[FFmpeg-user] overlay and drawtext

[Carl Eugen Hoyos]

jacky <renaux.jacky <at> orange.fr> writes:

> how could I made with ffmpeg a png file with transparency 
> and/or alpha like pink <at> 0.5 (example)
> I have tried
> ffmpeg -i uad.jpg  -vcodec png -pix_fmt rgb32 -y uad.png

jpg cannot contain transparency (at least typical jpgs), 
so above command line cannot "invent" an alpha compononent 
imo (I would consider it a bug).
There is a filter called "alphamerge" that probably does 
what you want.

Carl Eugen