Increase mean volume of a video/audio file
Yes. What you will need to do is "dynamic range compression", followed by an overall boost of volume level do bring the peaks back up to 0dBFS. Any of a large number of sound editing programs can do this. Audacity (free) simply calls the tool "Compressor" and it does have the gain compensation feature. Here's their help page: http://manual.audacityteam.org/index.php?title=Compressor