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I overlay using the following command:

ffmpeg -i video.mp4 -i logo.png -filter_complex "[1]geq=r='r(X,Y)':a=0.1[a];[0][a] overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0" out.mp4

I tried adjusting the opacity using 

fmpeg -i video.mp4 -i logo.png -filter_complex "[1]format=rgba,geq=r='r(X,Y)':a='1*alpha(X,Y)'[a];[0][a] overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0" out.mp4

but it is still transparent at the white color part.

It seems like the white color part has a transparency of 0, causing the second command to not work.

Is there any reason why this is happening? The logo I tried is

enter image description here

How can I preserve the white color?

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1 Answer 1

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There is no white color. That's the background color of the page showing through. Your input PNG is palettized 8-bit image where black color indicates transparency.

Apply the following filter to the image to convert black pixels to white and set a uniform transparency.

geq=r='if(p(X,Y),p(X,Y),255)':g='if(p(X,Y),p(X,Y),255)':b='if(p(X,Y),p(X,Y),255)':a=0.1
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  • I dont quite understand what do you mean by black color. I dont see any black color. Also, can you kindly explain what is p(X,Y)? The documentation says pixel at the current plane which is kind of vague.
    – user10024395
    Commented Apr 8, 2018 at 14:45
  • The actual color stored in the PNG in the area of the 'f' is black, which the viewer interprets as transparency. My geq expr checks if a pixel is non-black. If so, it keeps it, else changes it to white.
    – Gyan
    Commented Apr 8, 2018 at 14:49

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