Re: FFT class or routines

"MeMyselfAndI" <agp001@xxxxxxxxxxxxxxx> wrote in message
news:433b56ef$0$22741$afc38c87@xxxxxxxxxxxxxxxxxxxxxxx
> Maarten Wiltink wrote:
>> "MeMyselfAndI" <agp001@xxxxxxxxxxxxxxx> wrote in message
>> news:433ab0bf$0$6112$afc38c87@xxxxxxxxxxxxxxxxxxxxxxx

>>> I want to do an FFT analysis of audio data in a professional
>>> music production app. I've been trying to use a class called
>>> RealFFT, but I don't have the technical knowhow to peice the
>>> audio back together after the IFFT. I was wondering if there
>>> is some Delphi code of some component out there which will
>>> make it easy to get the frequency info and then convert that
>>> back into PCM.
>>
>> The Fourier Transform is its own inverse, except for a constant
>> factor of 2*pi IIRC. And it's common to multiply by the square
>> root of that to _make_ it its own inverse exactly.


> Sorry Maarten, I'm a caveman when it comes to the FFT. I need either
> code or advice that will simplfy things for me. The problem I'm having
> is with piecing each window back together into a continuous audio
> stream so that there are no phase conflicts.
>
> Any suggestions?

Well, not top-posting would be nice.

Seriously, are you having phase problems now? If you simply apply the
FFT twice, except for possible scaling the data should be identical
again. (What I mean is: check this first.)

What are you doing in between?

Groetjes,
Maarten Wiltink


.

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