[FFmpeg-user] how to use alpha channel to make transparent effect

[compname at verizon.net]

At 6/26/2015 02:15 AM, you wrote:
>Paul B Mahol <onemda <at> gmail.com> writes:
>
> > IMHO OP actually wants overlay filter.
>
>No, he wants to make the opaque parts of the
>logo slightly transparent.
>
>Carl Eugen

I just went through something like this, except I had another video 
that I wanted a transparent overlay out of.

Best to use a logo image that already has a transparent 
background.  Then you can use the overlay filter & it will work the 
way you want.  You might need to use a different tool to make the 
transparent BG in the logo file, then save it in a format (like PNG) 
that supports transparency.