Re: [LAD] FFT 1D real

 Citējot *Fons Adriaensen <fons@email-addr-hidden> [1]*:
> > How from ...1024 or 2048 or 4096... FFT return values i
> calculate
> > power magnitudes for all bands,
> > and finally values for visual 10-20 hopping bars, like in
> Winamp ,
> > XMMS , QMMP ... ?
>
> If you want such a display the FFT is not a good way to do it.
> It's possible but not simple if you want a correct result.
  What is good/best way to calculate values for visual 10-20 hopping
 bars like in GUI audio players ?
> > 43303.2715 + 796.7285 = 44100 or 44100 - 43303.2715 =
> 796.7285>
> > Why Frequency 796.7285 is mirrored as Frequency 43303.2715 ,
> and magnitude for both Frequencies is divided by 2 ????
>
> Because you are using a complex FFT, and the imaginary part
> of your signal is zero. That means that the spectrum must be
> symmetric.
>
> > Is here way direct calculate full magnitude and without
> Frequency
> > mirroring , in band 0 Hz ... FSampl/2 ONLY ,
>
> Use an FFT operating on real data instead of complex.
  Can U gimme pointers to such functions ?
 What about all Radix algorithms ?
  Tnx in advance
  Alf
 ---------- Pārsūtītās vēstules beigas ---------- Links: ------ [1] mailto:fons@email-addr-hidden

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Received on Tue Mar 15 00:15:01 2011