[Cin] ChomaKey's old bug

[Andrea paz]

> Can you try attached patch ?

It seems to me that the patch works. I used Camille's original video
where you can see the title fade from black to transparent and finally
to white as it should be.
I superimposed my own title on top of it ( on top) where instead the
fade always remains white.
The demonstration video is here:
https://streamable.com/cqg3u2

I recommend advancing frame by frame.

Thank you, Andrew