[FFmpeg-user] fftfilt

[Paul B Mahol]

On Thu, Oct 14, 2021 at 12:29 PM Michael Koch <astroelectronic at t-online.de>
wrote:

> Am 14.10.2021 um 12:07 schrieb Paul B Mahol:
> > Sorry but I'm not on windows, so I can not use your script.
>
> Then try the below (slightly improved) version. It would become much
> simpler with variables:
> ARRAY_H = pow(2,ceil(log(ceil(W*10/9))/log(2)))
> ARRAY_V = pow(2,ceil(log(ceil(H*10/9))/log(2)))
>
> The test image contains wavelengths from 4 to 8 (in the center) to 16
> pixels per linepair.
> The filter wavelength is independant of input size. You can change the
> size in the first command (but it must be 1:1 aspect ratio, otherwise
> hstack would fail)
>

Since when hstack fails because of different aspect ratio?


>
> Michael
>
>
> ffmpeg -f lavfi -i color=black:s=230x230 -lavfi
> geq='r=127.5+127.5*cos((X-W/2)*PI/(pow(2,(1+2*Y/H))))',colorchannelmixer=1:0:0:0:1:0:0:0:1:0:0:0,split[h][v];[v]transpose[v];[v][h]hstack
>
> -frames 1 -y test.png
>
> ffmpeg -i test.png -vf
> scale=2*iw:2*ih,fftfilt=dc_Y=0:dc_U=0:dc_V=0:weight_Y='lte(hypot(X/pow(2,ceil(log(ceil(W*10/9))/log(2))),Y/pow(2,ceil(log(ceil(H*10/9))/log(2)))),1.0/8)':weight_U=1:weight_V=1,scale=iw/2:ih/2
>
> -y lowpass.png
>
> ffmpeg -i test.png -vf
> scale=2*iw:2*ih,fftfilt=dc_Y=128:dc_U=1:dc_V=1:weight_Y='gte(hypot(X/pow(2,ceil(log(ceil(W*10/9))/log(2))),Y/pow(2,ceil(log(ceil(H*10/9))/log(2)))),1.0/8)':weight_U=1:weight_V=1,scale=iw/2:ih/2
>
> -y highpass.png
>
> ffmpeg -i test.png -vf
> scale=2*iw:2*ih,fftfilt=dc_Y=128:dc_U=1:dc_V=1:weight_Y='between(hypot(X/pow(2,ceil(log(ceil(W*10/9))/log(2))),Y/pow(2,ceil(log(ceil(H*10/9))/log(2)))),0.8/8,1.2/8)':weight_U=1:weight_V=1,scale=iw/2:ih/2
>
> -y bandpass.png
>
> ffmpeg -i test.png -vf
> scale=2*iw:2*ih,fftfilt=dc_Y=0:dc_U=0:dc_V=0:weight_Y='1-between(hypot(X/pow(2,ceil(log(ceil(W*10/9))/log(2))),Y/pow(2,ceil(log(ceil(H*10/9))/log(2)))),0.8/8,1.2/8)':weight_U=1:weight_V=1,scale=iw/2:ih/2
>
> -y notch.png
>
>
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