i successfully tore out old ftdx usb.html

I successfully tore out the old ftdx usb driver from Static and implanted libftdi which works completely differently, of course.

I spent all day Saturday racking my brain trying to figure out how to manipulate the quadrature data to make it suitable input for the Chebyshev IIR filter (without success). One reference seems to indicate that the frequency parameter to the filter is the percentage of the sampling frequency at which you want the cutoff. But. Hmm. It seems to make sense now that I'm talking about it.

Anyway, I tossed in partial Core Audio support. The rest of the app works on pushing data to modules while Core Audio works (at least in one mode) by requesting data from the app. And this data is sampled at 196KHz and I'm going to need to down-sample that to 44.1KHz before I play it, I suspect.

I learned something new about FFT's the other day: zero-pad the input data to increase the resolution. It looks sort of like zooming in. And jumping from 4k points to 16k points didn't noticeably affect performance (ooura ftw).

Here's an interesting looking AM signal (on the right).