Speex dev - Aug 2008 - MDF filter coefficients

Hi,

I would like to compute the inverse FFT of the MDF coefficients. I have noticed
that some coefficients are obviously missing since I do not see the mirror
effect, neither find the purely real frequency 0 coefficent that have to be
found for a "real" signal.
I guess the frequency 0 coefficient is 0 (average energy 0), but how should I do
the mirroring and how many coefficients should I expect ?

Thanks,

David


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David Giguet a ?crit :
> I would like to compute the inverse FFT of the MDF coefficients. 
See SPEEX_ECHO_GET_IMPULSE_RESPONSE (and
SPEEX_ECHO_GET_IMPULSE_RESPONSE). It's all been done for you.
> I have
> noticed that some coefficients are obviously missing since I do not see
> the mirror effect, neither find the purely real frequency 0 coefficent
> that have to be found for a "real" signal.
> I guess the frequency 0 coefficient is 0 (average energy 0), but how
> should I do the mirroring and how many coefficients should I expect ?
FYI, the DC (aka coef 0) is there. There's no symmetry because I'm using
a real to half-complex FFT.

Cheer,

	Jean-Marc