How to enhance old audio captures?
 

I have some old captures where audio is really bad. For moments you can ear it with bass predominance and for moments is the opposite.
The audio is mono.
Could it be enhanced in any way?

Demux -> (probably convert to WAV) -> GoldWave/CoolEdit -> (probably convert back) -> remux ?

Any of both programs have free editions?

I think Goldwave is. Isn't it ?
Else give a look to audacity (open source)
http://audacity.sourceforge.net/about/features

@Dialhot

Hi Phil, that freeware tool audacity looks really interesting. I think I may give it a try myself. :)

Yeah, it's a nice programm and with the support of VST and Nyquist modules you can always find a feature that fits your needs (a little like vdud and its filters). Nevetheless, I never used it, even if I know it since a long time :)

Thanks.