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Hi Jean-Marc and list, Is the spx_fft function in fftwrap.c a standard fft function? void spx_fft(void *table, spx_word16_t *in, spx_word16_t *out) When I say standard, I mean the input "in" is 128 point short data for example and the output "out" is 128 short complex value which is stored in 256 short array with real and image part. Looks like the function did some

...l fast and it produce > N complex fft results If that's the case, then you can still benefit by converting the N-point real FFT into an N/2 point complex FFT and an update pass. > RIRIRI...RI. How does it map to your N/2 complex > output especially > the first R and last R in your sequecne? The packing is actually R(0), R(1), I(1), R(2), I(2), ... R(N/2) Because the input is real, it means that I(0) and R(N/2) are equal to zero (so we don't need to include them). Also, everything above N/2 is the complex conjugate of what's below so it's uninteresting as well. >...

...ase, then you can still benefit by converting the N-point > real FFT into an N/2 point complex FFT and an update pass. This is what the kiss_fftr function does, right? > > RIRIRI...RI. How does it map to your N/2 complex > > output especially > > the first R and last R in your sequecne? > > The packing is actually R(0), R(1), I(1), R(2), I(2), ... R(N/2) > Because the input is real, it means that I(0) and R(N/2) are equal to I think you mean I(R/2), correct? > zero (so we don't need to include them). Also, e...