Use FFMPEG To Boost A Videos Audio

I find some video's just don't have a big audio footprint and that doesnt do well on my tablet. So I boost the origional video audio to a level that I can hear using my tablet using FFMPEG

ffmpeg -i origional.mp4 -vcodec copy -af "volume=12dB" boosted-audio.mp4

In this example I take origional.mp4 and boost the audio by 12db

The option -vcodec copy just tells ffmpeg to copy the video potion of the file
and -af "volume=12dB" is as you gussed the magic option to boost the audio by 12db