Re: Finding audio frequency
Re: Finding audio frequency
- Subject: Re: Finding audio frequency
- From: tahome izwah <email@hidden>
- Date: Tue, 26 Jan 2010 15:55:44 +0100
There is a great tutorial on the Fourier transform here:
http://www.dspdimension.com/admin/dft-a-pied/
Maybe that helps you out.
--th
2010/1/26 Paul Bruneau <email@hidden>:
> Hello-
>
> I fear this might be more of a general audio or digital signal processing
> question, but I have tried many google searches and fear that my wide
> ignorance of the topic is keeping me from even finding the first step.
>
> I want to create a Cocoa app that will record a short duration of audio--in
> my case it will be a single string being struck on a stringed
> instrument--either open or pressed down on a fret (I am sure I can do this
> part).
>
> It will look at a section of time from that sample starting at 20ms going to
> about 200ms (I think I can do this part).
>
> And it will then return a value representing a "best estimation" of the
> frequency (here is my question).
>
> I am only concerned with the "base" or "foundation" frequency--that is, I
> don't care about harmonics, I only care about how many times per second the
> string is "vibrating" (for lack of a better term).
>
> I think I could sort of brute-force my way through this by looking at each
> sample and keeping track of where the "wave" crosses zero, but I'm pretty
> sure there is some better "dsp" way to do this, perhaps using some nice open
> source algorithms.
>
> I don't care about real-time processing. It can be quite slow. I'm
> interested in an accuracy level that would be appropriate to the fact that
> if a person were to strike the same string many times, he might see
> different values depending on how he is fretting, etc.
>
> I don't want anyone to do my work for me, but I'm hoping someone can point
> me to the correct place to start looking where I can learn.
>
> Thank you!
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