Fancy Filtering Examples

Video

cellauto

ffplay -f lavfi -i cellauto=rule=110

Other interesting cellauto rule values: 9, 18, 22, 26, 30, 41, 45, 50, 54, 60, 62, 73, 75, 77, 82, 86, 89, 90, 97, 99, 101, 102, 105, 107, 109,  110 (default), 124, 126, 129, 131, 133, 135, 137, 145, 146, 149, 150, 151, 153, 154, 161, 167, 169, 181, 182, 183, 193, 195, 210, 218, 225.

life

ffplay -f lavfi -i life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16

ffplay -f lavfi -i life=s=640x480:mold=10:r=100:ratio=0.1:death_color=blue:life_color=#00ff00,boxblur=2:2

mandelbrot

ffplay -f lavfi -i mandelbrot

mirror effect

ffplay -i INPUT -vf "crop=iw/2:ih:0:0,split[tmp],pad=2*iw[left]; [tmp]hflip[right]; [left][right] overlay=W/2"

Audio

aevalsrc

Making some random "musical" keys:

% cat expr
# floor(t): 0 0 0 0 0 ... 1 1 1 1 1 ... 2 2 2 2 2
#  => set a random key when floor(t) changes
if(eq(floor(t),ld(2)),
    st(0,random(4)*3000+1000));

# the next value to compare floor(t) with
st(2,floor(t)+1);

# mod(t,1) makes t always in the range [0;1) for each key
st(1,mod(t,1));

# 0.6*... + 0.4*... for "echo" effect
# exp() to mitigate the sound according to the time
(0.6*sin(1*ld(0)*ld(1))+
 0.4*sin(2*ld(0)*ld(1)))*exp(-4*ld(1))

And to test it:

ffplay -f lavfi -i "aevalsrc=$(grep -v '^#' expr|tr -d '\n'|sed 's/\([,;]\)/\\\1/g')"

showwaves and showspectrum

Given the audio file april.flac:

ffplay -f lavfi 'amovie=april.flac,asplit=3[out1][a][b]; [a]showwaves=s=640x240,pad=iw:ih*2[waves]; [b]showspectrum=s=640x240[spectrum]; [waves][spectrum] overlay=0:h [out0]'