fftfilt is half-strength on FIR filters - check 0.5mhz and audio RF FIR filters

happycube / ld-decode

Software defined LaserDisc decoder

GNU General Public License v3.0

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fftfilt is half-strength on FIR filters - check 0.5mhz and audio RF FIR filters #878

Open happycube opened 5 months ago

happycube commented 5 months ago

While working on comb filters and setting up standalone overlap/merge fft code, I found out that FIR filters need to be doubled (by using (filtfft(filter) ** 2.0). There are thankfully only two such filters to look at.

(Thankfully, FFT filtering on IIR filters as implemented is accurate to within .0005 on 16-bit decoded video!)