Apply BiQuad filter to wav at certian timespans

Questions involving a Windows version of FFmpeg.
richardpl
Posts: 58
Joined: Sat Aug 01, 2015 6:35 pm

Re: Apply BiQuad filter to wav at certian timespans

Post by richardpl » Thu Jul 04, 2019 7:23 pm

Perhaps you want bandpass filter?
Also from zeranoe you can download latest devel version which have timeline support.

pandy
Posts: 255
Joined: Mon Feb 24, 2014 1:46 pm

Re: Apply BiQuad filter to wav at certian timespans

Post by pandy » Sat Jul 06, 2019 5:27 pm

richardpl wrote:
Thu Jul 04, 2019 7:23 pm
Perhaps you want bandpass filter?
Also from zeranoe you can download latest devel version which have timeline support.
I think bandstop, probably to remove second harmonics of 50Hz (i.e. 100Hz) - fullwave rectifier or something similar, he need bandstop (notch) filter - best option is fir filter or FFT.
IMHO this should be FIR with 2048 - 4096 taps at least

richardpl
Posts: 58
Joined: Sat Aug 01, 2015 6:35 pm

Re: Apply BiQuad filter to wav at certian timespans

Post by richardpl » Sat Jul 06, 2019 5:42 pm

He can do FFT with afftfilt at expense of huge latency, just set bins he want to 0 (or better to multiply values with very small factor greater than zero). Also he may need huge window size to have good resolution.
On another hand afir have options to control latency and performance of filtering no matter number of taps/coefficients.
But getting filtering coefficients for afir is non trivial task.

Also perfect bandstop/bandreject/notch or bandpass can be only done with introduction of various artifacts to audio.

High order IIR filter is also possible, but to get coefficient in proper format you need even more non-trivial task/software.
IIRs even with 0 latency can introduce phasing issues.

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