= Fancy Filtering Examples =

[[PageOutline(2-3, Contents)]]

== Video ==

=== cellauto ===
[[Image(cellauto.png)]]
{{{
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, [http://en.wikipedia.org/wiki/Rule_110 110] (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 ===
[[Image(life.png)]]
{{{
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
}}}
[[Image(life2.png)]]
{{{
ffplay -f lavfi -i life=s=640x480:mold=10:r=100:ratio=0.1:death_color=blue:life_color=#00ff00,boxblur=2:2
}}}

=== mandelbrot ===
[[Image(mandelbrot.png)]]
{{{
ffplay -f lavfi -i mandelbrot
}}}

=== mirror effect ===
[[Image(ffplay-mirror.jpg)]]
{{{
ffplay -i INPUT -vf "crop=iw/2:ih:0:0,split[tmp],pad=2*iw[left]; [tmp]hflip[right]; [left][right] overlay=W/2"
}}}

=== video channel separation effect with lut filter===
RGB version
[[Image(rgb_sep.jpg)]]
{{{
ffmpeg -f lavfi -i testsrc=d=10 -filter_complex "split=4[a][b][c][d];[a]pad=iw*4:ih[w];[b]lutrgb=g=0:b=0[x];[c]lutrgb=r=0:b=0[y];[d]lutrgb=r=0:g=0[z];[w][x]overlay=w:0[wx];[wx][y]overlay=w*2:0[wxy];[wxy][z]overlay=w*3:0" -f nut - | ffplay -
}}}
YUV version
[[Image(yuv_sep.jpg)]]
{{{
ffmpeg -f lavfi -i testsrc -filter_complex "split=4[a][b][c][d];[a]pad=iw*4:ih[w];[b]lutyuv=u=128:v=128[x];[c]lutyuv=y=0:v=128[y];[d]lutyuv=y=0:u=128[z];[w][x]overlay=w:0[wx];[wx][y]overlay=w*2:0[wxy];[wxy][z]overlay=w*3:0" -f nut - | ffplay -
}}}

=== histogram ===
[[Image(histograms.png)]]
{{{
ffplay -f lavfi -i mandelbrot -vf "split=4[a][b][c][d],[d]histogram=display_mode=overlay:level_height=244[dd],[a]histogram=mode=waveform:waveform_mode=row:display_mode=overlay[aa],[b]histogram=mode=waveform:waveform_mode=column:display_mode=overlay[bb],[c]pad=iw+256:ih+256[cc],[cc][aa]overlay=x=W-256[ccc],[ccc][bb]overlay=y=H-256[x],[x][dd]overlay=y=H-256:x=W-256"
}}}

== 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]'
}}}
[[Image(ffplay-waves-spectrum.png)]]