New subject: FFT 1D real

14 Mar 2011

 Citējot *Fons Adriaensen &lt;fons(a)linuxaudio.org&gt; [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
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Links:
------
[1] mailto:fons@linuxaudio.org

Re: [LAD] FFT 1D real