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Hi,

I am using FFTW to obtain freq values from an audio signal.The input and output arrays are the
same size. However, I need more precision (i need to detect frequencies which aren't whole
numbers) therefore as i understand it i need a larger output array than my input one.

i am using the real-to-real fftw_plan_r2r_1d function as follows: 
fftw_plan_r2r_1d (numSamples, in, out, FFTW_R2HC, FFTW_FORWARD); 

The fftw manual states that when using this function the input and output arrays must be of the
same size so i am assuming i should use a different function. I have read the documentation for
the other functions but none seem to really match my requirements. Has anyone come across
anything like this before?

Any suggestions are most welcome

Thank you

Dan

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Hello n...@yahoo.com

> I am using FFTW to obtain freq values from an audio signal.The input and
> output arrays are the same size. However, I need more precision (i need to
> detect frequencies which aren't whole numbers) therefore as i understand
> it i need a larger output array than my input one.

Just add as many zero samples at the end of the input as you need. Then
you'll get the spectrum of your signal with more precision.

-- 
Grzegorz "Krashan" Kraszewski
k...@morphos-user.com

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