    looks like a pretty good place to start!


  • #3
    Anima
    Registered Users, Registered Users 2 Posts: 3,945 ✭✭✭Anima


    DSP is quite difficult if you're not familiar with it. I think you're best bet is to find a C# DSP toolkit or some helper classes. I did a quick google and here is one: http://codearteng.blogspot.ie/p/dsp-toolbox.html. It has filtering classes at least.


  • #4
    naysayer
    Registered Users, Registered Users 2 Posts: 46 ✭naysayer


    carveone wrote: »
    This wikipedia entry:
    http://en.wikipedia.org/wiki/Low-pass_filter#Algorithmic_implementation
    looks like a pretty good place to start!

    This was extremely helpful, thanks.
    Anima wrote: »
    DSP is quite difficult if you're not familiar with it.
    I'm up to the challenge, i know math! :cool:


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