Drawing on video with ffmpeg

I'm trying to get some blocks of colour overlayed/burnt into video with ffmpeg. A bit like a watermark, I suppose but not a logo, just a block of color.

I've looked at using the drawbox fu开发者_JS百科nction, which appears to me as if it's only applicable to creating images, not video. Alternatively, I could layer an image on the video.

Has anyone got experience with this sorta thing?

Try:

ffmpeg -i in.avi -vf "color=red@0.5:50x50 [c]; [in][c] overlay=10:10" out.avi

That should overlay a semitransparent red square on the video. See the documentation for color and overlay for more information.