c# - FFT on WP7 shows two mirrors -

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hello i'm exploring audio possibilities of wp7 platform , first stumble i've had trying implement fft using cooley-tukey method. result of spectrogram shows 4 identical images in order: 1 normal, 1 reversed, 1 normal, 1 reversed. code taken c# project (for desktop), implementation , variables seem in place algorithm. can see 2 problems right away: reduced resolution , cpu wasted generate 4 identical spectrograms. given sample size of 1600 (could 2048) know have 512 usable frequency information leaves me 15hz resolution 8khz frequency span. not bad, not either.

should give on code , use naudio? cannot seem have explanation why spectrum quadrupled, input data ok, algorithm seems ok.

this sounds correct. have 2 mirrors, can assume 1 real part , other image part. standard fft.

from real , image can compute magnitude or amplitude of each harmonic more common or compute angle or phase shift of each harmonic less common.

gilad.


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