Finding audio frequency
Finding audio frequency
- Subject: Finding audio frequency
- From: Paul Bruneau <email@hidden>
- Date: Tue, 26 Jan 2010 09:46:27 -0500
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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