[FFmpeg-user] How to calculate the real (!) average variable video bitrate of a whole video with ffmpeg?

[Ben]

Assume I have a AVI, MP4 or MKV video which is encoded with a variable video bitrate.

Now I want to findout the average video bitrate across the WHOLE (!) video.

Now when I drag the video onto such tools like MediaInfo they show only the average video bitrate
of the first 5 or 20 seconds or so.

In rare cases they do not even show a value at all.

I could imagine that I can pass the video to ffmpeg and let it calculate the real variable video bitrate for the WHOLE video.

How does that work?

Ben