[FFmpeg-user] Blending two inputs with custom expression

[SviMik]

2017-05-10 1:02 GMT+03:00 Paul B Mahol <onemda at gmail.com>:
> Those equatitions are very strange.

That's off topic, but I'll answer. I have tested it with my own test
program using some sample screenshots, and it does what expected. Now I
want to apply it to a live video. Of course there may be a little sanity
check needed (I'm not sure yet how the filter deals with clippings), but in
my use case there was no clipping at all (unless the filter is applied to a
video it was not meant for). Of course, there is no completely opaque
pixels in the png image, all they do have some transparency. And I suppose
any equation will look strange without having a clue what the goal is, and
how I even came to this solution. (Spoiler: it's a reverse equation of what
some another filter does. If you like the quest - you may try to guess what
it is).