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

[Frank Tetzel]

> >> I use the below command to place one image on one video:ffmpeg
> >> -i ./file1.mp4 -i ./file2.jpg -filter_complex overlay ./file3.mp4
> >>
> >> But there is no transparent effect in resulting file, i.e.
> >> file3.mp4. What is the command to use alpha channel to make
> >> transparent effect?
> >
> > Have a look at the blend filter and its opacity and expression
> > options: http://ffmpeg.org/ffmpeg-filters.html#blend_002c-tblend
> 
> IMHO OP actually wants overlay filter.

When he uses an image format with alpha support like png instead of
jpeg, then yes. Just look at the second example here:
http://ffmpeg.org/ffmpeg-filters.html#Examples-55