[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

Regards,
Frank