[hatari-devel] LMC1992 and Microwire emulation

npomarede at corp.free.fr npomarede at corp.free.fr
Mon Mar 8 10:21:30 CET 2010


On Sun, 7 Mar 2010, David Savinkoff wrote:

> Hi,
> 
> A FFT is not the solution, an IIR filter is required. See:
> http://www.dspguide.com/
> for a freely downloadable book.
> My recommendation is to use a running average filter.
> This is similar to a FIFO, but where you add samples into
> a variable and subtract an old sample out every time you
> add a new one in. How many samples are averaged depends
> on the cut off frequency desired (this is a low pass filter) and
> the sampling frequency. To make a treble filter, subtract an
> averaged value from an input value. Note that the delay of
> the filter is considered to be half of the averaging length.

Hello,

thanks for the infos ; in that case, this looks like the filter I put in 
LowPassFilter(), so it shouldn't be too hard to code and won't take many 
cpu ressources.


Nicolas



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