[FFmpeg-devel] Information about FFT implementation in ffmpeg

Guillaume POIRIER poirierg at gmail.com
Tue Jul 26 17:42:24 CEST 2011


On Tue, Jul 26, 2011 at 5:38 PM, jogging song <joggingsong at gmail.com> wrote:
> Thanks for your timely reply, Vitor
> Today I find that FFT is followed by IFFT immediately, but the
> results is not same with original input data. The output is 16 times
> of original input data. Is this correct?

All FFTs behave this way (FFTW, MKL, CUFFT...). Chances are that the
number of elements you used as input was 16, right?

Just scale the output of FFT+IFFT by the number of elements and you'll be fine.

Best regards

"I am the Jesus Christ of politics. I sacrifice myself for everyone."

 -- Silvio Berlusconi

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