[FFmpeg-user] Color Channel Expression

[Gyan]

> input > red/alpha , green/alpha , blue/alpha > output
> ffmpeg -i video.mp4 -i lowerthird.png -filter_complex
>    [1:v]geq=r=r/a:g=g/a:b=b/a[gq];[0:v][gq]overlay ...
> >> output.mp4
>

Use

ffmpeg -i video.mp4 -i lowerthird.png -filter_complex
[1:v]geq=r='p(X,Y)/alpha(X,Y)':g='p(X,Y)/alpha(X,Y)':b='p(X,Y)/alpha(X,Y)':a='p(X,Y)'[gq];[0:v][gq]overlay
.. output.mp4