Add a logo watermark to a video
useful tips
// scenario
Overlay a logo at the top-right corner, scaled to 10% of the video width with a 2% margin from the edges.
// shell
$ ffmpeg -i input.mp4 -i logo.png -filter_complex "[0:v]split[base][ref];[1:v][ref]scale=rw/10:-1[logo];[base][logo]overlay=W-w-W*0.02:H*0.02" output.mp4