I have a very short video of some classical guitar music, in Windows .wmv. In order to listen I must have the soundcard and speaker volume controls at the max. (I have checked this on another computer to ensure it wasn't just me). Can the general level of audio in a video recording be raised, while still maintaining a normalised signal.
Yes. You can use FFmpeg, a free command-line tool, like so:
ffmpeg -i video.wmv -c:v copy -af dynaudnorm out.wmv
dynaudnorm is a dynamic audio normalizer, which will maintain the original range dynamics and avoid clipping while applying the maximum gain possible given those constraints.