[FFmpeg-user] bring up center channel and damp down surround during convert to stereo?

[Tom Horsley]

I find the sound on the BBC America show "Orphan Black" to
have the soundtrack cranked up so loud by default I can barely
hear the dialogue (and having lots of funny accents in use
make it worse :-).

Is there a nice prescription somewhere for using ffmpeg
audio filters to enhance the center channel and damp
down the others in a 5.1 soundtrack before converting
to stereo while converting recordings fetched from my
TiVo to play on my tablet?