Re: Finding audio frequency
Re: Finding audio frequency
- Subject: Re: Finding audio frequency
- From: John Proctor <email@hidden>
- Date: Tue, 26 Jan 2010 14:53:57 +0000
Hi Paul,
You could try looking at the CSound source code. The pvspitch opcode (http://www.csounds.com/manualOLPC/pvspitch.html) does this.
Cheers,
John Proctor - Developer
Camel Audio - http://www.camelaudio.com
Humanoid Sound Systems - http://www.humanoidsounds.co.uk
Twitter - http://twitter.com/jprocto
On 26 Jan 2010, at 14:46, Paul Bruneau wrote:
> 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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